Molecular evidence for Babesia ovis and a Novel Babesia in unfed Rhipicephalus sanguineus sensu lato

Abstract

Introduction: Babesiosis is caused by protozoa of the genus Babesia, with manifestations ranging from subclinical infection to life-threatening disease. Many Babesia species have been described in domestic and wild animals. This study aimed to investigate Babesia in unfed Rhipicephalus sanguin­eus sensu lato. Material-methods: One hundred and forty DNA samples extracted from tick pools comprising 5403 unfed R. sanguineus s.l. (503 adults, 3100 nymphs, 1800 larvae) were screened for Babesia by 18S ri­bosomal RNA PCR (Polymerase Chain Reaction) and RLB (Reverse Line Blot) hybridization. Result: Babesia infection was found in male, female, and nymph pools with an infection rate MLE (max­imum likelihood estimate) of 1.98 [CI (Confidence Interval) 0.65-4.74)], 0.50 (CI 0.03-2.40), and 0.07 (CI 0.01-0.21), respectively. Babesia ovis was detected in one adult pool (MLE 0.47, CI 0.03-2.27) ob­tained from dogs and a nymph pool (MLE 0.03, CI 0.00-016) collected from the shelter grounds. Three adult female tick pools (MLE 1.44, CI 0.38-3.88) and one adult male pool (MLE 0.50, CI 0.03- 2.40), collected from dogs, hybridized to the catch-all and Babesia genus probes but did not show sig­nals to other probes, suggesting the evidence of an unidentified Babesia. One nymph pool (MLE 0.03, CI 0.00-016) collected from the shelter grounds also hybridized to catch-all and Babesia genus probes but not species-specific probes. The maximum similarity (96.1-97%) observed was with Babesia sp. sable antelope, Babesia sp. Malbazar and Ludhiana isolates of dog origin, Babesia sp. of wild boar or­igin, Babesia sp. Kashi 2, and Babesia occultans of cattle origin. Conclusion: The analysis of unfed R. sanguineus s.l. to be infected with B. ovis and a novel species of Babesia. The latter isolate is suggested to be a new species based on its 18S rRNA sequences, and further studies in the vertebrate host, especially dogs, would help to determine its epizootiological significance.