Dallas' Zika Risk May Be Greater Than Previously Thought, UT Researcher Says

So far, no one has caught the Zika virus in Texas from a mosquito. The virus has only been transmitted once in the state, and that happened when a man returning to the Lone Star State from a trip to South America had sex with an uninfected woman. As mosquito season heats up, however, health officials and researchers are concerned that an influx of mosquitoes carrying the virus could increase that risk for pregnant women in Texas, especially if it turns out a second breed of mosquitoes, in addition to the known carrier Aedes aegypti, can effectively transmit the virus.

In adults, Zika infection can be mostly asymptomatic. The virus poses a far greater threat to children born to mothers with Zika, who can suffer from birth defects including microcephaly, which is characterized by a shrunken brain and head. Aedes aegypti are known as both an effective carrier of dengue fever and the Zika virus, but researchers led by the University of Texas' Sahotra Sarkar believe that a second Aedes mosquito, the Asian tiger mosquito or Aedes albopictus, might also be capable of transmitting the disease to large numbers of people. Because of the Asian tiger mosquito's greater range, it could put more people at risk.

"[Because the Aedes aegypti mosquito becomes less prevalent the farther north one goes], it does mean that by the time you get to North Texas, the chances of Zika establishing local cycles goes down — it goes down for the rest of the country. Now if both mosquito species are equally good at transmitting the virus, then the entire country and even Canada and much of Europe are at risk," Sarkar says

While it hasn't been proven that the Asian tiger mosquito can transmit Zika, that's what Sarkar and his fellow researchers say needs to be determined. He says there is at least some evidence that it can.

"There are areas where Zika has spread where [the Asian tiger] mosquito is the principle mosquito there. Unless some other mosquito species that we are not talking about at all is doing the transmitting, we wouldn't know [another way those areas could see an outbreak of the virus]," Sarkar says.

Add in the fact that Zika has been found in the saliva of the Asian tiger mosquito and that both of the mosquitoes spread dengue fever, and Sarkar says there is reason to believe there could be two mosquito carriers for the disease rather than one.

Zika research will become even more desperate with the approach of this year's Summer Olympics, which are set to take place in Rio De Janeiro this August. Brazil is one of the hot spots for the disease and people from around the world will hit the city for the two-week sports festival. The more mosquito carriers that are hanging out when those people, potentially infected with Zika, get back home, the more risk there is to towns and cities outside of South America. From a public health perspective, Sarkar says, it would probably be a good idea to reschedule or move the games, something that is exceedingly unlikely to happen on short notice.
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Stephen Young has written about Dallas news for the Observer since 2014. He's a Dallas native and a graduate of the University of North Texas.
Contact: Stephen Young