Detection of Babesia bigemina in Cattle Using the 18S rRNA Gene

Abstract

Bovine babesiosis caused by Babesia bigemina is an important tick-borne disease affecting cattle. This study investigated the occurrence of B. bigemina in clinically suspected cattle from Mathura and adjoining areas using microscopic examination and simplex polymerase chain reaction (PCR) targeting the 18S rRNA gene. A total of 200 cattle were examined. Samples were obtained from VCC (DUVASU, Mathura), Damodarpura, Farah, and Sikandra (Agra), and animals were screened based on clinical signs and tick infestation. Giemsa-stained blood smears were examined microscopically, and genomic DNA from jugular-vein blood was analysed by PCR. The PCR assay used B. bigemina-specific primers at an annealing temperature of 58 °C, with an expected amplicon of 359 bp. Microscopy detected B. bigemina in 5 ear-vein samples (2.5%) and 2 jugular-vein samples (1.0%), whereas PCR detected parasite DNA in 8 of 200 animals (4.0%). Fever was recorded in all PCR-positive cattle (100%), and haemoglobinuria occurred in 62.5%; anorexia and lymph-node swelling were each observed in 25%. No significant association was reported with age, breed, sex, or geographical area, while higher positivity was observed during summer. Overall, PCR detected more positive animals than microscopy, supporting its use as a supplementary method for detecting B. bigemina infection, particularly when microscopic detection is limited by low parasitaemia.