Clinicopathological features and histopathology of experimental hepatic capillariasis in muskrats (Ondatra zibethicus)

An overview of the host spectrum and distribution of Calodium hepaticum (syn. Capillaria hepatica): part 1-Muroidea

Calodium hepaticum (syn. Capillaria hepatica) is a worldwide-distributed species of zoonotic nematodes with a high affinity to the liver. Several rodent species of the superfamily Muroidea serve as main hosts for this pathogen. C. hepaticum has been found in Muroidean hosts in more than 60 countries in Europe; North, Central, and South America; Asia; Africa; and Oceania. C. hepaticum was documented in more than 90 Muroidean rodent species (Murinae, Deomyinae, Arvicolinae, Neotominae, Cricetinae, Sigmodontinae, Gerbillinae, and Cricetomyinae). Globally, the Norway rat (Rattus norvegicus) seems to be the main host species for this nematode. However, locally high prevalences (above 50 %) have also been observed in several other synanthropic (commensal and non-commensal) Muroidea species (e.g., Rattus tanezumi, Ondatra zibethicus, Apodemus sylvaticus). This review gives an overview of the distribution and host spectrum of C. hepaticum in Muroidea host species.

Prevalence of Calodium hepaticum (Syn. Capillaria hepatica) in house mice (Mus musculus) in the Azores archipelago

Calodium hepaticum (Syn. Capillaria hepatica) is a zoonotic liver nematode of mammals distributed worldwide. Rodents are believed to be the main reservoirs of this nematode. In this paper, prevalence of the parasite was analyzed in liver histological sections from 51 house mice (Mus musculus) caught in human-inhabited houses, from two localities (Furnas and Rabo de Peixe) on São Miguel island from the Azores archipelago (Portugal). Mean prevalence of infection was 19.6%, with 33.3% prevalence in Furnas and 4.1% in Rabo de Peixe (P=0.07). No significant differences were found between the prevalence of infection and the age, body weight and the sex of mice. Hepatic lesions found were either acute and/or chronic stage and consisted of moderate to severe multifocal pyogranulomatous hepatitis with encapsulated eggs with typical bipolar plugs and moderate to severe necrotizing hepatitis consistent with larva tracks. Periportal inflammatory infiltration, hepatocyte regeneration and bile duct hyperplasia were also noted. In most cases, hepatic lesions occupied more than 50% of the liver, but despite severe lesions, in some mice, no signs of hepatic failure were noticed. The high rate of infection found in the present study suggests that house mice are an important reservoir for this parasite in the Azores and could have a role in human transmission.