ENCEPHALOMYOCARDITIS VIRUS (EMCV): OPTIONS FOR VACCINATION OF ELEPHANTS
A. Rae Gandolf, DVM
Brief history of the encephalomyocarditis virus (EMCV) vaccine
- Oxford Laboratories in Worthington, MN previously manufactured inactivated EMC vaccine approved for use in domestic swine. This company has been bought and sold several times and some of the original founders have reformed as Newport Laboratories at the same location. They are currently making autogenous vaccine for domestic and exotic animals on request. Contact is Dr. Mark Titus (800) 220-2522.
- Several formulations of inactivated vaccines have previously been tested in many zoo and primate facilities, however, development of immunity following administration of these vaccines was in many cases variable. In other cases, animals were inadequately challenged with virus, leaving level of protection in question. (Gaskin et al., 1987;Gutter et al., 1993)
- An inactivated vaccine was also produced in the early 90’s at The Onderstepoort Institute, Exotic Disease Division, in response to an outbreak among African elephants in Kruger National Park. This vaccine produced effective antibody titers and prevented disease in all animals that were challenged with virulent virus 2 months post- inoculation. (Hunter et al., 1998; Raath and Bengis,1995) The vaccine was not commercialized due to lack of need for livestock.
- This same vaccine that was originally developed in South Africa has also been used in Australia.
Current investigations of the EMCV vaccine
- A genetically engineered, attenuated virus vaccine (live Mengo virus, which is serologically indistinguishable from EMCV, with shortened poly-C tracts) was developed and tested by Dr. Ann Palmenberg (University of Wisconsin, Dept of Animal Health and Biomedical Science) and colleagues. Success of the vaccine in some primates and pigs is described by Osorio et al., 1996. Efficacy of the vaccine has since been demonstrated in several primate species and various hoofstock species such as gerenuk, tapirs, and guanaco as reported by Backues et al., 1999. Dr. Backues has also used this vaccine in several Asian and African elephants with no adverse reactions and a resulting 4 fold titer increase in some of the vaccinated elephants. (Dr. Backues pers. comm.)
- Dr. Kay Backues (Tulsa Zoo and Living Museum) is beginning a study on seroprevalance of EMCV in elephants. Pending funding, and with support from Dr. Backues, virologist Dr. Earl Blewett at Oklahoma State is planning a study to determine risk and efficacy of the aforementioned vaccine in elephants and other non-domestic animals. Cost of the vaccine for those institutions that wish to participate will ideally be covered by the project funding (Dr. Blewett pers.comm.).
- While awaiting funding, Dr. Blewett should be able to offer the vaccine at cost plus shipping on ice to zoos on an emergency basis ($25-100). Dr. Blewett would like serum for research and quality control purposes in return if at all possible.
- Dr. Mark Davis (Peace River Wildlife Refuge) has made a killed vaccine that appears promising and may have a longer shelf live than the attenuated vaccine.
Backues, K.A., M. Hill, A.C. Palmenberg, C. Miller, K.F. Soike and R. Aguilar. 1999. Genetically engineered Mengo virus vaccination of multiple captive wildlife species. J. Wildl. Dis. 35(2):384-387.
Gaskin, J.M., T.L. Andresen, J.H. Olsen, E.E. Shobert, D. Buesse, J.D. Lynch, M.Walsh, S.Citino and D. Murphy. 1987. Encephalomyocarditis in zoo animals: Recent experiences with the disease and vaccination. Proc. International Conf. on Zoo. And Avian Medicine, p491.
Gutter, A.E. 1993. Encephalomyocarditis in zoo animals. In: Fowler, M.E. (ed.). Zoo and Wild Animal Medicine. 2nd ed. W.B. Saunders Co., Philadelphia, p50-51.
Hunter, P., S.P. Swanepoel, J.J. Esterhuysen, J.P. Raath, R.G. Bengis and J.J. van der Lugt. 1998. The efficacy of an experimental oil-adjuvenated encephalomyocarditis vaccine in elephants, mice and pigs. Vaccine 16(1):55-61.
Osorio, J.E., G.B. Hubbard, K.F. Soike, G. Girards, S. van der Werf, J. Moulin and A.C. Palmenberg. 1996. Protection of non-murine mammals against encephalomyocarditis virus using a genetically engineered Mengo virus. 1996. Vaccine 14(2):155-161.
Raath, J.P. and R.G. Bengis. 1995. The evaluation of a vaccine against encephalomyocarditis infection in elephants (Loxodonta africana) under controlled conditions. Proc. Joint Conf. AAZV/WDA/AAWV,p304-308.
Addendum on testing:
I also found out that Texas Veterinary Diagnostic Lab (970-845-3414) will run titers for EMC for $9/sample. This might be worth doing on elephants being transported to areas where this disease is a concern (usually the south). In addition, they can run virus isolation on tissue that is fresh refrigerated or frozen in any suspect cases ($17/sample).