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The Real Risks of Zika Virus

Tiger Mosquito

Tiny mosquitoes are causing big problems—and making big headlines—in South America, Central America and the Caribbean. The Zika virus is causing panic due to a possible link to birth defects in the babies of mothers who contracted the illness during pregnancy. However, very little is yet known about it.

"It is important to realize that we are in the early stages of understanding this outbreak," says Andrew Pavia, MD, the chief of the Division of Pediatric Infectious Diseases for University of Utah Health. "It is not yet completely proven that Zika is the cause of these birth defects, like microcephaly."

The connection is being made due to a marked increase in the number of children born with microcephaly during the time that Zika was spreading in several South American countries. The virus has been found in some amniotic fluid samples, though it still is not clear how it causes the defects. "We suspect that Zika virus reaches the blood stream of the fetus through the blood stream and/or infected amniotic fluid of an infected mother," says Pavia. "If it behaves similarly to other viruses that cause brain injury like CMV (cytomegalovirus), it crosses into the developing brain and causes damage through direct viral infection of brain cells."

Researchers also are looking at whether or not Zika is a serious threat to people other than pregnant women. "In general, Zika is not a very serious infection, and most infected people don't even develop symptoms" says Pavia. "There is some concern that Guillan Barre Syndrome, a condition that leads to transient muscle weakness or paralysis, may be a rare complication of Zika virus infection, but we don't yet know if this is true."

While more research is needed to understand the Zika virus, the concern now is stopping the spread of the illness. The virus has been documented in more than a dozen countries, though not yet in the United States. "You never want to say never or always, but it is very unlikely that we will have a massive outbreak of Zika virus in the U.S.," Pavia says. "However, it is very likely we will see limited transmission in the U.S."

The first place the illness is likely to be seen is in the south eastern and south central United States, where temperatures are warmer and the mosquitoes that carry the Zika virus already live. However, the risk may be lower than in South American countries. "The mosquito density is much higher in poor areas of tropical countries than in most areas in the southern U.S.," says Pavia. "In addition, screens and air conditioning mean that our exposure to mosquitoes in the U.S. is considerably less than in many other areas."

Pavia says the best way for people to avoid the Zika virus is to take typical mosquito abatement precautions in areas where the virus is detected. "This means using mosquito repellants, wearing long-sleeved pants and shirts, and using screens, air-conditioning or mosquito bed nets when sleeping," he adds. "Also, make sure there is no standing water around the house to allow mosquitoes to breed."