Naegleriasis
Naegleriasis (also known as primary amoebic meningoencephalitis; PAM) is an almost invariably fatal infection of the brain by the free-living unicellular eukaryote Naegleria fowleri. Symptoms are meningitis-like and include headache, fever, nausea, vomiting, a stiff neck, confusion, hallucinations and seizures. Symptoms progress rapidly over around five days, and death usually results within one to two weeks of symptoms.
| Naegleriasis | |
|---|---|
| Other names | Primary amoebic meningoencephalitis (PAM), amoebic encephalitis, naegleria infection, amoebic meningitis |
| Histopathology of primary amoebic meningoencephalitis due to Naegleria fowleri. Direct fluorescent antibody stain. | |
| Pronunciation |
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| Specialty | Infectious disease |
| Symptoms | Fever, vomiting, stiff neck, seizures, poor coordination, confusion, death |
| Complications | Brain damage, death |
| Usual onset | 1 - 12 days after exposure |
| Duration | 1 - 18 days |
| Causes | Deep nasal inhalation of Naegleria fowleri organisms from contaminated freshwater. |
| Risk factors | Roughly 75% of cases infect males; most cases are children or adolescents |
| Differential diagnosis | Bacterial or fungal meningitis |
| Prevention | Noseclips when swimming in fresh water, or avoiding freshwater environments, and proper chlorination of swimming pools |
| Treatment | Miltefosine, fluconazole, amphotericin B, posaconazole, voriconazole, targeted temperature management |
| Prognosis | 98.5% fatality rate; some, but not all, survivors have permanent neurological damage |
| Frequency | Extremely rare (.7 in 100,000 humans) |
N. fowleri is typically found in warm bodies of fresh water, such as ponds, lakes, rivers and hot springs. It is also found in an amoeboid or temporary flagellate stage in soil, poorly maintained municipal water supplies, water heaters, near warm-water discharges of industrial plants and in poorly chlorinated or unchlorinated swimming pools. There is no evidence of it living in salt water. As the disease is rare, it is often not considered during diagnosis.
Although infection occurs very rarely, it almost inevitably results in death. Of the 128 naegleriasis US cases in the half-century to 2016, only two survived.