In Florida, 328 people have been infected with the mosquito-borne Zika virus, an infection that causes only mild illness in most people but has been linked to severe brain and birth defects in newborn babies.
Until recently, all U.S. cases of Zika, including those in Florida, were linked to people who traveled to countries in Latin America and the Caribbean with outbreaks.
That changed this month, when health officials in Florida began investigating a possible non-travel related case in Miami-Dade County. Then another popped up in neighboring Broward County. The south Florida counties have the most cases of Zika virus statewide.
On Wednesday, the Florida Department of Health added two more possible non-travel related cases to their list, bringing the total to four, and suggesting that mosquitoes in the continental U.S. may be infected with the disease.
“Evidence is mounting to suggest local transmission via mosquitoes is going on in South Florida,” CDC spokesman Tom Skinner told Reuters.
Florida health department officials are urging residents and visitors to cooperate in the investigation, which began Wednesday, and will include door-to-door outreach and urine sample collection. Epidemiologists will survey people who live within a 150-yard radius — the flying range of the mosquitoes that carry Zika — of the infected person, Reuters reported.
“These results will help the department determine the number of people infected,” the state health department said in a press release.
Zika causes a rash, fever and joint pain in most people, according to health officials, but CDC researchers have determined that the virus leads to microcephaly in infants, a birth defect where a baby’s head and brain are smaller than normal. Microcephaly impairs cognitive function, according to the CDC, and has been known to cause seizures, hearing loss, vision problems, difficulty swallowing, developmental delays, speech defects and intellectual disabilities.
In June, the Florida Department of Health announced the state’s first confirmed case of microcephaly in an infant born to a mother with Zika. She contracted the virus while in Haiti, according to the health department.
Florida is tracking 53 Zika cases involving pregnant women.
