5 Things You Need to Know About West Nile Virus

As of last Tuesday, 693 cases of West Nile virus have been reported from 43 states to the Centers for Disease Control and Prevention (CDC). The disease is hitting the country early this year, with the CDC reporting the highest number of cases in the second week of August since the virus was first detected in 1999. Experts say a mild winter and rainy spring, followed by prolonged high temperatures and dry weather have contributed to the spike, by giving mosquitoes ample time to breed and ideal conditions to thrive.

Subsequently, the balmy South is seeing the majority of West Nile deaths and cases this year - an epidemic in Texas led Dallas County to declare a state of emergency and authorize the first aerial spraying of insecticide in nearly 50 years - but the disease is a nationwide problem, with the most recent deaths coming from Michigan and Illinois.

Here’s what you should know about the disease and how to stay protected.

1. What is West Nile virus?

West Nile virus is a disease that infects birds and is then spread by mosquitoes to humans. People can also become infected through blood transfusions and organ transplants. Human cases of the disease typically rise at the end of summer and fall. Most people who contract the virus won’t experience any symptoms at all, but others may develop mild symptoms of West Nile fever or, rarely, the more severe symptoms of neuroinvasive West Nile, including inflammation of the brain and surrounding tissues - the most severe form of the disease. Most of the cases reported to the CDC so far have been neuroinvasive disease: 406 cases versus 287 cases of non-neuroinvasive disease.

Other viruses in the West Nile family of viruses are responsible for dengue, yellow fever and Japanese encephalitis.

2. What are the symptoms of West Nile?

According to the CDC, about 80% of people infected with West Nile virus will get off scot free, with no symptoms. About 20% of infected people will come down with mild symptoms of West Nile fever, including fever, headache, fatigue, body pain, skin rash and swollen lymph glands. These symptoms can last anywhere from a couple of days to a few weeks.

What Is West Nile Virus?

West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. This fact sheet contains important information that can help you recognize and prevent West Nile virus.

What Can I Do to Prevent WNV?

New! Prevention measures consist of community-based mosquito control programs that are able to reduce vector populations, personal protection measures to reduce the likelihood of being bitten by infected mosquitoes, and the underlying surveillance programs that characterize spatial/temporal patterns in risk that allow health and vector control agencies to target their interventions and resources.