Onchocerciasis in British cattle: a study ofOnchocerca gutturosaandO. lienalisin North Wales

Abstract

Onchocerca gutturosaandO. lienalisinflections in British cattle were studied by examination of cattle post-mortem originating from North Wales and Cheshire (north west England). In 463 adult animals, the microfilarial (mf) prevalence was 28·5%. In 95·3% of the inflected animals, gravid worms could not be found at either the ligamentum nuchae or the gastro-splenic omentum. Dermal mf at the head were identified asO. gutturosaon the basis of their highly significant assocation with the presence of gravidO. gutturosaat the ligamentum nuchae, which were found in only 3·2% of cattle. Mfs were isolated from different skin sites and from adult worms and a minimum of 10 mfs from each isolate were examined for width and acid phosphatase (AP) staining pattern. The width ofO. gutturosadermal mf was <4 μm (4 isolations), narrower than of putativeO. lienalismf isolated from umbilical skin of cattle without evidence ofO. gutturosa, which were in 20/22 isolations >4 μm wide. The dermal mf were also distinguished on the basis of different AP staining patterns which, for each species, correlated closely with that of hatched intrauterine mf from their respective adult female worms. Based on the criteria of morphology and AP staining patterns the mf species prevalences in the survey population were estimated asO. lienalis24·1% andO. gutturosa2·2%, with a further 2·2% of cattle inflected with both species. The results indicate that the predilection site of adultO. lienalisis not the gastro-splenic omentum. In North Wales, the distribution of the two species was different;O. lienaliswas widely distributed in all cattle rearing areas both lowland and upland, whereasO. gutturosawas largely restricted to valleys close to major rivers.

Development of microfilariae of two bovine Onchocerca species in blackflies in Japan.

“…The present data are not enough to conclude that microfilariae of O. gibsoni or O. gutturosa were present in the materials used but could not develop to L3 in blackflies. Instead, it is considered that most of the Y type microfilariae examined were O. lienalis and a few, if present, were O. gibsoni or O. gutturosa, because an acid phosphatase activity pattern of Y type microfilariae observed (unpublished data) is consistent to that of O. lienalis, as reported by Trees et al (1987) . Further experiments are needed to determine the susceptibility of blackflies to O. gutturosa bidentatum serves as the natural vector of the fourth unnamed Onchocerca in both areas (unpublished data) .…”

Infections of blackflies (Diptera: Simuliidae) with three types of zoonotic Onchocerca larvae in Oita, Japan

“…However, no such an increased infection rate was observed in S. bidentatum for type I (1.2% for blood-fed flies vs. 2.0% for unfed ones) and type II (0.6% vs. 0.7%). Most of the thirdstage larvae of types I and II found in blood-fed S. bidentatum might have originated from the previous infection; it should be noted that the rate of S. bidentatum ingesting microfilariae resembling O. gutturosa is suspected to be very low, since majority of type X microfilariae are likely to be O. lienalis, judging from the characteristic consistent pattern of acid phosphatase activity (unpublished data), as observed in the microfilariae of O. lienalis (Trees et al, 1987). Further studies are needed to related type X microfilariae to types II and III third-stage larvae.…”

Theoretical Potential of Passerine Filariasis to Enhance the Enzootic Transmission of West Nile Virus

“…The prevalence of Onchocerca spp. MF in the dermis of European cattle are substantial, that is, Austria (131/345; Safar-Hermann and Supperer 1983) Germany (175/438; Dohnal et al 1990), Wales (130/463; Trees et al 1987), and Finland (77/209; Solismaa et al 2008). If bovine onchocerciasis were shown experimentally to accelerate the EIP of bluetongue virus in the midge vector, then antihelminthic treatment of cattle herds may prove to be an effective supplement to traditional bluetongue management strategies (i.e., vector control).…”