Advances in laboratory diagnosis of parasitic infections of sheep.

Parasitic infections constitute an important group of diseases in sheep concerning the health status, welfare and productivity. On a global scale, there are considerable differences concerning the epidemiological situation with respect of the various parasite species. However, there are also numerous species, which occur on all continents and, potentially, in every country. Accordingly, the present review aims to providing an overview about the recent developments in methods and technologies for the laboratory diagnosis of parasite infections in sheep. Following in principle a systematic order the review encompasses publications addressing the diagnosis of helminthes (i.e., trematodes, cestodes and nematodes) and arthropod species. New approaches using conventional (e.g., microscopic), immunological and molecular techniques are being considered. The diagnosis of anthelmintic resistance is highlighted separately, due to its significant importance. The review ends with an outlook into the future by discussing most recent technological advances, which might become of use for the diagnosis of parasite infections in sheep in the future.

Evaluation of the efficacy of emodepside+praziquantel topical solution against cestode (Dipylidium caninum, Taenia taeniaeformis, and Echinococcus multilocularis) infections in cats.

Emodepside+praziquantel topical solution was developed to provide broad-spectrum anthelmintic activity against gastrointestinal parasites in cats. Eight controlled studies were conducted to evaluate the efficacy of a topical solution of emodepside (3 mg/kg) and praziquantel (12 mg/kg) (Profender, BayerAG, Leverkusen, Germany) against feline infections with three species of cestodes. Studies featured naturally acquired infections of Dipylidium caninum or Taenia taeniaeformis, or experimental infections with Echinococcus multilocularis that were placebo-controlled, randomized and blinded. Cats were euthanatized and necropsied between 2 and 11 days after treatment, depending on the target parasite. The efficacy of emodepside+praziquantel topical solution was 100% against D. caninum and T. taeniaeformis, and 98.5- 100% against E. multilocularis. No significant systemic or local adverse reactions to treatment were noted in cats that received the combination. Topical treatment of cats with emodepside+praziquantel topical solution was safe and highly effective against cestode infections.

Crossreacting IgG antibodies against fox mite antigens in human scabies.

Scabies continues to be an important parasitic disease of mammals. There remain, however, major gaps in the understanding of the human host immune response, and a simple diagnostic test is lacking. In contrast to human mites, red fox mites (Sarcoptes scabiei var. vulpis) can be collected easily and have been used, due to crossreactivity, for enzyme-linked immunosorbent assay (ELISA) studies in dogs and pigs. We wanted to investigate the possibility that crossreactivity might also exist for the human mite, and determined titers against fox mite antigens by ELISA in 41 patients with scabies. Specific IgG was significantly higher in patients with scabies than in healthy controls (P=0.01). The sensitivity was, however, only 48%, although it increased slightly during treatment (P=0.86). A positive correlation was also noted between disease duration and severity of infestation (r=0.5), with specific IgG titers increasing in parallel with severity of symptoms (P=0.01). Patients with symptomatic scabies for more than 4 weeks had furthermore significantly higher IgG titers than patients with a shorter duration of disease (P=0.007). In conclusion, these findings demonstrate IgG antibodies in human scabies that crossreact with fox mite antigens, thus encouraging the search for improved ELISAs with more specific mite antigens to produce a more sensitive detection system for scabies in humans.

Detection of antibodies in sera of weaned pigs after contact infection with Sarcoptes scabiei var. suis and after treatment with an antiparasitic agent by three different indirect ELISAs.

Three commercial enzyme-linked immunosorbent assays (ELISAs) were compared for the detection of antibodies to Sarcoptes scabiei var. suis using experimental sera of six 8-week-old pigs after contact infection with Sarcoptes scabiei var. suis. Six non-infected pigs were monitored as a control group. Blood sera were taken once a week from all animals. After successful infection the pigs were treated with an antiparasitic agent (12 weeks post infection (p.i.)) and the antibody titres were monitored until they were negative. The antibody levels of the experimental pigs reached the cut-off level 5 weeks after introduction of an infected animal to the group and were positive by both the Sarcoptes-ELISA 2001 PIG and the Acar-Test P-ELISA. Four weeks after treatment mean results showed optical densities (% OD) below the cut-off level in the Sarcoptes-ELISA 2001 and 8 weeks after treatment in the Acar-Test P-ELISA. In the Chekit Sarcoptest pigs had elevated antibody levels in comparison to control animals, but ODs remained below the given cut-off level at all times. In a second examination with Chekit Sarcoptest (different lot) and at a lower cut-off level, the sera of most of the piglets tested positive. Eight weeks after treatment, four from six pigs still had positive OD values. Therefore this investigation showed a higher sensitivity for the Sarcoptes-ELISA 2001 and the Acar-Test P-ELISA than for the Chekit Sarcoptest. Different test sensitivities must be considered when serologic methods are used for the diagnosis of swine sarcoptic mange, especially for monitoring and controlling eradication programs.

