2024 microbiology columns - Healthcare Hygiene magazine

Exosomes: A Novel Diagnostics Platform for Infectious Disease

By Adeyemi A. Olanrewaju

This article originally appeared in the December 2024 issue of Healthcare Hygiene magazine.

Finding novel platforms to diagnose infectious disease has been in the forefront of research over the past decades. It has been particularly challenging because groups of organisms can share the same characteristics. This has always led to some cross-reactivities and has led to issues in the diagnosis of various infectious diseases. Exosomes are very small biological molecules, that are part of a larger family of extracellular vesicles (EVs). EVs are vesicles surrounded by membranes. They are cell-derived, carrying several types of molecular cargos such as DNA, RNA, lipids, proteins, and metabolites. EVs were first known to be derived from platelet as a procoagulant particles in normal plasma, which was reported by Chargaff and West in 1967. This was later referred to as platelet dust in 1967 by Wolf. In the early 1980s, extensive ultrastructural studies showed that EVs are released by the fusion of multi vesicular bodies (MVBs) to the cell membrane. These EVs are known to mediate intracellular communication. Following up on these studies, it was discovered that EVs can be isolated from all cell types and biological fluids such as plasma, breast milk, seminal fluid, amniotic fluid, saliva, urine, aspirations and nasal fluids. EVs have different subtypes which have varying sizes that overlap, and these create difficulty in separating them based on sizes. It is important to have a robust method to separate these vehicles which will allow scientists to narrow down the exact type of vesicle responsible for a particular biological function. Exosomes will aid in the early detection of infections which will prevent the spread of disease to different parts of the body. It will also increase the specificity in the diagnosis of infectious disease and allow for more targeted use of antimicrobial therapy rather than using broad-spectrum antibiotics.

Exosome composition
The specific content of exosomes is influenced by environmental factors and the types of cells that produce them. Also, the physiological and pathological states of the cell affect their content. Based on this, exosome-associated proteins or nucleic acids can serve as indicators of disease. The work from several laboratories has demonstrated that specific components of pathogens get packaged within the host exosomes during infection. The mechanisms by which pathogen components are packaged into exosomes have been investigated although there is still much to learn. Generally, regarding infectious disease, the content of exosome will include some proteins or nucleic acid from the pathogen. For instance, cells from patients that are infected with Rift Valley Fever Virus (RVFV) releases exosomes that contain the nucleic acids and proteins from the virus. This platform represents a targeted approach to determine infection with an organism, with reduced potential for cross-reactivity. Because of the specificity in the potential use of exosome as a diagnostics marker, there will be an improved approach in the use of antibiotics, which will in turn reduce antimicrobial resistance.

Exosome purification
Size of exosomes ranges from 30-150 nm in diameter. They originate from the invagination of the late endosome, which later forms an enclosed substance called the intraluminal vesicles (ILVs) containing cytoplasmic constituents. Later, these ILVs give rise to multivesicular bodies (MVBs), which are then transported via the microtubule and cytoskeletal networks to the plasma membrane of the cells. From here, they are released to the extracellular space. Several methods are currently being used to purify exosomes from biological fluids. There are several methods utilized to purify exosomes and other extracellular vesicles. The most used method is the differential ultracentrifugation. This method uses ultracentrifuge at a very high speed (120,000-160,000×g) to separate exosomes from other extracellular vesicles. Other methods include size exclusion chromatography, magnet-based isolation, affinity chromatography, charged-based isolation, and microfluidic based isolation. Ultracentrifugation is laborious and it requires expensive equipment. Kit isolation of exosomes can therefore be used, which will be less expensive and requires less time.

Exosomes for diagnosis of infectious disease
Exosomes are found in all biological fluids of patients with different disease conditions such as infectious disease, cancer and inflammatory disease. The composition of these exosomes largely depends on the disease state. Therefore, we can say that exosome composition of healthy individuals is different from that of diseased patients. Because of the specific content of exosomes, they can be used as biomarkers.

Examples for the use of exosomes as a biomarker for diagnosis has been suggested for the following infectious diseases:
1. Mycobacterium tuberculosis: More than 20 mycobacterial proteins that are involved in pathogenesis (survival) have been identified in exosomes purified from the serum of M. tuberculosis infected patients. Also, it has been observed that mRNA content of exosomes between patients with active tuberculosis, patients with latent tuberculosis and healthy subjects differs.
2. HIV : Several HIV proteins such as gp120, Nef, p24 and Pr55 have been observed to be present in exosomes that are purified from HIV virus infected cells. These proteins will be absent in healthy subjects, and this can be used as a good diagnostic tool for HIV.
3. Rift Valley Fever Virus (RVFV): In vitro studies have demonstrated the presence of RVFV proteins such as the L, NSs, N and glycoprotein Gn and Gc in exosomes purified from RVFV infected cells and these proteins have been shown to be absent in healthy individuals.

Isolation of exosome is non-invasive and because of the specificity of its content, it serves as a good platform for diagnosis of infectious disease. The use of this in diagnosis is still in its infancy stage. Several basic research are ongoing, and it is projected to be fully in use within the next decade.

Dr. Adeyemi Olanrewaju obtained his Bachelor of Science (Medical Laboratory Science) from Ladoke Akintola University of Technology, Nigeria, and Masters (Microbiology) from Western Illinois University. Olanrewaju received his PhD in infectious disease and microbiology from George Mason University, Virginia. He is currently an assistant professor of medical laboratory science in the college of health professionals at Texas State University. The main focus of his research is understanding the pathogenesis of pathogenic viruses and utilizing chemical compounds as a novel therapeutic countermeasure against these viruses.

Pertussis: Pathogenesis and Prevention

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the November 2024 issue of Healthcare Hygiene magazine.

Pertussis, also known as whooping cough, has made national news due to a surge in cases across the country. Numerous states, including Pennsylvania, New Mexico, Colorado, and Arizona, have reported a stark increase in cases over the past few weeks. As of Oct. 26, 2024, the Centers for Disease Control and Prevention (CDC) has reported 20,791 cases of pertussis (year to date), which is five times as many cases compared to the same time in 2023. Numerous factors may be contributing to this rise, such as increased circulation of the bacteria, genetic changes to the bacteria, waning immunity from previous vaccination, and decreased vaccination rates.

Once known as the “the cough of 100 days,” pertussis dates back to 1578 and was a major cause of infant morbidity and mortality. The bacteria Bordetella pertussis was discovered to be the cause of disease in 1906 and a vaccine was developed a few decades later in the 1940s. Before vaccination was introduced in the 1940s, more than 200,000 cases of pertussis occurred annually compared to approximately 10,000 annual cases pre-pandemic.

