Monday, September 12, 2016

New developments in the Zika epidemic

- John E. Delzell, Jr, MD, MSPH

In her AFP Community Blog post on February 29th, Dr. Jennifer Middleton provided a great overview of the health risks associated with the Zika virus and the recommendations from the Centers for Disease Control and Prevention (CDC). To a family doctor in South Florida, the risk of Zika seems very acute, so I have been thinking about it a lot this summer. Over the past month, 40 new patients have contracted Zika from local mosquitoes. The affected area includes the popular tourist destination, Miami Beach, and an area just north of downtown Miami. The CDC has taken the historic step of recommending against travel to these two areas. The recommendation states:

· Pregnant women should not travel to these areas.
· Pregnant women and their partners living in or traveling to these areas should follow steps to prevent mosquito bites.
· Women and men who live in or traveled to these areas and who have a pregnant sex partner should use condoms to prevent infection every time they have sex or not have sex during the pregnancy.
· Effective contraception to prevent pregnancy in women and their partners who want to delay or prevent pregnancy is a key prevention strategy for Zika.
· All pregnant women in the United States should be assessed for possible Zika virus exposure and signs or symptoms of Zika during each prenatal care visit.
· Pregnant women who live in or frequently travel to these areas should be tested in the first and second trimester of pregnancy.
· Women with Zika should wait at least 8 weeks after symptoms began before trying to get pregnant, and men with Zika should wait at least 6 months after symptoms began.

Aedes aegypti mosquitoes can transmit several emerging viral infections, including chikungunya, dengue, and Zika. The Aedes aegypti female mosquito can lay up to 1,000 eggs, and they love to live indoors. Since 2014, the chikungunya virus has begun to have local transmission from infected mosquitoes in Florida and Puerto Rico. Dengue fever had a resurgence in 2013 in Florida, and so far in 2016 there have been 40 travel related cases and one case of local transmission.

Why are we seeing and hearing about these new tropical diseases now? There are several reasons that South Florida (the three-county area of Miami-Dade, Broward, and Palm Beach counties plus the Everglades and the Keys) is at high risk. The climate is tropical with daily rain and average high temperatures in the 80s most of the year, making for an ideal breeding ground for mosquitoes. People come from all over the world to enjoy the beaches in Miami and Fort Lauderdale. Finally, South Florida includes large, diverse immigrant populations from affected countries such as Haiti, the Dominican Republic, Venezuela, Brazil, and Cuba.

So how are public health officials responding to the Zika virus? In downtown Miami, there has been an aggressive ground and aerial spraying campaign to control the mosquito population. This has caused some controversy in the Miami Beach area with protests and a delay in aerial spraying. In the Florida Keys, there is an unpopular proposal to release genetically modified mosquitoes that will produce sterile offspring and (hopefully) decrease the overall mosquito population. On August 5, the U.S. Food and Drug Administration approved these modifications as posing little to no risk of harm to humans, but the project has yet to begin.

Right now preventing Zika infection consists mostly of mosquito control and avoidance, but efforts to develop a vaccine have accelerated and may only be a year or two away, as reported in a fascinating story in the New Yorker. In the meantime, it is important for family physicians to stay up to date on the latest information about the Zika virus. The Featured Content section of the AFP homepage includes other useful resources on this evolving epidemic from the American Academy of Family Physicians, the CDC, and the World Health Organization.


Dr. Delzell (@Ed_in_Med) is Assistant Editor at AFP and Vice President and Designated Institutional Officer of Broward Health Medical Center in Fort Lauderdale, Florida.