Brain-Eating Amoeba Returns to the South

The by now infamous brain-eating amoeba caused its first U.S. fatality of 2012 in an 8-year-old South Carolina boy.

Blake Driggers from Sumter County was infected after tubing at a freshwater lake near his hometown. Blake did not present any symptoms until approximately one week after, when he began complaining of headaches. Within several days of symptom onset, the young boy was dead.

Laboratory tests confirmed Blake had died as a result of primary amebic meningoencephalitis (PAM), the brain infection caused by the microscopic amoeba, Naegleri Fowleri.

This parasite thrives in warm freshwater, such as lakes, rivers, and hot springs, where it usually infects people when they go swimming or diving. In some cases, the use of contaminated water in neti pots has also caused infection.

In the U.S., infection with N. Fowleri is a very rare, yet deadly occurrence. Over the past decade, only 32 cases of PAM have been reported. However, in other parts of the world, fatalities due to this brain-eating amoeba are far more commonplace.

A CDC study released in 2011 reported a staggering increase in PAM cases in Karachi, Pakistan. Between 2008 and 2009, within a period of 17 months, Karachi documented 13 infections due to N. Fowleri, 11 of which were fatal. The majority of patients did not partake in any freshwater recreational activities, however testing of the ground water revealed the presence of N. fowleri amoebae. Therefore, it is suspected that a common route of transmission in Karachi is the inhalation of water through the nostril, which is part of a traditional Muslim ritual.

This sudden increase in cases can be at least partially explained by the steep rises in temperature experienced in Karachi over the past several years. During the time of these deaths, summer temperatures reached a record high, and were only expected to increase in the future.

An isolated case in Minnesota in 2010 further confirms this suspicion. Historically, fatalities due to N. Fowleri have been concentrated in the southern states. However, changes in weather patterns and climate may contribute to the emergence of PAM in higher latitudes than previously recorded.

High temperatures may be beneficial for this parasitic amoeba. Primarily, many pathogens multiply more rapidly in warm and humid conditions. Additionally, changes in the ecosystem of lakes and other freshwater sources may all support pathogenic proliferation and spread. 

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