Invasive Snails and an Emerging Infectious Disease: Results from the First National Survey on Angiostrongylus cantonensis in China

Abstract

BackgroundEosinophilic meningitis (angiostrongyliasis) caused by Angiostrongylus cantonensis is emerging in mainland China. However, the distribution of A. cantonensis and its intermediate host snails, and the role of two invasive snail species in the emergence of angiostrongyliasis, are not well understood.Methodology/Principal FindingsA national survey pertaining to A. cantonensis was carried out using a grid sampling approach (spatial resolution: 40×40 km). One village per grid cell was randomly selected from a 5% random sample of grid cells located in areas where the presence of the intermediate host snail Pomacea canaliculata had been predicted based on a degree-day model. Potential intermediate hosts of A. cantonensis were collected in the field, restaurants, markets and snail farms, and examined for infection. The infection prevalence among intermediate host snails was estimated, and the prevalence of A. cantonensis within P. canaliculata was displayed on a map, and predicted for non-sampled locations. It was confirmed that P. canaliculata and Achatina fulica were the predominant intermediate hosts of A. cantonensis in China, and these snails were found to be well established in 11 and six provinces, respectively. Infected snails of either species were found in seven provinces, closely matching the endemic area of A. cantonensis. Infected snails were also found in markets and restaurants. Two clusters of A. cantonensis–infected P. canaliculata were predicted in Fujian and Guangxi provinces.Conclusions/SignificanceThe first national survey in China revealed a wide distribution of A. cantonensis and two invasive snail species, indicating that a considerable number of people are at risk of angiostrongyliasis. Health education, rigorous food inspection and surveillance are all needed to prevent recurrent angiostrongyliasis outbreaks.

Angiostrongylus cantonensis in China

“…The rates and intensities of infections in terrestrial snails and slugs are higher than in freshwater mollusks. This was confirmed by a recent national survey conducted in China (Lv et al 2009b). P. canaliculata and A. fulica were found in 11 and 6 provinces, respectively.…”

Prevalence and distribution of Angiostrongylus cantonensis (Nematoda, Angiostrongylidae) in Achatina fulica (Mollusca, Gastropoda) in Baixada Santista, São Paulo, Brazil

“…The variation of this rate is broad and has been observed in several municipalities, such as São Gonçalo (35.4%) and Barra do Piraí (10.3%), both in the State of Rio de Janeiro and Joinville/SC (27.4%) 12 , China (13.4% and 28.4%) 40,41 , Pernambuco (42%) 11 , and Japan (52.79%) 42 . The climatic characteristics of Baixada Santista are appropriate for the development of A. fulica and A. cantonensis.…”

O caramujo exótico invasor Achatina fulica (Stylommatophora, Mollusca) no Estado do Rio de Janeiro (Brasil): situação atual

“…No Brasil, larvas de A. cantonensis foram encontradas em A. fulica procedentes do Estado de São Paulo e casos dessa meningite foram registrados nos Estados do Espírito Santo (Caldeira et al 2007) e de Pernambuco (Lima et al, 2009). O estudo epidemiológico realizado em Pernambuco mostrou a participação ativa de A. fulica na transmissão (Thiengo et al 2010), tal como observado em países da Ásia e Ilhas do Pacífico (e.g., Lv et al, 2009).…”

“…Aelurostrongylus abstrusus (Railliet, 1898), nematódeo parasito de pulmão de felídeos causando pneumonia, é o metastrongilídeo mais fequentemente detectado em exemplares de A. fulica examinados no Laboratório de Referência Nacional em Malacologia Médica (LRNM, IOC, FIOCRUZ) (Thiengo et al 2008 Lv et al, 2009). A transmissão dos nematódeos pelo molusco para os demais hospedeiros ocorre através da ingestão de alimento contaminado pelo muco liberado pelo molusco infectado ou do próprio molusco infectado cru ou mal cozido.…”