Since 2002 when the West Nile Virus (WNV) first appeared in Ohio, there is usually some talk about the virus, particularly in the late summer and early fall.
"The West Nile virus is transmitted to people by infected mosquitoes," explained Lyn Pethtel, BS (ASCP), RN, CIC, Director of Quality Improvement and Infection Control at Salem Community Hospital. "While not all mosquitoes carry the virus, an infected mosquito can cause illness. The greatest risk of getting the virus is from July to mid-September."
Seasonal outbreaks of the virus may vary in local areas, based on factors such as the weather, numbers of mosquitoes that spread the virus and human behavior.
"The West Nile virus usually peaks with the life cycle of mosquitoes, which in Northeast Ohio is in August and September," Pethel continued. "A mild winter and many spring rains have allowed this year's mosquito population to increase, while summer's hot weather with little rain has created stagnant pools of water that are ideal for mosquito breeding grounds."
According to the Centers for Disease Control and Prevention (CDC), 43 states, including Ohio, have reported WNV infections in people, birds or mosquitoes; as of the second week of August 2012. Over 80 percent of the cases have been reported from 6 states (Texas, Mississippi, Louisiana, Oklahoma, South Dakota and California); with almost half of all the cases reported from Texas.
How Does WNV Spread?
- When outdoors, use insect repellent and follow the label directions. To apply, adults should spray it on their hands before using on the face and other exposed areas of skin; they should also apply insect repellant for their children according to directions. If sunscreen is needed, apply before using the insect repellent.
- Wear long sleeves and pants during peak biting hours of dusk to dawn, or consider staying indoors during these hours.
- Have good screens on windows and doors to keep mosquitoes out, and consider using air conditioning. Keep your gutters and drain pipes in working order.
- Eliminate mosquito breeding grounds, since standing water attracts mosquitoes. Empty water from flower pots, buckets, barrels, pool covers, etc. Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings to drain water. Empty wading pools and keep them on their sides when not in use.
"Usually, WNV is spread by the bite of an infected mosquito," Pethel added. "Mosquitoes become infected when they feed on infected birds. These infected mosquitoes can then spread WNV to humans and other animals when they bite.
"In a very small number of cases, WNV also has been spread through blood transfusions, organ transplants, breastfeeding and during pregnancy from mother to baby. However, the virus is not spread through casual contact, such as touching or kissing a person who has been infected."
People typically develop symptoms between three and 14 days after they are bitten by the infected mosquito. According to the CDC, about 1 in 150 people who are infected with WNV, will develop a severe illness.
Severe symptoms are more likely in people age 50 and older. "These symptoms can include high fever, headache, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis," Pethel advised.
Up to 20 percent of the people who become infected have milder symptoms such as fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. These symptoms can last anywhere from a few days to several weeks. Approximately 80 percent of people, who are infected with WNV will not show any symptoms at all.
"There is no specific vaccination against or treatment for a WNV infection," she said. "In cases with milder symptoms, people may experience fever and aches that usually pass on their own.
"However, if a person develops symptoms of severe WNV illness, such as unusually severe headaches or confusion, they should seek medical attention immediately. Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers are also encouraged to talk to their doctor if they develop symptoms that could be considered as WNV."
"The most effective way to avoid the West Nile virus is to take measures to prevent mosquito bites, which are the most common cause of infection," Lyn concluded. "Mosquitoes contract the virus from birds, and people are therefore advised not to touch dead birds with their bare hands.
"In addition, they should try to control the breeding grounds of mosquitoes on their property and protect themselves from mosquito bites when outdoors. Many mosquitoes are most active at dusk and dawn. Peak biting periods are several hours after daybreak and before dark, but mosquitoes can feed anytime during the day."