Federal health authorities issued a travel advisory Monday for a small area in Miami after the number of locally acquired Zika cases rose to 14.
The alert also was prompted by difficulties controlling the Aedes aegypti mosquito population that transmits the virus.
The increase in cases and challenges with mosquito control “suggests there is a risk of continued active transmission of Zika in that area,” said Tom Frieden, M.D., M.P.H., director of the Centers for Disease Control and Prevention (CDC).
He recommends pregnant women avoid a one-mile area north of downtown Miami where the cases have been concentrated. If a pregnant women passes on the infection to her fetus, it could result in microcephaly and other brain abnormalities.
The warning comes just days after the CDC announced the first locally transmitted cases in the continental U.S. There already have been 1,658 cases, including 433 pregnant women, among travelers returning from Latin America and the Caribbean and their sexual partners.
The 14 locally acquired cases in Florida include two women, and some of the infections have been asymptomatic, according to Florida authorities who have been testing residents in the area.
“That’s a large number but not a surprising number,” Dr. Frieden said.
Florida has requested the CDC’s Emergency Response Team provide additional assistance in combating the virus. The CDC issued the following recommendations:
- Pregnant women should not travel to the affected area.
- Pregnant women and their partners who spend time in the area should take steps to prevent mosquito bites and sexual transmission of the infection.
- Pregnant women who traveled to the area since June 15 should be tested for Zika.
- Asymptomatic pregnant women who live or work in the area should be tested in their first and second trimesters.
- All pregnant women in U.S. should be assessed for possible Zika exposure during each prenatal care visit and tested according to CDC guidance.
- Women and men who traveled to and left the affected area should wait at least eight weeks before attempting conception.
- Symptomatic men should wait six months before attempting conception.
- Anyone who may have been exposed to the virus and displays symptoms should be tested.
For the 20% of those infected who display symptoms, the illness is mild and may include fever, rash, joint pain and conjunctivitis. Dr. Frieden has said he would not be surprised to see additional cases and possibly clusters, although outbreaks are unlikely in the U.S.
The virus is a nationally notifiable disease and should be reported to local, state or territorial health departments. The CDC also is asking health care providers to contribute data to its Zika pregnancy registry that will follow children exposed to Zika for up to 1 year of age.