Molecular epidemiology network for promotion and support of delivery of live vaccines against Theileria parva and Theileria annulata infection in Eastern and Northern Africa

Tick-borne diseases, such as theileriosis, which are endemic in large parts of tropical and subtropical regions of the developing world, are ranked high in terms of their impact on the livelihood of resource poor farming communities. Theileriosis (East Coast fever caused by Theileria parva and tropical theileriosis caused by T. annulata) is considered a major constraint for development of livestock in regions where the disease is endemic. Currently, management of theileriosis and other tick-borne diseases is primarily through control of the tick vector using acaricides, although this is unsustainable due to increasing acaricide resistance and food safety concerns. A highly effective “infection and treatment” live vaccine based on the injection of a potentially lethal dose of sporozites together with a long acting dose of tetracycline has long been available for control of East Coast Fever in a number of countries. However, there are fears that the introduction of foreign parasites by this vaccination to a region might result in novel more virulent genotypes. Therefore, this vaccine was not applied in a number of other countries like the Sudan, although there is urgent demand for vaccination. For T. annulata a live vaccine based on inoculation of schizont-infected leukocytes attenuated through passage in vitro culture has been utilized for control and is deployed in North Africa, the Middle East and South Asia, but it has not been established in regions of East Africa, Egypt and Sudan, where the disease is also found. The aim of the project will be to molecularly characterize parasite strains in the regions and to identify strains of T. parva and T. annulata suitable for the deployment of live vaccines.