Search

Mast cells and eosinophils have been identified by differential stainings and counted in mucous membrane of nasal septum, turbinates and sinus of 77 ewes naturally infected with Oestrus ovis. Results have been compared with those of nine parasite free lambs. Anova tests indicate significant differences between infected and parasite-free sheep for the cell numbers and their distribution among the septum, the turbinates and the sinus and according to their position in mucous membrane, interglandular chorion of sub-mucosa. In infected sheep, the mean number of mast cells is twice the number present in parasite free animals. The burdens of eosinophils are multiplied by 17 for the septum, 29 for the turbinates and 58 for the sinus. The hypothesis of the development of an hypersensitivity phenomenon in ovine oestrosis is sustained by these results.

Sera from 421 Djallonke and Sahelian Bali Bali sheep from Burkina Faso were analyzed with ELISA tests using a crude antigen from stage 2 (L2) larvae of Oestrus ovis. Seropositive mean prevalence was 86.3% with no significant difference between both breeds. In Sahelian and Djallonke sheep optical densities (OD) were, at most, 450% and 250% higher, respectively, than those in control seropositive animals. In addition, a few Sahelian sheep displayed very high seropositivity (OD intensity compared to that of positive control animals), whereas seropositivity intensity was more homogenously distributed in Djallonke sheep. This study emphasizes the importance and usefulness of ELISA method of detection. It confirms the high prevalence of Oestrus ovis infestation in healthy animals, which would justify the use of strategic controls.

A survey performed in Dakar (Senegal) showed, for the first time, the presence of Rhinoestrus usbekistanicus in donkeys in the South of the Sahara desert. Out of the 138 heads examined between November and June, 84% were infected by a mean burden of 15.9 larvae (9.7 L1, 1.8 L2 and 4.1 L3). There is a hypobiotic period starting in March during the dry season.

A simplified list of the principal Diptera capable of causing myiasis is followed by a brief presentation of the biology, lesions inflicted, and methods of treatment and control of the myiases of economic importance. Cochliomyiasis caused by Cochliomyia hominivorax is of greatest interest, in view of the damage and losses caused by this disease. A brief account of the outbreak of infestation in Libya illustrates the danger of this parasite. Other important traumatic myiases are described: that due to Chrysomya bezziana, which causes an African myiasis similar to cochliomyiasis, and those due to Lucilia cuprina and related species. Hypodermyiasis (warble fly infestation) and oestrosis (nasal bot fly infestation in sheep) still cause major economic losses in domestic animals, justifying their inclusion in control campaigns. The same applies to stomach bot flies of the family Gasterophilidae. The account of each myiasis includes notes on parasiticides which have been found to be effective. Given the rapidity with which a parasite can now be transported from one continent to another, it is important for Veterinary Services to be well-informed and vigilant.

The combined drug Mebendazole plus Trichlorfon (Telmin plus Trichlorfon, Janssen Pharmaceutica, Beerse/Belgium) has been tested in a field trial against naturally acquired Gasterophilus spp. infestations in horses. 44 foals (1 to 1.5 years old, 350-450 kg body-weight) originating from different endemic areas of Switzerland, have been randomly allocated to two groups as follows: 28 foals were treated with Mebendazole plus Trichlorfon, 16 animals served as untreated controls. The drug (paste) was administered and dosed according to the user's instruction. Macroscopic examinations of the digestive tractus and the larval counting has been performed immediately after slaughtering, i.e. 30 and 33 days after treatment, resp.. The efficacy of the product against Gasterophilus spp. amounts to 97.04% which is considered as highly effective. A further proof for the high efficacy is the observation of a lot of larvae-carrying foals in the control group. Since the larvae of Gasterophilus spp.--according to their life cycle--are essentially found in their hosts between November and February, an appropriate treatment should be performed during that period of time.

The changes of antibody titers in the sera of colts infested naturally or artificially with Gasterophilus have been determined in relation to the life cycle of this arthropod using passive hemagglutination, complement fixation, double diffusion techniques and saline extracts of antigens from the third larval stages of Gasterophilus intestinalis and G. nasalis.In the sera of the infected animals the hemagglutinating antibodies were present at low titers at the third week post-infestation by using somatic extract of G. intestinalis and at the seventh week in case of G. nasalis. At eight weeks post-infestation the antibody titers reached their maximum 1:8192 (G. intestinalis) and 1:4096 (G. nasalis), then dropped at 12 weeks post-infestation. The complement fixing antibodies were present occasionally between the seventh and 11th weeks after infestation. Precipitating antibodies were absent in all sera.