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B. mandrillaris: A rare infection with a 90% fatality rate
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Infection with Balamuthia mandrillaris is rare in the United States, occurring in just 109 patients between 1974 and 2016, according to recent findings. But it is nearly always fatal, and clinicians should be aware of it as a possible cause of encephalitis in patients, researchers said.
“I want clinicians to be aware of this infection,” Jennifer R. Cope, MD, MPH, medical epidemiologist in the Division of Foodborne, Waterborne and Environmental Diseases at the CDC, told Infectious Disease News. “It is a rare infection with 109 cases going back to 1974. But I do think it’s something clinicians should be aware of because you can’t diagnose something that you don’t think of.”
According to Cope and colleagues, B. mandrillaris is a free-living ameba (FLA) found in the environment. It has been isolated from soil, dust and water and likely enters the body via the skin or lungs. The CDC maintains an FLA registry that includes laboratory-confirmed cases of Balamuthia infection. Writing in Clinical Infectious Diseases, Cope and colleagues said they used several sources — such as case report forms, CDC laboratory results, published case reports and media information — to complete the registry.
Cope said the CDC encourages clinicians to report suspected cases because the agency has the expertise and resources to test and treat a patient with Balamuthia.
“There’s no routine testing capability for this infection in most hospitals. These cases came to the CDC for consultation and diagnosis, and then we were able to collect the information. That’s how, with this rare infection, we were able to even do this report and share what we know about it.”
Between 1974 and 2016, the researchers identified 109 Balamuthia cases in the United States, including 99% with reported encephalitis. The median age of the patients was 36 years, with a range from 4 months to 91 years. Additionally, 68% of the case population was male.
Cases were reported from 27 states, plus the District of Columbia, with the highest number reported in California (n = 12), followed by Arizona (n =4) and Texas (n = 3). Of the 58 cases with documented ethnicity, Hispanics comprised 55% of individuals infected with Balamuthia. Soil exposure was commonly reported, according to the report.
According to Cope and colleagues, B. mandrillaris has a 90% fatality rate, based on available reported outcomes. The median reported length of time from symptom onset until death, was 24 days, the researchers reported.
“Unfortunately, it is a highly fatal infection, but there have been a few cases of successful treatment and recovery,” Cope said.
The researchers emphasized the need for clinicians to be aware of Balamuthia as a potential cause of encephalitis, which could lead to earlier diagnosis, initiation of treatment and better patient outcomes.
“Clinicians should definitely know to reach out to their local or state health department or the CDC,” Cope said. “The tough part of this infection is that we don’t know why something that seems to be just present in the environment only causes a few infections a year.” – by Marley Ghizzone
Disclosure: The authors report no relevant financial disclosures.
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