Phone

News & Perspectives

Infection from West Nile Virus Less Likely than Feared

What the Study Showed
How It Was Done
Why its Important

What the Study Showed

Even during a prolonged epidemic of the West Nile Virus (WNV), a disease that primarily affects bird species, the risk that it will pass to humans and cause the disease is much lower than scientists once feared. This is the finding of a 2001 Annals of the New York Academy of Science report. The virus is transmitted to people by mosquitoes who first bite an infected bird and then pass along the virus when they subsequently bite a human. WNV was first identified in the United States in 1999, when it caused outbreaks of severe neurological disease in the New York City area.

How It Was Done

The researchers examined human blood samples taken during October of 2000 in an 18-square-mile area in Connecticut, where the disease was most intense in the avian population. In all, 739 people from a representative sampling of 645 households participated in the survey. Most houses were single-family homes with yards, nearly all with window screens and air conditioning. Only a few participants had noticed a dead bird on their property. Yet over half were concerned to some degree about contracting WNV.

In addition to providing blood samples, the participants filled out a questionnaire on their use of preventative measures, such as using mosquito repellent, wearing long shirts and pants, checking window and door screens, cleaning gutters, and removing standing water sources where mosquitoes can breed.

Blood samples were tested for WNV at a Connecticut Department of Public Health laboratory and then sent to the Centers for Disease Control in Atlanta for confirmation. The results showed that no person participating in the survey was infected with the virus.

Why its Important

In Connecticut, each WNV outbreak in humans was preceded by an epidemic of the disease in birds. This population survey suggests that that protective measures taken against mosquitoes in the wake of the previous epidemics have helped prevent WNV in humans, and most likely will continue to do so. The finding reinforces the importance of public education and awareness campaigns.

Source: McCarthy TA, et al. West Nile virus serosurvey and assessment of personal prevention efforts in an area with intense epizootic activity: Connecticut, 2000. Ann NY Acad Sci 2001;951:307-316.


Date Published: 06/30/2002
> Printer-friendly Version Return to Top