- THE CARRIER OF ZIKA: The Aedes aegypti (above) and Aedes albopictus, mosquitoes that live close to houses, in pooled water.
The mosquito-borne Zika virus, which can cause serious birth defects in infants, has yet to develop a significant presence in Arkansas. Only five cases of the virus have been diagnosed in Arkansas, and all of those were in people* who had recently traveled from South or Central America. No one has been infected with Zika by a mosquito in the continental United States.
Zika is carried by Aedes aegypti and Aedes albopictus mosquitoes, and is transmitted to humans either directly through bites or by sexual contact with infected persons. Infected humans may also transmit the virus to uninfected Aedes mosquitoes. While most Zika-infected mosquitoes are in South and Central America, health experts expect the virus to spread to North American Aedes species; the only question is when, Arkansas Department of Health epidemiologist Dr. Dirk Haselow says.
"I imagine [the number of cases] will increase significantly," Haselow said. "We are preparing for an increased burden of cases."
To fight the virus will require mosquito control, which over the past 50 years has shifted from being a federal responsibility to a local one. There is no statewide office for mosquito control in Arkansas. Instead, city governments are left to develop their own programs. In total, 16 municipalities have mosquito control programs around the state, mainly in the urban areas of Central and Northwest Arkansas and farming areas of Southeast Arkansas.
A majority of the programs focus on preventing "nuisance mosquitoes," an umbrella term for the roughly 30 species in Arkansas that don't carry Zika, by using trucks to spray chemicals at night. However, this prevention method doesn't work well for the Aedes aegypti and Aedes albopictus species, because they tend to breed around houses in places like flowerpots or plugged drains. Aedes mosquitoes travel only roughly 250 yards in their lifetimes.
"Essentially no one around the country has recent experience doing major control efforts for Aedes mosquitoes," Haselow said. "It requires very labor-intensive efforts."
The species is common along the Gulf Coast and in Florida, and as summer begins, they awake from hibernation in places like Arkansas. The health department is collecting data of every county's mosquito density to pinpoint Arkansas's densest Aedes populations. AHD workers have placed 20 mosquito traps throughout the state, and 45 more are coming soon. The research will be finished sometime this winter.
"We're focusing now where we have the highest human populations, because Aedes mosquitoes are urban mosquitoes," Haselow said. "As we branch out, we'll try to get a comprehensive picture of what mosquitoes we have and where."
For the past 13 years, Little Rock's Public Works department has partnered with the University of Arkansas at Little Rock's Department of Biology to do surveillance on mosquitoes. Undergraduate students, along with program leader and UALR biology professor Carl Stapleton, primarily use oviposition and gravid traps to collect data. Oviposition traps collect eggs to estimate the wider mosquito population, and gravid traps collect live mosquitoes. The project was developed to test for West Nile virus; it has set traps at 10 sites around Little Rock.
"The whole idea is about capturing the kinds of mosquitoes, the numbers of mosquitoes, and getting an indication so that we can go back to the city and say, 'Hey, you need to do some more targeted spraying in this area,' " Stapleton said.
When citizens call and ask the city of Little Rock for truck spraying, Stapleton and his students go to their neighborhoods to find which species are present. Educating callers about the dangers of disease-carrying mosquitoes and what preventive steps can be taken is an important part of the program.
Due to the risks of Zika for pregnant women, testing humans for the virus through blood samples has been prioritized over testing mosquitoes. Despite Florida's 132 travel-related Zika cases — the second most in the country, second to New York — that state has only one lab equipped to test mosquitoes. Arkansas doesn't have any. Stapleton says he will test mosquitoes for Zika once an affordable test is available.
Research has yet to reveal all of Zika's effects. The virus stays in blood for seven days after infection, and could remain in pregnant women's blood for longer periods. Some data has shown the virus lingering in semen for two months after infection. The Centers for Disease Control and Prevention recommends infected males avoid unprotected sex for six months. Zika is the first virus in 50 years associated with birth defects and the first mosquito-borne virus to ever be sexually transmitted. Scientists have confirmed the virus can cause microcephaly, a birth defect that causes newborns to have smaller heads.
"We believe that microcephaly may only be the tip of the iceberg of what's really going on," Haselow said. "There are likely to be many other problems, whether they be cognitive, developmental or physical, that aren't apparent early in infancy."
Insufficient government funding could perpetuate the disease's spread. The Obama administration asked for $1.9 billion in funding from Congress to fight the virus. The U.S. Senate then approved a $1.1 billion measure, and in turn, the House approved a $622 million measure that requires all money to be reallocated from existing programs, including funding to fight Ebola. Senate and House negotiators have yet to reach an agreement on a final version of the bill.
"When we talk about expanding our efforts to improve mosquito control efforts around the state, even the budgets being considered are woefully inadequate," Haselow said.
While nobody has contracted the virus from mosquitoes located in the continental United States yet, health experts expect that to change.
"If we get a home-grown case of Zika and a newborn baby with microcephaly, you watch how fast the funding will flow," Stapleton said.
While research depends on government funding, everyone can take to avoid contracting the Zika virus by repeatedly using repellents and emptying standing water around their homes.
"We're not powerless in reducing our risk," Haselow said. "We can make these changes and protect our loved ones."
*A previous version of this article said that five women had been diagnosed with Zika in Arkansas. The gender of those who have been diagnosed with the virus has not been released.