Babesiosis through Molecular Detection of Babesia bovis in Suspected Carrier Cattle of Selected Localities in Sri Lanka

Abstract

Emergence of babesiosis in both public health and food security concern in global perspectives cannot be ignored. The dairy farming plays an important role in food industry that, fulfilling the protein requirement through producing both milk and meat. The farming operations may get hampered due to non-infectious and infectious diseases. Infectious diseases also cause huge production losses in all farming operations in time to time. Babesiosis is well known as an emerging zoonotic disease causing heavy production losses due to both the clinical diseases and carrier animals. Babesia parasites, mainly Babesia bovis and B. bigemina, are tick-borne hemoparasites inducing bovine babesiosis in cattle globally, and these parasites are considered to be endemic in central Sri Lanka and the prevalence of babesiosis is high in other areas. Carrier cattle infected with babesiosis have low number of parasites in circulation. Babesiosis is difficult to detect and is a challenge to conventional diagnostic methods. However, diagnosis of carrier animals in herd is important for preventing outbreaks by transmission through vector ticks to healthy animals and for obtaining epidemiological data of the disease. Here, we have conducted nested PCR detection of B. bovis in carrier cattle (Jersey crosses, Friesian crosses and Australian milking zebu) of selected localities of Sri Lanka. For this study, 30 blood samples collected from suspected carrier cattle were analyzed using light microscopy and nested PCR. Screening by light microscope indicated that 47% of the samples were positive. PCR analysis of samples diagnosed that 80% of the samples were positive. Hence, 33% of the animals appeared to be healthy through routine light microscope diagnosis were in fact carriers posing a threat for the healthy herd population. The high prevalence of babesiosis in carrier cattle in Sri Lanka emphasized that island-wide control and prevention programs against bovine babesiosis are needed to minimize the financial burden caused by the parasites to reduce to production losses. This preliminary study on molecular detection of B. bovis in selected localities offers a rapid and efficient screening method for suspected carrier herds while providing new avenues to minimize losers incurred in milk production due to unidentified carrier animals.