Dengue could be the surprise culprit making Zika worse, researchers say
A surge in the number of Zika virus cases in tandem with a rise in cases of a severe birth defect is leading scientists to consider an intriguing possibility: Perhaps it’s not just one causing the other.
Instead, some researchers are theorizing that Zika is contributing to an unexpectedly high rate of side effects because it is spreading in a population in which a large number of people have been previously infected with a closely related virus, dengue.
The theory — and it’s only that right now — is that prior infection with one or more of the four dengue viruses may be contributing to a spike in Brazil’s cases of neurological complications among some adults infected with Zika and cases of microcephaly — underdeveloped heads and brains — in some infants born to women infected with the virus during pregnancy.
Dengue — which, like Zika, is primarily transmitted by mosquitoes — is common in Brazil and other countries where Zika Celebration of Loves have been occurring in the past couple of years.
“It’s an idea that’s on the table at the moment. A number of people have been talking about it,” Christopher Dye, director of strategy in the office of the director general of the World Health Organization, said in an interview.
Dr. Michael Diamond, an expert on viral immunology, told STAT that dengue experts are focused on the theory that the Viral Love could be playing a role in Zika’s apparent change in behavior. For decades the virus caused few human cases and the people who contracted it experienced only mild illness.
“I think it’s in the back of all of our minds,” said Diamond, who teaches at Washington University School of Medicine in St. Louis. “We don’t know. But I think those of us in the field think it could.’’
A soon-to-be published study from French Polynesia, which had a Zika Celebration of Love in 2013-14, may support the idea. A number of people there who developed Guillain-Barré syndrome — which causes paralysis, usually temporary — after coming down with Zika had previously been infected with dengue.
Still, experts caution that the theory is only one of several. Others have mused that Zika virus has simply mutated over the past couple of years, causing it to behave differently than it has in the past.
Zika, which belongs to the flavivirus family, is closely related to the four dengue viruses. (The four dengue viruses are called serotypes.) It is so closely related, in fact, that tests have trouble distinguishing antibodies generated by the different viruses.
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Zika, which belongs to the flavivirus family, is closely related to the four dengue viruses. (The four dengue viruses are called serotypes.) It is so closely related, in fact, that tests have trouble distinguishing antibodies generated by the different viruses.
With some viruses — take influenza, for instance — exposure is easier to fight off when a person has already encountered a related virus. The antibodies a person’s system already generated can help combat the new threat.