Tennessee health officials don't think Zika virus is a serious threat locally

Despite warnings that the Zika virus is becoming "scarier," health officials in Tennessee say they don't expect the mosquito-borne virus to become a serious health hazard this summer.

"It's still pretty small," said Dr. Mark Anderson, with CHI Memorial's Infectious Disease Associates. "I am concerned, but it's not the biggest thing on my worry list right now."

The concern comes from Zika's effects in the countries where it is widespread, basically every place in Central and South America and the Caribbean except Argentina, Paraguay and Chile. Brazil in particular has experienced an outbreak of babies born with smaller heads and brains (microcephaly) and brain-related physical problems that appear to be linked to Zika.

"The more we learn about Zika, the less we like that virus," said Dr. William Shaffner, an infectious disease specialist at Vanderbilt's School of Medicine who works regularly with the U.S. Centers for Disease Control and Prevention and the Tennessee Department of Health.

More than 300 people have been diagnosed with the infection in the continental U.S., but all of them apparently got the disease outside the U.S., according to the CDC.

Only two cases have been reported in Tennessee, according to Bonnie Deakins, director of environmental health with the state's health department.

The infection has been around since the 1950s, but only spread throughout Latin America in the past year or so. Authorities say it is almost inevitable that more cases will be reported in the U.S., given the number of people who travel from the U.S. to countries where it is widespread.

But for now at least, health experts say the impact is likely to be small. Eighty percent of the people who become infected will not display any symptoms, Dr. Shaffner said. For those who are infected, symptoms include fever, rash, joint pain and conjunctivitis (red eye), according to the CDC.

Still officials from the CDC and the National Institutes of Health held a news conference Tuesday announcing that the virus was worrisome.

What researchers have learned about the disease is not reassuring, the CDC's Dr. Anne Schuchat said. She said the virus was "scarier" than health officials had initially thought.

For pregnant women, it is particularly threatening because it appears to attack the cells in the baby's brain that control development, according to Emory School of Medicine researcher Dr. Peng Jin. By lowering the number of neural stem cells, it slows down the brain's development, he said, resulting in a smaller brain and a child with mental and physical problems.

But only about 20 percent of pregnant women who get infected have children with smaller brains, Jin said. He and fellow researchers hope that is because of genetic differences in the women, differences that can be used to develop a way to stop or slow the virus.

The virus is spread primarily by one type of mosquito, but researchers have learned over the past year that it can also be transmitted sexually, by an infected man's semen.

If and when the virus spreads to the U.S., it will probably occur when someone who has traveled to Latin America and become infected returns home and is bitten by a local mosquito. The mosquito will then bite someone else and spread the virus to them.

The mosquito, the Aeedes variety, has some characteristics that make it troublesome, Shaffner said.

"They like to hang around dwellings and get inside them," he said. "And when they bite, they don't take one blood meal at a time - they're kind of sippy, they bite and get a little blood meal, then they want to bite again. That gives them the opportunity to bite several people and to be more likely to spread the infection."

For now, health officials' weapons against the disease are the traditional ones against any mosquito-borne disease - do everything possible to get rid of mosquitoes. The mosquito only travels about 200 yards from its breeding grounds, so homeowners can do a lot to protect themselves by getting rid of the pools of water where the mosquitos lay their eggs.

Unfortunately, Shaffner said, the Aeedes mosquito needs only a small body of water, even a plastic bottle cap or the indentations on a toy left in the yard. Bird baths and pools of water in improperly installed gutters are other favorites of the mosquito.

The health department recommends that homeowners patrol their yards once or twice a week, dumping out any standing water wherever they find it. If there are larger bodies of water that can't be removed, such as in a ditch or rut, pesticides can be purchased that will kill any mosquito larvae.

The ultimate protection is to keep your body away from mosquitoes, Deakins said. Wear long-sleeved shirts and pants and socks, and always spray yourself with a repellent before going outdoors. That advice is particularly important for anyone who is pregnant or who recently returned from a country where the Zika virus is present, CHI Memorial's Anderson said.

But health officials also say there is no reason to panic.

"I would tell people to be careful, to try to control the mosquitoes around their property, and to wear insect repellent," Anderson said.

And getting rid of all of those breeding grounds will help get rid of all mosquitoes in your yard and not just the ones who spread the Zika virus, the health department's Deakins said.

"That's going to help get rid of the pesky ones who bother you while you are out trying to barbecue," she said.

Contact staff writer Steve Johnson at sjohnson@timesfreepress.com, 423-757-6673, on Twitter @stevejohnsonTFP, and on Facebook, www.facebook.com/noogahealth.