Establishment of Bovine Anaplasmosis in Canada: Current Status and Development of Rapid Tests to Control an Emerging Disease

Background

Bovine anaplasmosis is a blood-borne disease caused by a bacterium called Anaplasma marginale that causes respiratory problems, anemia, fever, weakness, and a high mortality rate, particularly in older cattle. Survivors remain infected for life. Anaplasmosis is spread by ticks, biting flies, needles, dehorning equipment (and other things that can transfer blood from animal to animal). There are no approved vaccines or treatments for bovine anaplasmosis in Canada. Consequently, it will be important to be able to accurately detect the disease before it can spread widely within a herd.

Until 2014, bovine anaplasmosis was a reportable disease in Canada, meaning that the Canadian Food Inspection Agency would respond to eliminate it when cases were detected. Because bovine anaplasmosis is not a threat to human health and is common in much of the US, Canada recategorized anaplasmosis as an “immediately notifiable” disease in 2014. Laboratories are still required to notify the CFIA when they suspect or diagnose it, but the CFIA won’t impose control measures, and imported cattle no longer need to be tested. This eased a trade irritant but also placed the burden of dealing with this disease onto producers.

Responding quickly to bovine anaplasmosis requires early and accurate detection of A. marginale. However, current A. marginale tests are slow, costly and require specialized equipment and technical expertise. The cELISA and a diagnostic PCR test also cross-react with other closely related organisms (e.g., Ehrlichia bacteria), accidentally mistaking them for A. marginale and producing false positive results. These researchers will develop a better diagnostic test for A. marginale.

Objectives

• Use current and a newly-developed diagnostic test to specifically detect A. marginale DNA or cattle antibodies to A. marginale in beef cattle herds from different geographic regions of Canada, and estimate and compare the within-herd prevalences of A. marginale.
• Research and develop a rapid point-of-care diagnostic test that is sensitive enough to detect chronic infections and specific enough to distinguish A. marginale from other genetically similar bacteria.

What They Will Do

These researchers will test herds in BC, southern Alberta, Manitoba and Ontario for anaplasmosis or the presence of A. marginale. An annual producer survey will identify herd and grazing management factors that may be related to anaplasmosis risk.

These blood samples will also be used to develop a more sensitive, highly specific, rapid and affordable biosensor-based test to detect A. marginale in cattle.

Implications

This project is specifically focused on anaplasmosis, but rapid, accurate, user-friendly, and cost-effective diagnostic tests would help producers and veterinarians deal with many diseases better.