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Introduction: Angiostrongylus cantonensis is a serious public health problem and is widely distributed in the country. When the parasite infects the snails, it becomes deeply embedded in their interior and accidentally, it can infect people and other mammals. Objective: To establish the geographical distribution of A. cantonensis intermediate hosts (Achatina fulica) and definitive hosts (Rattus spp.) in Ecuador from 2014 to 2017. Materials and methods: We collected 2,908 A. fulica specimens in 16 provinces using the capture method per unit of effort for 30 minutes. We captured 211 hosts of which 20 were Rattus rattus and 191 R. norvegicus. The specimens were transported to the Instituto Nacional de Salud Pública e Investigación in Guayaquil where the larvae L3 were identified and counted in the tissues of the snail, which were then inoculated in laboratory rats to reproduce the life cycle. In the rodents, the brains, hearts, lung arteries and lungs were dissected, and the parasites were identified by taxonomic morphology. Results: Of the snails harvested, 441 were positive for A. cantonensis (15.2%) and a total of 6,166 L3 larvae were found; 77 (36.5%) specimens of Rattus spp., were infected with A. cantonensis and a total of 220 parasites (L4-L5 larvae and adult worms) were collected. Conclusions: We confirmed the presence of A. cantonensis in several provinces, which ratifies the endemic nature of this zoonosis in the national territory. Rattus spp. specimens constitute the definitive hosts of the parasite, which together with the presence of intermediate hosts, indicates the zoonotic potential of this parasitic infection.

Objective: To observe the effect of artificially construction of the life cycle of Angiostrongylus cantonensis in the laboratory condition, so as to provide the basis for the research of angiostrongyliasis., Methods: SD rats were infected orally with the third-stage larvae of A. cantonensis collected from infected Pomacea canaliculata. Six weeks after the infection, the first-stage larvae were isolated and counted from fresh feces of the rats and then were used to infect P. canaliculata. Three weeks later, the snails were dissected for counting the third-staged larvae of A. cantonensis., Results: The first-stage larvae were detected in the feces of the rats 6 weeks after the infection, and the third-staged larvae were successfully isolated after the infection of P. canaliculata., Conclusion: The animal model of the entire life cycle of A. cantonensis is successfully established in the laboratory with the infection of 50 larvae per rat.

Angiostrongylus cantonensis is a metastrongyloid nematode in the family Angiostrongylidae. It is the cause of angiostrongyliasis (rat lungworm disease), which manifests as eosinophilic meningitis. First described in 1935 from rats in China, A. cantonensis was placed in the genus Parastrongylus in 1986, but most workers have not adopted this treatment. The taxonomy of A. cantonensis and related worms is largely based on adult morphology, notably of the male bursa. However, identification of infective third stage larvae is more difficult. The natural life cycle involves rats as the definitive host and snails or slugs as the intermediate host. Human infection, as accidental hosts, results in worms maturing in the brain, but dying there instead of moving back into the bloodstream, as in rats, thereby leading to eosinophilic meningitis. The disease is an emerging infectious disease; Angiostrongylus cantonensis continues to be reported in new regions beyond its native range.

The metastrongyloid nematode genus Angiostrongylus includes 18 species, two of which are relevant from a medical standpoint, Angiostrongylus costaricensis and Angiostrongylus cantonensis. The first was described from Costa Rica in 1971 and causes abdominal angiostrongyliasis in the Americas, including in Brazil. Angiostrongylus cantonensis, first described in 1935 from Canton, China, is the causative agent of eosinophilic meningitis. The natural definitive hosts are rodents, and molluscs are the intermediate hosts. Paratenic or carrier hosts include crabs, freshwater shrimp, amphibians, flatworms, and fish. Humans become infected accidentally by ingestion of intermediate or paratenic hosts and the parasite does not complete the life cycle as it does in rats. Worms in the brain cause eosinophilic meningitis. This zoonosis, widespread in Southeast Asia and the Pacific islands, has now been reported from other regions. In the Americas there are records from the United States, Cuba, Jamaica, Brazil, Ecuador, and Haiti. In Brazil seven human cases have been reported since 2007 from the southeastern and northeastern regions. Epidemiological studies found infected specimens of Rattus norvegicus and Rattus rattus as well as many species of molluscs, including the giant African land snail, Achatina fulica, from various regions of Brazil. The spread of angiostrongyliasis is currently a matter of concern in Brazil.

This study was conducted to gain an understanding of the Angiostrongylus cantonensis infection status of rodent definitive host, snail intermediate host, and local residents in Guangzhou, China. A total of 430 rats were captured and 23 rats, from two species, were infected, with an average infection rate of 5.35%. A total of 795 Achatina fulica snails and 734 Pomacea canaliculata snails were collected. The average infection rates of these two species were 13.96% (111 of 795) and 1.50% (11 of 734), respectively. As for the seroprevalence of different occupations, the rate among the "general group" was significantly lower than the "occupational group." From this survey, Guangzhou is implicated to be the natural focus of Angiostrongylus cantonensis. Rattus norvegicus and Achatina fulica play important roles in spreading this nematode in Guangzhou. Residents who live in Guangzhou, especially those working in certain industries such as agriculture, food-making, and aquaculture, face a higher risk of infection.