Free-Living Amoebae and Central Nervous System Infection: Report of Seven Cases

The Free-Living Amoeba (FLA) is an opportunistic protozoan with a cosmopolitan distribution that can cause Central Nervous System (CNS) infection. It develops in relatively stagnant waters such as swimming pools, lagoons and ponds but only species belonging to the genera Hartmannella, Naegleria, Acanthamoeba and Balamuthia have been found in humans. The resulting pathology is highly lethal due to the lack of effective treatment. The aim of this study is to describe a series of neuroinfection cases treated at the Hospital de Infectología in Mexico City. This is a descriptive study conducted between July 2008 and June 2016. It includes all patients admitted with signs and symptoms of meningoencephalitis and a laboratory work-up confirming the presence of FLA trophozoites in Cerebrospinal Fluid (CSF). Statistical Analysis. Nominal variables are reported as relative frequencies and quantitative variables, as medians, maximum and minimum. Seven cases were identified, 43% of which were male. The median number of days between exposure and symptom development was nine days. The most frequent symptoms were: Headache 57%, vomiting 29%, fever 57%, meningeal irritation 43% and altered consciousness 86%. Three of the seven analyzed cases died and one case was also HIV positive.  It is important to consider this presumptive diagnosis in order to search for FLA in tissues or CSF and obtain cultures in selected media. Mortality is high, particularly when the brain is compromised.