Vet gives West Nile Virus update

Rebecca Schultze

Rebecca Schultze

As a population naive to West Nile Virus, its causes and its effects, the next few years of dealing with this disease will be rocky in the United States, according the Dr. David Zeman.

Zeman, professor of veterinary science and director of the Animal Reserarch and Diagnostic Lab at SDSU presented background material and an update on the West Nile Virus on Thursday afternoon in the Northern Plains Biostress Laboratory.

First isolated in the province of Uganda in 1937, the West Nile Virus has caused epidemics in Africa, the Middle East and Europe. In August 1999, New York City reported eight cases of human encephalitis, a common symptom of the disease. At the same time, a veterinary pathologist at the New York City zoo noticed more birds dying. West Nile Virus was positively identified as the culprit.

“We had a new virus enter this hemisphere; one that was previously on the other side of the world,” Zeman said.

Like the pioneers settling North America, the virus has spread westward across the country. Noticing this western march beginning in 1999, South Dakota recieved a grant from the Center for Disease Control in 2001 to prepare for the disease to infect this state.

Although a month later than expected, the first case of West Nile Virus in South Dakota was reported July 26 of this year.

Except for one case in California, Colorado is the western edge of the virus’s domain as the 2002 mosquito season wraps up. Oregon, Idaho, Nevada, Utah and Arizona are the only states yet to report infection of the West Nile Virus.

The eastern states initially hit with the virus are still experiencing new reports. Thus, West Nile Virus is considered an endemic disease, occurring again and again, year after year.

Human, horse and bird cases continue to be a concern throughout the nation.

In 1999, there were 62 human cases, resulting in seven deaths, and 25 cases in horses. In three years, the numbers have grown to 3,506 human cases, 206 resulting in death, and 12,843 cases in horses.

“It’s actually a pretty weak pathogen in peope, for the most part,” Zeman said. He cited numbers such as: 20 percent develop mild symptoms such as fever, headache and body aches, one out of 150 people exposed to West Nile Virus develop severe symptoms and less than one out of 1,000 infections result in death.

A new concern is one of hunters and their families. They may be concerned about wild game being infected with West Nile Virus.

Zeman said that there are no cases of transmission from handling an infected bird documented.

“Basic hygiene should be adequate,” he said. “Eating [virus carrying birds] poses no issue if it is cooked normally.”

He also reassured pet owners that the virus shouldn’t be an issue in hunting dogs that handle infected birds.

The gastrointestinal tract is not an effective way for the disease to be transmitted, Zeman said.

Zeman said that other species of animals besides humans, horses and birds may be susceptible to the disease, but clinical cases in other animals are rare.

People, horses and other mammals are “dead end hosts,” meaning that the disease cannot be contracted from them.

Zeman suggested that controlling mosquitos and common sense are the best way to protect yourself.

“There are probably more serious things for us to get upset and worried about than this disease,” he said.