Epidemiological Update - Zika Virus Infection - 25 May 2017
Situation summary in the Americas
To date, 48 countries and territories in the Americas have confirmed autochthonous, vector-borne transmission of Zika virus disease, while five countries have reported sexually transmitted Zika cases. Since epidemiological week (EW) 44 of 2016, no additional countries or territories of the Americas have confirmed autochthonous, vector-borne transmission of Zika virus disease.
In the United States of America, the Florida Department of Health reported that Florida no longer has any identified areas with active Zika transmission, and cases of local transmission have not been reported.4 The Texas Department of State Health Services has not reported cases of local transmission during 2017.
Meanwhile, Mexico continues to report confirmed cases with a declining trend observed since epidemiological week (EW) 40 of 2016. Since the last epidemiological update, no new states have confirmed local transmission of Zika virus.
The trend of reported cases in Central America continues to decline, with the exception of Belize,7 where an increase in the number of suspected and confirmed Zika cases was observed between EW 49 of 2016 and EW 7 of 2017. The majority of the confirmed cases are from the Corozal district.
From EW 10 to EW 14 of 2017, in this sub-region, an average of 71 suspected and confirmed cases were reported per week.
In Turks and Caicos, an increase in the number of suspected cases was observed between EW 4 and EW 8 of 2017. In the other countries/territories of this sub region, the decreasing trend of reported cases continues, with a weekly average of 330 suspected and confirmed cases reported between EW 10 and EW 14 of 2017.
Since EW 1 of 2017, an increasing trend of suspected and confirmed cases has been observed in South America, mainly due to increases in the number of reported cases in Argentina, Bolivia (Plurinational State of), Brazil, Ecuador, and Peru (Figure 3). Between EW 10 and EW 14 of 2017, an average of 1,246 suspected and confirmed cases were reported per week in this sub-region.
In Argentina, an increase in suspected and confirmed cases was observed between EW 1 and EW 16 of 2017; this increase is related to outbreaks in the provinces of Formosa, Salta, and Chaco.10 In these last two provinces, the date of symptom onset of the last confirmed cases was EW 16 of 2017.
In Brazil, there was a slight increase in notified Zika cases between EW 1 and EW 9 of 2017, after which reported cases decreased up to EW 15 of 2017 – similar to what was observed with chikungunya during the same period in the country.
In Ecuador, since EW 5 of 2017, there has been an upward trend in the number of suspected and confirmed cases, with a peak in EW 16 of 2017. About 65% (448) of the cases confirmed in the first 17 weeks of 2017 are from the province of Guayas.
In Peru, the increase is mainly due the ongoing outbreak in the department of Loreto14 and, from EW 10 of 2017, an upward trend in the number of suspected and confirmed cases has been observed, with a peak in EW 14 of 2017 due to an outrbreak in the Chincha province, Ica department.