Tick and tick-borne disease control in Zimbabwe: What might the future hold

Compulsory short-interval dipping of cattle for tick control has been enforced in Zimbabwe since the early part of this century. Intensive dipping was initially introduced as a measure to control East Coast fever (ECF), following its introduction from eastern Africa. Dipping was subsequently found to be effective in the control of heartwater and other tick-borne diseases, and it continued to be enforced after ECF was eradicated in the 1950s. Communal Land dipping was disrupted in the 1970s, and tick-borne diseases caused the deaths of large numbers of susceptible cattle. These events illustrated the danger of maintaining situations of endemic instability. Serological surveys in 1981/82 showed that endemic stability was widespread among the surviving Communal Land cattle, and it was concluded that this would be adversely affected if intensive dipping were to be re-introduced. However, for political and other reasons intensive dipping was re-introduced. Costs of dipping have since increased considerably. The Government still has the option to revert to a policy of strategic or minimal dipping. Another serological survey is being conducted at present and this will indicate whether or not a relaxation in Communal Land dipping will need to be accompanied by vaccination against tick-borne diseases, in order to restore endemic stability. A possible danger posed by reduced tick control in Communal Lands in the highveld is that Amblyomma hebraeum and heartwater could become established in these areas. In determining future tick control policy for highveld Communal Lands the potential costs of controlling heartwater will have to be weighed against the costs of maintaining intense dipping.