Host specificity of abomasal nematodes in free ranging alpine ruminants

Abomasums from 641 alpine wild ruminants representing five different species (Cervus elaphus, Capreolus capreolus, Rupicapra rupicapra, Capra ibex, Ovis musimon) and from 19 domestic sheep (Ovis aries) from alpine areas were examined in order to investigate the host-specificity of abomasal helminths. Nine out of 20 helminth species were found in at least five different host species. A discriminant analysis was able to significantly discriminate the hosts on the basis of their helminth community composition with the exception of O. musimon and O. aries. Based on the correlation between each variable represented by helminth species with the most explanatory discriminant axis, it was possible to classify helminths into specialists and generalists. Specialists are represented by the dominant species in a community of an host species or family while generalists appear in the communities of many different hosts as intermediate species. Due to the pathogenic potential of some of these generalist species (i.e. Haemonchus contortus, Trichostrongylus axei) and their ability to adapt easily to the conditions found in several different hosts, they appear to be the most important from a sanitary point of view.     

Infectivity, pathogenicity, and genetic characteristics of mammalian gastric Cryptosporidium spp. in domestic ruminants.

Farm ruminants were infected experimentally with four mammalian gastric Cryptosporidium, namely Cryptosporidium andersoni LI03 originated from cattle and three isolates of Cryptosporidium muris from brown rat (isolate RN66), Bactrian camel (isolate CB03) and firstly characterized isolate from East African mole rat (isolate TS03). Sequence characterizations of the small-subunit rRNA gene showed that the LI03 isolate was C. andersoni and the other three isolates belonged to C. muris, although the TS03 isolate showed unique sequence variations (one single nucleotide change and four nucleotide insertions). C. andersoni LI03 was infectious for calves only, whereas lambs and kids were susceptible to C. muris CB03. C. muris TS03 and RN66 were not infectious for any farm ruminants. Infection dynamics including prepatent and patent period and infection intensity of the isolates used differed depending on the host species, but no clinical signs of cryptosporidiosis were observed in any of experimentally infected hosts. Cryptosporidium developmental stages were only detected in infected animals in the abomasum region. Histopathological changes were characterized by dilatation and epithelial metaplasia of infected gastric glands with no significant inflammatory responses in the lamina propria.     

Cryptosporidium spp. in ruminants at the Lisbon Zoo.

Feces from 34 species of ruminants housed at the Lisbon Zoo was examined for Cryptosporidium spp. oocysts. Three hundred and eighty-eight samples were analyzed. Three hundred and eighty species-specific group fecal samples were collected monthly, from September 1998 until August 1999, along with eight individual specimens from eight neonates. All samples were examined by four different techniques: microscopic observation of direct and concentrated fecal smears, staining with modified Ziehl-Nielsen, immunofluorescent assay, and immunoenzymatic assay. The prevalence of infection was 3.6%. Five neonates with diarrhea were infected. Cryptosporidial oocysts were shed more frequently during winter months. Some facilities may have permitted oocysts to remain viable, possibly contributing to cryptosporidial transmission between animals.