Cases of West Nile virus in Texas have been the lowest in years, and researchers may know why, according to Texas A&M AgriLife Extension Service experts.
Mike Merchant, Ph.D., AgriLife Extension entomologist, Dallas, said a publication by health officials in Dallas County may shed light on factors that contribute to outbreaks and help forecast outbreaks in the future.
There has been one case of West Nile in humans this year in Fort Worth, but Merchant said vector indexes used to measure the conditions under which the disease is spread are the lowest they’ve been in five years.
Mosquito numbers this year are normal to high, Merchant said, but the presence of the disease has remained low. A report by the Dallas County epidemiologist showed West Nile virus outbreaks correlate with weather conditions, and this season was not conducive to its production and spread.
Looking back over previous years and case numbers, Merchant said the researchers concluded that an unusually mild winter followed by rainfall patterns ideal for mosquito breeding in the spring followed by a very hot summer created ideal conditions for an outbreak.
Take precautions despite low case numbers
Sonja Swiger, Ph.D., AgriLife Extension entomologist, Stephenville, said the rest of the state has also experienced a lower number of West Nile cases this year.
Swiger reached out to the state medical entomologist and entomologists in Dallas and Harris counties and said the consensus is numbers are slow at this time but that may or may not predict the year.
Merchant said health officials in Dallas County have found West Nile-positive mosquitoes, but their numbers have been very low, especially when compared to 2012. While he doubts a major increase in transfers to humans will occur, people should take precautions to avoid mosquito bites.
“We still need to treat mosquitoes with respect and take proactive measures to avoid them, but we wanted to give some good West Nile news for a change,” he said.
For a comprehensive look at how to reduce mosquito populations around the home and protect against bites, go to AgriLife Extension’s Mosquito Safari.
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