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The epidemiology of primary amoebic meningoencephalitis in the USA, 1962-2008

J S Yoder1, B A Eddy, G S Visvesvara

  • 1Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA. jey9@cdc.gov

Epidemiology and Infection
|October 23, 2009
PubMed

Insights

Naegleria fowleri causes primary amoebic meningoencephalitis (PAM), a rare and fatal brain infection. Despite widespread water contact, PAM cases remain infrequent, posing challenges for risk reduction strategies.

Area of Science:

  • Environmental microbiology
  • Infectious diseases
  • Neuroparasitology

Background:

  • Naegleria fowleri is a thermophilic amoeba found in warm freshwater environments.
  • It causes primary amoebic meningoencephalitis (PAM), a rare but almost invariably fatal central nervous system infection.
  • Despite frequent human contact with freshwater, diagnosed PAM cases are infrequent globally.

Purpose of the Study:

  • To analyze the epidemiology of Naegleria fowleri infections in the USA.
  • To identify environmental and host-specific factors contributing to PAM.
  • To inform the development of science-based risk reduction messages for recreational water users.

Main Methods:

  • Analysis of 111 prospective PAM case reports in the USA since 1962.
  • Review of documented case reports for demographic and exposure patterns.
  • Examination of temporal trends in annual PAM case reports.

Main Results:

  • PAM cases primarily affect young, healthy males exposed to warm recreational waters during summer.
  • Infections are concentrated in warm-weather regions, particularly associated with lakes and ponds.
  • The annual incidence of PAM in the USA has not shown a significant increasing trend since 1962.

Conclusions:

  • Understanding the rarity of PAM despite environmental presence of Naegleria fowleri is crucial.
  • Further research into environmental and host factors is needed for effective risk communication.
  • Targeted public health messaging for swimmers in warm freshwater environments is essential.

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