Cytopathic effects of Tritrichomonas foetus on bovine oviduct cells.

Tritrichomonas foetus is an extracellular parasite of the reproductive tract in cattle. To investigate the cytopathic effects of T. foetus in deeper parts of the reproductive tract, a bovine primary oviduct epithelial cell system (BOECs) was developed. Reproductive tracts were obtained from cows and the effect of co-incubating T. foetus with BOECs was analyzed by scanning electron, transmission electron and fluorescence microscopy. Viability tests were performed using colorimetric methods, TUNEL (Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling), fluorescein diacetate, propidium iodide, JC-1 and annexin-V. The results demonstrate that: (1) the in vitro oviduct epithelium is useful for interaction experiments with T. foetus; (2) T. foetus adheres to the BOECs as single separate cells, and later on the cells aggregate as large clusters; (3) the posterior region of the cell initiates the process of adhesion and forms filopodia and digitopodia; (4) T. foetus severely damages BOECs leaving imprints in the epithelial cells, wide intercellular spaces, and large lesions in the epithelium; and (5) T. foetus provokes bovine oviduct cell death by apoptosis and secondary necrosis. Our observations indicate the possibility that T. foetus can move through the reproductive tract to the oviduct and that infertility in cows can be mediated by an attack on the oviduct cells by T. foetus.

Egg Drop syndrome '76 in Bolivia.

Four outbreaks of Egg Drop Syndrome '76 (EDS '76) were diagnosed between April 1993 and July 1993 in the Santa Cruz Department of Bolivia, around the department capital Santa Cruz. Three outbreaks involved commercial laying birds and the fourth a broiler breeder unit. Clinical signs were typical of EDS '76 with decreases in egg production of up to 55% being recorded as well as the production of thin shelled and shell-less eggs. A total of 183 serum samples from the 4 farms were tested for the presence of antibodies to the EDS '76 virus using a haemagglutination inhibition test, with titres of 16 or above being considered as a positive result. Of 63 samples from groups of birds showing signs of EDS '76, 58 (92.1%) had positive titres, and 88 out of 90 samples (97.8%) from unaffected groups of birds had negative titres. Out of 30 samples from birds not yet in lay from the affected farms 28 (93.3%) had tires below 16. EDS '76 had not been reported in Bolivia prior to these outbreaks and vaccination was not practised. The most probable source of virus was from day old chicks imported from South American countries which had recorded outbreaks of EDS '76 before April 1993. The source of the virus, its spread and the control measures implemented in the Santa Cruz area are discussed.