First local transmission of Zika in continental US

ECDC comment

​Local transmission in Florida, US, was not unexpected due to its geographical proximity to affected areas in the Caribbean and the Americas and the intense travellers’ flow, as well as the presence of mosquitoes which can transmit Zika. 

On 29 July, four locally-acquired Zika cases were reported in two counties in Miami by the Florida Health Department. On 1 August, an additional 10 cases were reported by the State of Florida bringing the total number of locally transmitted Zika cases in Florida to 14. This is likely to be the first known occurrence of local mosquito-borne Zika virus transmission in the continental United States.

While the investigations are still ongoing, it is likely that the cases are a result of local mosquito transmission. The CDC was informed in the previous weeks by the State of Florida that the Zika virus infections were likely caused by bites of local Aedes aegypti mosquitoes and is now supporting the local authorities in the investigations.

The areas where the cases occur is restricted to two counties of Miami, Miami-Dade and Broward, and are marked on the ECDC Zika maps.

On 2 August, CDC issued a travel guidance for the affected neighbourhoods in Florida. It is the first time that CDC releases a travel warning for a neighbourhood in the US.

Comment from ECDC, 2 August 2016

Local transmission in Florida, US, was not unexpected due to its geographical proximity to affected areas in the Caribbean and the Americas and the intense travellers’ flow, as well as the presence of mosquitoes which can transmit Zika.

At present the transmission is confined to a small area and will not significantly change the risk in Europe and the existing information for travellers stated in the latest ECDC Rapid Risk Assessment. However, it highlights the importance of current information for travellers due to the intense travellers’ flows between the US and the EU.

Read more: Florida investigation links four recent Zika cases to local mosquito-borne virus transmission

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