Clearance of Tritrichomonas foetus in experimentally infected heifers protected with vaccines based on killed-T. foetus with different adjuvants

Abstract

Tritrichomonas foetus is a flagellated protozoan that causes a sexually transmitted disease in cattle. Trichomonosis is characterized by early abortions, subfertility and a significant decrease in productivity. Vaccine preparations containing whole T. foetus can reduce the time of residence of the pathogen in the host cervix after experimental infection. Here, T. foetus vaccines prepared with different adjuvants were tested, in parallel with a commercial vaccine, for their efficacy to clear the infection. The median time for clearance of infection was 69 days in non-immunized animals, 55 days in animals treated with aluminum hydroxide, 41 days with oil-in-water or saponin based vaccines or with a commercial vaccine and 27 days in animals treated with saponin plus aluminum hydroxide. A slight increase in the risk of T. foetus clearance from the genital tract was found with the saponin based vaccine (hazard ratio, 2.52; 95% confidence interval, 1.03–6.17) or the commercial vaccine (hazard ratio, 2.61; 95% confidence interval, 1.07–6.38). A significant increase in the risk of T. foetus clearance was found with the combination of saponin plus aluminum hydroxide based vaccine (hazard ratio, 5.12; 95% confidence interval, 2.04–12.83).