Detection of antibodies to Babesia bovis using an ELISA test.

An enzyme-linked immunoassay (ELISA) is described for the detection of antibodies to Babesia bovis using a partially purified antigen. The optimum conditions required to perform the test were determined and 210 serum samples were comparatively tested using ELISA and indirect immunofluorescence (IFA) tests, finding a diagnostic coincidence of 96.1%, a relative sensitivity of 96%, and a relative specificity of 96.4%.

Development of a Babesia bovis live attenuated vaccine.

Babesia bovis is the blood parasite causing the highest morbidity and mortality of cattle in Cuba. Thus a control program based on immunization with a vaccine using an attenuated strain of the parasite was developed. For this purpose, a virulent B. bovis strain was isolated and then attenuated by the traditional method in which biological characteristics, proteolytic activity and vector transmissibility were studied. The protection conferred by the vaccine was measured by vaccinating cattle which then was challenged with a heterologous strain. In order to assess postvaccination accident risks, 2603 cattle were vaccinated and those showing clinical signs of babesiosis were treated. A study of cost-benefit was performed in a herd where frequent outbreaks of babesiosis occurred; prevalence and clinical case incidence in vaccinated and nonvaccinated animals were determined. Vaccinated animals survived to challenge whereas two control animals died. In 2% of the vaccinated animals less than 6 months of age, postvaccination accidents occurred, whereas in older animals this index was higher (p < 0.001). The cost-benefit study showed a rate of approximately $10 pesos (national currency) for each peso invested due to the high mortality caused by the parasite. Until an effective, killed vaccine is available, vaccination with live vaccines is advantageous to prevent bovine babesiosis.

[Presence in Cuba of screw worms (Cochliomyia hominivorax) in the livestock]. / Présence à Cuba de la lucilie bouchère du bétail (Cochliomyia hominivorax).

Screw-worms (Cochliomyia hominivorax Coquerel) constitute a serious plight for livestock in the New World, because they inflict high losses on animals and man. A survey was done by means of an epizootic surveillance system with geographic squares to check for the presence of the insects in Cuba. Screw-worms were detected in 54.8% of myiasis cases all over the island, affecting various animals species, cattle first, followed by swine, sheep and others. Small injuries appeared to be the main enabling factor for screw-worm development. The reasons for the presence of screw-worms without serious consequences on the Cuban livestock are discussed.

[Determination of the protease activity in a Cuban strain of Babesia bovis]. / Détermination de l'activité protéase sur une souche cubaine de Babesia bovis.

The attenuation of a Babesia bovis strain depends on its protease content. The present work evaluates this parameter on a virulent strain, before and after attenuation by quick passages on splenectomized calves. The protease activity at different pH values was determined in protein fractions from the blood of calves. The enzymatic test showed marked differences between the protease content of both substrains.

[Diagnosis of Babesia bigemina with the immunoperoxydase test]. / Diagnostic de Babesia bigemina avec le test à l'immunoperoxydase.

An immunoperoxidase assay for the serological diagnosis of Babesia bigemina was developed. The antigen slides were prepared from B. bigemina-infected blood and stored at -20 degrees C. One hundred and sixty five sera were tested, comparing the immunoperoxidase assay to the indirect fluorescent antibody test. A coincidence of 95% was observed between both tests. For the immunoperoxidase assay, a relative sensitivity of 94.8%, a relative specificity of 95.5%, and a positive predictive value of 96.8% were calculated. The results demonstrated the efficacy of this technique for detecting antibodies to B. bigemina.

Produtos de escreçäo e secreçäo de Dictyocaulus viviparus em diferentes meios de cultivo / Excretory-secretory products of Dictyocaulus viviparus in different culture media

Espécimes adultos de Dictyocaulus viviparus foram cultivados in vitro em diversos meios líquidos (RPMI, Tyrode e Ringer) para obtençäo de produtos de excreçäo e secreçäo. A análise estatística pelo teste t de Student para dados näo pareados mostrou näo haver diferença significativa entre o meio RPMI e o meio Tyrode, mas entre este último e o meio Ringer as diferenças foram evidentes. Pela eletroforese foram observadas bandas que oscilaram entre 94 e 20kDa, sendo as mais nítidas de 50,1; 39,8; 35,4; 30,0 e 28,1kDa em todos os meios estudados