In a study presented Monday at the annual meeting of the American Society of Tropical Medicine & Hygiene (ASTMH), researchers said they had evidence that Aedes aegypti mosquitoes could be infected with Zika and dengue fever simultaneously, and could potentially pass both viruses to humans in a single bite.
The findings strengthen prior studies which suggested that people can be infected simultaneously with two or more mosquito-borne viruses. A study published last year found that Aedes aegypti can transmit dengue fever and chikungunya at the same time. Research conducted in Nicaragua found that about one in five patients who tested positive for dengue, chikungunya or Zika actually had more than one of the viruses simultaneously.
“A mosquito in theory could give you both viruses at once,” said Claudia Rueckert, a Colorado State researcher involved in the research presented at the ASTMH meeting. “If a mosquito can take up both viruses from a patient and transmit both later on, you could have a continuous perpetuation of this co-infection cycle.”
First identified in Africa in 1947, Zika virus came to the Americas for the first time early last year in Brazil. That was the flashpoint of an unprecedented outbreak that has rapidly spread north and reached over 20 countries to date.
Recent screenings suggest that Zika infections remain exceedingly rare in the U.S. Among 800,000 blood donations tested over the past six months, only about 40 initially tested positive for the virus. However, these results may represent the extreme low end of the spectrum given that blood banks discourage people from donating if they recently traveled to a region where Zika is prevalent.
According to the Centers for Disease Control and Prevention (CDC), Aedes aegypti mosquitoes are typically found throughout the lower third of the Western U.S., but have recently spread to the east, reaching as far north as New York and Connecticut. They prefer warm, wet weather, so they can cover more area during the summer months.
The most distinguishing feature of Aedes aegypti mosquitoes is their hind legs. If you can see that they are striped in black and white, then it is likely a mosquito that can carry and transmit viruses like Zika and dengue fever. However, if you can see their hind legs it means you’re probably catching them mid-bite, by which time it’s too late.
There is currently no treatment for Zika virus. Painkillers and fever reducers can help manage symptoms until the infection clears, usually in about a week. President Obama has called for increased efforts to find a Zika vaccine. Most estimates are that it will take at least three to five years to develop such a treatment, although there are reports of a vaccine that could go into trials by the end of this year.