COLLEGE STATION Winter isn’t officially over yet, but officials are already watching mosquito and virus activity in Texas and warning residents to take precautions now against mosquito-borne diseases.
“We never run out of mosquitos at least in this part of Texas we just change species with the season,” said Dr. Jim Olson, entomologist with the Texas Agricultural Experiment Station.
In fact, some species, of which two or three are prime vectors of the West Nile virus, are just reaching their population peaks from Central Texas to Southeast Texas and along the Rio Grande River. It’s been wetter than normal in some regions, and that always produces a bumper crop of mosquitos.
“Right now, the water is still too cold, the weather is still too cold for the onslaught of typical early-spring flood water mosquito species we see every year,” Olson said.
When the weather starts warming up and temperatures start exceeding 60 degrees and staying there at night as well during the day, there will be a shift to the mosquitos species which occur in Texas in the spring. As temperatures continue to rise into the 80s, entomologists expect the summer species to appear.
Officials are anticipating cases of mosquito-borne viruses like West Nile, Eastern and St. Louis encephalitis when bird nesting season begins in Texas soon. West Nile virus made its entrance into Texas last year at the end of the normal bird nesting season, Olson said.
“Nesting birds are a nursery for a virus like West Nile and St. Louis encephalitis in terms of ready access to mosquitos that feed on birds and transmission of the disease agents from birds to mosquitos and back to birds,” he said.
“We sort of build the incubator up, and then it spills out from there to horses and humans,” Olson added.
“We’ve got the virus now, so we’re going to have to see how it builds up in the bird population and how it spreads from there. We really don’t have a feel on just how much immunity we’ve got in the resident populations of birds, horses and humans from last year,” he said.
Also, certain sections of Texas, particularly Southwest and Far West Texas, have not been impacted by West Nile yet. “Those are vulnerable areas,” he said.
Mosquito-control and health officials in cities such as Houston and Dallas are anticipating the worst, so they can be ready.
According to Olson, the primary species which probably will spread West Nile this summer is Culex quinquefasciatus, or the southern house mosquito. It may get some help from the black and white striped Asian tiger mosquito, or Aedes albopicuts, he said.
“If it warms up with all this standing water around we could see an early rise of the southern house mosquito,” he said. “The earlier those things start to show up, the earlier we see cycling of viruses like St. Louis and West Nile.”
To avoid mosquito-borne viruses, Olson urged, everyone should “break your association with mosquitos by your behavior. Avoid areas where mosquitos are concentrated during the day, confine your activities to the daylight hours and locations where mosquitos are least active.”
Also, ensure homes and other premises are not mosquito havens by getting rid of breeding areas (anything that holds water), Olson said. Also, using yellow outside lighting instead of white or mercury-type bulbs makes homes less attractive for nocturnal insects. Make sure screens over windows and doors are snug and don’t have holes.
The primary mosquito carrying of West Nile and St. Louis encephalitis in the summer is predominantly a bird feeder that only occasionally feeds on humans, Olson said.
“But, it is more apt to feed on humans when get inside a house where they don’t have the option,” Olson said. “So it’s very important to keep mosquitos out where they belong.” Since West Nile virus can be transmitted to horses, they should be vaccinated now.
“Keep in mind the vaccination regimen requires the initial vaccination and then a follow-up, then it’s two or three weeks before they are protected,” Olson said.
“Now is when they should be vaccinated. Don’t wait until the virus shows up,” he added.
According to the U.S. Department of Agriculture Agricultural Plant Health and Inspection Service Web page, horses should receive an annual booster.
Olson said there is still no vaccine for pets, so those should be protected from mosquito access and attack. Last year, a few dogs died from West Nile virus, Olson said.
“It is infrequent but it does occur,” he said.
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