Nilgai Harvesting for the Cattle Fever Tick Eradication Program

Cattle fever ticks are established within a permanent quarantine zone in South Texas. USDA and the Texas Animal Health Commission (TAHC) work fervently to detect, quarantine, and treat infestations found in and sometimes out of the zone. Complications occur when wildlife move ticks undetected from one area to another. Historically white tailed-deer have been seen as the main culprit. More recently nilgai (Boselaphus trogocamelus) are emerging as a larger threat in controlling cattle fever ticks. Nilgai antelope are large ungulates native to India. In India, they have been known to transmit foot and mouth disease and malignant catarrhal fever, carry numerous endo- and ectoparasites, and can be infected with babesiosis. Furthermore, they have been found (by PCR) to be infected with Babesia bovis and Babesia bigemina (the agents of bovine babesiosis) in Mexico . They serve as hosts for cattle fever ticks (Rhipicephalus microplus and R. annulatus) and move these ticks (and potentially Babesia parasites) throughout their range including over the border from Mexico. In South Texas, nilgai have no native predators, live in favorable environmental conditions, and are valued for exotic game hunting. Their numbers have blossomed from 13 individuals introduced in the late 1920s to presently around 38,000. They are popular game animals with hunts running $2,000 to $5,000 and no closed season. They are large animals (males can weigh over 600 pounds) and have large home ranges (as large as 31,533 hectares). Female year-long home ranges are 20% larger than the males'. During "tick friendly" July and August they experience a spike in their space use potentially helping the tick population grow and spread.