Geographic distribution of Angiostrongylus cantonensis in wild rats (Rattus rattus) and terrestrial snails in Florida, USA

Abstract

The parasitic nematode Angiostrongylus cantonensis is a major cause of eosinophilic meningitis in humans, and has been documented in other incidental hosts such as birds, horses, dogs and non-human primates. It is endemic in Hawaii, and there have been sporadic reports in the southern continental United States. This parasite uses rats as definitive hosts and snails as intermediate hosts. In this study, we collected potential definitive and intermediate hosts throughout Florida to ascertain the geographic distribution in the state: Rats, environmental rat fecal samples, and snails were collected from 18 counties throughout the state. Classical diagnostics and morphological identification, along with molecular techniques were used to identify nematode species and confirm the presence of A. cantonensis.Of the 171 Rattus rattus collected, 39 (22.8%) were positive for A. cantonensis, and 6 of the 37 (16.2%) environmental rat fecal samples collected in three of the surveyed counties were also positive for this parasite by real time PCR. We examined 1,437 gastropods, which represented 32 species; 27 (1.9%) were positive for A. cantonensis from multiple sites across Florida. Three non-native gastropod species, Bradybaena similaris, Zachrysia provisoria, and Paropeas achatinaceum, and three native gastropod species, Succinea floridana, Ventridens demissus, and Zonitoides arboreus, which are newly recorded intermediate hosts for the parasite, were positive for A. cantonensis. This study indicates that A. cantonensis is established in Florida through the finding of adult and larval stages in definitive and intermediate hosts, respectively, throughout the state. The ability for this historically subtropical nematode to thrive in a more temperate climate is alarming, however as the climate changes and average temperatures rise, gastropod distributions will probably expand, leading to the spread of this parasite in more temperate areas. Through greater awareness of host species and prevalence of A. cantonensis in the United States, potential accidental infections may be avoided.

Inhibiting Interleukin 17 Can Ameliorate the Demyelination Caused by A. cantonensis via iNOS Inhibition

“…A. cantonensis infection is endemic in the Pacific Islands, Southeast Asia, China, and Hawaii. Sporadic infections are reported in Southern United States and Florida [ 14 ]. Outbreaks of eosinophilic meningitis have been reported due to the consumption of raw snails harboring L3 or associated with the consumption of contaminated raw vegetable juice in Taiwan [ 15 , 16 ].…”

Rat Lungworm Infection in Rodents across Post-Katrina New Orleans, Louisiana, USA

“…Accordingly, the distribution and abundance of infected intermediate hosts are probably key factors affecting transmission risk, especially in cities such as New Orleans, where interest in urban agriculture is on the rise ( 27 , 28 ). It is also possible that risk is influenced by climate-driven spread of invasive mollusks ( 29 , 30 ), such as apple snails, that can serve as reservoirs ( 1 , 3 ). Further study of infection prevalence in intermediate hosts would thus probably improve understanding of transmission risk across New Orleans and other cities that are vulnerable to climate change.…”

“…Concern is increasing about the spread of rat lungworm ( Angiostrongylus cantonensis ), especially in the southeastern United States ( 1 – 5 ). A parasitic nematode carried by intermediate mollusk hosts and definitive rat hosts ( 6 , 7 ), rat lungworm can cause eosinophilic meningitis in humans who become infected by ingesting intermediate hosts or paratenic hosts, such as freshwater shrimp and frogs ( 6 , 7 ).…”

Rat Lungworm Infection Associated with Central Nervous System Disease — Eight U.S. States, January 2011–January 2017

“…The possibility of autochthonous transmission is supported by evidence of infection with A. cantonensis among intermediate snail hosts and nonhuman vertebrate hosts in the southern United States. Infection has been observed in exotic and native snail species in Florida and Louisiana ( 6 , 7 ) and in rat species in Louisiana, Florida, and Oklahoma ( 6 ). Infection with larvae has been documented in other vertebrates including opossums and nine-banded armadillos in Louisiana and Florida ( 8 ), an American miniature horse in Mississippi, and captive exotic primates in Louisiana, Florida, and Alabama ( 7 ).…”