Validation of an internal method for the diagnosis of infections with Chlamydophila abortus and Coxiella burnetii by real-time multiplex PCR.

Chlamydophila abortus and Coxiella burnetii are one of the major pathogens implicated in abortion in cattle. Their characteristic of obligate intracellular bacteria, and of zoonotic agents, makes their culture difficult in diagnostic laboratories, and the traditional tools of diagnosis (detection of sera antibodies by ELISA, Stamp's coloration) encounter specificity, sensitivity and interpretability limits. Individual PCR have recently been developed. Nevertheless, their income/cost is a limiting factor for breeders. As the symptoms are not specific, the request for analysis often concerns the two valences. Consequently, the development and the validation of an internal multiplex PCR appears to be a suitable solution.

[Sensitivity of double microcentrifugation for the research of trypanosomes]. / Sensibilité de la double microcentrifugation pour la recherche des trypanosomes.

The double microcentrifugation technique, described by KRATZER and ONDIEK (1989) for the parasitological diagnosis of trypanosomes, has been tested both in the laboratory and in the field. The limits of detection obtained here were not as low as those described in the original experiment, but the sensitivity of this technique for the detection of Trypanosoma brucei, T. congolense and T. vivax was better than the phase contrast buffy coat method. This technique, which is easy to apply in the field, is highly recommended, especially for epidemiological surveys. A protocol and a list of equipment are included.

False positive serological reactions in bovine brucellosis: evidence of the role of Yersinia enterocolitica serotype O:9 in a field trial.

To investigate the epidemiology of false positive serological reactions (FPSR) in bovine brucellosis, 1259 bovines from 20 herds were sampled on three successive occasions during the winter of 1993-1994 in an area where the herd prevalence rate of FPSR was high. Serum samples were examined by classical brucellosis serological tests (Rose Bengal and complement fixation) and faeces were cultured for the presence of Yersinia enterocolitica O:9. Thirty-nine bovines expressed at least one positive serological reaction during the study. In the herds with FPSR during the 1993-1994 annual brucellosis surveillance campaign, the specificity of the brucellosis serological tests varied significantly from December to March (97.0% to 99.1%). Y enterocolitica O:9 was isolated from 42 bovines but only three of them showed a positive serological response during the study. Y enterocolitica O:9 isolation rates also decreased with time. Young animals and animals having demonstrated FPSR in the past had a greater risk of having a FPSR. Older animals, which rarely showed FPSR, could form a reservoir for Y enterocolitica O:9. While isolation of Y enterocolitica O:9 was not linked to presence of FPSR and conversely, the FPSR phenomenon should be considered, either at the herd level or at the individual level. This work reinforces the link, at least partial, between FPSR and infection by Y enterocolitica O:9.