Capillariaisis (Trichurida, Trichinellidae, Capillaria hepatica) in the Brazilian Amazon: low pathogenicity, low infectivity and a novel mode of transmission

Abstract

BackgroundHuman capillariasis caused by Capillaria hepatica (syn. Calodium hepaticum) is a rare disease with no more than 40 cases registered around the world. Classically, the disease has severe symptoms that mimic acute hepatitis. Natural reservoirs of C. hepatica are urban rodents (Mus musculus and Rattus novergicus) that harbor their eggs in the liver. After examining the feces of 6 riverine inhabitants (Rio Preto area, 8° 03'S and 62° 53' W to 8° 14'S and 62° 52'W) of the State of Rondonia, Brazil, and identifying C. hepatica eggs in their feces, the authors decided to investigate the real dimension of these findings by looking for two positive signals.MethodsBetween June 1st and 15th, 2008, 246 out of 304 individuals were clinically examined. Blood samples were collected, kept under -20°C, and test by the indirect immunofluorescence technique.ResultsThe first positive signal was the presence of specific antibodies at 1:150 dilution, which indicates that the person is likely to have been exposed to eggs, most likely non-infective eggs, passing through the food chain or via contaminated food (total prevalence of 34.1%). A second more specific signal was the presence of antibodies at higher titers, thus indicating true infection.ConclusionsThe authors concluded that only two subjects were really infected (prevalence of 0.81%); the rest was false-positives that were sensitized after consuming non-embryonated eggs. The present study is the first one carried out in a native Amazonian population and indicates the presence of antibodies against C. hepatica in this population. The results further suggest that the transmission of the parasite occurs by the ingestion of embryonated eggs from human feces and/or carcasses of wild animals. The authors propose a novel mode of transmission, describing the disease as a low pathogenic one, and showing low infectivity.

Capillaria hepatica (Bancroft, 1893) (Nematoda) entre populações indígenas e mamíferos silvestres no noroeste do Estado do Mato Grosso, Brasil, 2000

“…Calodium hepaticum; Hepaticola hepatica) é um helminto hepatotrópico da família Trichinellidae que comumente infecta roedores, lagomorfos e outros vertebrados como canídeos, felinos, 1,2,3,4 pecaris e primatas não humanos . Este parasita, potencialmente zoonótico, também é associado a casos 5,6,7,8 esporádicos de infecção em humanos .…”

Helminth parasites of Lemniscomys striatus (striped grass mouse) and Cricetomys gambianus (giant African rat) in Nsukka, Nigeria

“…Hepatic necrosis, parasitic hepatitis, hepatic fibrosis, persistent fever, hepatomegaly and eosinophilia have been recorded in human infections [21]. Also Hymenolepis spp.…”

Helminths in rodents from Wet Markets in Thailand

“…Nevertheless, the habitats in which captures were performed are not well defi ned and so it is not easy to compare these author's results with those of the present study. In the Brazilian Amazon, Camargo et al (2010) immunofl uorescence techniques to establish an association between infected rodents and the incidence of hepatic capillariosis in workers in markets where there is a high incidence of C. hepatica in rodents. Although the high prevalence of C. hepatica in commensal rodents may increase the health risk in humans, to date human seroprevalence has not been examined in SEA.…”