The great thing about fall is the cooler weather and with it the end of mosquito season. That also means a decline in West Nile Virus. West Nile Virus is an infection transmitted between mosquitoes and birds. People can be infected if they are bitten by a West-Nile-Virus-infected mosquito. Almost 80 percent of individuals who are infected with this virus have absolutely no signs or symptoms related to the condition. However, the remaining 20 percent of individuals have symptoms serious enough to make the person want to seek medical help from a doctor.
According to the US Centers for Disease Control (CDC), West Nile virus infections have dramatically increased since they were first reported in the US in 1999. Up through November 14, 2012, 5,128 US cases have been diagnosed, representing the highest tally since the last peak in 2003. Seventy percent of cases are from 10 states: Texas, California, Louisiana, Mississippi, Illinois, South Dakota, Michigan, Oklahoma, Nebraska, and Colorado; a third of all cases are from Texas alone.
How do I know if I have a West Nile Virus infection?
West Nile virus cases are typically divided into two types, depending upon whether the nervous system (brain and spinal cord) is involved. The non-neurologically invasive disease type typically presents nonspecific symptoms such as fever, headache, body aches, tiredness, skin rash, occasional swelling of some lymph nodes, and on rare occasions eye pain. These symptoms tend to last a few days. The more severe form of infection tends to involve the nervous system and can linger for weeks or cause permanent disability. This means that the virus has infected the brain tissue itself, a condition known as encephalitis, or has infected the brain’s protective coverings (meninges), causing meningitis. Fifty-one percent of all reported West Nile Virus cases this year — 2, 601 cases — have involved the nervous system. This form of the disease is severe and symptoms typically include changes in behavior, stiff neck, severe headache, high fever, coma, tremors or muscle jerking, lack of coordination, seizures and in some cases paralysis, coma and death.
Is an infected person contagious and what treatment is available?
You cannot transmit this virus by touching, kissing or direct contact with someone with the disease. The period between the time you are bitten by an infected mosquito and the appearance of signs and symptoms ranges from 3-14 days. The majority of cases in the U.S. occur between the month of July and September, but with gradual global warming trends, the season can be expanded, especially if there is high humidity and stagnant water, the perfect breeding recipe for mosquitoes. Diagnosis of this virus is through blood tests. There is no special treatment for the non-neurological form of infection besides over the counter pain relievers to ease headache and muscle aches. Antibiotics do not help. The severe neurological version of the illness requires hospitalization.
What you should know about the West Nile Virus
- Avoid unnecessary outdoor activity where there are a lot of mosquitoes. This is obvious, given that the condition is spread through a mosquito bite.
- Make sure that if you are going to be outside with exposure to mosquitoes that you have some type of insect repellent and wear long sleeved shirts and long pants in mosquito-infested areas. Avoid peak times when mosquitoes are most likely to feed, like early morning or early evening.
- One does not necessarily have to avoid contact with people who are infected with the virus, as it is not transmitted in this manner.
- Should you contract an illness with an unusually severe headache or confusion in late summer to fall, seek medical attention immediately, given that the severe form of the disease requires hospitalization.
Dr. Joseph Sirven is a first-generation Cuban American. He is Professor and Chairman of the Department of Neurology and was past Director of Education for Mayo Clinic Arizona. He is editor-in-chief of epilepsy.com and has served US and global governmental agencies including the Institute of Medicine, NASA, FAA, NIH and CDC.