Note: The Epidemiological Update publication schedule is being changed monthly until further notice. 

Zika virus - Incidence and trends

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. To date, 48 countries and territories in the Americas have confirmed autochthonous, vector-borne transmission of Zika virus disease,1 while five countries have reported sexually transmitted Zika cases (Figure 1).[2]

Figure 1. Countries and territories in the Americas with confirmed autochthonous (vector-borne) Zika virus cases, 2015-2017. 

2017-25-aug-zika-epi-update-1

see larger image |

Highlighted below is a summary of the Zika epidemiological situation by sub-regions of the Americas. 

North America[3]

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 in 2017.[4] In EW 30 of 2017, the Texas Department of Health and Hidalgo county reported a probable case of local vector-borne transmission that occurred in 2017.[5]

In Mexico, an increase of confirmed cases was observed between EW 16 and EW 27 of 2017 (Figure 2), a trend similar to that observed for dengue in the country during the same period.[6] Approximately 51% of the confirmed Zika cases in the first 32 weeks of 2017 correspond to the states of Nayarit (171 cases), Tamaulipas (146 cases) and San Luis Potosí (123 cases), while the number of confirmed cases in those states is higher than reported in 2015-2016.[7,8]

Figure 2. Distribution of confirmed Zika cases. Mexico, 2015 - 2017 (as of EW 30).

2017 aug 25 confirm zika cases mexico

Source: Data provided by the Mexico Secretariat of Health and reproduced by PAHO/WHO

Central America[9]

From EW 20 to EW 30 of 2017, a small surge in suspected and confirmed cases was observed in the sub-region due to a slight increase reported in Belize and Costa Rica, with an average of 117 suspected and confirmed cases between EW 21 and EW 30 of 2017 in this sub region (Figure 3).

Figure 3. Distribution of suspected and confirmed Zika cases. Central America, 2015 - 2017 (as of EW 32).

2017 25 aug susp confirm zika central america
Source: 
Data provided by countries of Central America[10] and reproduced by PAHO/WHO

Caribbean[11]

In countries and territories of this sub region, sporadic cases continue to be reported, with a weekly average of 252 suspected and confirmed cases reported between EW 21 and EW 30 of 2017. In Puerto Rico, the trend of cases observed in the last 10 weeks is decreasing.[12]

South America[13]

From EW 14 of 2017, a decreasing trend of suspected and confirmed cases has been observed in South America (Figure 4), with the exception of Ecuador where an increase in the number of suspected and confirmed cases between EW 4 and EW 20 of 2017 was reported. Between EW 21 and EW 30 of 2017, an average of 293 suspected and confirmed cases were reported per week in this sub-region.

Figure 4. Distribution of suspected and confirmed Zika cases by EW and sub-region. Region of the Americas, 2015 - 2017 (as of EW 32).[14]

2017 25 aug susp conf zika subregion

Source: Data provided by countries and territories of the Americas and reproduced by PAHO/WHO

Congenital syndrome associated with Zika virus infection[15]

Since October 2015, a total of 27 countries and territories in the Americas have reported confirmed cases of congenital syndrome associated with Zika virus infection. Since the last epidemiological update, Guyana was added to the list of countries and territories that reported cases of congenital syndrome associated with Zika virus infection.[16] In the last four weeks (EW 30 to EW 33 of 2017), Brazil, Colombia, Ecuador, Martinique, Mexico, Panama, Puerto Rico, and the United States of America updated their number of cases of congenital syndrome associated with Zika virus infection.

The table with the number of confirmed cases of congenital syndrome is published on a weekly basis on the PAHO/WHO website and is available at the PAHO/WHO Zika Cumulative Cases website.

Guillain-Barré syndrome (GBS) and other neurological disorders

Since the last epidemiological update, no countries or territories have reported for the first time confirmed cases of Guillain-Barré syndrome (GBS) or other neurological syndromes associated with Zika virus infection.

Figure 5. illustrates the trends in Zika and GBS cases.17 The downward trend in Zika cases in the region of the Americas is accompanied by a similar trend in GBS cases.

Figure 5. Distribution of suspected and confirmed cases of Zika and GBS by EW. Region of the Americas, 2015 - 2017 (as of EW 32).

2017 25 aug distrib susp conf zika subregion

Source: Data provided by countries and territories of the Americas and reproduced by PAHO/WHO


Epidemiological Alert List - Zika virus infection

(Click to expand/collapse)

Zika Epidemiological Reports per country