Featured Research

from universities, journals, and other organizations

Research supports mosquito indexing system that identifies best time to act against potential West Nile virus outbreaks

Date:
July 16, 2013
Source:
UT Southwestern Medical Center
Summary:
Researchers have unlocked some of the mysteries of West Nile virus outbreaks and shown that use of a mosquito vector-index rating system works well to identify the best time for early intervention.

UT Southwestern Medical Center researchers have unlocked some of the mysteries of West Nile virus outbreaks and shown that use of a mosquito vector-index rating system works well to identify the best time for early intervention.

Related Articles


West Nile infections in humans can cause long-term neurological damage and even death. The investigation analyzed a decade of West Nile infections, weather, and housing data. The 2012 data -- from the nation's largest West Nile outbreak that occurred in Dallas County, Texas -- revealed that the best way to avoid an outbreak and stave off the resultant rise in human infections was to determine a mosquito vector index. The vector index value is calculated from the abundance of mosquitoes and the percentage of mosquitoes infected with West Nile virus.

"When the vector index goes above 0.5 early -- in June or July -- large numbers of people are silently infected, and this is the best time to intervene," said Dr. Robert Haley, chief of epidemiology and professor of internal medicine at UT Southwestern and senior author of the study published in the July 17 edition of the Journal of the American Medical Association. "In years when the vector index did not rise until late July or August, impending outbreaks just sputtered -- in late summer mosquito abundance declines, and mosquitoes become less active and stop biting as much."

The study also showed that determining the number of West Nile virus infections in people is a poor way to determine how to respond to an outbreak.

"After the infecting mosquito bite, it takes a week for the first symptoms to develop, a week to see people turning up at hospitals, and a week for laboratory confirmation of the diagnosis and reporting to health officials," Dr. Haley said. "That three-week time period is crucial. Acting early from the vector index rather than after human case reports and deaths mount up can nip an outbreak in the bud. However, if mosquito data are unavailable or a decision to intervene takes longer, later intervention may still be important to terminate the outbreak."

The analysis also found that milder winters and unusually warm spring temperatures contributed to epidemic years for West Nile, a major concern as global temperatures continue to warm, Dr. Haley said.

A fourth critical finding in the paper related census track data to the 2012 outbreak, demonstrating that areas of higher property values, housing density, and percentages of unoccupied homes were at greater risk. The researchers said that this result is likely due to fostering the types of environment and mosquitos most likely to transmit the disease, which is carried more by house mosquitoes than forest mosquitoes. In Dallas County, their data showed year after year clustering in the Park Cities and North Dallas areas.

The analysis tools used in the study may be applicable elsewhere, but due to variations in weather, mosquito populations, and other factors, each region or county will need to conduct their own analysis to identify the most appropriate vector-index rating signaling when to act, Dr. Haley said. Along with the paper, the authors provide an instruction manual for other counties to calculate the vector index from their own mosquito infection surveillance data.

"Given the leading character of this index, epidemiologists and government officials can implement, in a more timely manner, preventative measures to reduce the impact of future West Nile Virus outbreaks," said Dr. Tom Fomby, professor of economics in the Dedman College of Humanities and Sciences at Southern Methodist University, who contributed statistical methods more commonly used in economics to evaluate the vector index.

Other authors of the study were Dr. Wendy Chung, chief epidemiologist of Dallas County Health and Human Services, and DCHHS colleagues Dr. Christen Buseman, Sibeso Joyner, and Sonya Hughes; and Dr. James Luby, professor of internal medicine in the division of infectious diseases at UT Southwestern.


Story Source:

The above story is based on materials provided by UT Southwestern Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Wendy M. Chung et al. The 2012 West Nile Encephalitis Epidemic in Dallas, Texas. JAMA, 2013 DOI: 10.1001/jama.2013.8267

Cite This Page:

UT Southwestern Medical Center. "Research supports mosquito indexing system that identifies best time to act against potential West Nile virus outbreaks." ScienceDaily. ScienceDaily, 16 July 2013. <www.sciencedaily.com/releases/2013/07/130716161839.htm>.
UT Southwestern Medical Center. (2013, July 16). Research supports mosquito indexing system that identifies best time to act against potential West Nile virus outbreaks. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2013/07/130716161839.htm
UT Southwestern Medical Center. "Research supports mosquito indexing system that identifies best time to act against potential West Nile virus outbreaks." ScienceDaily. www.sciencedaily.com/releases/2013/07/130716161839.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins