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Auburn University researchers have discovered the presence of Aedes aegypti, the primary mosquito that transmits Zika virus, in Alabama.
According to the news release, Auburn School of Forestry and Wildlife Sciences Assistant Professor of Disease Ecology Sarah Zohdy and wildlife sciences undergraduate student Victoria Ashby have discovered the species in Mobile. Ae. aegypti was thought to have been eliminated from the state and is the first sighting of it in 26 years.
“Our CDC-funded research has not only allowed for the detection and molecular confirmation of the mosquito in the state, but over the last year we have documented the spread of the mosquito from central Mobile to all of Mobile County,” Zohdy said.
Zika Mosquito Study
The study was conducted from July 2016 to September 2017. Mosquitoes were collected twice a month from the grounds of various tire shops, gas stations, abandoned buildings and open containers quantified to estimate larval abundance. A total of 1,074 mosquitoes were collected, with Ae. aegypti being detected most commonly in the 36606 area code of southwest Mobile, where there were more open containers than any other area in the city.
The detection of Ae. aegypti confirms that Alabama residents could be at risk to contract several mosquito-transmitted diseases.
“This work demonstrates that citizens of Alabama may be exposed to the mosquito vector of Zika, chikungunya and Dengue fever viruses,” Zohdy said.
How Zika Spreads
Zika virus spreads to people primarily through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). Female mosquitoes become infected by ingesting microbes from a person’s blood while biting them and then passing those microbes to the next person’s blood stream. Once infected, the mosquito is then thought to remain infected and able to pass on the virus throughout the remainder of its life, or about two to four weeks. During this period they may take three to four blood meals, biting up to four or five people during their lifespan. Ae. aegypti is particularly problematic because it will also bite during the day and is very adaptive to different environments.
The Centers for Disease Control and Prevention, or CDC, has developed estimated-range maps using models that predict potential geographic ranges where the Zika-transmitting mosquitoes would likely survive and reproduce based on local and historical records and suitable climate variables. According to the 2017 maps, the Zika-transmitting mosquito species are very likely to exist throughout the southeastern U.S. and as far west as California and as far north as Delaware.
Despite the state of Alabama being an ideal habitat for mosquitoes that transmit Zika virus, very little mosquito surveillance data has been collected from around the state. Zohdy said that because of their research efforts and the discovery of Ae. aegypti, her team is now working with the Alabama Department of Public Health.
According to the CDC, there were 449 symptomatic Zika virus disease cases reported within the U.S. in 2017, with three reported in Alabama and two in Georgia. The majority of cases were instances of travelers contracting the disease from affected areas. Seven cases were acquired through presumed local mosquito-borne transmission, including two in Florida and five in Texas. In 2018, no local mosquito-borne Zika virus transmission has been reported in the continental United States. According to the Alabama Department of Public Health, there has been one confirmed case of Zika in Alabama in 2018. To reiterate, there have been no local mosquito-borne Zika cases in the continental US and the chances of coming upon an infected Aedes aegypti mosquito are “very very very very small” according to the researchers.
“I can’t clarify enough that this doesn’t mean the mosquitoes in Alabama have Zika virus and can infect citizens, it just means that citizens should implement vector control practices, wearing long sleeves and pants, using insecticide, and most importantly, dumping out standing water in artificial containers in and around your house. Aedes mosquitoes are container breeders and reproduce very well in discarded tires, empty flower pots, bird baths, plastic containers or bottles, etc. They are also most active during the day.” – Sarah Zohdy
Outbreaks of Zika have been reported in tropical Africa, Southeast Asia, the Pacific Islands, and most recently in the Americas. Because the mosquitoes that spread Zika virus are found throughout the world, it is likely that outbreaks will continue to spread.
Zohdy’s team is now conducting research in all 67 counties in Alabama to determine how widespread Ae. aegypti and Ae. albopictus are across the state.
In an effort to crowd-source mosquito surveillance data around the state, Zohdy’s research team has partnered with Prakash Lab at Stanford University to develop and implement an app called “Abuzz,” which will allow Alabama citizens to record the sound of a mosquito flying. From this recording, the app can identify the species of mosquito and whether or not that species could potentially carry a disease by the sound of the buzzing of its wings.
Once deployed, the app can empower volunteer “citizen scientists” to participate in mosquito surveillance to help researchers increase the volume and locations of data collection. “Alabama has had little mosquito surveillance in the past and we hope this app can change that to make it the best sampled state in the nation,” Zohdy said.
Though Zika virus is primarily spread by infected Aedes species mosquitoes, the disease can also be transmitted through sexual contact with an infected person or from an infected pregnant woman to her fetus during pregnancy or at birth.
Read more about Zohdy’s research findings with the Journal of Medical Entomology.