Pertussis is an exclusively human disease with no animal reservoirs. Transmission occurs via contact with respiratory, oral, or nasal secretions from an infected person or contaminated objects. The incubation period is between seven to 10 days on average with a range of four to 21 days. After colonizing the mucous membranes in the respiratory tract, the bacteria attach to cilia (hair-like extensions on respiratory epithelial cells that are essential to clear mucous and other pulmonary secretions) and release numerous toxins. Some of these toxins damage or paralyze the cilia, preventing mucous to be cleared and leading to swelling of the airway and continuous coughing in effort to clear the mucous.

Clinical course is divided into three stages: (1) catarrhal, (2) paroxysmal, and (3) convalescent. The catarrhal stage is characterized by common cold symptoms, such as runny nose, sneezing, and the occasional cough. This is the most contagious this stage since symptoms are similar to other upper respiratory infections and may be less severe in adults than in children and infants which could lead to delayed recognition. The cough progresses to the paroxysmal stage after one to two weeks, becoming severe with uncontrolled and rapid coughing bursts – called paroxysms – due to the difficulty in removing mucous from the respiratory tract. The characteristic high-pitched “whoop” noise occurs at the end of the paroxysm when gasping for air. Vomiting and exhaustion typically follow after the paroxysm. The paroxysmal stage usually lasts one to six weeks but may persist for up to 10 weeks. People are infectious from catarrhal stage through the third week of paroxysms. Recovery is gradual during the convalescent stage which lasts for one to three weeks. The cough becomes less paroxysmal and disappears in two to three weeks. Pneumonia is the most common and frequent complication, but other complications include sinusitis, otitis media, viral and bacterial superinfections, apnea, and hypoxia, and neurologic complications. In adolescents and adults, coughing can become so severe that rib fractures, hernias, syncope, and urinary incontinence may occur.

In healthcare settings, unprotected close contact with an infectious person or contact with their secretions may be considered an exposure to pertussis. Patients should ideally be placed in a single room and droplet and standard precautions should be followed until five days after effective antibiotic therapy. Hand hygiene and thorough environmental cleaning and disinfection are essential. Because vaccinated healthcare personnel may still be at risk for pertussis infection, post-exposure prophylaxis should be considered. With the rise in cases, it is imperative to remember that pertussis is a vaccine-preventable disease. Per the CDC, children should receive five doses of the DTaP given at 2, 4, and 6 months, with booster doses given at 15 to 18 months and between 4 to 6 years old. Adolescents should receive a Tdap booster at 11 to 12 years old to maintain protection. Pregnant women should get a dose of Tdap during every pregnancy, preferably during the early part of the third trimester.

Priya Dhagat, MS, MLS(ASCP) CM, CIC, is an infection preventionist and the associate director of the system-wide Special Pathogens Program within the Department of Emergency Management at New York City Health + Hospitals, overseeing special pathogen preparedness and response efforts across New York City Health + Hospitals frontline healthcare facilities. Additionally, she supports and offers subject matter expertise for infection prevention topics for the National Emerging Special Pathogens Training and Education Center (NETEC).

Oropouche Virus Activity

By Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM, MBCM, FACSc

This article originally appeared in the October 2024 issue of Healthcare Hygiene magazine.

My family, friends, colleagues and students often comment to me and say, “Doc R, it seems like every time we hear from you, some new nasty microbe is turning up in our concern.” Indeed, in the world of emerging and reemerging pathogens, there is never a dull moment. The most recent microbe to push its way into our view is known as Oropouche virus. This virus is spread to people primarily by the bite of infected biting midges. Some mosquitoes can also spread the virus. Most infected people will develop symptoms that can often reoccur.

To date, there are no vaccines to prevent or medicines to treat Oropouche. The best way to protect yourself from Oropouche is to prevent bites from biting midges and mosquitoes. As of Sept. 3, 2024, there were 32 reported cases of Oropouche virus disease in the United States, all from travelers returning from Cuba. Twenty of the cases were in Florida and one was in New York. There is no evidence that Oropouche virus has been spread in the United States. Oropouche virus has been found in South America, Central America, and the Caribbean.

Prior to 2000, Oropouche virus outbreaks were reported in Brazil, Panama, and Peru. Evidence of animals being infected was also noted in Colombia and Trinidad during this time. In the last 25 years, cases of Oropouche have been identified in many countries, including Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Panama, and Peru. In addition, one child was found to be infected in Haiti in 2014. In June 2024, Cuba reported its first confirmed Oropouche case.

CDC Health Alert Network Issues Health Advisory

The Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory [Aug. 16, 2024, CDCHAN-00515] to notify clinicians and public health authorities of an increase in Oropouche virus disease in the Americas region, originating from endemic areas in the Amazon basin and new areas in South America and the Caribbean.

Roughly, more than 8,000 cases of Oropouche virus disease have been reported between Jan. 1, 2024, and Aug. 1, 2024, including two deaths and five cases vertical transmission associated with fetal death or congenital abnormalities. The following countries have reported cases: Brazil, Bolivia, Peru, Colombia, and Cuba. Cases reported in the United States and Europe are associated with travelers returning from Brazil and Cuba. It should be noted that specific diagnostic laboratory testing and surveillance is necessary for accurate reporting and should be expected to increase in the Americas.

The CDC Health Advisory advises on evaluating and testing travelers who have been in impacted areas with signs and symptoms consistent with Oropouche virus infection. It also raises awareness of the possible risk of vertical transmission (e.g., from gestational parent to fetus during pregnancy) and associated adverse effects on pregnancy and highlights prevention measures to mitigate additional spread of the virus and potential importation into unaffected areas, including the United States.

Background and Current Epidemiology

The Oropouche virus belongs to the Simbu serogroup of the genus Orthobunyavirus in the Peribunyaviridae family. It was first detected in 1955 in Trinidad and Tobago and is endemic in the Amazon basin. Bolivia, Brazil, Colombia, Ecuador, French Guiana, Panama, and Peru have experienced previous outbreaks. The current 2024 outbreak is occurring in endemic areas and new areas outside the Amazon basin; countries reporting locally acquired (autochthonous) cases include Brazil, Bolivia, Peru, Colombia, and Cuba. Only travel-associated cases have been identified in the United States with no evidence of local transmission.

Oropouche virus transmission is primarily via sylvatic (enzootic) route. The virus is transmitted in forested areas between mosquitoes and non-human vertebrate hosts (e.g., non-human primates, birds, sloths, and rodents). Humans can become infected as an accidental host while visiting these areas and are probably the reason for virus emergence into urban environments. Humans contribute to the transmission cycle in urban environments because of sufficient viremia to serve as amplifying hosts. Biting midges (Culicoides paraensis) and possibly certain mosquitoes (Culex quinquefasciatus) are responsible for transmitting the virus from an infected person to an uninfected person in urban areas.

