Geographic Range Expansion for the Rat Lungworm in North America

E infectious diseases negatively impact humans and wildlife, causing disease outbreaks and deaths and local and global extinctions (1). Zoonotic disease emergence or re-emergence results from numerous factors (e.g., globalization of trade, increased interaction of humans and animals, anthropogenic climate change) that function independently or synergistically (2,3). Consequently, the means by which parasitic zoonoses are studied must be constantly advanced to promote identification, control, and prevention of outbreaks. The rat lungworm, Angiostrongylus (Parastrongylus) cantonensis, causes eosinophilic meningitis in humans (4) and various disease manifestations (meningoencephalitis, neurologic disorders) in atypical host species, including wildlife and captive animals (5). Transmission of these worms occurs by ingestion of third-stage larvae in raw or undercooked intermediate or paratenic hosts (6). Although variable among geographic regions and within host species, the prevalence of rat lungworms might be high under favorable conditions (7). The occurrence of A. cantonensis rat lungworms has been documented worldwide, and its distribution has been attributed largely to the spread of intermediate molluscan host species (e.g., Achantina fulica) and definitive rodent host species (e.g., Rattus spp.) (8). Moreover, host specificity of rat lungworms is highly plastic, which contributes to its continuous geographic expansion (4). These factors indicate that the rat lungworm is an emerging zoonotic pathogen of concern to humans and wildlife, and therefore provides an excellent opportunity to evaluate the sensitivity and effectiveness of epidemiologic surveying techniques.