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New Commercially Available PCR Test Detects 3 Brain-Eating Amoebas in 3 Hours
A new commercially available PCR test can detect three common brain-eating amoebas in three hours: Naegleria fowleri, Balamuthia mandrilaris, and Acanthamoeba spp.
Primary amebic meningoencephalitis (PAM) — a deadly disease caused by infection with Naegleria fowleri, a “brain-eating” amoeba commonly found around the world in soil and warm, fresh water — is becoming a growing health concern given the global temperature increase caused by anthropogenic climate change.
“In North America, there are only five known survivors of this infection,” Jose Alexander, MD, clinical microbiologist and director of microbiology, virology, and immunology for AdventHealth Orlando, told LifeSciencesIntelligence.
When this amoeba enters through the nose and travels to the human brain, it can kill its host in 3–7 days. Traditional testing methods take up to 6 days to obtain results, meaning patients often die before the results come back and treatment begins.
Although infection is always nearly fatal, cases do not occur often enough to be deemed profitable for companies to invest the capital in improving testing, explained Alexander. According to the CDC, only 154 people have been infected by this amoeba between 1962 and 2021.
However, warming climates, lower water levels, and the popularity surrounding water sports and other water-related activities may lead to a rise in cases and a renewed need for diagnostic approaches.
Last month, a Nevada boy died after contracting N. fowleri while swimming in Lake Mead at the beginning of October, the largest reservoir in the United States, located in Nevada and Arizona. “Infections were more prevalent in the southern part of the US, like Texas and Florida. But now, we’ve seen cases in northern states,” mentioned Alexander, suggesting that the infection range of N. fowleri is expanding upward.
A New Testing Method
By leveraging their expertise and internal resources, Alexander and his clinical team have helped close this severe gap in diagnostic approaches and developed the first commercially available molecular test designed to quickly detect free-living amoebas in 1 mL of cerebrospinal fluid (CSF) within three hours.
After three years of research and development, Alexander revealed that “one of the main advantages me and my team had was that the amoeba testing platform is also used for COVID-19 testing. In the future, it will also be used for detecting the Legionella spp. in respiratory samples,” noting that high volume and multiuse testing platforms are more practical from an investment point of view.
This new rapid polymerase chain reaction (PCR) test detects not only N. fowleri but also Balamuthia mandrilaris and Acanthamoeba spp. — two other common free-living amoebas.
B. mandrilaris, found in soil, causes a severe and rare brain and spinal cord infection called granulomatous amebic encephalitis (GAE). Acanthamoeba spp. can also be found in soil, bodies of water, animal tissue, food, and air heating and cooling systems. Additionally, this amoeba species can be found on surfaces, including the surfaces of contact lenses, leading to eye infections.
Traditional Testing Methods of Diagnosis
Clinical symptoms of infection with N. fowleri usually appear within 2–8 days of infection, including headache, fever, nausea, or vomiting. Later symptoms may include a stiff neck, seizures, hallucinations, confusion, lack of attention, and coma.
An N. fowleri infection can be verified with a microscopic examination or culture of fresh, unfrozen, unrefrigerated CSF or brain tissue. Still, as Alexander mentioned, traditional testing methods can take up to 6 days to obtain conclusive results. These time-consuming and invasive approaches mean “many patients are diagnosed postmortem,” he stressed.
Health Risks of Warming Waters
Climate change and its environmental health implications are increasingly ratcheting up healthcare costs and continuously threatening physicians' ability to protect the health of patients across the United States and the rest of the world. And as global temperatures continue to rise, Alexander shared that this heat-loving amoeba will continue to increase in geographical range — similar to tickborne and zoonotic illnesses.
“The Southern United States used to be the main hot spot for these cases,” reiterated Alexander. “Amoebas could easily be in water reservoirs in the northern states, but temperature plays a big role. When the temperature reaches a certain level, they become more active and infectious,” he warned.
According to the CDC, scientists analyzed freshwater temperatures linked to several PAM cases and found that they were all typically higher than 80°F. However, data suggests amoebas may be able to live in water below 80°F but grow best at high temperatures (115°F).
“Because amoebas are considered natural living organisms in freshwater, reporting is not mandatory in many states,” Alexander clarified. Still, health officials and providers are aware of this growing concern and recommend that people be mindful of the potential risk associated with the following locations:
- warm fresh water, such as lakes and rivers
- geothermal (naturally hot) water, such as hot springs
- warm water discharge from industrial or power plants
- untreated geothermal (naturally hot) drinking water sources
- swimming pools, splash pads, surf parks, or other recreational venues that are poorly maintained or don’t have enough chlorine
- tap water
- water heaters
- soil, including sediment at the bottom of lakes, ponds, and rivers
“It's just a matter of time before the temperatures reach a level to allow them to become more active and infectious,” cautioned Alexander.