Oropouche virus becomes symptomatic in roughly 60 percent of people with an incubation timeline of three to 10 days. Clinical presentation is like other vector borne diseases caused by dengue, Zika, and chikungunya viruses. Acute onset of fever, chills, headache, myalgia, and arthralgia are common. Other symptoms can include retroorbital (eye) pain, photophobia (light sensitivity), nausea, vomiting, diarrhea, fatigue, maculopapular rash, conjunctival injection, and abdominal pain.

Medical laboratory findings can include lymphopenia and leukopenia, elevated C-reactive protein (CRP), and slightly elevated liver enzymes. Most symptoms go away in a few days, about 70 percent of individuals experience recurrent symptoms days to weeks after resolution of their initial illness. While the illness is usually mild, some (5 percent) of patients can develop hemorrhagic manifestations (e.g., epistaxis, gingival bleeding, melena, menorrhagia, petechiae) or neuroinvasive disease (e.g., meningitis, meningoencephalitis). Neuroinvasive disease symptoms may include intense occipital pain, dizziness, confusion, lethargy, photophobia, nausea, vomiting, nuchal rigidity, and nystagmus. Clinical laboratory findings for patients with neuroinvasive disease include pleocytosis and elevated protein in cerebrospinal fluid (CSF).

Laboratory diagnosis is generally accomplished by testing serum. Cerebrospinal fluid can also be tested in patients with signs and symptoms of neuroinvasive disease. Diagnostic testing is available at some public health laboratories (e.g., Wadsworth Center, NYS Department of Health) and at CDC. CDC and other public health laboratories are currently working to validate additional diagnostic assays. Contact your state, tribal, local, or territorial health department for more information and to facilitate testing.

Information and Recommendations

The CDC Health Advisory asks that public health departments, healthcare providers, and the public help raise awareness about Oropouche virus, especially if traveling. All travelers can protect themselves from Oropouche, dengue, Zika, and other viruses transmitted by insects by preventing insect bites, including using an Environmental Protection Agency (EPA)-registered insect repellent; wearing long-sleeved shirts and pants; and staying in places with air conditioning or that use window and door screens. No specific antiviral treatments or vaccines are available for Oropouche virus disease.

For complete information on this infection, see the CDC Health Advisory Report issued March 28, 2024.

Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM,MBCM, FACSc, is the Regents’ Professor, Texas State University System; University Distinguished Chair & Professor, Clinical Laboratory Science (CLS); TEDx Speaker & Global Fellow – Global Citizenship Alliance; Texas State Honorary Professor of International Studies; associate director, Translational Health Research Initiative; Past President, Texas Association for CLS.

A Growing List of Listeriosis: An Update on the Boar’s Head Deli Meat Outbreak

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the September 2024 issue of Healthcare Hygiene magazine.

Listeria infection is the third leading cause of foodborne illness in the United States. According to the CDC, about 1,600 people are infected with Listeria and 260 people die from the infection each year in the United States. There are numerous species of Listeria which are commonly found in the environment, but Listeria monocytogenes has historically been pathogenic and has caused numerous outbreaks over the past decade linked various products, such as Cotija cheese (2024), soybean sprouts (2023), and cantaloupe (2011).

Most recently, the national recall of several Boar’s Head deli products has made national headlines due to a deadly multi-state outbreak linked ready-to-eat liverwurst and deli meat products. On July 26, 2024, the Maryland Department of Health issued a health advisory for Boar’s Head products due to possible Listeria contamination after six cases were confirmed in Maryland on July 19 and a liverwurst sample collected by the Maryland Department of Health tested positive for L. monocytogenes. The product recall expanded on July 30, recalling 7 million additional pounds of ready-to-eat meat and poultry products including 71 products produced between May 10, 2024, and July 29, 2024 that were distributed nationwide and to the Cayman Islands, Dominican Republic, Mexico, and Panama. This is the second largest multistate outbreak of Listeria in over a decade with 57 hospitalized cases and nine deaths across 18 states as of August 27 ,2024. Since some people are not tested and may recover without medical treatment, cases linked to this outbreak are likely higher.

The 2011 Listeria outbreak involving cantaloupe was the largest recorded multistate and was linked to a single Colorado farm leading to 147 cases in 28 states. The majority of patients were 60 years of age or older and were hospitalized and seven cases were among pregnant women and newborns.

But what leads to listeria outbreaks and why can it be difficult to control? Let’s take a deeper look.

Listeria is an intracellular bacterium with unique virulence factors that allow it to survive and replicate in harsh conditions. It lives naturally in soil, water, and decaying vegetation. Farm animals can be asymptomatic carriers of Listeria which can contaminate the environment, various surfaces, farming equipment. Cross-contamination can occur during any point along the food production chain and into food-processing plants—during initial production, processing, distribution, or preparation—where it can persist for years by forming biofilms and adapting to and surviving in cold temperatures.

Once ingested, Listeria is able to resist stressful conditions in the gastrointestinal tract, such as the acidic pH in the stomach and high osmolality in the gut. It invades the gastrointestinal tract and disseminates through the bloodstream to target certain organs, such as the liver and spleen, and can even cross the blood-brain-barrier and the placental barrier. Fever, flu-like symptoms, and intestinal symptoms may begin within two weeks after consuming contaminated products and may progress to invasive disease. Although listeriosis is usually a self-limiting gastrointestinal infection in healthy people, high risk populations for invasive infection include people who are pregnant, infants, immunocompromised individuals, and the elderly. Infection in people who are pregnant can lead to miscarriage, death of the unborn baby, a low-birth weight infant, health problems for the newborn, or even infant death.

Healthcare providers may refer to the CDC’s patient management framework here, which outlines considerations for testing and treatment. Standard precautions are recommended for patients who are hospitalized, as person-to-person transmission is rare. Click here to stay updated with this current outbreak and view case numbers and US states affected.

Invasive Serogroup Y Meningococcal Diseases

By Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM, MBCM, FACSc

This article originally appeared in the August 2024 issue of Healthcare Hygiene magazine.

The bacterium Neisseria meningitidis is a rare but severe illness which causes meningococcal disease with a case-fatality rate of 10 percent to 15 percent even with appropriate antibiotic treatment. It most often presents as meningitis, often resulting in symptoms such as fever, headache, stiff neck, nausea, vomiting, photophobia, or altered mental status; or as meningococcal bloodstream infection, with symptoms that may include fever and chills, fatigue, vomiting, cold hands and feet, severe aches and pains, rapid breathing, diarrhea, or, in later stages, a dark purple rash. While initial symptoms of meningococcal disease can at first be non-specific, they worsen rapidly, and the disease can become life-threatening within hours. Meningitis infections may also be caused by other microorganisms such as viruses, parasites, and fungi.

CDC Health Alert Network Issues Health Advisory

The Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory [CDCHAN-00505] to alert healthcare providers to an increase in invasive meningococcal disease, mainly attributable to Neisseria meningitidis serogroup Y. From 2014-22, cases reported in the United States had been typical of normal epidemiology. However, in 2023, the U.S experienced 422 cases which was the highest annual number since 2014. Since March 25, 2024, 143 cases have been reported for the year which is a 76.5% increase [81 to 143] in cases as compared to this date in 2023. Interestingly, sequence type [ST] 1466 has been responsible for the majority [101 of 148, of 68%] serogroup Y [specific meningococcal strain] cases across the U.S. in 2023.

