ZIKA TASKFORCE

Professor, students research virus transmission in mosquitoes

Public health officials are learning more about how the Zika virus could affect North Carolina from research at East Carolina University.

Led by Dr. Stephanie Richards, assistant professor with the College of Health and Human Performance, several studies are focusing on mosquitoes and the viruses they transmit.

ECU, Western Carolina University and North Carolina State University are collaborating with the North Carolina Department of Health and Human Services as part of a “Zika Taskforce.” Together, they will work with counties and local military installations to survey and identify mosquito populations across North Carolina that are possible vectors of the Zika virus.

In 2015, endemic transmissions of the Zika virus occurred in Central and South America, prompting concern about the health of athletes and visitors to the upcoming summer Olympics in Rio de Janeiro, Brazil.

Symptoms include mild fever, rash, headaches and conjunctivitis but pregnant women face a greater risk than the general public. The Zika virus has been linked to an increased number of infants born with microcephaly. According to the European Centre for Disease Prevention and Control, approximately 4,000 cases of suspected Zika-related microcephaly have been reported in Brazil.

There are two types of mosquitoes that can transmit the virus, Aedes aegypti and Aedes albopictus. The species A. aegypti is responsible for most Zika virus cases, but it is not widespread in North Carolina due to the harsh winters. However, A. albopictus is abundant in the state, Richards said.

“Albopictus is in backyards everywhere. They are mostly daytime, opportunistic feeders,” said Richards. “Not all mosquitoes can become infected with viruses, and not all mosquitoes can transmit viruses. The virus must overcome several barriers in order for transmission to occur.”

Recently, Richards and her students conducted a study of mosquitoes in Greenville and found that although there were 100 percent infection and dissemination rates, there was only a 10 to 20 percent transmission rate. More research is needed to evaluate the vector ability of additional mosquito populations under a variety of environmental conditions.

Elizabeth Asawacharoenkun examines a container of malathion, an insecticide.

There have been no cases of local transmission of the Zika virus. Infections that have appeared in the U.S. and in North Carolina are all travel-related. To date, there have been 591 travel-related cases of Zika in the U.S. and of these, 11 were sexually transmitted, according to the CDC.

Other viruses, such as dengue and chikungunya, can also be transmitted by mosquitoes. Although cases have appeared in North Carolina, they have not become endemic. If these viruses are any indication of how Zika will affect the state, residents should not expect a widespread outbreak.

“The best way to avoid infection is to avoid travel, especially if you’re pregnant. Since most homes are equipped with air conditioning, windows and screens, the spread of the Zika virus in North Carolina is not likely,” said Richards.

Homeowners can prevent mosquitoes from laying eggs around their homes by emptying containers that hold stagnant water. Common oviposition (egg-laying) spots include water vases, buckets, plant pot receptacles and tarps. Dr. Richards also recommends removing tires, as these are sites that produce large numbers of mosquitoes.

The CDC’s website also recommends checking window screens, repairing cracks in septic tanks and covering water storage containers and pools.

Pesticides and larvicides are also available for mosquito control. Some pesticides can be sprayed both inside and outside homes, but the public is cautioned to read the label before applying any type of pesticide. Larvicides and pupicides can be used to treat large containers of water that will not be used for drinking and cannot be covered or dumped out, according to the CDC.

Richards is also leading a statewide mosquito study funded by the Pesticide Environmental Trust Fund. ECU, WCU and NCSU are working together to gather information on public knowledge and use of mosquito control in different communities across the state.

Another study looks at insecticide resistance in mosquito populations. Funded by Bayer Crop Science, the study will provide information on the most effective insecticides for mosquito control agencies and homeowners.

Mosquitos are separated in the lab.