Zika: A report from the front lines
Dr Lockwood, editor in chief, is Senior Vice President, USF Health, and Dean, Morsani College of Medicine, University of South Florida, Tampa. He can be reached at [email protected].
The moment we all dreaded has come: confirmation of local Zika virus transmission by mosquitoes in the continental United States. The first cases were found in the Wynwood section of Miami, an area at particular risk because many of its inhabitants are frequent travelers to areas in the Caribbean and Latin America with active mosquito-borne Zika transmission. Additional cases were then identified in areas of Miami Beach and Tampa Bay.
The state of Florida had been preparing for this moment for some time. Interviewing and testing of potentially infected patients has been ongoing, as has testing of mosquitoes. The state’s response has been efficient, effective, and thus far reasonably successful in containing this incipient outbreak. It has also been very expensive.
Information was up to date at time of publication. For the latest Zika news visit ContemporaryOBGYN.net/Zika-updates
Lessons from dengue fever
The hope and expectation of tropical disease experts in Florida is that Zika will follow the pattern of another flavivirus infection, dengue, which is endemic in the same tropical regions as Zika. Fortunately, mosquito-borne dengue outbreaks in Florida have been isolated and transient. One occurrence in Key West in 2010 and another in Martin County in 2013 were both quickly contained by aggressive mosquito abatement programs.1
However, effective local control has not been the case for the Zika epidemic in Puerto Rico. There the virus spread quickly across the island and it is expected that 1 in 4 people will have been infected by year end. Indeed, as of this writing, about 8000 locally acquired cases have been documented in Puerto Rico, including nearly 700 in pregnant women.2
Various factors have been cited for the unprecedented rapid spread of the virus in Puerto Rico. Chief among them is an inadequate mosquito control response exacerbated by the island’s current and deepening financial crisis. Other factors cited include more “mosquito-permissive” building designs, especially in rural settings, and a failure to communicate the magnitude of the threat to pregnant women.
The thinking by Florida Department of Health experts is that air-conditioned and tightly screened dwellings, coupled with aggressive epidemiological surveillance and intense mosquito-abatement processes, will prevent the rapid spread of Zika in Florida and that Zika will mimic the dengue pattern of infrequent, transient, easily localized outbreaks. While the sexual transmissibility of Zika adds a wrinkle not present in dengue outbreaks, I believe the virus will follow the dengue pattern of easily contained outbreaks in the continental United States.
What obstetricians need to know today about Zika
In nonpregnant patients, Zika is most often asymptomatic, although it can be associated with fatalities in elderly patients with comorbidities and has been linked to an increased occurrence of postviral Guillain-Barré syndrome.
In pregnancy there is the potential for transplacental transmission with catastrophic neurodevelopmental consequences, including microcephaly. Best epidemiologic estimates of the risk of severe congenital Zika central nervous system (CNS) pathology range from 0.95% to 13.2% of affected pregnancies.3 Other associated CNS abnormalities include ventriculomegaly, hydranencephaly, intracranial calcifications, and hypogyria.4,5 Ocular findings have been reported as have hydrops, fetal growth restriction, and fetal loss.4-7