On Friday, August 19, 2016, following the detection of local transmission ofZika virus on Miami Beach, the US CDC hassuggestedthat pregnant women and their partners, if possible, should postpone any non-essential travel to any part of Miami-Dade county. For those of you not following the history of Zika virus, this relatively unknown cousin of dengue and yellow fever, only known to exist in Uganda, where it wasidentified in 1947, hasemergedin South America in 2015, and has been spreading unabated since then on the continent. Until August 11, 45 countries and territories in the Americas (i.e. most of them) havereportedlocal, autochtonous transmission of this mosquito-borne virus. While it usually causes a relatively mild febrile illness, the most important health concern related to Zika virus is thepotential for birth defects, including microcephaly, when pregnant mothers are infected. Zika virus has also beenimplicated in causing Guillain-Barre syndromein adults. In addition, recent research with mice has demonstrated the ability of this virus todamage adult neurons. The virus is capable of sexual transmission in sperm, and men with confirmed Zika virus infection arerecommendedto use barrier methods or abstain from sex for at least 6 month after infection, which is a concern for family planning.

In terms of the United States,territories in the Carribean已经报道当地传播早d的吗uring the year. In Puerto Rico alone, where Zika virus transmission is widespread, there areover 10,000 cases reported, including more than a 1,000 pregnant women. Resources to deal with the epidemic are scarce due to theongoing fiscal crisis, and the federal governmentdeclared a public health emergencyso that it can release additional funds to support the island’s response. Hawaii has so farnot reportedlocal transmission of the virus, but both it’s vectors,Aedes aegyptiandAedes albopictusis present on the islands, creating the potential for a local outbreak. In the continental United States, experts have longwarnedabout the potential for localized outbreaks, and unfortunately they were proven right so far. The CDC has publishedmapsof the estimated ranges of both vector species, which includes the entire Gulf Coast and much of the Atlantic Coast and the South-east. In addition, severalstatisticalandmathematicalmodels forecasted the potential risk of local virus transmission within the continental United States, with all models suggesting that Florida, especially southern Florida, as well as the Gulf Coast, are the most likely locations for local transmission to occur. Sure enough, on July 29, 2016, the Florida Department of Healthreported4 non-travel related confirmed Zika virus infections, all connected to a 1 square mile area in the popularWynwoodneighborhood in Miami. In a matter of days, the CDC sent an emergency team to assist and declared atravel advisoryfor pregnant women to avoid the Wynwood neighborhood, which has not happened for a US city since thepolio outbreak in the US. The number of non-travel related cases continued to increase, with some of them not connected to the Wynwood neighborhood, until on August 19, the Florida Department of Health announced that they have detected a second area of active transmission inMiami Beach. The CDC expanded their travel advisory for the entire Miami-Dade county, which willlikely have an effecton the $90 billion tourism industry of Florida. For pregnant women who live in the area, the CDC is recommending that they avoid mosquito bites, which translates to anear-house arrest, and is not very practical. In the meantime, the money that the state and the federal government had toscrape togetherfor response is running out. TheUS Congress went on summer recessbefore approving any additional funding for the Zika response, even though President Obama requested an additional $1.9 billion in extra funds.

What can we expect in the near and longer term with regards to Zika virus in the continental United States? First of all, more cases, both travel-related and local transmission.Kara Dapenaat the Miami Herald has created a marvelousdynamic mapshowing how the outbreak is developing in Florida.Dr. Henry L Nimanupdates amap across the USbased on media reports, while the CDC and other agencies are updating their ownmapsbased on reported cases. The Florida Department of Health isemploying mosquito controlto eliminate active transmission in the affected areas, includingaerial spraying, with mixed results. On August 23, a non-travel related confirmed case wasreported in Pinellas county, on the western side of the state, increasing the number of local cases to 41. However, since most Zika infection cases are mild, only 1 in 5 infections are likely to be reported. This means that thetrue number of infectionsat the point in Florida is somewhere around 200. According to a modelrecently publishedby Alessandro Vespigniani and Ira Longini, mosquito-borne transmission is likely to continue in Florida until October or November, and the number of confirmed cases will likely increase to around 80. We can also expect small clusters of local transmissionin other Gulf states, particularTexas and Louisianain the coming few month. This will put additionalpressureon the US Congress, especially in anelection year, to approve funding to help control the outbreak. This will hopefully be sufficient to accelerate the development of aZika vaccine, especially for couples planning a family. During the fall and winter, with mosquito season ending, I expect that the anxiety will die down, and we’ll be distracted by electing the next President of the United States. However, sometime in April and May, we will be reminded of Zika virus by thepictures and sad storiesof babies born with microcephaly, to mothers who were not aware that they or their fetuses were infected previously. Hopefully, by that time, we will be better prepared to protect our citizens, perhaps including therelease of genetically modified mosquitoesorWolbachia. WhileNeil Fergusonis probably right that in 3 years Zika virus will infect enough people in the Americas to burn itself out and disappear, I worry that Zika virus will joindengueandchikungunyaas mosquito-borne diseases that we need to be concerned about, especially in Florida, California, and the Gulf States. And I don’t dare to imagine thedamagethat will occur in the meantime.