Background and Current Epidemiology

Several different bacteria can cause meningitis. Streptococcus pneumoniae, Haemophilus influenzae, and N. meningitidis are the most frequent ones. N. meningitidis, causing meningococcal meningitis, is the one with the potential to produce large epidemics. Meningococcal disease, caused by the bacterium Neisseria meningitidis, is a rare but severe illness with a case-fatality rate of 10 percent to 15 percent even with appropriate antibiotic treatment. Immediate diagnosis and antibiotic treatment for meningococcal disease is critical. Survivors may experience long-term effects such as deafness or amputations of the extremities.

Of the six N. meningitidis serogroups — A, B, C, W, X, and Y — responsible for most meningococcal disease worldwide, the four serogroups B, C, W, and Y circulate in the U.S. Vaccines against serogroups A, C, W, Y (MenACWY) and serogroup B (MenB) are available in the U.S. MenACWY vaccines are routinely recommended for adolescents and for people with other risk factors or underlying medical conditions, including HIV.

Analysis of current reported cases in the U.S. caused by ST 1466 are disproportionately occurring in people ages 30 to 60 years (65 percent), Black or African American people (63 percent), and people with HIV (15 percent). Additionally, many invasive meningococcal disease cases caused by ST-1466 in 2023 had a clinical presentation other than meningitis: 64 percent presented with bacteremia, and at least 4 percent presented with septic arthritis. Of 94 patients with known outcomes, 17 (18 percent) died; this case-fatality rate is higher than the historical case-fatality rate of 11 percent reported for serogroup Y cases in 2017 through 2021.

Information and Recommendations

The CDC Health Advisory asks that public health departments, healthcare providers, and the public help raise awareness about the current increase in invasive serogroup Y meningococcal diseases. Healthcare providers should 1) have a heightened suspicion for meningococcal disease, particularly among populations disproportionately affected by the current increase, 2) be aware that patients may present without symptoms typical of meningitis, and 3) ensure that all people recommended for meningococcal vaccination, including people with HIV, are up to date for meningococcal vaccines.

Specific recommendations include:

Continue submitting all meningococcal isolates to CDC for whole-genome sequencing and antimicrobial susceptibility testing.
Contact CDC at meningnet@cdc.gov with any questions or concerns about increasing meningococcal disease cases in their jurisdiction or outbreak investigation or control measures.
Maintain a heightened suspicion for invasive meningococcal disease and start immediate antibiotic treatment for persons with suspected meningococcal disease. Blood and cerebrospinal fluid (CSF) cultures are indicated for patients with suspected meningococcal disease.
Be aware that patients with invasive meningococcal disease may present with bloodstream infection or septic arthritis and without symptoms typical of meningitis (e.g., headache, stiff neck).
Ensure that all people recommended for meningococcal vaccination are up to date for meningococcal vaccines.
All 11-12-year-olds should receive a MenACWY vaccine. Since protection wanes, CDC recommends a booster dose at age 16 years.
For people at increased risk due to medical conditions (e.g., with HIV), recommended vaccination includes a two-dose primary MenACWY series with booster doses every three to five years, depending on age.
Seek medical attention immediately if you or your child develops symptoms of meningococcal disease.
Talk to your healthcare provider about meningococcal vaccines that may be recommended for you and your household or family members, including any recommended booster doses.

For complete information on this infection, see the CDC Health Advisory Report issued March 28, 2024.

Group A Strep: A Menacing Bacteria Responsible for a Multitude of Infections

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the July 2024 issue of Healthcare Hygiene magazine.

Streptococcus pyogenes – Greek for “a chain; berries” and “pus forming” – is a contagious bacteria that can cause a numerous non-invasive and invasive infections, such as pharyngitis (i.e., strep throat), scarlet fever, impetigo, cellulitis, streptococcal toxic shock syndrome (STSS), rheumatic fever, pneumonia with bacteremia, meningitis, and necrotizing fasciitis. It can be found on the skin and in the throat and is ubiquitous in the environment. People who are colonized may not show symptoms but the bacteria can easily spread from person to person through respiratory droplets via coughing or sneezing.

Also called Group A Streptococcus (GAS) per the Lancefield classification of carbohydrate and antigen composition on the bacterial cell wall, GAS can infect the skin and upper respiratory tract, secreting numerous enzymes and toxins that trigger inflammation, prohibit recruitment of immune cells to the site of infection, and prevent immune cell function. GAS is a deceptively well-adapted human pathogen that uses a unique immune evasion strategy – called molecular mimicry – in which bacterial proteins lyse human red blood cells and then coat itself with red blood cell fragments in order to imitate host cells and promote survival.
In the United States, the CDC estimates that each year there are approximately 5.2 million outpatient visits for non-invasive GAS infections, between 20,000 to 27,000 cases of invasive GAS infections (iGAS), and between 1,800 and 2,400 deaths. Around 1 in 3 iGAS infections are now resistant to erythromycin and clindamycin.

Over the past couple of years, many countries have noted a rise in severe iGAS infections. In 2022, several European countries (France, Ireland, the Netherlands, Sweden, and the U.K.) observed an increase of iGAS disease and scarlet fever cases affecting children under 10 years of age. Australia experienced an increase of iGAS in 2022 compared to 2020 and 2021. In the United States, GAS infections reached a 20-year high in 2023 per the CDC. As of June 15, 2024, there have already been 403 reported cases of STSS, compared to last year’s total of 412 cases. Japan has recently reported a surge is STSS cases – over 1,000 cases just in the first half of 2024. STSS occur when GAS produces exotoxins that spread into tissues and the bloodstream, inducing a strong immune response, called a cytokine cascade, which leads to the body going into shock. Initial symptoms include fever, chills, muscle aches, nausea, and vomiting. Infection rapidly progresses within 24-48 hours causing hypotension, tachycardia, tachypnea, and organ failure. Patients require prompt medical care and hospitalization for immediate antibiotic treatment and sepsis management. The mortality rate for STSS can exceed 30% regardless of treatment.

Differential diagnosis of STSS may be difficult for healthcare providers which can include other viral or bacterial infections. The case definition of STSS includes hypotension, organ involvement, and bacterial isolation of group A strep. CDC recommendations for healthcare providers include following protocols for sepsis diagnosis and management, beginning antibiotic therapy as soon as possible, obtaining culture for suspected iGAS infections, monitoring patient progress, and reassessing antibiotic therapy as needed. In healthcare settings, healthcare professionals should adhere to infection prevention and control measures, including hand hygiene, to prevent outbreaks and secondary transmission to other patients and healthcare personnel. This includes following contact, droplet, and standard precautions when caring for patients with skin infections and draining wounds that cannot be covered with a dressing, and droplet and standard precautions when caring for patients with pharyngitis and invasive disease for 24 hours after effective antibiotic therapy.

