MIAMI, Fla-- Health officials say a drop in Zika cases in the Caribbean and South America has helped slow the spread of the mosquito-borne virus in Florida this year.
The Miami Herald reports that experts say herd immunity likely has contributed to Zika's decline outside the continental United States.
Dr. Henry Walke of the U.S. Centers for Disease Control and Prevention says people who were infected with Zika can't be infected again, which reduces the amount of the virus that is circulating.
However, experts warn that herd immunity elsewhere won't stop the virus from re-emerging in this country. That has happened in Florida with other mosquito-borne viruses such as dengue fever in recent years.
So far this year, Florida health officials have reported a total of 135 Zika cases. None have been linked to mosquitoes in the state.