Epidemiology of Rare But Life-Threatening Diseases: How to Improve Surveillance and Support for Free-Living Ameba Infections

Brief Summary:
Infections caused by free-living amebae (Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp.) have been well documented worldwide. These amebae can cause fatal or severe skin, eye, neurologic, and disseminated infections (e.g., N. fowleri causes primary amebic meningoencephalitis [PAM]; B. mandrillaris and several species of Acanthamoeba cause granulomatous amebic encephalitis [GAE]; and Acanthamoeba can also cause keratitis). In recent years, changes in the epidemiology of these rare but life-threatening infections have brought them to the forefront of the public’s attention.  Historically, cases of PAM were thought to only occur in southern states. Since 2010, 4 cases of PAM have been identified in northern and Midwestern states. In 2011, two cases were identified in two persons who had no freshwater lake exposure but had performed nasal irrigation with a neti pot. B. mandrillaris infections are typically reported in isolation; however, since 2009, 3 clusters of B. mandrillaris infections have been associated with organ transplantation. Acanthamoebaspp. have recently been associated with large outbreaks of microbial keratitis associated with contact lens wear. While they remain relatively rare with no more than 8 PAM cases reported annually since 1962 and 11 GAE cases reported annually since 1978, the outcomes are often severe and can undermine the public’s confidence in the safety of certain activities and procedures such as swimming in freshwater lakes, nasal irrigation, and organ transplantation. For the state or territorial health department that has identified an FLA infection within its jurisdiction, the resulting public health response can require extensive time and resources that may seem out of proportion to those typically devoted to single case reports. CDC offers consultation for clinicians who suspect FLA infection in a patient, and laboratory testing for diagnosis of FLA infection including serology, immunohistochemical staining, and PCR. Recently, we have also revised and expanded the Naegleria website to offer comprehensive referenced information for clinicians, public health practitioners, and the public. CDC wishes to partner with CSTE to further support state and territorial health departments in the recognition, reporting, and management of these infections and in the development of communications and health messaging to educate the public and medical community, in order to prevent future infections.