Zika virus – Incidence and trends
To date, 46 countries and territories have confirmed autochthonous, vector-borne transmission of Zika virus disease in the Region of the Americas since 2015. In addition, five countries in the Americas have reported sexually transmitted Zika cases.2 Since the last Zika Epidemiological Update of 25 August 2016, the British Virgin Islands have confirmed vectorborne autochthonous transmission of Zika virus (Figure 1).
North America
Mexico has been showing a downward trend in the number of confirmed cases for four consecutive weeks (EW 30 to EW 33). In the United States of America, the Zika virus transmission continues to expand and, to date, three counties in the state of Florida have confirmed autochthonous cases of Zika virus infection: Miami Dade, Palm Beach and Pinellas.
Central America
Over the last four weeks, a decreasing trend of cases has been observed in all countries in Central America with the exception of Costa Rica, where there has been an increasing trend of cases since the beginning of the outbreak up to EW 31. In Guatemala, following a downward trend that began on EW 23, the reported cases increased again in EW 32; therefore, it will be important to monitor whether the upward trend continues in the coming weeks. In Nicaragua, where the number of reported cases has mostly been on the rise since the beginning of the outbreak, cases have declined for the third consecutive week (EW 32 to 34).
The greatest increase in Zika cases in Central America occurred between late 2015 and early 2016.
Caribbean
In the Caribbean, Grenada, Puerto Rico and Saint Barthelemy show a declining trend of Zika cases between EW 32 and EW 33, following the increase in number of cases observed since the beginning of the outbreak. However, in the following weeks, it will be necessary to monitor whether the declining trend continues in these countries/territories.
Other countries/territories in the Caribbean also show a declining trend of Zika cases.
South America
In South America, all countries are reporting decreasing numbers of Zika cases.