Phylogeography of Angiostrongylus cantonensis (Nematoda: Angiostrongylidae) in southern China and some surrounding areas

Abstract

Angiostrongylus cantonensis is of increasing public health importance as the main zoonotic pathogen causing eosinophilic meningitis or meningoencephalitis, which has been documented all over the world. However, there are very limited studies about its phylogeography and spread pattern. In the present study, the phylogeography of A. cantonensis in southern China (including Taiwan) and partial areas of Southeast Asia were studied based on the sequences of complete mitochondrial cytochrome b (Cytb) gene. A total of 520 individuals of A. cantonensis obtained from 13 localities were sequenced for the analyses and grouped into 42 defined haplotypes. The phylogenetic tree (NJ tree and BI tree) revealed a characteristic distribution pattern of the four main lineages, with detectable geographic structure. Genetic differentiation among populations was significant, but demographic expansion could not be detected by either neutrality tests or mismatch distribution analysis, which implied a low gene flow among the local populations in different regions where the samples were collected. Two unique lineages of the A. cantonensis population in Taiwan were detected, which suggests its multiple origin in the island. Populations in Hekou (China) and Laos showed the highest genetic diversities, which were supported by both genetic diversity indices and AMOVA. These results together infer that the area around Thailand or Hekou in Yunnan province, China are the most likely origins of Angiostrongylus cantonensis.

Genetic diversity and population structure of Angiostrongylus vasorum parasites within and between local urban foxes (Vulpes Vulpes)

“…Following the introduction of the pet passport (European Union Regulation 998/2003) many of these dogs travel to/from Europe, creating opportunities to import different parasite strains and facilitating the spread of novel haplotypes throughout the UK. (Eamsobhana et al, 2013;Peng et al, 2017). The work described here reinforces the geographic split between Europe and North America, but reveals no notable geographic structure within European A. vasorum populations (Jefferies et al, 2009b).…”

The invasive giant African land snail,Achatina fulica(Gastropoda: Pulmonata): global geographical distribution of this species as host of nematodes of medical and veterinary importance

“…Significant variation ( P = 0.001) was found in the number of papers published on the different species of nematode found infecting A. fulica , with the largest number of papers referring to A. cantonensis (Chen, 1935), primarily in the countries of Asia ( n = 14) and South America ( n = 15). In Asia, A. fulica infected with A. cantonensis were recorded in Taiwan, Thailand, Japan, Malaysia, Indonesia, Philippines, China and Singapore (Lim & Heyneman, 1965; Bisseru, 1971; Stafford et al, 1976; Lv et al , 2009; Hu et al , 2011; Deng et al , 2012; Yang et al , 2012; Constantino-Santos et al , 2014a; Kim et al, 2014; Song et al, 2016; Peng et al , 2017) while in South America, this nematode has been recorded in Brazil, Colombia and Ecuador (Thiengo et al, 2010; Giraldo et al , 2019; Solórzano-Alava et al , 2019). Angiostrongylus cantonensis was also recorded in Cuba and Guadalupe ( n = 3) in the Caribbean (Vázquez & Sanchez, 2015; Dard et al , 2017), in Florida, ( n = 6) in North America (Smith et al, 2015) and in Hawai'i, in the Pacific Ocean ( n = 1), and in the Mariana Islands (Wallace & Rosen, 1969; Kim et al, 2014), Papua New Guinea (Scrimgeour & Welch, 1984), French Polynesia (Fontanilla & Wade, 2012) and Micronesia (Kim et al , 2014) in Oceania.…”

“…Significantly ( P = 0.007) more studies were based on the collection of specimens during the daylight period ( n = 14 papers), in particular in South America (Moreira et al , 2013; Peng et al , 2017; Bechara et al , 2018; Ramos-de-Souza et al , 2018; Silva et al , 2020; Souza et al , 2021), with only five surveys being conducted at night (Lim & Heyneman, 1965; Morocoima et al , 2014; Cuasapaz-Sarabia, 2016; Peng et al , 2017; Bechara et al , 2018), and thirty-two studies did not specify the collection period (online supplementary file table S2). Five studies referred to the collection of specimens during the rainy season (Caldeira et al , 2007; Vitta et al , 2011; Andrade-Porto et al , 2012; Cuasapaz-Sarabia, 2016).…”

“…2.Nematodes found infecting A. fulica and their geographical distribution Significant variation (P = 0.001) was found in the number of papers published on the different species of nematode found infecting A. fulica, with the largest number of papers referring to A. cantonensis (Chen, 1935), primarily in the countries of Asia (n = 14) and South America (n = 15). In Asia, A. fulica infected with A. cantonensis were recorded in Taiwan, Thailand, Japan, Malaysia, Indonesia, Philippines, China and Singapore(Lim & Heyneman, 1965;Bisseru, 1971;Stafford et al, 1976;Lv et al, 2009;Hu et al, 2011;Deng et al, 2012;Yang et al, 2012;Constantino-Santos et al, 2014a;Kim et al, 2014;Song et al, 2016;Peng et al, 2017) while in South America, this nematode…”

Population genetic structure and phenotypic diversity of Aspidodera raillieti (Nematoda: Heterakoidea), a parasite of Didelphini marsupials in Brazil’s South and Southeast Atlantic Forest

“…Among them, gene flow is considered of fundamental importance, as it allows the exchange of genetic information between populations, homogenizing the variation among them [ 65 ]. Population genetic studies of parasitic helminths have shown that gene exchange between populations is strongly influenced by the movement of their vertebrate [ 17 , 22 ] and invertebrate hosts [ 66 ]. Aspidodera raillieti is a parasite with a monoxenous life cycle [ 10 ], depending on its mammalian hosts for dispersion.…”