West Nile Virus reappears on campus, in B-CS area
Published: Thursday, July 19, 2012
Updated: Wednesday, July 25, 2012 19:07
West Nile Virus is officially here. Texas A&M University, College Station and Bryan have tested positive for mosquitoes that carry this virus.
For the fourth week in a row, the golf course at Texas A&M has tested positive for mosquitoes carrying West Nile Virus. Other sites that have tested positive for the virus include the area around the Jack K. Williams Administration Building, Brison Park and Sue Haswell Park.
While there have been 23 human cases of the virus in Texas this year, there have yet to be any in Brazos County. Texas has highest number of reported human cases of West Nile, according to the Centers for Disease Control and Prevention. The nation’s first West Nile related death this year occurred in Dallas earlier this month.
“We usually see mosquito cases first,” said Mark Johnsen, environmental health specialist and medical entomologist at the Brazos County Health Department. “We see most human cases in late July and early August. We haven’t entered the worst part of the season yet.”
As summer progresses, more mosquito test pools are testing positive.
“Earlier we’d see only one or two cases per week,” Johnsen said. “This week we had eight positive mosquito pool cases. So we’re increasing the amount of West Nile that’s out there.”
Although rainy days may serve as a nice break from the hot days of summer, the aftermath is not always beneficial.
“Because of all the rain we’ve had, there’s going to be a lot of standing water for mosquitoes to lay their eggs in,” said Roger Gold, professor in the Department of Entomology. “If the water stands around for just a few days, we’ll complete another generation of mosquitoes. The number is going to increase in these next 10 days.”
The life cycles of mosquitoes are very short compared to other insects. They can go from an egg to an adult in less than two weeks. And because of the temperature and the warm water, they can put off a generation continuously.
The female mosquitoes take blood meals from a host and use it for protein, which allows them to lay eggs. They need to have a blood meal in order to reproduce. Male mosquitoes don’t bite. They can survive by feeding on flower nectar.
The reason West Nile Virus is spreading is because a vector carries and transfers the disease to a susceptible host. In this case, the vector is the southern house mosquito and humans and horses play the role of host.
“West Nile Virus itself is in birds that are infected, in horses and in people,” Gold said. “Depending on where the mosquito takes her blood meal, she’ll pick the virus up, it will go into her gut and it will multiply in the tissues. As she takes another blood meal, she’ll inject that virus into another host. We’re moving a virus of other animals through the mosquito.”
In order to solve the problem of West Nile Virus, the vector must to be removed.
Presumably, the easiest way to do so would be to spray around the county. But this only kills the adult mosquitoes and the next day there would be a new population of adults.
The best way to rid our area of these pests would be to modify their habitat.
“We can make it more difficult for the mosquitoes to survive,” Gold said.
Mosquitoes lay their eggs in sewer systems, catch basins, ponds, fountains and any place with standing water. Since their flight range is approximately a mile, the Health Department goes to these places where the test pools for mosquitoes have been positive, according to Johnsen.
In these areas, the department tries to eliminate the eggs and larvae to prevent them from developing into adults, which will fly off to spread the virus. The process is called “dunking.”
A “dunk” is a pesticide that is put in standing water. It dissolves and kills the larvae.
For the rest of the mosquito population, there are ways to protect against their bite. Take some personal protections to stay safe and follow the four D’s, according to Johnsen.
Don’t go out during dusk or dawn because those are the peak mosquito biting times of the day. Mosquitoes are too fragile to be out in the hot summer sun.
Drain any standing water.
Dress wearing long sleeves and long pants. Wear light colored clothing that has a loose fit. This way, even if mosquitoes still try to bite you, they can’t get through to your skin.
Wear repellent with DEET. Mosquitoes don’t like the smell of the chemicals in repellent that contain this and will not bite.