LONG-TERM STUDY OF INCIDENCE AND FINANCIAL LOSS DUE TO CATTLE BABESIOSIS IN AN ARGENTINEAN DAIRY FARM

The incidence and direct financial loss caused by babesiosis were evaluated in 121 Holstein Friesian female cattle that formed eight cohorts (1981-1988) of a dairy farm located approximately 24-degrees-55'S 65-degrees-29'W in Salta, Argentina. Female calves born in 1986 and 1987 (n = 32) were vaccinated with a live Babesia vaccine at six months of age. No cases of babesiosis occurred in the vaccinated cattle. The incidence of babesiosis in the six non-vaccinated cohorts was 23.6% (21/89). Eighteen of the cases were the result of Babesia bovis, one to Babesia bigemina and two to a mixed infection. Two cattle died of B. bovis infection in spite of drug treatment (diaminazene, 3.5 mg kg-1). No disease occurred in cattle younger than seven months or older than 24 months. The number of cases according to age of cattle was: 7-9 months, 5; 10-12 months, 6; 13-24 months, 10. Financial loss for the six cohorts that suffered clinical cases amounted to US $ 1624.6 (prices in October 1990)-62% were the result of physical losses and 38% to costs of control. A benefit-cost analysis of vaccination was carried out assuming that 95% of the mortality and morbidity losses of the six non-vaccinated cohorts was prevented after a single inoculation of a live vaccine (cost of a dose plus administration was US $ 4.2. The benefit-cost ratio was 4:1 for each US dollar expended.