November 14, 2016

Zika Virus Mosquito Possibly Spreads Dengue in Same Bite

Written by Betsy McKay, Wall Street Journal

This post originally appeared in The Wall Street Journal.

ATLANTA—A single species of mosquito—Aedes aegypti—now spreads multiple viruses in the Western Hemisphere, including Zika, chikungunya, and dengue. That has prompted researchers to examine whether it may transmit more than one type of virus at once to people—and if so, what consequences that may have.

In a new study presented Monday at the annual meeting of the American Society of Tropical Medicine & Hygiene, scientists from Colorado State University said they had evidence that Aedes aegypti mosquitoes could be infected with Zika and chikungunya simultaneously and could potentially transmit both viruses to humans in a single bite.

“A mosquito in theory could give you both viruses at once,” said Claudia Rueckert, a Colorado State researcher involved in the work.

The findings add to evidence that people may commonly be infected simultaneously with more than one mosquito-borne virus. A study last year by other researchers found that the mosquitoes can transmit chikungunya and dengue at the same time. Another recent study in Nicaragua found that about one in five patients who tested positive for dengue, chikungunya or Zika actually had two or three of the viruses.

“Before that, we were thinking that co-infection was a rare occurrence,” said Ms. Rueckert. “Based on the study in Nicaragua, it’s a lot more common than we thought.”

“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,” she said.

The work was conducted in the lab of Greg Ebel, an associate professor at Colorado State.

It isn’t clear what implications co-infection has on patients. Scientists are trying to determine whether previous infection with dengue affects Zika, either by worsening or lessening an infection.

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