References:
To view national trends in Group A Strep (case rates, death rate, syndromes, antibiotic resistance, etc):
• ABCs Bact Facts Interactive Data Dashboard | ABCs | CDC
To learn more about Group A Strep (for the public and for healthcare personnel)
• Healthcare Provider Home | Group A Strep | CDC
• Group A Strep Infection | Group A Strep | CDC

Fungal Meningitis

By Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM, MBCM, FACSc

This article originally appeared in the June 2024 issue of Healthcare Hygiene magazine.

Meningitis is a dangerous, and sometimes deadly, inflammation of the tissues surrounding the brain and spinal cord. This infection can be caused by species of bacteria, viruses, fungi, and parasites. Fungal meningitis can develop systemically from a fungal infection somewhere else in the body to the central nervous system. While rare, medical, and surgical procedures can lead to fungal meningitis if medical devices or medications are contaminated with fungi, or if proper infection prevention control practices are not taken. This type of healthcare-associated infection (HAI) can cause severe illness or mortality. An example of this type of healthcare-associated fungal meningitis outbreak has occurred from spinal anesthesia.

Fungal Meningitis Outbreak Associated with Procedures Performed under Epidural Anesthesia in Matamoros, Mexico

In a report from the Centers for Disease Control and Prevention (CDC), the Mexican Ministry of Health, and U.S. health and local health departments are responding to a multinational outbreak of fungal meningitis among people who had procedures under epidural anesthesia in Matamoros, Tamaulipas, Mexico. Officials identified two clinics associated with the outbreak: River Side Surgical Center and Clinica K-3. These clinics were closed on May 13, 2023.

Epidemiology Situation

On May 11, 2023, the CDC notified the Mexico General Directorate of Epidemiology [DGE] through the International Health Regulations National Focal Point (IHR NFP), the identification of five female cases with central nervous system infection (CNSI) in the US, with a history of undergoing surgical procedures performed under spinal anesthesia in two private clinics in a city in Mexico, bordering the U.S.

As of May 26, 2023, the health authorities from Mexico and the U.S. reported a total of 20 cases presenting with signs and symptoms compatible with CNSI, including two deaths reported by the CDC. Patients presented to the hospital with symptoms including headache, fever, nausea, vomiting, sensitivity to light, and fainting after receiving surgical procedures in two private clinics located in the city of Matamoros, Tamaulipas state in Mexico, on the border with the US between January and April 2023.

The Mexico Epidemiological Diagnosis and Reference Institute (InDRE per its acronym in Spanish) has received five samples of cerebrospinal fluid (CSF) that tested positive for a fungus, Fusarium solani by real-time polymerase chain reaction (RT-PCR). Additionally, according to the health authorities from the US, the laboratory results from nine suspected cases were consistent with meningitis, of which two CSF and two blood samples showed elevated levels of (1,3)-beta-D-glucan, a biomarker for fungal infection. Two pan-fungal PCR tests were negative.

According to the investigation performed, a total of 547 people had these procedures between January and April 2023 in the concerned two private clinics, of whom 304 (56 percent) reside in Mexico, 237 (43 percent) in the United States, and one in Canada.

Anyone who had procedures under epidural anesthesia in these clinics from January 1 to May 13, 2023, is at risk for fungal meningitis. Anyone who is at risk for fungal meningitis should go to the nearest emergency room right away to be tested. Testing is done by a lumbar puncture (LP), also called a spinal tap. People who are infected should begin antifungal treatment as soon as possible.

Information for those at Risk

If you had epidural anesthesia in Matamoros, Mexico, at River Side Surgical Center or Clinica K-3 from January 1 to May 13, 2023:

Early testing and treatment, especially before symptoms start or worsen, can save lives. The typical signs and symptoms of fungal meningitis include fever, headache, stiff neck, nausea, vomiting, sensitivity to light, and confusion.

It can take weeks to months for symptoms to develop, and they may be very mild or absent at first. However, once symptoms start, they can quickly become severe and life-threatening. If you know or believe you are at risk, follow the instructions below:

Go to the nearest emergency room as soon as possible to be evaluated for fungal meningitis, even if you do not currently have symptoms.
Some people without symptoms or with mild symptoms have tested positive for infection and started treatment. Receiving treatment early can prevent severe illness.
Fungal meningitis can start off mild and very quickly become a life-threatening illness.
Consider printing and sharing this web page to help make sure staff and healthcare providers are aware of the situation and recommended tests.
If you cannot go to an emergency room (for example, because it is too far away), consider calling your local health center or urgent care facility to see if they can do spinal taps. In most situations, the emergency room will be the best or only option for testing.
When you arrive, inform the emergency room staff that you need to be evaluated for possible fungal meningitis. Tell them that you recently had epidural anesthesia at one of the clinics in Mexico involved in this outbreak.

Meningococcal Disease: A Nationwide Increase Requiring Prompt Attention and Treatment

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the May 2024 issue of Healthcare Hygiene magazine.

Cases of meningococcal disease have sharply increased in the United States since 2021 and now surpass pre-pandemic levels. A total of 422 confirmed and probable cases were reported to the Centers for Disease Control and Prevention (CDC) in 2023 - the highest annual number of cases reported in almost a decade. On March 28, 2024, the CDC issued a health advisory to alert healthcare providers about an increase in invasive meningococcal disease, attributable to Neisseria meningitidis serogroup Y. In Colorado, the Denver Department of Public Health and Environment confirmed five cases of meningococcal disease among people experiencing homelessness since January 12, 2024. All five individuals were hospitalized and no deaths have been reported. In Virginia, health officials have been responding to a state-wide outbreak of serogroup Y since 2022, in which the outbreak was initially declared in the eastern region, and has now been detected in the Central, Southwest, and Northern regions of the state with a total of 36 confirmed cases and 7 deaths state-wide.

According to a recent report from the National Notifiable Disease Surveillance System, as of April 13, 2024 there have been 170 reported cases of all serotypes (year-to-date) across all regions of the country. Texas, California, Arizona, and Florida have reported the highest number of cases, in addition to Virginia and Colorado. People disproportionately affected include people between the ages of 30 and 60 years, Black or African American people, and adults with HIV.

What is Meningococcal disease?

Neisseria meningitidis is a bacterium that can cause meningococcal disease. There are six N. meningitidis serogroups that cause meningococcal disease worldwide: A, B, C, W, X, and Y. Serogroups B, C, W, and Y circulate in the United States. A specific strain from serogroup Y, called sequence type (ST) 1466, caused 68 percent of cases in the United States last year.

How does Neisseria meningitidis cause infection?

