As of mid-August, only one confirmed case of locally transmitted Zika had been recorded in the continental U.S., compared to hundreds of locally transmitted cases last year, John Cohen reports for Science.
That's because Zika cases have "plummeted" in Latin America and the Caribbean, which were hit hard by the virus, and now much of their population is immune to it, Cohen writes. And that means fewer Americans are being infected while traveling and bringing it home with them, which reduces the chances of local transmissions in the U.S.
Zika is a virus that is spread primarily through the bite of an infected mosquito. It can also spread through sexual transmission and from a mother to her child during pregnancy. Click here for more information about Zika.
Infectious disease experts told Cohen that this respite could last for years.
They had expected the Zika virus, much like dengue, West Nile and yellow fever, to initially surge through the population, then decrease as people developed immunity, but "few predicted that cases would disappear so quickly," Cohen writes.
Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, told Cohen that this "herd immunity" has reduced the number of vulnerable people to the point that the virus can't easily move between humans and mosquitoes.
But caution was advised by Lyle Petersen, head of the vector-borne disease division of the Centers for Disease Control and Prevention. "Just because cases go down, it doesn't mean we should stop worrying about it," he told Cohen. "We need to maintain our vigilance."
Peterson said the decline in Zika cases doesn't lessen the need for a vaccine against the virus, but Cohen says the sharp decline in cases will make it hard to perform clinical trials for a vaccine.
The CDC cautions that anyone living in or traveling to areas with the risk of Zika should continue to protect themselves from mosquitoes, especially if you are pregnant or going to become pregnant.
Last year in the U.S., the CDC recorded 224 cases of local transmission, all in Florida and Texas, and 4,830 travel-related cases. This year, the CDC has recorded no locally transmitted cases and 213 travel-related ones, though Cohen reports that one case of locally transmitted Zika was recorded on July 26 in Hidalgo County, Texas, which borders Mexico.
"I think it's highly unlikely we will see any resumption of significant transmission for at least a decade," Neil Ferguson, a mathematical biologist at Imperial College London, told Cohen.
Biostatistician Ira Longini of the University of Florida in Gainesville disagreed. He said his models predict Zika "will still thrive in susceptible populations that have yet to be hit by the first wave of transmission, leading to 'flare-ups here and there'," Cohen writes.
That's because Zika cases have "plummeted" in Latin America and the Caribbean, which were hit hard by the virus, and now much of their population is immune to it, Cohen writes. And that means fewer Americans are being infected while traveling and bringing it home with them, which reduces the chances of local transmissions in the U.S.
Zika is a virus that is spread primarily through the bite of an infected mosquito. It can also spread through sexual transmission and from a mother to her child during pregnancy. Click here for more information about Zika.
They had expected the Zika virus, much like dengue, West Nile and yellow fever, to initially surge through the population, then decrease as people developed immunity, but "few predicted that cases would disappear so quickly," Cohen writes.
Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, told Cohen that this "herd immunity" has reduced the number of vulnerable people to the point that the virus can't easily move between humans and mosquitoes.
But caution was advised by Lyle Petersen, head of the vector-borne disease division of the Centers for Disease Control and Prevention. "Just because cases go down, it doesn't mean we should stop worrying about it," he told Cohen. "We need to maintain our vigilance."
Peterson said the decline in Zika cases doesn't lessen the need for a vaccine against the virus, but Cohen says the sharp decline in cases will make it hard to perform clinical trials for a vaccine.
The CDC cautions that anyone living in or traveling to areas with the risk of Zika should continue to protect themselves from mosquitoes, especially if you are pregnant or going to become pregnant.
Last year in the U.S., the CDC recorded 224 cases of local transmission, all in Florida and Texas, and 4,830 travel-related cases. This year, the CDC has recorded no locally transmitted cases and 213 travel-related ones, though Cohen reports that one case of locally transmitted Zika was recorded on July 26 in Hidalgo County, Texas, which borders Mexico.
"I think it's highly unlikely we will see any resumption of significant transmission for at least a decade," Neil Ferguson, a mathematical biologist at Imperial College London, told Cohen.
Biostatistician Ira Longini of the University of Florida in Gainesville disagreed. He said his models predict Zika "will still thrive in susceptible populations that have yet to be hit by the first wave of transmission, leading to 'flare-ups here and there'," Cohen writes.
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