With much focus on Zika, officials warn of West Nile
Virus still spreads in Texas, though cases are down
State and county health officials are reminding people to take precautions against West Nile virus even as it has been overshadowed this summer by concerns about the Zika virus.
“West Nile illness is again spreading in Texas,” state health officials said on their website.
Only three cases of West Nile virus have been confirmed in Harris County so far this year, compared to a total of 23 cases in 2015. The city of Houston also has reported a case. In Montgomery County, a man in his 70s became the first confirmed human case, county officials said this week.
There are currently 69 cases of West Nile virus in Texas. Last year, 275 human cases were reported in Texas, including 16 deaths.
“This is what we consider a not-as-heavy West Nile virus season,” said Dr. Umair Shah, executive director of the Harris County Public Health Department. But he said things could change.
Shah said it’s difficult for health officials to predict how many cases of the virus will occur this season.
“You have heavier seasons and lighter seasons,” Shah said. “There is incredible uncertainty around mosquito-borne diseases that we can’t predict. We have to always be ready.”
One factor contributing to the low number of West Nile cases might be the heavy rainfall in Harris County in April, Shah said. Rain helps wash away eggs left by mosquitoes. Other factors are the climate and how mosqui-
toes are breeding.
Despite the relatively low number of West Nile virus cases so far, health officials are warning people to continue to protect themselves against mosquito diseases, whether it be West Nile or Zika virus.
State health officials urge people to put on mosquito repellent, wear longsleeve clothing, and to avoid any standing water. Those with low immune systems are particularly at risk.
Different species
Texas has had 127 reported cases of Zika virus, state officials reported Thursday, but “all the cases were associated with travel to an area where Zika is being spread.”
No West Nile cases have been reported so far in Fort Bend and Galveston counties, but both have reported cases of Zika virus.
Shah noted that West Nile virus has affected Harris County since the early 2000s. The culex mosquito that carries the West Nile virus usually is active at night, while the aedes mosquito, which carries Zika, typically is active during the day. West Nile mosquitoes also like to bite other animals, while mosquitoes that carry Zika exclusively bite humans.
“You’re not going to see the (Zika) virus amplifying in other animal populations like we see with West Nile,” said Chris Van Deusen of the Texas Department of State Health Services. “The ecology of the virus and the mosquitoes are different. The things you can do to stop them are just the same.”
If infected with West Nile virus, 70 to 80 percent of people won’t show any symptoms, said Deusen. Only about 20 percent will develop West Nile fever and less than one percent will develop the more severe West Nile neuroinvasive disease.
The neuroinvasive disease affects the brain, spinal cord and other parts of the nervous symptoms. It also can result in tremors, coma and death.
Mosquito control
Harris County continues to monitor West Nile by setting traps across the county, capturing insects to determine what viruses they might carry. Officials then can spray pesticides in areas accordingly. Shah said traps show that mosquitoes are not carrying West Nile virus as much as they’ve seen in past years.
Harris County spent $4.5 million this year on mosquito control, with an additional $1.1 million specifically focusing on the Zika virus.
“They are different viruses and different mosquitoes,” Shah said. “However we put them in the one category. We want our community to protect itself from mosquito-borne diseases, whether it’s a mosquito that bites you during the day or during the night.”
“There is incredible uncertainty around mosquito-borne diseases that we can’t predict. We have to always be ready.”
Dr. Umair Shah, executive director of the Harris County Public Health Department