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Allentown School District

Zika and West Nile Viruses

Mosquito bites can be more than just annoying and itchy, they can also make you sick. Mosquitos are vectors which means they are capable of carrying and spreading diseases. Certain diseases are only carried and transmitted by specific species of mosquitos. There are approximately 60 species of mosquitos found in Pennsylvania. Of those, the species that pose the most risk to human health are Culex pipiens and the Aedes albopictus or Asian tiger mosquito.
West Nile
The Culex pipiens is found in Pennsylvania and responsible for the majority of West Nile Virus transmissions. These mosquitos are most active at dusk and dawn.
West Nile Virus Facts
  • Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals.
  • The incubation period is usually 2 to 6 days but ranges from 2 to 14 days. This period can be longer in people with certain medical conditions that affect the immune system.
  • There are no medications to treat or vaccines to prevent West Nile virus infection.
  • Most people (70-80%) who become infected with West Nile virus do not develop any symptoms.
  • About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.
  • Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis. The symptoms of neurologic illness can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis.
  • Serious illness can occur in people of any age, but people over 60 years of age and those that are immunocompromised are at a higher risk.
The Aedes species is responsible for carrying and transmitting the Zika Virus. These mosquitos are aggressive, fly low to the ground and bite mostly during the daytime. These mosquitos also prefer to feed on humans. The Aedes aegypti is the primary vector for Zika, but is not found in the Lehigh Valley. The Aedes albopictus or Asian tiger mosquito is established in some areas of Pennsylvania, but its population is small. The risk of contracting a serious illness from mosquitoes is relatively low in the United States compared to the risk in developing countries. However, the unique characteristics of the Zika Virus and the amount of travel that is done to and from the United States makes this virus a public health concern. The Zika Virus is spread to people primarily through the bite of an infected Aedes species mosquito, but can also be transmitted in utero from mother to child, through sexual contact and through blood transfusions.
Zika Virus Facts
  • Anyone who lives in or travels to an area where Zika virus is found and has not already been infected with Zika virus can get it from mosquito bites. Go to for travel advisories.
  • No local mosquito-borne Zika virus disease cases have been reported in the United States, but there have been travel-associated cases.
  • A vaccine or treatment for Zika virus infection is not currently available.
  • The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes).
  • Symptoms can last for several days to a week after being bitten by an infected mosquito.
  • People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika.
  • Zika virus can be spread by a man to his sex partners. The virus can be spread before symptoms start and after symptoms resolve.
  • Men who do not develop symptoms should use condoms for at least 8 weeks after possible exposure.
  • Men with Zika virus exposure who develop symptoms should wait at least 6 months after symptoms resolve before having unprotected sex.
  • The virus is present in semen longer than in blood.
  • Zika virus infection during pregnancy has been linked to serious birth defects. A woman with Zika virus infection can pass Zika virus to her fetus during pregnancy or near the time of delivery.
  • Women with Zika virus exposure who develop symptoms should wait at least 8 weeks after symptoms resolve before attempting pregnancy.
  • Women and men with Zika virus exposure but not developing symptoms should wait at least 8 weeks after exposure before attempting pregnancy.
  • There are no reports of infants getting Zika virus through breastfeeding to date.
  • Persons with Zika virus exposure who do not develop symptoms should self-defer from blood donations for 4 weeks after possible exposure.
  • Persons with Zika virus exposure who develop symptoms should self-defer from blood donations for 6 months.
  • Once a person has been infected, he or she is likely to be protected from future infections.
To help decrease the risk of mosquito borne disease transmission by reducing the number of breeding sites, use Environmental Protection Agency registered repellents, repair screens and doors to fit tight, and limit outdoor activities to periods of time when mosquitos are less active and dressing appropriately.
Reduce the number of breeding sites
  • Remove old tires, cans, buckets, pots, and similar items that can trap rainwater.
  • Position tarps and boat covers to allow rain runoff and limit water pooling
  • Potted plants with water-capture bases should be drained or screens should be applied to the overflow vents.
  • Turn plastic wading pools and wheelbarrows upside-down when not in use.
  • Change birdbath water at least once a week.
  • Keep swimming pools chlorinated and stock ornamental ponds with surface-feeding minnows.
  • Rain gutters should be installed with sufficient slope to prevent the pooling of water; remove leaves and other obstructions from downspouts.
  • Remove trash and litter.
Protect your family from getting mosquito bites
  • Wear long-sleeved shirts, long pants, and closed toed shoes
  • Use Environmental Protection Agency registered repellent with one of the following: DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. EPA-registered insect repellents are proven safe and effective, even for pregnant and breast-feeding women. 
  • Treat clothing and gear with permethrin (but do not apply to skin).
  • Use and reapply insect repellent as directed.
For Travelers
  • Follow the CDC guidelines on Mosquito Bite Prevention for Travelers
  • If you have Zika or have recently traveled to an area with Zika
  • Even if you do not feel sick, travelers returning to the United States from an area with Zika should take steps to prevent mosquito bites for 3 weeks so they do not spread Zika to mosquitoes that could spread the virus to other people.
  • During the first week of infection, Zika virus can be found in the blood and passed from an infected person to another mosquito through mosquito bites. An infected mosquito can then spread the virus to other people.
  • To help prevent spreading Zika from sex, you can use condoms correctly every time you have sex. This includes vaginal, anal, and oral sex. Not having sex is the only way to be sure that someone does not get sexually transmitted Zika virus.
More information on mosquitos and mosquito borne illnesses can be found at The Lehigh County Cooperative Extension’s West Nile Virus Program office is a good source of information - call (610) 366-8345. You can also contact the Allentown Health Bureau at (610) 437-7599.