CONTROL OF GAMMAHERPESVIRUS-ASSOCIATED MALIGNANT CATARRHAL FEVER IN RUMINANTS
Location: Animal Diseases Research
Title: Development of a Management Program for a Mixed Species Wildlife Park Following an Occurrence of Malignant Catarrhal Fever
Submitted to: Journal of Zoo and Wildlife Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 2008
Publication Date: September 1, 2008
Citation: Cooley, A.J., Taus, N.S., Li, H. 2008. Development of a Management Program for a Mixed Species Wildlife Park Following an Occurrence of Malignant Catarrhal Fever. Journal of Zoo and Wildlife Medicine. 39(3):380-385.
Interpretive Summary: During late 2001 and early 2002, a mixed species wildlife park in North Carolina experienced a disease outbreak in Pere David's deer, axis deer, blackbuck antelope, white-tailed deer and elk. Laboratory findings confirmed that these animals died from sheep-associated malignant catarrhal fever (MCF), which is caused by a herpesvirus (called ovine herpesvirus 2) carried by domestic and wild sheep. Ovine herpesvirus 2 (OvHV-2) was detected in all cases examined, but no other MCF viruses were detected, although wildebeest, goats and other MCF virus-carriers were present in the park. A serological test was done for all possible OvHV-2 reservoirs in the park including domestic and non-domestic sheep among which the most prevalent sheep was mouflon sheep and the result showed that over 90% of these animals were positive. To prevent further losses, the initial recommendation was removal of all sheep and goats. Subsequently MCF virus-free mouflon sheep were produced and reintroduced to the park. No further cases of MCF have occurred since the removal of OvHV-2 positive sheep and reintroduction of the virus-free mouflon lambs about 5.5 years ago. This is the first time that MCF virus-free mouflon sheep derived by early weaning from positive ewes have been produced and reintroduced to a densely populated animal park with multiple susceptible species. Management control of MCF in high population animal parks is possible and practical with such techniques.
During late 2001 and early 2002, a mixed species wildlife park in North Carolina experienced an acute outbreak of morbidity and mortality in Pere David's deer, axis deer, blackbuck antelope, white-tailed deer, and Rocky Mountain elk. Clinical signs varied from fulminant disease progressing from depression to bloody scours to death in fewer than four days in Pere David's deer, to a more protracted form of disease, ranging from two weeks to three months in axis deer. In moribund axis deer, high levels of anti-MCF virus antibody by cELISA were found. Ovine herpesvirus 2 (OvHV-2) DNA was also detected in peripheral blood leukocytes of the affected axis deer. No other MCF viruses were detected. Retrospective examination of frozen tissue samples from the affected Pere David's deer and blackbuck antelope also confirmed the presence of OvHV-2 DNA. Initial control efforts were directed at preventing further deaths of clinically susceptible animals by removing MCF virus reservoir species, particularly ovine species. The most prevalent ovine species in the wildlife park was mouflon sheep. All sheep were removed from the park by June, 2002 and the last MCF death occurred in October, 2002. Since mouflon sheep had been a prominent attraction in the wildlife park, the owner wanted a means to reintroduce this species to the park. Derivation of OvHV-2 uninfected mouflon lambs was undertaken using the previously described program for production of OvHV-2-free sheep. The rederived MCF virus-negative mouflon sheep were introduced into the park approximately January, 2004. As of December, 2007, no further cases of MCF have occurred since the removal of OvHV-2 positive mouflon sheep and reintroduction of the virus-free lambs. This paper describes the successful management and control of MCF in a densely populated mixed species animal park.