West Nile Virus Infection to be Studied in St. Louis Metro-area Residents;

Study Teams to Make Home Visits in Parts of the City and County

Public health officials are conducting a new research study this spring to gain a clearer picture of how much West Nile virus infection actually has occurred in the city of St. Louis and St. Louis County the past two mosquito seasons. Funded by a grant from the Centers for Disease Control and Prevention (CDC), the study is being coordinated among members of Missouri’s West Nile Virus Working Group. The Missouri Department of Health and Senior Services (DHSS), St. Louis University School of Public Health (SLUSPH), St. Louis City Health Department, and St. Louis County Department of Health are conducting the study.

It is estimated that more than 80 percent of all West Nile virus (WNV) infections go unnoticed. One in five infected people will have a mild flu-like illness, and only about one out of 150 infections results in illness requiring hospitalization. However, risk of severe illness from WNV infection is higher in the elderly and people with compromised immune systems.

 

For more information on West Nile Virus visit:

The Center for the Study of
Emerging Infections

St. Charles County Department of Community Health and the Environment

Missouri Department of Health and
Senior Services

Centers for Disease Control and Prevention

The WNV study involves testing blood samples from approximately 1,000 persons living in the St. Louis metropolitan area for evidence of past WNV infection. Study teams take blood samples from people living in areas that appear to be at lower risk for WNV, and compare these samples to samples from people in higher-risk areas. Recruitment began the last week of April, and the study must be concluded in early summer, before the height of the new mosquito-breeding season. Study leaders hope to meet a number of objectives, including:

  • Estimate how many people were infected with WNV in the St. Louis metro area during the 2002 and 2003 combined transmission seasons. This will be achieved by looking for WNV antibodies in the blood samples and using those results to estimate the WNV infection rate for the region.
  • Determine how effective various surveillance methods are in predicting areas that may be at higher risk for WNV infection.
  • Seek to show what specific factors, such as mosquito-avoidance behaviors, are associated with infection risk.

The study includes randomly selected households in communities that have experienced a large number of dead birds or WNV-infected mosquitoes, and households in areas where there were few dead birds or infected mosquitoes. Study teams, consisting of an interviewer and a trained phlebotomist, visit these randomly selected homes and ask if one person in the household will agree to provide survey information and donate one tube (about two teaspoons) of blood for the study. Participants must be at least five years old and be able to provide either written informed consent or have an adult guardian who can provide consent and answer the survey questions. 

The only persons who are excluded from the study are those who have not lived at their current address since June 2002, and those who have known bleeding disorders, since blood samples will be taken from an arm vein.  Participants are given free WNV educational material that outlines strategies that may help reduce their risk of future infection. Then, later in the study, they will be able to learn the results of their blood test.  After the blood draw, participants are asked a few survey questions, which is standard in studies like this one.  The survey gathers basic demographic information, but also includes an assessment of possible routes of exposure to mosquito-borne illness, possible risk factors for WNV-related illness, and questions that help rule out infections that would have occurred outside the St. Louis metro region.

The blood samples will only be tested for infections transmitted by mosquitoes, including WNV. Information gathered during the survey and all blood test results will be kept confidential and used only for the study. No identifying information will be shared outside of the study and results detailed in the final study report will be in aggregate form and not show any identifiers.

Study teams will work only during daylight hours and will complete their work each day by 8 p.m. to limit disrupting households in the evening and for the teams‚ own safety. The teams will wear official identification and will clearly identify themselves when making a house call. The St. Louis City Police Department and the police departments of the municipalities in St. Louis County will also be notified of the study and the teams‚ work throughout  the city and county.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


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