shutterstock_121589452By Rachel Bocchino

On July 23 and for the first time this summer, a mosquito pool located in Jamaica Plain tested positive for West Nile virus (WNV).  Another pool tested positive the following week in Hyde Park.  It may surprise some people to learn that WNV has actually been detected in Boston every year since 2000.   Though WNV poses very little risk to most humans, in order to ensure everyone remains healthy and free of this mosquito-borne illness, it is important to understand the basics about the virus and the methods of prevention.

What is West Nile virus?

West Nile virus is a serious virus that is most commonly spread by infected mosquitoes.  It was first detected in the United States in 1999.

How do people become infected with West Nile virus?

West Nile virus is most frequently spread to people by the bite of an infected mosquito.  Although mosquitoes get infected by feeding on an infected bird, people cannot get WNV directly from a bird.  In extremely rare cases, WNV can also be spread through blood transfusions, organ transplants, and from mother to child during delivery and breastfeeding.

When are people most likely to become infected?

In Boston, mosquitoes are most likely to carry WNV during the late summer and early fall months.

What are the symptoms of West Nile virus?

  • Most people who are infected will experience no symptoms at all.
  • Some people – about 1 in 5 – will develop a fever along with headaches, nausea, rash, vomiting and body aches.
  • Few people – only 1% – will develop a serious neurological illness, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the spinal cord and lining of the brain).  Symptoms of neurological illness include severe headache, neck stiffness, high fever, confusion, seizures, tremors, and paralysis.
  • Symptoms of the virus usually appear 2-6 days after being bitten by an infected mosquito, but this varies from person to person.

How can people reduce the chance of becoming infected with West Nile virus?

The most important and effective way of avoiding infection is to avoid being bitten by mosquitoes.

  • Use a mosquito repellent that contains DEET, oil of lemon eucalyptus, Picaridin or IR3535.
    • Read the repellent directions to ensure that you are applying properly.
    • Do not let children apply repellent themselves.
    • Wear protective clothing.
    • Avoid being outside dusk through dawn, when mosquitoes are most active.
    • Mosquitoes breed in water.  Empty any containers that collect water.

How will I know if mosquitoes in my neighborhood tested positive for West Nile virus?

The Suffolk County Mosquito Control Project tests mosquito pools at several sites around the city.  They report all findings to the Boston Public Health Commission.  Positive test results are posted on the BPHC website.

For more information on West Nile virus visit the Infectious Disease Bureau website or call at (617) 534-5611.

Rachel Bocchino is the IDB Social Media Outreach Intern for STI Education.  She attends the College of the Holy Cross, is a Classics Major/Chemistry Minor and in the Pre-Health Program.  She will graduate in 2014.