Angiostrongylus (Parastrongylus) cantonensis on intermediate and definitive hosts in Ecuador, 2014-2017

In the Dawn of an Early Invasion: No Genetic Diversity of Angiostrongylus cantonensis in Ecuador?

The nematode Angiostrongylus cantonensis has been reported worldwide. However, some basic questions remain unanswered about A. cantonensis in Ecuador: (1) Was the invasion of A. cantonensis in Ecuador unique, or did it occur in different waves? (2) Was this invasion as recent as historical records suggest? (3) Did this invasion come from other regions of South America or elsewhere? To address these issues, we assessed the genetic diversity of MT-CO1 gene sequences from isolates obtained in 11 of Ecuador's 24 provinces. Our Bayesian inference phylogenetic tree recovered A. cantonensis as a well-supported monophyletic group. All 11 sequences from Ecuador were identical and identified as AC17a. The haplotype AC17a, found in Ecuador and the USA, formed a cluster with AC17b (USA), AC13 (Thailand), and AC12a-b (Cambodia). Notably, all the samples obtained in Ecuadorian provinces' different geographic and climatic regions had no genetic difference. Despite the lack of genetic information on A. cantonensis in Latin America, except in Brazil, our finding differs from previous studies by its absence of gene diversity in Ecuador. We concluded that the invasion of A. cantonensis in Ecuador may have occurred: (1) as a one-time event, (2) recently, and (3) from Asia via the USA. Further research should include samples from countries neighboring Ecuador to delve deeper into this.

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

The giant African land snail, Achatina fulica, is an important invasive species in many countries, where it causes losses in biodiversity and agriculture, as well as impacting the health of both humans and animals, as the intermediate host of medically important nematodes. The present study is based on a comprehensive review of the literature on the nematodes that have been found in association with A. fulica, worldwide. We searched a number of different databases and used the findings to investigate the methods used to extract and identify the nematodes, their larval stages, and environment and collecting procedures of the infected molluscs. Between 1965 and 2021, 11 nematode species were recorded in association with A. fulica in 21 countries. Most of the studies recorded associations between A. fulica and Angiostrongylus cantonensis, which causes cerebral angiostrongyliasis in humans and Aelurostrongylus abstrusus, which provokes pneumonia in felines. The nematodes were extracted primarily by artificial digestion with hydrochloric acid or pepsin, and identified based on their morphology or through experimental infection to obtain the adult. In most cases, the nematodes were at larval stage L3, and the infected A. fulica were collected from anthropogenic environments. The results demonstrate the importance of A. fulica as a host of nematodes of medical and veterinary importance, as well the contribution of anthropogenic environments to the occurrence of the parasites, and give information about the different methods used to collect and identify the nematodes found associated with this species.