The effect of short-interval deltamethrin applications to control tsetse on the seroprevalence of babesiosis in cattle

For the past decade, treatment of cattle with 0.00375% deltamethrin (Decati x, Coopers) at two-weekly intervals has been part of an integrated approach to counteract continuous invasion of Zimbabwe by tsetse from the Mozambiqu e fly-belt. To determine the effect of these regular deltamethrin treatment s on the epidemiology of babesiosis, a survey was conducted to estimate the prevalence of antibodies against Babesia bigemina in adult communal cattle . The seroprevalence of antibodies against B. bigemina in adjacent areas, w here cattle are treated with short-residual acaricides, was also determined for comparison. The prevalence of antibodies to B. bigemina was much highe r in areas where dipping with a non-pyrethroid acaricide was conducted. Thi s was attributed to the successful control of Boophilus spp. and hence a ve ry low level of B. bigemina transmission in the 'deltamethrin treatment zon e'. This low level of disease transmission was confirmed by the low prevale nce of antibodies against B. bigemina in sentinel cattle that were introduc ed to the 'deltamethrin treatment zone'. The potential adverse effects of s everely reducing the tick population should be taken into consideration at the onset of tsetse control operations in which cattle are to be treated wi th deltamethrin at short treatment intervals.