Mosquitoes are an annoying part of outdoor summer fun, buzzing around at picnics and playgrounds and causing itchy red skin bumps when they bite. However, mosquitoes also can transmit serious illnesses to humans through those bites.
West Nile virus is the most prevalent mosquito-borne illness in Pennsylvania and has been present here for almost 20 years. Of the approximately 50 species of mosquito that live in the state, 12 can infect humans with West Nile virus.
There are no vaccines to prevent West Nile virus, and no anti-viral medications to treat it. Fortunately, most people infected with the virus do not experience any symptoms. About 1 in 5 infected people develop a fever and other symptoms, such as headache, body aches or a rash. Most people recover completely, but fatigue can last for weeks or months.
Less than 1 percent of infected people develop encephalitis or meningitis. This can lead to severe symptoms such as seizures, paralysis, coma or even death.
Other disease risks
Eastern equine encephalitis is another disease transmitted by mosquitoes in the eastern United States, although usually fewer than 10 cases a year are reported in humans. As with West Nile virus, most infected people do not show symptoms. However, children are among those with the greatest risk of developing severe disease when infected.
Often, Pennsylvanians are infected when they travel to warm-weather countries, or even to the southern United States. Mosquitoes can transmit other diseases that are not usually present in Pennsylvania and nearby states:
Zika virus — reported in every state and transmitted by local mosquitoes in Florida and Texas. As with many mosquito-borne illnesses, most people infected with Zika do not get sick or have only mild symptoms. However, when a pregnant woman is infected, she can transmit the disease to her unborn baby, causing severe brain defects.
Dengue fever — infects as many as 400 million people a year around the world, primarily in tropical and subtropical areas, including Puerto Rico and the Virgin Islands.
Chikungunya — first local transmission in the Americas was identified in late 2013.
Local transmission means that mosquitoes in the area have been infected and are spreading the disease to people. Mild winters in recent years have allowed mosquitoes to flourish in cooler areas of the United States. That makes it more likely that mosquitoes here could bite someone who was infected in another country and begin transmitting a disease locally.
Preventing mosquito bites
The best way to prevent the spread of mosquito-borne disease is to avoid being bitten.
– Use window screens to keep mosquitoes out of the house.
– In the yard, eliminate standing water, where mosquitoes like to breed. This includes stagnant ponds, old tires, unused swimming pools and depressions where puddles form.
– Wear long-sleeve shirts, long pants and socks when outdoors, if mosquitoes are prevalent.
– Apply an insect repellant to exposed skin before going outdoors.
– Use a long-lasting, EPA-approved repellant, such as DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol. The higher the concentration of DEET in a product, the longer it will last before reapplication is needed. A higher concentration is not more effective in repelling mosquitoes.
– If you apply both sunscreen and insect repellant, apply the sunscreen first, let it dry and then apply the insect repellant.
– Consider buying permethrin-treated clothing or treating clothing at home with permethrin.
The Centre County Planning & Community Development Office operates a state-funded West Nile virus control program which will spray, at no cost, areas where the adult mosquito population is unusually high.
Despite precautions, if mosquito bites occur, don’t panic. In Pennsylvania, red skin bumps usually go away in a few days, with no lingering effects or risk of disease. In the meantime, ease the itch by applying calamine lotion, an over-the-counter hydrocortisone cream or an ice pack.
Barbara H. Cole, MS, CRNP, is a nurse practitioner with Penn State Medical Group, located at 1850 E. Park Ave., Suite 207, in State College. Penn State Medical Group is now accepting new patients. To make an appointment, call (814) 235-2480.
