At the peak of the mosquito season, there have been four confirmed cases in Smith County, with 10 more cases being reported in Gregg, Smith, Van Zandt, Henderson, Wood, Rains and Anderson counties.
“We don't have the disease burden that Dallas/Fort Worth has, but we have significant activity in our area,” said Dr. Paul McGaha, regional director at the Texas Department of State Health Services. “The important message is about prevention.”
The health department is investigating other counties, so more statistics could become available soon. McGaha noted that there is a lag time between when a patient sees a doctor and when lab results are entered into a database.
There have been 586 confirmed cases of West Nile in Texas this year. About half of those have been in the Dallas area. Of the cases in Texas, 326 have resulted in neuroinvasive illnesses and the average age of those patients is 55.8.
Of the total cases, 263 only experienced West Nile fever, a mild form of the disease. There have been 21 deaths related to the virus in Texas and the average age of those patients is 80.3.
The number of fatalities stemming from the West Nile virus already has exceeded what was recorded for 2007, when Texas saw 17 deaths for the year.
The basic precautionary measures include: staying indoors at dusk and dawn; dressing in long sleeves/pants and with loose and light colored clothing when outdoors; using an insect repellent that contains DEET, Picaridin or oil of lemon eucalyptus; and draining standing water in yards and around the neighborhood.
Doctors recommend up to 30 percent DEET, but do not advise using it on children less than 2 months old.
Items such as flower pots, tires, wading pools and trash are breeding grounds around the house. Health officials suggest cleaning gutters and scouring over the yard to limit the opportunities for mosquitoes to breed.
“It's simple, but it's unbelievably difficult to change culture,” said Dr. Jonathan MacClements, Smith County Health Authority and chairman of the health science center's Department of Family Medicine.
“You'd be surprised when you go home tonight and look around the house, how many areas water is residing and the mosquitoes are proliferating.”
The recent rains that hit East Texas have been a blessing and a burden.
“If you have a flowing stream of water like in a heavy rain, it actually flushes out that mosquito larvae and it suffocates,” said Brenda Elrod, deputy director of the health district's Environmental Health Department.
“When the water is stagnant is when the problems start because then the female mosquito eggs are hatched and grow into adults. After it rains, it flushes out some areas, which is great, but it'll also create big pockets of water. So it's important to look on your property, flip those containers over and bird baths. Spray them out pretty often.”
City of Tyler officials began using a larvacide in the spring and started ground spraying in July. They say at this time they do not expect to implement aerial spraying.
What is west nile?
“West Nile's a little bit different in that it was first recognized in birds,” Wallace said. “One of the explanations for its rapid spread is that it was recognized in migratory birds. So instead of spreading from population to population, we have birds that flew thousands of miles basically north and south, essentially affecting populations along the way.”
It is difficult to predict when and where the virus will show up.
“We really don't have a very good answer,” Wallace said. “It may have as much to do, perhaps, with the birds and how many birds are actually carrying the disease. There is a suggestion that some of the spread of West Nile virus is actually east to west and has to do with the migration of mosquitoes. Those are factors for which we don't know a great deal and they must change from year to year, depending on probably herd immunity in the birds, and which birds are available.”
Horses have been a major incidental host for the virus, and veterinarians urge that owners get their horses vaccinated. It is uncommon for dogs to become infected and there have been no reports in felines, said Dr. Melinda Hergert, the regional veterinarian for the Texas Department of State Health Service's zoonosis control division.
People with West Nile fever may have mild flu-like symptoms. Some patients have rashes and muscle aches, which is classic for any viral disease. The incubation time for the virus is two to 14 days.
Generally, West Nile is like many other viruses that may not lead to an illness but can be dangerous in people with compromised immune systems.
“If it were not for doing specific testing for West Nile, you wouldn't know it from any other virus, especially during this time period,” Wallace said.
Doctors say the virus becomes troubling when it causes neuroinvasive diseases, such as encephalitis or meningitis. Symptoms of a neuroinvasive disease include dizziness, lightheadedness, confusion, unresponsiveness and coma. Some patients have primarily meningitis, a condition that affects the lining of the brain. With the brain being involved, people may not always have a headache, but may have confusion. Paralysis is also seen in this disease. No vaccine is available for humans.
“There is no quality therapy,” Wallace said. “For the most part the therapy is supportive.”
With a neuroinvasive disease, the fatality rate is about 5 percent. In addition, some patients, like those who develop encephalitis, could have residual abnormalities.
Immunity wanes as humans get older so the risk of becoming ill from the virus increases with age. The risk for people who are 50 and older is tenfold, while an 80-year-old's risk is 43 times higher. There is an even greater risk for an older person with an underlying medical condition or who has undergone chemotherapy or an organ transplant.
People who are asymptomatic or who have mild flu-like symptoms are encouraged not to overburden the medical system. MacClements said it can be treated with normal home remedies.
However, if a high fever doesn't go away and a person develops a rash, abdominal pain, neck stiffness, severe headache and/or weakness in the arms, they need to see a doctor.