The Helminthic Eosinophilic Meningitides: Emerging Zoonotic Parasitic Diseases Worldwide

ABSTRACT

The helminthic infections that can cause eosinophilic meningitis (EM) share many of the characteristics of emerging infectious diseases, such as the influences of international trade and travel on pathogen dissemination in a warming ecosystem. In order to assess the evolving epidemiology of EM worldwide, define the case diagnosis of EM based on cerebrospinal fluid (CSF) microscopy, and stratify the causes of EM as infectious versus non-infectious; this review analyzes scientific articles selected by MEDLINE search, 1966-2009. In addition, this review compares the clinical manifestations, management, and outcomes of the most common causes of helminthic EM worldwide in order to alert clinicians to populations at increased risk of helminthic EM as a result of age, ethnicity, lifestyle, food choices, location of permanent residence, or recent travel. The most common helminthic causes of EM worldwide are angiostrongyliasis and gnathostomiasis. Angiostrongyliasis, a rodent zoonosis endemic in Southeast Asia, was imported to North and South America and the Caribbean following the embarkation of infected rodents from cargo ships. Gnathostomiasis, a zoonosis of wild carnivores in Southeast Asia and Latin America, has been recently recognized as an emerging cause of EM in travelers returning to England and the United States (US). Baylisascariasis, a North American raccoon zoonosis, is an additional, although unusual, emerging cause of EM, that has extended distribution range across the US since the 1980s, and was exported to Japan by the exotic pet trade. Although EM occurs worldwide, its differential diagnosis is limited to infectious and non-infectious etiologies with non-infectious etiologies, such as intracranial hardware and malignancies, causing more cases, especially in regions that are not endemic for the most common causative parasites. Most cases of helminthic EM can be prevented by public health education, human behavior modification, and proper food preparation.