Survey on tick-borne pathogens in thoroughbred horses in the Hidaka district, Hokkaido, Japan.

This research investigated the prevalence of tick-borne diseases in thoroughbred horses and ticks in Hidaka district, Hokkaido, Japan. The study concluded that horses in this region showed a high rate of infection of Anaplasma phagocytophilum, Rickettsia helvetica, and Borrelia garinii, although none showed active infections. The study also found ticks carrying pathogens closely related to these diseases.

Study Methodology

• A total of 87 thoroughbred horses and 10 ixodid ticks from a ranch in the Hidaka district of Hokkaido, Japan were included in the research.
• The researchers tested them for tick-borne diseases using the indirect fluorescent antibody (IFA) method. This technique is commonly used to detect antibodies in a patient’s serum.
• Both the horses and the ticks were tested for the presence of three common tick-borne pathogens: Anaplasma phagocytophilum, Rickettsia helvetica, and Borrelia garinii.
• The researchers also utilized Polymerase Chain Reaction (PCR) testing. PCR is a method used to amplify trace amounts of DNA on or in an organism, allowing for more accurate detection of bacterial, viral, or other genetic material. In this study, this test tool was used to identify any Anaplasma, Rickettsia, and Borrelia species in the peripheral blood of the horses.

Findings

• The research found that a significant number of horses had antibodies against each of the tested pathogens – 3.4% for Anaplasma phagocytophilum, 92.0% for Rickettsia helvetica, and 97.7% for Borrelia garinii. This indicates that these horses had been exposed to these diseases at some point in their lives.
• However, none of the horses were found to have active infections at the time of the study, as determined by the lack of DNA of the pathogens in their blood.
• The ticks collected in the study showed to be carriers for some of the pathogen species. The DNA of Anaplasma species, closely related to A. phagocytophilum in Japan, and A. bovis were found in Haemaphysalis megaspinosa ticks. And, a Borrelia japonica species was detected in an H. flava tick for the first time in Japan.
• It concludes that while infection rates may be high, current active infestations amongst the equine population appear low, and this is the first report of infection with the three pathogens in horses in Japan.