The bacteria spreads to others by exchanging respiratory and throat secretions (saliva or spit) during close contact. N. meningitidis colonizes the nasopharynx and then attaches to mucosal epithelial surfaces using various types of proteins. Several key virulence factors protect it from being killed, including different types of proteins, a capsule, and pili. These virulence factors contribute to the attachment and adhesion to host cells, evasion of the host immune system, and survival in the bloodstream.

Once in the bloodstream, these virulence factors allow the bacteria to cross the blood-brain-barrier, thereby causing neurologic complications like meningitis. People with meningococcal disease may present with symptoms of meningitis, such as fever, headache, stiff neck, nausea, vomiting, photophobia, or altered mental status; or with symptoms of meningococcal bloodstream infection, such as fever and chills, fatigue, vomiting, severe aches and pains, rapid breathing, diarrhea, and rash. These non-specific initial symptoms of meningococcal disease can worsen rapidly and may quickly become life-threatening. With a case fatality rate of 10 percent to 15 percent, immediate antibiotic treatment is critical.

Treatment, Vaccination, and Infection Prevention and Control

Per the recent CDC advisory, healthcare providers should have a heightened suspicion for meningococcal disease, considering patients that may present without symptoms typical of meningitis, start immediate antibiotic treatment if meningococcal disease is suspected, and ensure that all people recommended for meningococcal vaccination are up to date for meningococcal vaccines.

Extended-spectrum cephalosporins, such as cefotaxime or ceftriaxone, can be used as empiric treatment and continued as definitive treatment after susceptibility and microbiologic testing. Penicillin G or ampicillin may also be used for definitive treatment. Vaccines against serogroups A, C, W, Y (MenACWY) and serogroup B (MenB) are available in the United States. In healthcare facilities, patients should be promptly isolated and healthcare providers should follow droplet and standard precautions until 24 hours after initial effective treatment.

Measles Once Again?

By Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM, MBCM, FACSc

This article originally appeared in the April 2024 issue of Healthcare Hygiene magazine.

Measles is caused by the measles virus, a single-stranded, negative-sense, enveloped RNA virus of the genus Morbillivirus within the family Paramyxoviridae. Unfortunately, a resurgence of this dangerous virus is occurring in pockets of states around the country. It is a highly contagious, vaccine-preventable infectious disease. For most countries, the recommendation is that children be immunized against measles at 12 months, generally as part of a three-part MMR vaccine (measles, mumps, and rubella). Waiting until an infant is 12 months old is necessary due to their immune system not adequately responding to the vaccine due to immaturity. Further, children between the ages of four and five are given a second dose of the to increase rates of immunity.

U.S. Measles Outbreak

According to the Centers for Disease Control and Prevention (CDC), as of March 22, 2024, a total of at least 58 cases were reported by 17 jurisdictions: Arizona, California, Florida, Georgia, Illinois, Indiana, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York City, Ohio, Pennsylvania, Virginia, and Washington. Measles was declared eliminated from the United States in 2000 which means the disease is no longer constantly present in this country. If a measles outbreak continues for a year or more, the U.S. could lose its measles elimination status. Healthcare officials should be aware of possible measles cases.

Measles cases usually occur when unvaccinated or under vaccinated citizens from the United States travel abroad and then transmit the infection (disease) to other individuals who are not vaccinated or have no immunity to measles. During this most recent outbreak over the past several weeks, the increased number of imported measles cases is mirroring the rise in global cases of measles and the growing global threat from this dangerous pathogen.

Due to these ongoing public health concerns, the CDC has asked that before one is going to travel internationally, to make sure you’re protected against measles. The best way to protect yourself and others from measles is via vaccination. You should plan to be fully vaccinated at least two weeks prior to departure. However, even if your trip is less than two weeks away and you’re not protected against measles, you should still get a dose of the measles-mumps-rubella (MMR) vaccine. The MMR vaccine protects against all three diseases.

Two doses of MMR vaccine provide 97 percent protection against measles.
One dose provides 93 percent protection.
Transmission

As an airborne agent, the virus spreads easily from one person to the next through the coughs and sneezes of infected people. Measles resides in the nose and throat mucus of an infected person, so it is perfectly positioned to spread to others via respiratory droplets. If other people breathe the contaminated air or touch the infected surface, then touch their eyes, noses, or mouths, they can become infected.

The CDC states that measles is so contagious that if one person has it, up to 9 out of 10 people around him or her will also become infected without protection. An infected individual can transmit measles to others from four days prior through four days post time of the typical rash appearance. The viability of measles for up to two hours in an airspace after an infected person leaves an area is possible. The virus poses a threat to those who are pregnant and not immunized for the developing fetus.

Humans are the sole reservoir of the virus; animals do not get or spread measles. Interestingly and important, this characteristic makes measles theoretically an obvious pathogen for eradication via vaccination much like that of smallpox.

Signs and Symptoms

Symptoms from an infection usually appear one to two weeks after virus contact and usually include high fever, cough, runny nose, and watery eyes. Measles rash appears three to five days after the first symptoms. This isn’t a typical rash, and it can be dangerous, especially for babies and young children. Classic symptoms include a four-day fever (the four Ds) and the 3 Cs—cough, coryza (head cold, fever, sneezing), and conjunctivitis (red eyes)—along with a maculopapular rash.

Koplik spots, which appear as tiny white spots, may appear inside the mouth two to three days after symptoms begin. Then, three to five days after symptoms begin, a rash breaks out. It usually begins as on the face as flat red spots just on the hairline and spread downward to the neck, trunk, arms, legs, and feet. One may see small, raised bumps on top of the flat red spots and the spots may coalesce as they spread. Finally, one’s fever can spike to 104 degrees Fahrenheit with the rash appearing.

Measles can be serious. Children younger than 5 years of age and adults older than 20 years of age are more likely to suffer from complications. These complications may be rare but in the case of subacute sclerosing panencephalitis (SSPE), a fatal disease of the central nervous system that results from a measles virus infection acquired earlier in life can occur.

If one suspects a measles infection, a physician should be consulted. Laboratory diagnosis of measles can be done with confirmation of positive measles IgM antibodies or detection of measles virus RNA from throat, nasal or urine specimen by using the reverse transcription polymerase chain reaction (RT-PCR) assay. RT-PCR is particularly useful to confirm inconclusive IgM antibody results.

Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM,MBCM, FACSc, is the Regents’ Professor, Texas State University System; University Distinguished Chair & Professor, Clinical Laboratory Science (CLS); TEDx Speaker & Global Fellow – Global Citizenship Alliance; Texas State Honorary Professor of International Studies; Associate Director, Translational Health Research Initiative; Past President, Texas Association for CLS.

Norovirus: Facts and Prevention

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the March 2024 issue of Healthcare Hygiene magazine.

