Zika virus – Incidence and trends
To date, 35 countries and territories have confirmed local, vector-borne transmission of Zika virus in the Region of the Americas since 2015 (Figure 1). Since the last Pan American Health Organization/ World Health Organization (PAHO/WHO) Zika Epidemiological Update of 14 April, no new countries or territories have confirmed vector-borne autochthonous transmission of Zika virus.
Trends of Zika virus, at the Regional level, have been showing a downward trend in most countries of the Region of the Americas, as is being observed with other vector-borne diseases in the same areas. However, this trend could change in the coming weeks when retrospective data is received and with some sub-regions entering their seasons of highest circulation of vector-borne diseases.
This week the Zika virus situation in Martinique and French Guiana are highlighted below.
In Martinique Zika virus cases have been increasing since epidemiological week (EW) 52 of 2015 to EW 7 of 2016 (Figure 2). Subsequently a stable trend with elevated case numbers is observed between EW 7 to 11 with an average of 1,650 cases per week. A noticeable decrease in case numbers is observed in EW 12 and the following weeks; this decline is likely due to school holidays, including Easter, and the closure of some medical offices.
Accordingly data from those weeks should be interpreted with caution. During the EW 14 the number of cases increased slightly compared to the previous week.
Similarly, in French Guiana, reports of Zika virus cases started increasing since EW 1 to EW 8 of 2016 (Figure 2). After a sharp increase in EW 8, a stable trend with 454 cases per week was reported until EW 11. Subsequently, a decrease in cases is observed in EW 12 and EW 13, for the first time since the beginning of the outbreak. French Guiana, like Martinique, observes the same holidays signifying the closure of schools and some medical offices during that time. The data for that period should be interpreted with caution. Like Martinique, in EW 14 the number of cases increase slightly compared to the previous week.