A perspective on Theileria equi infections in donkeys

The donkey population has remained unchanged in the last two decades despite a decrease in the overall population of equids, emphasizing the usefulness of the donkey as a draught and pack animal. Piroplasmosis in donkeys, caused by Theileria equi and Babesia caballi, has been recognized as a serious problem of major economic importance as the affected animals manifest decreased working capacity, loss of appetite, etc. In tropical countries, T. equi infections are more wide-spread and pathogenic than those caused by B. caballi. Donkeys usually remain asymptomatic carriers with positive antibody titres throughout life. Transmission of infection occurs from animal to animal through ticks such as Hyalomma spp. Rhipicephalus spp. and Dermacentor spp. The clinical form of the disease is diagnosed by peripheral blood smear examination, but in carrier donkeys it is very difficult to demonstrate the parasite in stained blood smears as the parasitaemia is extremely low. For diagnosis of such low grade infection or carrier animals, serological tests and DNA-based molecular diagnostic techniques, which are discussed in the present review, have become mandatory. Currently, there is no suitable pharmacotherapy available to clear the T. equi infection from affected donkeys, though some new drugs and drug combinations used against this disease condition have been discussed. In the present situation, there is an urgent need for international cooperation and coordination for development of sensitive molecular diagnostic tools and effective pharmacotherapies for curtailment of the disease condition. Hence, it is imperative to develop and exchange reagents and technology developed through human resource sharing in the interest of sustainability of donkey husbandry.