Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection, 14 April 2016

Epidemiological update

​In the week to 13 April, Belize reported mosquito-borne Zika virus transmission for the first time.

​New developments since the last epidemiological update published on 8 April 2016

In the week to 13 April, Belize reported mosquito-borne Zika virus transmission for the first time.

Publications

NEJM 13 April: Zika Virus and Birth Defects — Reviewing the Evidence for Causality
The authors reviewed available data using Shepard’s and Bradford Hill criteria and concluded that sufficient evidence has accumulated to infer a causal relationship between prenatal Zika virus infection and microcephaly and other serious brain anomalies.
 
Epidemiology and Infection 4 April: Potential exposure to Zika virus for foreign tourists during the 2016 Carnival and Olympic Games in Rio de Janeiro, Brazil
The resulting risk for Zika infection for tourists visiting Rio during the one-week Carnival festivities in February and the three weeks of the Olympic Games in August are 36 per million tourists and 1.8 per million tourists, respectively.
 
MMWR 14 April 2016: Sexual Transmission of Zika Virus – Texas, January 2016
A case of Zika virus transmission associated with sexual contact between a male traveller (patient A) who returned to Dallas, Texas from an area of active Zika virus transmission and his male non-travelling partner (patient B) is supported by epidemiological, laboratory, and environmental investigations.
 
NEJM 13 April 2016: Evidence of Sexual Transmission of Zika Virus
Hypothesis of sexual transmission (either oral or vaginal) of ZIKV from Patient 2 to Patient 1, which cannot rule out the possibility that transmission occurred not through semen but through other biological fluids, such as pre-ejaculate secretions or saliva exchanged through deep kissing.

Detailed epidemiological situation

As of 15 April 2016, autochthonous cases of Zika virus infection have been reported from 45 countries and territories worldwide in the past two months (see Table 1 and Figure 1). 49 countries and territories have reported autochthonous cases of Zika virus infection in the past nine months (see Table 1 and Figure 2).
 
Several countries in the Americas, Caribbean and the Pacific continue to report an increase in autochthonous cases of Zika virus infection.
 

Table 1. Countries and territories with reported confirmed autochthonous cases of Zika virus infection in the past two months, as of 15 April 2016

Country/Territory  Affected in the past 2 months Affected in the past 9 months
American Samoa Increasing or widespread transmission Yes
Aruba Sporadic transmission Yes
Barbados Increasing or widespread transmission Yes
Belize Sporadic transmission Yes
Bolivia Increasing or widespread transmission Yes
Brazil Increasing or widespread transmission Yes
Bonaire No Yes
Cape Verde Increasing or widespread transmission Yes
Colombia Increasing or widespread transmission Yes
Cuba Sporadic transmission Yes
Costa Rica Increasing or widespread transmission Yes
Curaçao Increasing or widespread transmission Yes
Dominica Sporadic transmission Yes
Dominican Republic Increasing or widespread transmission Yes
Ecuador Increasing or widespread transmission Yes
El Salvador Increasing or widespread transmission Yes
Fiji Increasing or widespread transmission Yes
French Guiana Increasing or widespread transmission Yes
Guadeloupe Increasing or widespread transmission Yes
Guatemala Increasing or widespread transmission Yes
Guyana Increasing or widespread transmission Yes
Haiti Increasing or widespread transmission Yes
Honduras Increasing or widespread transmission Yes
Jamaica Sporadic transmission Yes
Kosrae  Sporadic transmission Yes
Marshall Islands  Increasing or widespread transmission Yes
Martinique Increasing or widespread transmission Yes
Mexico Increasing or widespread transmission Yes
New Caledonia Sporadic transmission Yes
Nicaragua Increasing or widespread transmission Yes
Panama Increasing or widespread transmission Yes
Papua New Guinea Sporadic transmission Yes
Paraguay Increasing or widespread transmission Yes
Philippines Sporadic transmission Yes
Puerto Rico Increasing or widespread transmission Yes
Saint Lucia Sporadic transmission Yes
Saint Martin Increasing or widespread transmission Yes
Saint Vincent and the Grenadines Sporadic transmission Yes
Samoa Increasing or widespread transmission Yes
Sint Maarten Sporadic transmission Yes
Solomon Islands No Yes
Suriname Increasing or widespread transmission Yes
Thailand No Yes
Tonga Increasing or widespread transmission Yes
Trinidad and Tobago Increasing or widespread transmission Yes
Vanuatu No Yes
Venezuela Increasing or widespread transmission Yes
Vietnam Increasing or widespread transmission Yes
US Virgin Islands Increasing or widespread transmission Yes