The common stomach flu, caused by norovirus, is hitting headlines once again due to recent outbreaks across the United States. Norovirus is the leading cause of viral gastroenteritis in the country, causing 19 to 21 million cases per year, approximately 109,000 hospitalizations, more than 2 million outpatient visits, and more than 450,000 emergency department visits annually, according to the National Foundation for Infectious Disease.

According to the latest CDC data, the average rate of positive norovirus tests is 12.3% as of February 17 – an increase from 9 percent in mid-January – and with positivity rates highest in the Northeast, at around 16 percent. In Fairhope, Alabama, more than 1,200 students and staff were infected, forcing an electuary school closure. In Madison County, New York, 15 confirmed cases and 55 suspected cases at Colgate University have been reported. Michigan, Connecticut, and Philadelphia are also reporting outbreaks.

While we’re all too familiar with this common stomach bug, why is it such as concern? Let’s take a deeper look into what makes norovirus a uniquely perfect pathogen capable of causing widespread outbreaks.

Norovirus has multiple methods of transmission. The virus is transmitted via the fecal–oral route and vomit–oral route through foodborne, waterborne, contact with contaminated environments, and direct contact with an infected individual.
Norovirus is highly contagious due to its low infectious dose being as little as 18 viral particles capable of causing infection coupled with extreme viral shedding. Billions of virus particles can be shed in the stool and vomit of infected individuals which can easily infect others (105–1011viral copies per gram of stool).
Norovirus is a single-stranded non-enveloped RNA virus, meaning it does not rely on an exterior “envelope” for protection. This makes it environmentally stable and resistant the common disinfectants and alcohols. Regardless of the percentage of alcohol in common hand sanitizers, alcohol cannot penetrate the protein shell that surrounds the viral RNA, known as the capsid.
Noroviruses are a genetically diverse. They can rapidly evolve, leading to a lack of prolonged cross-protective immunity following infection. There are over 30 genotypes that can infect humans.
Norovirus particles may be infectious for 2 weeks on environmental surfaces and for greater than two months in water.
In the United States, cases of norovirus occur most frequently during late fall, winter, and early spring, likely due to the virus’s ability to survive in cooler temperatures.
Infection is rapid, with an incubation period of 24–48 hours, followed by vomiting, diarrhea, nausea, abdominal cramps, stomach pain, fever, and body aches. Resolution of symptoms can occur after 12 to 72 hours, however, gastroenteritis can be severe and prolonged in specific risk groups, especially infants, children, and immunocompromised individuals. There is no vaccine for norovirus. Treatment consists of supportive care, especially oral or intravenous rehydration.

Norovirus outbreaks frequently occur in schools, cruise ships, healthcare settings, and disaster relief settings. In the United States, about 62% of all norovirus outbreaks occur in healthcare settings. In fact, a recent study reported 13,092 norovirus outbreaks and 416,284 outbreak-associated cases in long-term care facilities between 2009 and 2018 in all 50 states, Washington D.C., and Puerto Rico.

Norovirus outbreak management relies on basic principles of infection prevention: hand hygiene, limiting exposure to infectious individuals, and thorough environmental decontamination. In healthcare settings, patients with norovirus gastroenteritis must be placed on Contact Precautions for a minimum of 48 hours after the resolution of symptoms. Healthcare personnel must wear a gown and gloves when caring for patients and use a mask and eye protection if there is an anticipated risk of splashes, particularly among patients who are vomiting. Strict adherence to hand hygiene using soap and water and environmental

Walk Like a Mycoplasma pneumoniae!

By Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM, MBCM, FACSc

This article originally appeared in the February 2024 issue of Healthcare Hygiene magazine.

Since late December 2023, there has been higher pneumonia case activity in children across China, Denmark, France, and the Netherlands. In the U.S., there was also a surge in Ohio, especially in one county, and it these reports have raised some alarm in the public health and healthcare communities as we continue to navigate COVID-19 and other respiratory agents early in 2024.

Currently, there is no other outbreak activity being reported in the U.S. and typically, Mycoplasma pneumoniae infections are not consistently high. Usually, there is higher activity about every three years and the U.S. has not seen significant cases occurring since before the pandemic. We may therefore see more frequent infections during the 2024 winter respiratory season.

What is Mycoplasma pneumoniae?

The Centers for Disease Control and Prevention (CDC) and the National Institutes of Health share that Mycoplasma species are the smallest living organisms that can survive alone in nature. Interestingly, and sometimes frustrating to physicians and medical laboratory professionals, diagnosis and treatment can be challenging. This is because they have no cell wall which means it can easily be missed on a clinical Gram stain. Gram stains are usually reliable, accurate, easy to perform, and have a relatively short turnaround. However, the staining mechanism relies on a bacterial cell wall for the staining differential to perform. Thus, an initial stain with M. pneumoniae as a causative agent is often not detected on microscopy of a clinical gram stain. To make matters worse, it is a fastidious [difficult to culture on normal bacteriological media], and isolation is not usually performed in most medical and clinical laboratories. Due to these reasons, one would have to suspect it and utilize special culture media supplemented with serum while waiting for the longer incubation time to grow.

The genus is large with more than 120 species, but only 13 have been isolated from humans, and only four are known to be human pathogens. Mycoplasma pneumoniae is the pathogen most associated with disease in humans. It is a short rod and most often excreted from the respiratory tract after many weeks of acute infection; therefore, isolation of the organism is not specific for acute infection at that time.

Transmission, Signs, Symptoms, and Illnesses

pneumoniae is now considered a common cause of community-acquired pneumonia (CAP) and is transmitted from person to person via respiratory droplets during close contact. The incubation period ranges between two to three weeks. Like most respiratory pathogens, infection usually occurs during the winter months but can happen year-round. It is commonly referred to as walking pneumonia or atypical pneumonia. The infection can mimic the common cold and symptoms may be mild. This can often lead to one not needing to stay in bed or seek healthcare. People may not need bedrest or a hospital stay and likely will not want to stay home from work or school. Since you may feel well enough to just keep walking around, the illness was often called “walking pneumonia.”
The CDC states Infections caused by Mycoplasma pneumoniae are generally mild but sometimes can be severe. Once someone becomes infected with the bacteria, symptoms usually appear after one to four weeks. Symptoms can last for several weeks.

Symptoms depend on the type of infection.

Tracheobronchitis (chest cold)
Pneumonia (lung infection) can sometimes occur.
Sore throat
Feeling tired
Fever and chills
Slowly worsening cough
Headache
Cough
Shortness of breath
Symptoms in young children

Children younger than 5 years old who get M. pneumoniae infection could have symptoms that are different from older children and adults. Instead, they may have the following symptoms:

Sneezing

Stuffy or runny nose
Sore throat
Watery eyes
Wheezing
Vomiting
Diarrhea
Prevention, Diagnosis, and Treatment

People can get infected with Mycoplasma pneumoniae more than once. While there is no vaccine to prevent M. pneumoniae infections, there are things people can do to protect themselves and others. Some of the best preventative measures and strategy are now commonplace considering the COVID-19 pandemic – practice good hand hygiene, cough and sneeze etiquette, physical distancing, staying home when sick, and seeking testing if a severe illness develops.

