environmental assay data sheet

Naegleria fowleri PCR test

Test code: X0050 - Ultrasensitive qualitative detection of Naegleria fowleri by real time PCR

Naegleria fowleri is a free-living, single-celled amoeba that belongs to the genus Naegleria. It is well-known as the "brain-eating amoeba" because it can cause a rare but severe brain infection known as primary amebic meningoencephalitis (PAM), which destroys brain tissue and is almost always fatal. This protozoan likes to live in warm environments and grows best at temperatures between ~80°F and 115°F (~26-46°C). It primarily feeds on bacteria and is commonly found in warm freshwater sources like lakes, rivers, ponds, hot springs, and soil worldwide, but it does not survive in saltwater or properly treated swimming pools.

This amoeba has a life cycle consisting of three stages: cyst (dormant form), trophozoite (feeding and reproductive form), and flagellate (swimming form). The size of the amoeba varies between 8 and 15 micrometers in size depending on its stage.

Infection occurs when water containing the amoeba enters the nose (e.g., during swimming, diving, or nasal irrigation), allowing it to travel along the olfactory nerve to the brain. This parasite is not contracted by drinking contaminated water or through person-to-person contact. The amoeba is unable to cause disease through ingestion because it cannot penetrate or migrate to the brain from the stomach or intestines. The stomach acid likely destroys the amoeba upon swallowing so that the chance of getting an infection through ingestion is very low.

Infected individuals will usually develop symptoms from 1 to 9 days after exposure. These symptoms include severe headache, fever, nausea, vomiting, stiff neck, seizures, and altered mental status, progressing rapidly to coma and death within 3–7 days. The mortality rate is very high.

Diagnosis of infection by this agent relies on detecting the amoeba in cerebrospinal fluid (CSF), brain tissue, or environmental samples. Several techniques, such as microscopy, culture, staining, and serological methods, have been used. However, polymerase chain reaction (PCR) has become the method of choice due to its high sensitivity and specificity (Qvarnstrom et al., 2006; Shaukat et al., 2024).

Utilities:

• Check for Naegleria fowleri in water sources
• Selection of appropriate remediation regimens
• Check for post-remediation absence of this agent
• Help confirm the presence of this agent in animals
• Help minimize human exposure to this agent

References:

Qvarnstrom Y, Visvesvara GS, Sriram R, da Silva AJ. Multiplex real-time PCR assay for simultaneous detection of Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri. J Clin Microbiol. 2006 Oct;44(10):3589-95.

Specimen requirements: 2 ml of water, or water filter media; or 0.2 ml CSF or fresh, frozen or fixed tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time polymerase chain reaction

Normal range: Nondetected