The classification of countries above is based on: 1) number of reported autochthonous confirmed cases; 2) number of affected areas in the country; 3) duration of the circulation.
 

EU/EEA and EU Outermost Regions and Territories

As of 15 April, no autochthonous vector-borne Zika virus transmission has been reported in the continental EU. ECDC is collecting data regarding imported cases through the media and official government communication lines. As of 15 April 2016, ECDC has recorded 409 imported cases in 17 EU/EEA countries. Twenty-three of the imported cases are pregnant women. In addition, one confirmed case has been published following diagnosis in a Slovenian hospital.
 
Several of the EU’s Outermost Regions and Territories continue to report autochthonous transmission.

  • Martinique: As of 14 April 2016, 17 990 suspected cases have been reported, an increase of 1 340 since last week.
  • French Guiana: As of 14 April 2016, 4 090 suspected and 411 laboratory-confirmed cases have been reported, an increase of 470 suspected and 28 laboratory-confirmed cases since last week.
  • Guadeloupe: As of 14 April 2016, 1 335 suspected and 239 laboratory-confirmed cases have been reported, an increase of 245 suspected and 48 laboratory-confirmed cases since last week.
  • Saint Martin: As of 14 April 2016, 175 suspected and 43 laboratory-confirmed cases have been reported, this is an increase of ten suspected and one laboratory-confirmed cases during the past week.

Figure 1. Countries or territories with reported confirmed autochthonous cases of Zika virus infection in the past two months, as of 15 April 2016

Figure 2. Countries and territories with reported confirmed autochthonous cases of Zika virus infection in the past nine months, as of 15 April 2016

Update on the observed increase of congenital Zika syndrome and other neurological complications 

Microcephaly and other foetal malformations potentially associated with Zika virus infection or suggestive of congenital infection have been reported in Brazil (1 113 cases), Cape Verde (two cases), Colombia (seven cases), French Polynesia (eight cases), Martinique (three cases) and Panama (three cases). Two additional cases, each linked to a stay in Brazil, were detected in Slovenia and the United States of America. One more case was reported in a traveller returning from the affected countries in the United States of America.
 
In the context of Zika virus circulation, 13 countries or territories have reported an increased incidence of Guillain–Barré syndrome (GBS) and/or laboratory confirmation of a Zika virus infection among GBS cases.
 
Brazil
Between October 2015 and as of the 9 April 2016, Brazil reported 7 015 suspected cases of microcephaly from 1 386 municipalities in all states and in the Federal District. Of these cases, 1 113 are reported as confirmed cases of microcephaly with 189 having laboratory confirmation of Zika virus infection. Of the remaining cases, 2 066 were investigated and discarded as they did not fit the case definition, while 3 836 cases are still under investigation.

Among the 7 015 suspected cases of microcephaly, 235 intrauterine or neonatal deaths were reported. Of these, 50 cases were investigated and confirmed (microcephaly and/or central nervous system malformations). One hundred and fifty-five cases are still under investigation, and 30 cases have been discarded.
 
Colombia
Since the beginning of 2016, 33 microcephaly cases have been detected in Colombia, which is not unexpected. Of these, 30 are under investigation for Zika virus and three have been discarded.

Since December 2015 and as of epidemiological week 13 2016, 416 cases of neurological syndromes including GBS have been associated with Zika virus infection.