Is Zika Starting to Spread Across Florida?

Active Zika Transmission Confirmed in Miami Beach

The Florida Department of Health (DOH) confirmed that active Zika transmission in a one-square-mile area in the Wynwood region of Miami-Dade County, Florida has been ongoing since the beginning of July. Now, reports of a second area with active transmission have been confirmed.

Yesterday, an article published in the journal Cell Stem Cell confirmed that Zika infection can pose a threat to anyone, regardless of age. Nonetheless, those most affected by the virus are the developing fetuses of infected pregnant women. Although scientists recently identified the Zika proteins that cause microcephaly in developing fetuses, they are still in the process of developing targeted therapy.

Today, the Centers for Disease Control and Prevention (CDC) and the Florida DOH confirmed that Zika transmission has reached Miami Beach. The CDC is extending its travel guidance for pregnant women to include both areas of Miami-Dade County, Florida (Wynwood and Miami Beach). Pregnant women, women of child-bearing age, and the sexual partners of these populations are all urged to visit their healthcare provider and be tested for Zika infection if they have travelled to the affected areas within the last month. Furthermore, the CDC recommends consistent and correct use of condoms for couples who are expecting. Women are recommended to wait 8 weeks after symptom onset before conception, while men are recommended to wait 6 months.

To ensure the safety of developing fetuses, the CDC is urging nation-wide Zika testing, and stated in an official press release, “All pregnant women in the United States should be evaluated for possible Zika virus exposure during each prenatal care visit. Each evaluation should include an assessment of signs and symptoms of Zika virus disease (acute onset of fever, rash, arthralgia, conjunctivitis); their travel history; as well as their sexual partner's potential exposure to Zika virus and history of any illness consistent with Zika virus disease to determine whether Zika virus testing is indicated.” Currently, the Florida DOH is providing “free Zika risk assessment and testing to any pregnant women who would like to be tested.”

Officials in areas with Zika vector prevalence are urged to monitor for Zika infections and implement vector control measures. Since only 20% of infected individuals experience symptoms, and these symptoms may take up to two weeks to manifest, detecting local Zika transmission can be difficult. On a telebriefing this afternoon, Tom Frieden, MD, MPH, director of the CDC, stated that he believes that there are currently more Zika cases in Florida than reported, in addition to the possibility of other Florida areas with active transmission that have yet to be identified.

According to Dr. Frieden, there have been incidences with local transmission in other areas of Florida, however, these were isolated cases that did not cause localized outbreaks. Dr. Frieden reassured those on the telebriefing call that the current Zika situation in Florida was not unforeseeable; the CDC initially anticipated that active transmission would manifest in localized clusters. He stated that controlling Zika in Miami Beach will be difficult due to several factors: Miami Beach is a densely populated area, with a majority of the individuals exposing skin, which can potentially lead to mosquito bites if DEET-containing mosquito repellent is not used; and high rise buildings will hinder aerial spraying, since the spraying aircrafts need to be closer to the ground for targeted spraying.

Aedes aegypti, the Zika vector, is, according to Dr. Frieden, the “cockroach of mosquitos,” since its larvae can survive for up to one year and can hatch in very low volumes of water, such as bottle caps. On the other hand, the mosquito appears to not be naturally resistant to the sprays being used in the areas with active transmission.

The CDC is working closely with the Florida DOH to monitor for additional Zika cases, as well as to investigate existing cases.