A veterinary student was diagnosed with West Nile virus (WNV) in May 2009 after performing a necropsy on a 4-month-old Welsh pony from Gauteng, South Africa.

Six days after performing the necropsy, the student developed fever, malaise, myalgia (muscle pain), stiff neck, and a severe headache. A rash appeared two days later and symptoms persisted for approximately 10 days. RNA (genetic material) extracted from the student and the pony identified lineage 2 WNV–a fatal form of the virus previously diagnosed in horses in South Africa in 2008.

WNV is a mosquito-borne flavivirus that circulates primarily in birds and mosquitoes. Humans and horses are considered incidental, dead-end hosts for WNV. An infected horse does not normally pose a risk for infecting humans with WNV since the virus is present at very low levels in the blood, insufficient to infect mosquitoes.

"The student used a bone saw and was the one that removed the brain from the horse and would have had much more exposure to droplets," said Marietjie Venter, PhD, associate professor at the University of Pretoria, South Africa. "At the time, the veterinarians did not take extra precaution besides wearing gloves when doing horse autopsies since they did not see them as being high risk for zoonotic diseases in Africa