Preventing the Bite of West Nile Virus

The West Nile virus is one of a family of viruses that can be spread to humans through the bite of an infected mosquito. The virus first appeared in New York City in 1999 and quickly spread across the United States. It is spread by the Culex type of mosquito, and although no one knows for sure how many of these mosquitoes carry the virus, it is thought to be a very low percentage.

Most West Nile virus infections are mild and are often not clinically apparent. Only one-fifth of those infected show any signs or symptoms of the disease. These can include a mild to moderate fever, headache, muscle aches and weakness, rash and/or swollen lymph nodes. Only 1 in 150 infections (or less than 1%) result in severe neurologic disease, the most common of which is West Nile encephalitis: a direct infection of the brain by the virus. There is no treatment for this form of the illness and although rare, it can be fatal for immunocompromised people and adults greater than fifty years old.

Obviously, mosquito bite prevention is the best way to avoid infection. The only clinically proven forms of insect repellent are those that contain DEET. Most pediatricians recommend a repellent that contains approximately 10% DEET. This is safe for children and infants as young as two months old and should offer 2-3 hours of protection. The repellent should never be sprayed near a child’s face; instead spray some on your hands and apply a thin coating on your child. Preparations containing up to 30% DEET may be used on older children and will last a longer time period. DEET also protects against the tick that carries the bacteria that causes Lyme Disease.

Combination products that contain both sunscreen and DEET based repellents are not advised. Sunscreen should be reapplied frequently throughout the day, while DEET should only be applied once. It is okay to use insect repellent on top of already applied sunscreen. At the end of the day, any product containing DEET should be washed off the skin.