A longitudinal study of Angiostrongylus cantonensis in an urban population of Rattus norvegicus in Brazil: the influences of seasonality and host features on the pattern of infection

Abstract

Background: The nematode Angiostrongylus cantonensis is a zoonotic parasite and the most important cause of eosinophilic meningitis worldwide in humans. In Brazil, this disease has been reported in the states of Espírito Santo and Pernambuco. The parasite has been detected in the naturally infected intermediate host, in the states of Rio de Janeiro, Pernambuco and Santa Catarina. The murid Rattus norvegicus R. rattus were recently reported to be naturally infected in Brazil. In this study, we conducted a two-year investigation of the dissemination pattern of A. cantonensis in R. norvegicus in an urban area of Rio de Janeiro state, Brazil, and examined the influence of seasonality, year, host weight and host gender on parasitological parameters of A. cantonensis in rats. Methods: The study was conducted in an area of Trindade, São Gonçalo municipality, Rio de Janeiro, Brazil. Prevalence of infected rats, intensity and abundance of A. cantonensis were calculated, and generalized linear models were created and compared to verify the contribution of host gender, host weight, year and seasonality to the variations in A. cantonensis abundance and prevalence in rats. Results:The prevalence of A. cantonensis infection was stable during the rainy (71%, CI 58.9-81.6) and dry seasons (71%, CI 57.9-80.8) and was higher in older rats and in females. Seasonality, host weight (used as a proxy of animal age) and gender were all contributing factors to variation in parasite abundance, with females and heavier (older) animals showing larger abundance of parasites, and extreme values of parasite abundance being more frequent in the dry season. Conclusions: The high prevalence of this parasite throughout the study suggests that its transmission is stable and that conditions are adequate for the spread of the parasite to previously unaffected areas. Dispersion of the parasite to new areas may be mediated by males that tend to have larger dispersal ability, while females may be more important for maintaining the parasite on a local scale due to their higher prevalence and abundance of infection. A multidisciplinary approach considering the ecological distribution of the rats and intermediate hosts, as well as environmental features is required to further understand the dynamics of angiostrongyliasis.

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

“…In comparison with some other cities/provinces in China, e.g., Shenzhen [ 26 ] and Xiamen [ 27 ] and Hainan [ 28 ], the infection rates of P. canaliculata were lower than those from our findings, but they were higher in Dali [ 29 ] and Guangzhou [ 30 ]. However, our reported rate of infected rats was lower than those reported in Rio de Janeiro in Brazil [ 31 ], Canary Islands [ 32 ] and Nueva Ecija in the Philippines [ 33 ]; while it was higher than those found in Guangzhou [ 34 ] and Zhongshan [ 35 ] in China.…”

Angiostrongylus cantonensis infection in molluscs in the municipality of São Gonçalo, a metropolitan area of Rio de Janeiro, Brazil: role of the invasive species Achatina fulica in parasite transmission dynamics

“…Recent studies have reported A. cantonensis infection in Brazil in Rattus rattus and R. norvergicus, with both acting as definitive hosts ( Simões et al 2011 , Moreira et al 2013 ). In the studied area, infected R. norvergicus were observed to have high prevalence and abundance of A. cantonensis and to contribute to dispersing the parasite to new areas ( Simões et al 2014 ).…”

The Prevalence of Angiostrongylus cantonensis/mackerrasae Complex in Molluscs from the Sydney Region

“…Several rat species are recognised as definitive hosts of A . cantonensis , while terrestrial and freshwater molluscs are intermediate hosts [ 1 , 5 , 6 ]. In Australia, two exotic rat species; Rattus rattus and Rattus norvegicus are the preferred definitive hosts for A .…”