Update: West Nile virus activity in Florida camelids
Maureen T. Long, DVM, PhD, Diplomate ACVIM-Large Animal
University of Florida College of Veterinary Medicine
During the first few years that West Nile virus (WNV) encroached into the US, it was discovered that llamas and alpacas were susceptible to development of brain and spinal cord disease from this virus. While low numbers of cases were reported in the early outbreaks, it was noted that camelids developed the same clinical paralytic syndrome as seen in people and horses. Camelids can also become unable to rise and develop brain signs such as seizures.
During the mosquito seasons of 2012 and 2013, the US experienced dramatic increases in West Nile virus activity in humans, horses and mosquitoes. With this increase in activity, camelids are also at increased risk for developing the disease. In early October, there was a fatal case of WNV in an alpaca residing in north Florida.
Given that activity is high enough in Florida to affect this less commonly affected species, owners should consider having their veterinarians immunize their camels, alpacas, and llamas against WNV. There are no approved vaccines and use of the horse vaccine is considered “off-label,” however there are research studies that demonstrate an adequate immune response when given the horse vaccines.
In the study by Kutzler in 2004, greater than 90% of llamas and alpacas responded after two injections of a killed vaccine given 4 weeks apart. Three vaccines as an initial series demonstrated 97% of llamas responded appropriately to the vaccine. In this study of 53 camelids, no animal had any adverse effect, but with any vaccine there can be very low numbers of side effects such as stiffness and mild soreness. In other species a very, very infrequent severe side effect, anaphylaxis, has been described.