"Babesia odocoilei In Elk"

Babesiosis in "Farm-Raised" Elk by Donald P. O’Connor, DVM, Staff Veterinarian, WDATCP, Excerpted From Animal Health Newsletter July 1998

                                                               Babesia odocoilei, generally found in white-tailed deer, is the only Babesia of wildlife ruminants speciated in North America. Although Babesiosis has been reported in free-ranging white-tailed deer, the infection appears to exist within the native population without causing clinical disease problems. However, with the increased interest in "farm-raised" deer, non-domestic hoof stock are moving into many areas where they are not normally found.

This can be problematic to the new, susceptible animals (the "farm-raised" deer) as they enter an environment which may be endemically stable, relative to disease agents, for the native population, but may represent an exotic infection to the new arrivals. The introduction of Babesia odocoilei into a non-traditional host such as elk with the addition of stressful situations, such as change of environment, gathering of velvet, de-worming or other management techniques, may result in significant death loss as in the following case report.

In March, a Wisconsin elk producer reported finding seven elk dead over the course of six days. Two of the animals were referred to the Wisconsin Animal Health Laboratory for necropsy and diagnosis. At necropsy, the animals were found to be jaundiced, with enlarged livers and spleens. The preliminary diagnosis was an intravascular crisis possibly caused by Leptospirosis, Anaplasmosis or Babesiosis.  Serological testing for Leptospirosis was negative. Blood smears, however, revealed the presence of red blood cell inclusion bodies, which were morphologically similar to Babesia spp. Blood samples were forwarded to Dr. Gale Wagner, Texas A&M University, College Station, Texas for confirmation and determination of the species. Dr. Wagner confirmed the presence of Babesia odocoilei. The herd veterinarian was notified of the diagnosis and treatment was initiated. The herd was treated with Imidocarb with apparent success, however, from the onset of clinical findings until treatment, a total of 13 animals had died. 

Perhaps the detection, treatment and the control of factors leading to Babesia infections should be considered in a cervid herd health program. Babesia odocoilei infections are thought to be transmitted, in Wisconsin, by Dermacentor albipictus (the elk or deer tick). Therefore, perhaps a tick control program and a decrease in stressful management activities during peak tick season should be discussed with your producer. A second consideration may be a periodic screening for Babesia and a treatment program if identified in the herd. Some babesiacidal drugs are so effective that one treatment will eliminate the causative agent, however, most babesiacidal compounds are toxic to the host, so caution is required in their use.