Migratory Gaddi sheep and goats as potential carriers of Theileria infection: a molecular survey

Theileriosis caused by parasites of the genus Theileria, is a vector-borne haemoprotozoan parasitic disease of critical concern in small ruminants. This study aimed to explore the infection status of migratory Gaddi sheep and goats with parasites from the Theileria genus in concurrence with ectoparasite infestations using molecular methods. Seventy three apparently healthy animals were randomly sampled from different flocks of migratory Gaddi sheep and goats and were systematically screened for ectoparasitic infestations. Molecular investigation for theileriosis was conducted using the genus wide polymerase chain reaction (PCR) technique. Out of 56 (76.71%) animals positive for the genus Theileria, 2 randomly selected amplicons were sequenced and subjected to BLAST analysis and were showing 99.71% identity with Theileria luwenshuni, a pathogenic Theileria species of small ruminants. To confirm the presence of T. luwenshuni, species-specific PCR was attempted to identify that 38 (52.05%) animals were infected by T. luwenshuni. On analysing the molecular prevalence data of Theileria to the ectoparasitism, it was evident that the infection existed in the animals irrespective of the type of ectoparasitic infestation and even T. luwenshuni was found in non-infested animals also. This is the first report of subclinical infections of T. luwenshuni in sheep and goats of Northern India and its potential carrier status. The asymptomatic carrier status of these nomadic animals is a matter possessing serious implications on the disease transmission rates and the production economics of small ruminant production in this region.