Prevalence and molecular heterogeneity of Bartonella bovis in cattle and Haemaphysalis bispinosa ticks in Peninsular Malaysia.

BACKGROUND: Bartonellosis is an emerging zoonotic infection responsible for a variety of clinical syndromes in humans and animals. Members of the genus Bartonella exhibit high degrees of genetic diversity and ecologic plasticity. The infection is usually transmitted to animals and humans through blood-feeding arthropod vectors such as fleas, lice, ticks and sandflies. This study was conducted to investigate the prevalence of Bartonella species in 184 beef cattle, 40 dairy cattle, 40 sheep and 40 goats in eight animal farms across Peninsular Malaysia. Bartonella-specific PCR assays and sequence analysis of partial fragments of the citrate synthase gene were used for detection and identification of B. bovis. Isolation of B. bovis was attempted from PCR-positive blood samples. Molecular heterogeneity of the isolates was investigated based on sequence analysis of gltA, ITS, rpoB genes, ERIC-PCR, as well as using an established multilocus sequence typing (MLST) method. The carriage rate of B. bovis in ticks was also determined in this study.

RESULTS: B. bovis was detected using Bartonella gltA-PCR assays from ten (4.5 %) of 224 cattle blood samples, of which three (1.3 %) were from beef cattle and seven (3.1 %) were from dairy cattle. None of the blood samples from the sheep and goats understudied were positive for B. bovis. Haemaphysalis bispinosa and Rhipicephalus (Boophilus) microplus were the predominant tick species identified in this study. B. bovis was detected from eight of 200 H. bispinosa ticks and none from the R. microplus ticks. Isolation of B. bovis was successful from all PCR-positive cattle blood samples, except one. Strain differentiation of B. bovis isolates was attempted based on sequence analysis of gltA, ITS, rpoB, and ERIC-PCR assay. B. bovis isolates were differentiated into six genotypes using the approach. The genetic heterogeneity of the isolates was confirmed using MLST method. Of the six MLST sequence types identified, five were designated new sequence types (ST23-27), while one (ST18) had been reported previously from Thailand isolates. All except one isolates were segregated into lineage II. A new lineage (IIa) is proposed for a single isolate obtained from a dairy cow.

CONCLUSIONS: The current study reported the first detection of B. bovis infection in the cattle and H. bispinosa ticks in Peninsular Malaysia. At least six genotypes of B. bovis were found circulating in the cattle understudied. New MLST sequence types were identified in Malaysian B. bovis isolates. Further study is necessary to explore the zoonotic potential of B. bovis and the vector compatibility of H. bispinosa ticks.