Severity of Zika Threat Still Open for Debate—US Health Officials Not Taking Any Chances

With 43 “local” cases of Zika virus infection now reported in Florida, and as far north as St. Petersburg, health officials in other Gulf states are ramping up responses in the event of potential outbreaks—even as there remains some disagreement as to the true nature of the threat of local transmission in the United States.

A release from the Florida Department of Health on August 24, noted that there are already more than 550 confirmed cases of the mosquito-borne virus in the state. Although most (523) of these cases have involved people who have traveled to areas where the virus has been rampant for more than a year, such as Brazil and the Caribbean, or have acquired the virus via sexual transmission from people who have traveled to these areas, some 43 cases have been traced to mosquito bites sustained within the Sunshine State. To date, nearly 4,000 Floridians have been tested for the virus.

Florida officials have been quick to point out that “one case does not mean ongoing active transmission is taking place.” However, the fact that Aedes aegypti mosquitos carrying the virus have been active in the state this summer has not been a complete surprise. Research published in the journal PLOS Currents/Outbreaks in April noted that areas from Florida to Texas are “at the nexus of high seasonal suitability” for the mosquitos associated with Zika transmission, and on August 21 Anthony Fauci, MD, said that Louisiana could see Aedes aegypti as a result of standing water—the ideal breeding ground for some mosquito species—remaining from recent flooding in the state.

Health officials from Alabama did not respond to requests for comment at press time on August 24. However, Liz Sharlot, director of communications for the Mississippi Department of Health told Contagion that her state has seen 17 cases of Zika so far, and that all were travel-related. At present, she added, ongoing vector surveillance programs in the state have not revealed the presence of Aedes aegypti mosquitos, which haven’t been identified there since the 1980s. Still, surveillance has confirmed the presence of Aedes albopictus mosquitos, which have also been linked with Zika transmission.

“So, of course, we are concerned,” Sharlot said. “The Mississippi State Department of Health continues to work with all of its partners regarding education and prevention. We have an ongoing campaign including social media, cinema, posters, and airport displays, as well as information passed through pharmacies, with a major emphasis on pregnant women and our Hispanic population.”

Sharlot went on to say that the state’s action plan is currently reviewed every two weeks, although that may change should a localized outbreak occur. Mosquito control efforts in the state are ongoing, as they are every year during mosquito season, but they have not been stepped up specifically because of Zika, according to media reports. The state does not currently have a budget in place for Zika-related mosquito control; at present, the spraying of pesticides and other measures are coordinated at the local level.

Similarly, officials in Georgia said that while the state has not, as yet, “experienced any local transmission of Zika, vector surveillance has confirmed the presence of both Aedes aegypti and Aedes albopictus mosquitos there,” according to Nancy Nydam, a spokesperson for the Department of Public Health (GPDH). “The Aedes aegypti historically had been found in two locations in Georgia—the coastal area around Savannah/Chatham County and Columbus,” she added. “Surveillance to date indicates only a few aegypti in one location, in one trap near Columbus. Aedes albopictus are found throughout Georgia, but so far this year, their numbers have been lower compared to previous years. We are being vigilant and monitoring the mosquito population carefully, but are hopeful the situation will stay relatively unchanged. The fewer mosquitoes we have that are capable of transmitting Zika, the lower the risk for local transmission.”

Nydam went to say that should local transmission occur within the state, GDPH officials plan to follow current Centers for Disease Control and Prevention (CDC) guidance with regard to epidemiological surveillance, testing, mosquito control, and community education.

The CDC is not currently on the ground in Georgia or Mississippi, but has been assisting Florida authorities for weeks. According to statement released by the agency on August 24, the CDC “has provided $35 million in federal funds for Zika and emergency response, including public health and emergency preparedness funds… that can be used to purchase items for Zika prevention kits. CDC also has provided 10,000 bottles of DEET mosquito repellent for the kits, as well as support for Zika lab testing. CDC’s Fort Collins laboratory is also testing specimens from pregnant women for the Florida Department of Health.”

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.