[Liver fluke infection and sarcoptic mange in red foxes in Berlin]. / Leberegelbefall und Räude beim Rotfuchs in Berlin.

396 red foxes originating from the city of Berlin were examined for opisthorchiid liver flukes and clinical sarcoptic mange between January 1997 and March 1998. Out of 232 (= 58.6%) foxes positive for opisthorchiid flukes 221 animals harboured Metorchis bilis and 70 were infected with Opisthorchis felineus. Pseudamphistomum truncatum was found only in 8 foxes. M. bilis occurred as mono-infection in 154 animals. M. bilis in combination with O. felineus was found in 61 cases. Pure Opisthorchis infection as well as other fluke combinations were found in a small number of animals only. 85 (= 21.5%) foxes showed clinical sarcoptic mange. Liver fluke positive foxes showed a higher mange prevalence than uninfected animals. However, significant associations between flukes and manage were only found when comparing uninfected foxes with those having the highest worm burden. The association of liver flukes and mange could be established for adult female foxes by a significant Odds Ratio of 4.3.

[Eradication of Chorioptes bovis mange in a dairy herd with turn-out to graze by Eprinex Pour-On]. / Versuch der Tilgung der Chorioptes bovis-Räude in einem Milchviehbestand mit Weidehaltung mit Eprinex Pour-On.

The possibility to control or even eradicate chorioptes manage by a single herd treatment with EPRINEX Pour-On (dosage: 0.5 mg Eprinomection/kg bodyweight) during pasture season was investigated in a dairy herd of 320 dairy cows. A further aim of the study was to evaluate whether such mid-summer treatment with EPRINEX Pour-On due to its endo-ectocide action would at the same time also result in a metaphylaxis of gastro-intestinal and lung worms and in a reduction of fly infestation. Due to clinical symptoms manage prevalence in the herd prior to treatment was 11 percent. After treatment, clinical symptoms disappeared within 2 months completely and did not re-occur during the subsequent housing period. Chorioptes mites during the entire trial period no longer were detected. The final clinical and parasitological investigation shortly before turn-out the next year (April 1999) demonstrated chorioptes mange to be eradicated clinically and parasitologically. Due to the mid-summer treatment infestation with gastrointestinal helminths also was eliminated and clinical symptoms of helminth infestations during the pasture season no longer were observed. However, at housing in November, low numbers of eggs of gastrointestinal nematodes were detected in 6% of dairy cows, 32% of second-season and 63% of first-season heifers, respectively. Milk yield per cow and day on average increased by 1 litre after treatment with EPRINEX Pour-On. This increase in production is likely a result of the reduction in total parasite burden of lactating cows.

'Babesia gibsoni' of dogs from North America and Asia belong to different species.

18S rDNA sequences from 4 isolates of Babesia gibsoni originating from Japan, Malaysia and Sri Lanka were compared with a previously published, 0.5 kb portion of the 18S rDNA from a B. gibsoni isolate from California, USA, and with the corresponding 18S rDNA sequences of other Babesia spp. Distance, parsimony and maximum likelihood analyses showed almost identical genotypes among the small canine Babesia from Asia, but an unexpectedly distant genetic relationship to that from the USA. While the American isolate segregated together with B. equi, the Asian isolates showed a close relationship to B. divergens and B. odocoilei. These results indicate that small Babesia of dogs originating from North America and Asia belong to different, genetically distantly related species.

Detection of a new pathogenic Babesia microti-like species in dogs.

Small babesiae in dogs are generally considered to belong to Babesia gibsoni. Here we describe the genotypic characterisation of small piroplasms found in the blood of a dog which suffered from clinical babesiosis. Pairwise identities as well as distance, parsimony and maximum likelihood analyses of the 18S rDNA clearly demonstrated that this isolate was only distantly related to the other canine piroplasms characterised genetically so far, including B. gibsoni. It was more closely related to B. microti, B. rodhaini, and Theileria equi. It is concluded that the small canine piroplasms described in this study represent a hitherto unknown species and that the fauna of piroplasms occurring in dogs is more diverse than assumed so far.

Lymphocyte stimulatory capacity of Theileria annulata-infected ovine lymphoblastoid cells.

T. annulata, the causative agent of tropical theileriosis in cattle, is transmitted by ticks of the genus Hyalomma. Sporozoites of this parasite invade their target cells, where they differentiate to macroschizonts. T. annulata additionally invades and transforms ovine and caprine leukocytes. T. annulata infection in the ovine system is poorly studied, thus we used a mixed lymphocyte culture (MLC) to analyze the capacity of these cells to activate naïve uninfected ovine cells. The peak response was observed on day three or four and the response could not be induced by lysates of infected cells or their supernatants. The stimulated cells expressed IL-2 and secreted an IL-2-like growth factor.