Space-time pattern and environmental drivers of bovine anaplasmosis.

Researchers at the Kansas State Veterinary Diagnostic Laboratory and the Center of Excellence for Vector-borne Diseases, both in the university’s College of Veterinary Medicine, have established a set of models to evaluate the space-time pattern and environmental drivers of a devastating cattle disease, bovine anaplasmosis, in Kansas. Bovine anaplasmosis affects beef and dairy production in almost all the U.S. states, causing significant economic losses to producers. The control of this disease currently relies primarily on infection-avoidance, although an experimental vaccine is used in many areas of the U.S. The causative bacterium anaplasma marginale lives in red blood cells and causes a hemolytic disease in cattle, which manifests as anemia, abortion, icterus(jaundice) and lethargy. It can cause death, primarily in older animals. Cattle that survive infection are persistent carriers of the bacteria and are a source of infection for other cattle through inadvertent mechanical transmission via blood-contaminated multi-use needles and surgical equipment, as well as via tick and fly transmission. The number of positive anaplasmosis samples submitted to the Kansas State Veterinary Diagnostic Laboratory has increased over the years, and the geographical area from where these samples originated has expanded, as noted by Gregg Hanzlicek, director of production animal field disease investigations for the diagnostic laboratory. These changes may have occurred because veterinarians have become more aware of the disease, but this study suggests environmental conditions and management practices may have also played a role. Ram Raghavan, a spatial epidemiologist at the diagnostic laboratory, worked closely with Hanzlicek in evaluating the space-time patterns of this disease. The increase in the expansion of tick-borne diseases in the Midwestern region may be attributed to geographic expansion of tick populations over time. New evidence suggests a growing potential threat for bovine anaplasmosis in newer areas, but a quantitative evaluation of whether or not bovine anaplasmosis has spread to previously unreported areas over time is not readily available. Likewise, information on any potential environmental and climatological drivers behind the space-time expansion of bovine anaplasmosis cannot be easily found, which has disease management implications. Three climate change indices—minimum land surface temperature, diurnal temperature range and relative humidity—are drivers of the space-time pattern for bovine anaplasmosis . This finding is significant in the context of climate change implications on infectious diseases and adds to the mounting evidence of climate change linkages to animal health. The results appear in PLOS ONE, “Bayesian Space-Time Patterns and Climatic Determinants of Bovine anaplasmosis.” Data used in the study were from diagnostic samples submitted to the diagnostic laboratory between the years 2005-2013.(http://www.hpj.com/livestock/kansas-state-veterinary-diagnostic-laboratory-researchers-evaluate-space-time-pattern/article_63d900aa-daba-5ebe-aa9b-5e11436abb37.html)