As previously mentioned, a diagnosis for this pathogen is not simple. There’s no quick way to test for M. pneumoniae infections, unlike some other respiratory illnesses. You physician may observe the signs and symptoms described above, and if needed, a chest X-ray may be ordered to rule out pneumonia. Testing is rare. If they do choose to test, a physician or provider may collect a specimen and send it to a medical laboratory. The more common type of specimen collected will be a swab of the nose or throat and less commonly a blood specimen.

Due to the lack of a cell wall, some classes of antibiotics will not work on this infection. Mild cases may not even need treatment. However, if an illness is considered severe, then physicians can use several types of antibiotics to treat people with pneumonia caused by M. pneumoniae. Antibiotics are most effective if started early in the infection.

Typical antibiotics include macrolides, doxycycline, or fluoroquinolones. Azithromycin is the most frequently used antibiotic and is usually prescribed for 5 days (500 mg for the first dose, followed by 250 mg daily for four days). Patients receiving doxycycline or fluoroquinolones should be given seven to 14 days of treatment. As with other bacteria and microbes, some M. pneumoniae are resistant to some antibiotics used for treatment. Physicians and medical laboratory professionals should be updated on current resistance and antibiotic susceptibility breakpoints.

Rodney E. Rohde, PhD, MS, SM(ASCP) CM, SVCM,MBCM, FACSc, is the Regents’ Professor, Texas State University System; University Distinguished Chair & Professor, Clinical Laboratory Science (CLS); TEDx Speaker & Global Fellow – Global Citizenship Alliance; Texas State Honorary Professor of International Studies; Associate Director, Translational Health Research Initiative; Past President, Texas Association for CLS.

Anthrax Awareness

By Priya Dhagat, MS, MLS(ASCP) CM, CIC

This article originally appeared in the January 2024 issue of Healthcare Hygiene magazine.

Last month, the World Health Organization (WHO) reported large anthrax outbreaks in five African countries—Kenya, Malawi, Uganda, Zambia, and Zimbabwe— with more than 1,100 suspected cases and 20 deaths. Zambia reported the largest and most widespread outbreak out of the five countries, with 684 suspected cases, 25 confirmed cases, and four deaths in nine of Zambia's ten provinces. According the WHO report, the outbreak began in the summer within a southern province where 26 people developed sores on their face, arms, and fingers after eating meat from wild hippopotamus carcasses. Cattle, goats, and hippos were reportedly dying from an unknown cause in surrounding areas.

Though anthrax is endemic in these countries, the WHO said the recent uptick in cases is caused by a combination of climate change, food insecurity, and a low perception of risk when handling meat and animal products and a high risk of spread due to frequent movement of animals and animal carcasses between Zambia and its neighboring countries, especially alongside the Zambezi, Kafue, and Luangwa rivers that flow into lakes in Malawi, Mozambique, and Zimbabwe. Numerous response activities have been taken, including active surveillance, health promotion, community engagement, meat inspections, and livestock vaccination.

Anthrax is a disease caused by the spore-forming bacteria Bacillus anthracis. Anthrax spores are extremely stable and resistant to desiccation, heat, ultraviolet light, gamma radiation, and many disinfectants. Spores are found naturally in soil and can remain dormant for years until they find a host that produces key amino acids that stimulate the spores to germinate and become vegetative bacteria. Herbivores, such as sheep, goats, horses and cattle are become infected by ingesting vegetation, soil, or water that is contaminated with B. anthracis spores. Humans can be infected when handling infected animals or contaminated animal products (e.g., handling carcasses, butchering or consuming raw or undercooked meat, handling unprocessed hides, drumheads, or wool). Interestingly, infection manifests differently depending on the route of exposure: cutaneous, gastrointestinal, inhalation, and injection.

Cutaneous anthrax is the most common and mildest form and occurs when spores directly enter the body through a cut, sore, or open wound on the skin. Cutaneous anthrax presents as a raised, itchy papule resembling an insect bite that progresses to a lesion that eventually ruptures and becomes an ulcer with a black center, called an eschar.

Gastrointestinal anthrax is the result from ingesting raw or undercooked meat from an infected animal. Once spores germinate in the intestinal tract, a rapid onset of nausea, vomiting, abdominal pain, fever, and diarrhea occur roughly two to five days after infection, eventually leading to ulcerative lesions, hemorrhage, obstruction or perforation. This form of anthrax can affect the throat, esophagus, stomach, and intestines.

Inhalation anthrax is the most lethal form for anthrax. In fact, according the CDC, “B. anthracis is a Tier 1 select agent and considered one of the most likely bioterrorism agents to be used because it is relatively easy to acquire from the natural environment, mass produce, and disseminate as spores via aerosolization.” Inhaled spores accumulate within the lung alveoli, become engulfed by macrophages, neutrophils, dendritic cells, and are then transported to lymph nodes where the bacteria germinate and produce toxins. During an incubation period of two to 10 days, influenza-like symptoms, fever, and a nonproductive cough develops. Of note, while symptoms of inhalation anthrax usually begin a week after exposure, the incubation period may be prolonged and expand up to two months. Inhalation anthrax can lead to severe dyspnea, hypotension, and septic shock. Without treatment, only 10 - 15% of people survive.

Injection anthrax is a rare but newer form of anthrax and results in skin and tissue infections associated with injection drug use that is contaminated with B. anthracis spores. It appears as small swollen blisters or eschars and deeper skin abscesses at the injection site.

In the United States, anthrax among livestock is controlled through vaccination programs which has greatly reduced human infections, although wildlife and livestock anthrax infections still occur sporadically in southwest Texas through Colorado, North Dakota, South Dakota, and Montana. Despite the hardiness of the anthrax spore and the different types of anthrax infections, anthrax is not considered to be contagious. According the to the CDC, person-to-person transmission of untreated cutaneous anthrax is possible, but rare. Person-to-person transmission does not occur from pulmonary or gastrointestinal anthrax. In healthcare settings, standard precautions should be followed for all forms of anthrax. Contact precautions are recommended if uncontained copious drainage is present. If a patient is potentially contaminated with spores, they should be isolated in an airborne infection isolation room until decontamination procedures are completed. Healthcare workers should wear appropriate PPE, most importantly a respirator (N95 mask or Powered Air Purifying Respirators). Anthrax can be diagnosed by several laboratory methods such as bacterial culture and identification from various specimen types, serology tests, and antigen detection. Infection can be treated with antibiotics based upon anthrax disease manifestation. Refer to the CDC Anthrax Diagnosis page and this CDC MMWR report for more information on diagnostic testing and updated guidelines for prevention and treatment.