Small-scale spatial analysis of intermediate and definitive hosts of Angiostrongylus cantonensis

Abstract

BackgroundAngiostrongyliasis is a food-borne parasitic zoonosis. Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis. The life cycle of A. cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts. This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts, which are key components in the strategy for the prevention and control of angiostrongyliasis.MethodsThree villages from Nanao Island, Guangdong Province, China, were chosen as study area by stratified random sampling. The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016, with spatial correlations of the positive P. canaliculata and the infection rates analysed by ArcGIS, scan statistics, ordinary least squares (OLS) and geographically weighted regression (GWR) models.ResultsA total of 2192 P. canaliculata specimens were collected from the field, of which 1190 were randomly chosen to be examined for third-stage larvae of A. cantonensis. Seventy-two Angiostrongylus-infected snails were found, which represents a larval infection rate of 6.1% (72/1190). In total, 110 rats including 85 Rattus norvegicus, 10 R. flavipectus, one R. losea and 14 Suncus murinus were captured, and 32 individuals were positive (for adult worms), representing an infection rate of 29.1% of the definitive hosts (32/110). Worms were only found in R. norvegicus and R. flavipectus, representing a prevalence of 36.5% (31/85) and 10% (1/10), respectively in these species, but none in R. losea and S. murinus, despite testing as many as 32 of the latter species. Statistically, spatial correlation and spatial clusters in the spatial distribution of positive P. canaliculata and positive rats existed. Most of the spatial variability of the host infection rates came from spatial autocorrelation. Nine spatial clusters with respect to positive P. canaliculata were identified, but only two correlated to infection rates. The results show that corrected Akaike information criterion, R2, R2 adjusted and σ2 in the GWR model were superior to those in the OLS model.ConclusionsP. canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts, demonstrating that there was a risk of angiostrongyliasis in this region of China. The distribution of positive P. canaliculata and rats exhibited spatial correlation, and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A. cantonensis.Electronic supplementary materialThe online version of this article (10.1186/s40249-018-0482-8) contains supplementary material, which is available to authorized users.

The Prevalence of Angiostrongylus Cantonensis in Rodent Hosts in China and Several Asian Countries: A Systematic Review and Meta-Analysis

“…The difference of the infection rates among seven kinds of rats may be relative to the factors: the susceptibility to A. cantonensis, rat's habitat, activity range and hunted objects, and so on. For example, the front several rodents(Rattus norvegicus, Rattus avipectus and Bandicota indica) : (i) are considered as dominant species in several Asian countries [20,21]; (ii) live close to human dwellings [22]; (iii) they were also known to prey on snails not plants [23]. This result is consistent with Chen D's report [24].…”

The prevalence ofAngiostrongylus cantonensisin rodent hosts in China and several Asian countries: a systematic review and meta-analysis

“…The difference of the infection rates among seven kinds of rats may be relative to the factors: the susceptibility to A. cantonensis, rat's habitat, activity range and hunted objects, and so on. For example, the front several rodents : (i) be considered as dominant species in several Asian countries [20,21]; (ii) live close to human dwellings [22]; (iii) they were also known to prey on snails not plants [23]. The outcome is comparable to the previous report [24].…”

Newly developed SYBR Green-based quantitative real-time PCRs revealed coinfection evidence of Angiostrongylus cantonensis and A. malaysiensis in Achatina fulica existing in Bangkok Metropolitan, Thailand

“…The clinical symptoms can range from headaches to coma, depending on the number of parasitic larvae ( Wang et al, 2012 ; Pozio, 2015 ; Ansdell and Wattanagoon, 2018 ; Johnston et al, 2019 ). Many terrestrial and freshwater snails, including, Achatina fulica , Cryptozona spp., Pomacea spp., and Pila spp., are reported to be important vectors of A. cantonensis ( Thiengo et al, 2010 ; Hu et al, 2018 ; Vitta et al, 2016 ). Moreover, the widespread distribution of some invasive vector species ( A. fulica and Pomacea spp.)…”