Calodium hepaticum (Nematoda: Capillariidae) in synanthropic rodents (Rattus norvegicus and Rattus rattus) in Eastern Amazonia

Abstract

Calodium hepaticum (syn. Capillaria hepatica) is a trichurid nematode that parasitizes the hepatic parenchyma of rodents and other mammals. Infections in humans are rare, although they have been reported worldwide. A number of factors contribute to the distribution of this zoonosis, particularly the presence of dense populations of rodents associated with relatively poor urban environments, such as those found in parts of the northern Brazilian city of Belém in the eastern Amazon Basin. This study quantified Calodium infections in commensal synanthropic rodents in Belém. Rodents were captured in three neighborhoods characterized by poor public sanitation and the city's highest incidence of human leptospirosis. A total of 50 rodents were captured (26 Rattus rattus and 24 R. norvegicus), and 23 (10 R. rattus and 13 R. norvegicus) presented macroscopic lesions typical of C. hepaticum. Light microscopy of fresh samples and histological specimens permitted the identification of larvae and adult specimens containing numerous eggs with a double-striated shell and bipolar opercula with plugs. This is the first report of C. hepaticum in R. rattus and R. norvegicus from the Amazon Basin, and it shows a considerable risk of transmission to the local human population.Keywords: Calodium hepaticum, Rattus rattus, Rattus norvegicus, public health, synanthropic animals, zoonosis. ResumoCalodium hepaticum (syn. Capillaria hepatica) é um nematódeo trichurídeo parasito de parênquima hepático de roedores e outros mamíferos. As infecções em humanos são raras, mas são relatadas em diversas regiões do mundo. Numerosos fatores contribuem para a distribuição desta zoonose, particularmente, uma densa população de roedores associada com ambientes urbanos com carência de saneamento básico, tais como aqueles encontrados em algumas cidades da região Norte do Brasil, como a cidade de Belém, localizada na Amazônia Oriental. Este estudo quantifica e demonstra a infecção por Calodium em roedores comensais sinantrópicos, de três bairros da cidade de Belém, Estado do Pará, com carência de saneamento público e alta incidência de leptospirose humana. Um total de 50 roedores foram capturados para análise (26 Rattus rattus e 24 R. norvegicus) e destes, 23 (10 R. rattus e 13 R. norvegicus) apresentaram típicas lesões hepáticas, macroscópicas, causadas por C. hepaticum. A análise de amostras por microscopia de luz direta e histopatológica do fígado dos roedores permitiu a identificação de espécimes desse parasito em fase larvar e adulta, além de numerosos ovos apresentando dupla casca estriada e dois tampões operculares. Este é o primeiro registro da ocorrência de C. hepaticum in R. rattus and R. norvegicus na região Amazônica, alertando para um considerável risco de transmissão para a população humana.Palavras-chave: Calodium hepaticum, Rattus rattus, Rattus norvegicus, saúde pública, animais sinantrópicos, zoonose.

PREVALENCE OF Calodium hepaticum (SYN. Capillaria hepatica) IN Rattus norvegicus IN THE URBAN AREA OF RIO DE JANEIRO, BRAZIL

“…The prevalence in this study is high and similar to that found in the states of São Paulo (59%) 5 , Bahia (56%) 8 and Pará (42%) 13 . The short life cycle of rats causes rapid release of large numbers of eggs in the environment.…”

“…In Brazil, this parasite has been reported infecting humans and various species of domestic and wild mammals 2,12,13,14,15,18,20 . In synanthropic rodents, C. hepaticum has been recorded in the states of São Paulo, Bahia and Pará 5,7,13 .…”

“…In synanthropic rodents, C. hepaticum has been recorded in the states of São Paulo, Bahia and Pará 5,7,13 . In Rio de Janeiro, a previous survey has been performed to monitor Rattus norvegicus for detection of zoonotic parasitic diseases in a densely populated urban region 19 .…”

Zoonosis associated to Rattus rattus and the impacts of the public actions to control the species

“…Records of the nematode were also recently registered in the city of Belém, in Eastern Amazon (Moreira et al, 2013). In most rodents, infection by C. hepaticum ranges from mild to severe, but it is not associated with a clinical disease.…”

Helminth fauna of wild rabbit Oryctolagus cuniculus in the Canary Islands, Spain

“…The same fact might explain the prevalence of A. cuniculi in Tenerife and El Hierro. Finally, C. hepaticum is a cosmopolitan zoonotic nematode that parasitizes the liver of mammal species, particularly rats and mice, although the list of host species is exceptionally long, including wild lagomorphs (Moreira et al, 2013). Cases of human infections with C. hepaticum have been reported in different continents and many of them have proved to be fatal (see Mowat et al, 2009).…”