Long-term studies on the economic impact of ticks on Sanga cattle in Zambia.

Three different tick control policies were tested in groups of traditionally managed Sanga cattle in the Central Province of Zambia over a period of 3 years. One group was given strategic tick control using 12 pyrethroid acaricide spray applications between the onset and the end of the wet season (October to March). The productivity of this herd was compared with that of a group with no tick control and a group under an intensive tick control regimen of spraying every week in the wet season and every 2 weeks in the dry season (36 applications per year). The highest output was associated with intensive tick control, followed by strategic control and then no tick control policies. However, when the costs of tick control were taken into account, the strategic tick control policy produced the best economic result, followed by the intensive and then the no tick control policies. Neither the strategic nor the intensive tick control policy was sufficient to prevent the transmission of East Coast fever (ECF) infection when this disease was introduced to the area.