A deadly new outbreak in New York City that has killed at least 11 people and sickened more than 100 has been linked to a previously unknown strain of Zika.
Health officials say the strain is a repeat of a strain that surfaced in Brazil in March.
“There are some indications that the new strain has been circulating in Brazil for some time,” said Dr. Daniel Marder, a health department spokesman.
A spokesman for the New York State Department of Health said the outbreak is being investigated and there is no indication the virus is linked to any new cases.
New York and New Jersey reported a record-breaking number of cases in October.
The Centers for Disease Control and Prevention says it has tested more than 5,600 people in New Jersey and New York, and that most of those tested have been confirmed positive for Zika.
There have been a total of 2,092 cases of Zika in the United States, which is more than the total number of confirmed cases of the disease that were reported in 2014.
The New York virus has not been detected in the blood or semen of anyone in the US.
Health experts say the new outbreak raises questions about the ability of the federal government to control Zika outbreaks.
“We’re very concerned that we don’t know exactly what’s going on,” said Chris Stessel, an epidemiologist with the American Civil Liberties Union.
“But if there’s a way to do this, why wouldn’t we do that?”
Health officials also say the CDC is working with the New Jersey Department of Environmental Protection and the New Mexico Department of Public Health to find out how the virus could have reached New York.
A spokeswoman for the US Department of Justice, which has been leading the investigation, said the Department has not identified a single person who has contracted Zika.
The virus was first detected in Brazil during a massive outbreak of the virus that began in March, killing thousands of people and leaving thousands more sick.
The United States has reported about 30 confirmed cases, with 2,817 new cases since then.
The US has a total population of nearly 17 million people, and it has the largest percentage of people with Zika infection in the world, according to the World Health Organization.