When Infections Occur - Credit CDC
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Every spring we take a look at a rare, mostly fatal brain infection caused by free living amebas (Naegleria fowleri) that inhabit warm, fresh water (see A Reminder About Naegleria Season - 2019).
Dubbed the `brain eating amoeba' by the press - this infection is called PAM (Primary amebic meningoencephalitis) - and occurs when the amoeba enters the brain through the nasal passages, usually due to the forceful aspiration of contaminated water into the nose.
As a thermophilic (heat-loving), free-living ameba, it is hardly surprising that is is mainly reported in the summer and that Florida and Texas lead the nation in cases over the past three decades, although infections have occurred as far north as Minnesota.
We generally only hear about 3 or 4 cases in the United States each summer, but in 2017 a research letter written by epidemiologists at the CDC (see EID Journal: Estimation of Undiagnosed Naegleria fowleri (PAM), United States) estimated the yearly number PAM cases in the United States probably averages closer to 16 (8 males, 8 females).
Meaning that right now - although almost universally fatal if untreated - 70%-80% likely go unrecognized.
Until a few years ago, nearly all of the Naegleria infections reported in the United States were linked to swimming in warm, stagnant freshwater ponds and lakes (see Naegleria: Rare, 99% Fatal & Preventable), making this pretty much a summer time threat.
Over the past decade we've also seen a number of PAM infections acquired from using unsterilized tap water for nasal irrigation (see EID Journal: (Mis)perception and Use of Unsterile Water in Home Medical Devices).
As a result, public health experts recommended that people `use distilled, sterile or previously boiled water to make up the irrigation solution’ (see Neti Pots & Naegleria Fowleri).
The CDC maintains a large (and recently updated) Naegleria Website where you can find information for both healthcare professionals and the general public. They offer the following prevention advice:
Take precautions while enjoying water activities in fresh water
Most Naegleria fowleri infections occur in young boys, although the reasons for this aren’t clear.
It’s possible that young boys are more likely to participate in such activities as diving into the water and playing in the sediment at the bottom of lakes and rivers.
People should always assume there is a risk for infection whenever entering warm fresh water. The only sure way to prevent an infection is to avoid water-related activities in warm fresh water, especially during summer months.
If you choose to swim, you can reduce your risk of infection by trying to prevent water from going up your nose.
Seek medical attention if you or someone you know develops a headache, fever, or vomiting after swimming in fresh water. Initial symptoms of PAM start about 5 days after infection but could begin anytime from 1 to 12 days.
- Avoid jumping or diving into bodies of warm fresh water, especially during the summer.
- Hold your nose shut, use nose clips, or keep your head above water when in bodies of warm fresh water.
- Avoid putting your head under water in hot springs and other untreated geothermal waters.
- Avoid digging in, or stirring up, the sediment in shallow, warm fresh water. The amebae are more likely to live in sediment at the bottom of lakes, ponds, and rivers.
Tap & Faucet Water
Most Naegleria fowleri infections are associated with swimming in warm freshwater lakes and rivers. However, very rarely, Naegleria fowleri has caused deaths associated with tap or faucet water going up the nose 1-5. Naegleria fowleri can grow in public and private water tanks and pipes, especially where little or no disinfectant (like chlorine or chloramine) is present. It can also grow in the pipes and water heaters of homes and buildings.
Naegleria fowleri infections have been reported when people put their heads underwater, rinse their sinuses through the nose, and cleanse their noses during religious practices using contaminated tap or faucet water.
Visit the pages below to learn how you and your water utility company can protect your health.
After three years of COVID restrictions, many people are understandably anxious to get out and enjoy summer activities, and while fears of Naegleria shouldn't deter them, taking a few simple precautions can help prevent a tragic outcome.
