Parasitoses caprines dans la région de Chefchaouen: épidémiologie et prophylaxie

Cette étude épidémiologique des parasitoses caprines a été effectuée, de septembre 1993 à août 1994, dans la région de Chefchaouen (Rif). Les caprins conduits en élevage extensif sont exposés à un polyparasitisme interne et externe très diversifié. La population des strongles gastro-intestinaux, constituée de sept espèces, est maximale en décembre et en avril. Les strongles respiratoires composés principalement de protostrongylidés montrent une forte charge parasitaire en septembre, décembre et mai. Au niveau hépatique, le trématode Fasciola hepatica manifeste un pic bicuspidal automno-hivernal. Les parasitoses de moindre importance sont la monieziose et l'oestrose. Parmi les parasitoses transmises au caprin par le chien, la cysticercose hépato-péritonéale prédomine l'hydatidose. Les ectoparasites dominants sont les mallophages en hiver et les ixodidés en été. Un programme de traitement anthelminthique est proposé

Evaluation of rK39 rapid diagnostic tests for canine visceral leishmaniasis : longitudinal study and meta-analysis

Canine visceral leishmaniasis is a vector-borne disease caused by the intracellular parasite Leishmania infantum. It is an important veterinary disease, and dogs are also the main animal reservoir for human infection. The disease is widespread in the Mediterranean area, and parts of Asia and South and Central America, and is potentially fatal in both dogs and humans unless treated. Diagnosis of canine infections requires serological or molecular tests. Detection of infection in dogs is important prior to treatment, and in epidemiological studies and control programmes, and a sensitive and specific rapid diagnostic test would be very useful. Rapid diagnostic tests (RDTs) have been developed, but their diagnostic performance has been reported to be variable. We evaluated the sensitivity of a RDT based on serological detection of the rK39 antigen in a cohort of naturally infected Brazilian dogs. The sensitivity of the test to detect infection was relatively low, but increased with time since infection and the severity of infection. We then carried out a meta-analysis of published studies of rK39 RDTs, evaluating the sensitivity to detect disease and infection. The results suggest that rK39 RDTs may be useful in a veterinary clinical setting, but the sensitivity to detect infection is too low for operational control programmes

Comparison of effects of low and high tick infestations on acquired cattle tick resistance:

Three Holstein calves were infested with low numbers of ticks, two or three pairs of adults Hyalomma marginatum marginatum in cloth bag daily for 21 days. Infestation was carried out during tick proliferation periods. Two months later, cattle leads were challenged with 100 pairs of ticks. Another group of three Holstein calves were infested five times with 100 pairs of adult ticks of the same species. The five infestations were performed two weeks from the previous infestation. Three tick characteristics were recorded for each experiment: survival to detachment, females weight at detachment and egg mass weight. Light continuous infestations did not cause a significant change in this parameter, but every parameter declined gradually in the heavy infestations. Female and egg mass weight reached a significant difference from the first infestation by the fourth infestation. The circulating antibodies anti-salivary glands of Hyalomma m. marginatum showed that light infestation may induce like immuno-suppression. However, there is an inverse relationship between these antibodies and manifestation of resistance when calves were heavily infested. This is discussed in relation to a fraction of produced antibodies against protective antigens, and participation of another effector mechanism

Female tick

Proteins extracted from salivary glands of unfed, three days and five days fed adult Hyalomma marginatum marginatum were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). We have noticed changes during the three feeding steps. Some proteins disappeared during feeding process (23, 38, 39, 40 to 50, 95 and 112 kDa), they might be proteins which were converted in other substances and are secreted. Other antigens (13 to 14, 20, 25, 29, 165 and 210 kDa) were synthesized as a result of tick attachment and feeding. They may be related to growth and development or are the ciment which fixed the adult. Also, three Holstein calves were infested five times with 100 pairs of adult ticks of the same species. The five infestations were performed two weeks from the previous infestation. The sera before infestations and after each infestation were used in western-blot analyses to identify antigens from five days salivary gland extracts of the primary infestation of ticks. Three antigens (18.7, 50 and 80 kDa) were revealed weakly after the first and the second infestations by sera samples but not at infestation onward. Others (13.5, 17 to 18.5, 25, 30, 70, 133, 176 and 193 kDa) were revealed only by sera taken after manifestation of resistance (third infestation). A 13.5 kDa antigen was particularly revealed when resistance had appeared and became more evident after the fourth and fifth infestations. The late antigens recognized might be associated with establishment of calves resistance against ticks

Molecular and serological prevalence of Anaplasma marginale in cattle of North Central Morocco.

A cross sectional study was conducted to investigate the epidemiological distribution of Anaplasma marginale in North Central Morocco. Blood samples from five provinces of Morocco were collected from apparently healthy cattle (n=668) and simultaneously analyzed by a nested polymerase chain reaction (nPCR) assay and competitive enzyme-linked immunosorbent assay (cELISA). The overall prevalence of A. marginale was 21.9% by nPCR and 16.5% by cELISA. The Kappa coefficient between nPCR and cELISA indicated a modest level of agreement (0.54). The prevalence of A. marginale varied significantly according to the province and the month of sampling. However age, gender and breed did not have a significant effect on the prevalence of this pathogen. The highest prevalence of A. marginale was found in the Gharb, a sub-humid area while the lowest was reported in the Saiss, a semi-arid area. These results indicate that an A. marginale infection are widespread in the country and suggests that either or both techniques are excellent tools for epidemiological studies and control programs

ticks: bovine resistance under field conditions as related to host age and breed

Field collection of ticks from two breeds of cattle [Native breed (local) and purebred (Friesian)], showed that the number of ticks was higher on purebred than on native cattle. The susceptibility seemed to increase with the age of the animals. Furthermore, breed appeared to exert more influence than age. There was no correlation between the number of ticks associated with each animal, the antibody production and antigens recognized. The immune response under field condition looked more like immune suppression than immune protection