Factors affecting carriage and intensity of infection of Calodium hepaticum within Norway rats (Rattus norvegicus) from an urban slum environment in Salvador, Brazil

Abstract

SUMMARY Urban slum environments in the tropics are conducive to the proliferation and the spread of rodentborne zoonotic pathogens to humans. Calodium hepaticum (Brancroft, 1893) is a zoonotic nematode known to infect a variety of mammalian hosts, including humans. Norway rats (Rattus norvegicus) are considered the most important mammalian host of C. hepaticum and are therefore a potentially useful species to inform estimates of the risk to humans living in urban slum environments. There is a lack of studies systematically evaluating the role of demographic and environmental factors that influence both carriage and intensity of infection of C. hepaticum in rodents from urban slum areas within tropical regions. Carriage and the intensity of infection of C. hepaticum were studied in 402 Norway rats over a 2-year period in an urban slum in Salvador, Brazil. Overall, prevalence in Norway rats was 83% (337/402). Independent risk factors for C. hepaticum carriage in R. norvegicus were age and valley of capture. Of those infected the proportion with gross liver involvement (i.e. >75% of the liver affected, a proxy for a high level intensity of infection), was low (8%, 26/337). Sixty soil samples were collected from ten locations to estimate levels of environmental contamination and provide information on the potential risk to humans of contracting C. hepaticum from the environment. Sixty percent (6/10) of the sites were contaminated with C. hepaticum. High carriage levels of C. hepaticum within Norway rats and sub-standard living conditions within slum areas may increase the risk to humans of exposure to the infective eggs of C. hepaticum. This study supports the need for further studies to assess whether humans are becoming infected within this community and whether C. hepaticum is posing a significant risk to human health.

The helminth community of a population ofRattus norvegicusfrom an urban Brazilian slum and the threat of zoonotic diseases

“…These pathogens impart a large burden of disease in human populations, with leptospirosisis being by far the most important with an estimated 1 000 000 annual human cases and 60 000 deaths (Costa et al 2015 a ). Norway rats are also reservoir hosts of several helminths that cause disease in humans (Rafique et al 2009; Hancke et al 2011; Walker et al 2017). For example, the cestode Hymenolepis nana is associated with diarrhoea cases, whereas the nematode Angiostrongylus cantonensis can cause eosinophilic meningitis (EoM) (Alicata, 1965; Schantz, 1996; Alruzug et al 2016).…”

Enzootic Hepatic Capillariasis (Calodium hepaticum) in Street Rats (Rattus norvegicus) from Marseille City, France

“…Though few rat specimens were herein tested, which represent a limitation of the study, we cannot conclude about changing in the prevalence of this parasitosis. In other large cities, the prevalence in the urban rat population is variable, for example: 88% (176/201) in Baltimore (USA), 83% (337/402) in Salvador de Bahia (Brazil), 45% (33/74) in Rio de Janeiro (Brazil), 36% (241/671) in Vancouver (Canada), 26% (109/422) in Henan Province (China), 22% (21/97) in Kuala Lumpur (Malaysia), 20% (51/254) in Medellin (Colombia), 17% (17/100) in Barcelona (Spain) and 6% (18/302) in Belgrade (Serbia) [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”

Discovery of two highly divergent negative-sense RNA viruses associated with the parasitic nematode, Capillaria hepatica, in wild Mus musculus from New York City

“…C. hepatica is a zoonotic parasitic nematode that commonly infects house mice [28], brown rats [29][30][31] and other incidental hosts, including humans [32]. In mammals, ingestion of embryonated C. hepatica eggs precedes larval penetration of the intestine and migration to the liver.…”