Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection, 1 September 2016

Epidemiological update

​Since 1 February 2016, Zika virus infection and the related clusters of microcephaly cases and other neurological disorders constitute a public health emergency of international concern (PHEIC). Since 2015, and as of 2 September 2016, there have been 63 countries and territories reporting mosquito-borne transmission. According to WHO and as of 1 September 2016, 20 countries or territories have reported microcephaly and other central nervous system (CNS) malformations potentially associated with Zika virus infection or suggestive of congenital infection.

​New developments since the last epidemiological update

The USA

Five new autochthonous cases have been reported in Florida since the last CDTR, bringing the number of locally transmitted cases to 47. As of 1 September, the number of autochthonous cases reported in Florida state is as follows: 40 cases in Miami-Dade, one in Broward, three in Palm Beach and one in Pinellas. The department is currently conducting an investigation into the other two cases to determine where exposure occurred. Health officials have been collecting and testing human samples, and mosquito abatement activities are underway in some of the involved areas.

On 26 August, the Food and Drug Administration (FDA) issued advice that all donations of blood and blood components should be tested for Zika.

WHO

According to the latest situation report, genetic sequencing of Zika virus isolates from four samples collected in Guinea-Bissau has preliminarily identified that these are related to the African lineage of the virus. Although the African lineage has not been associated with microcephaly and other neurologic complications, further surveillance is needed as there have been very few confirmed cases of the African lineage. At this point it is still too early to dismiss this possible threat.

British Virgin Islands (UK)

On 25 August, health authorities reported five locally acquired Zika cases for the first time.

Singapore

Following the detection of a case of Zika virus infection on 27 August 2016, testing was done on 124 people living and working in the Aljunied Crescent and Sims Drive area who were recently or currently symptomatic. Of those, 41 tested positive. As of 1 September, the Ministry of Health reports 115 locally-acquired cases including the first case diagnosed in a pregnant woman. In addition, media report​ an imported Zika case in Malaysia in a person who had visited Singapore.

Thailand

On 31 August, health authorities in Chiang Mai report seven cases of Zika virus infection in the province. The first case was discovered on 19 June, while the most recent case was on 23 August. Besides Chiang Mai, cases of Zika virus have been documented in other three provinces including Chanthaburi, Phetchabun and Bueng Kan during August 2016.

Publications

The US-CDC reported in the Morbidity and Mortality Weekly Report (MMWR) a likely sexual transmission of Zika virus from a man with no symptoms of infection in Maryland. In addition, The Lancet published a case series of the first 1 501 live births with congenital Zika virus syndrome in Brazil and their complete investigation.

EU/EEA imported cases

Since week 45/2015, 19 countries (Austria, Belgium, the Czech Republic, Denmark, Finland, France, Ireland, Italy, Luxembourg, Malta, the Netherlands, Norway, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and the UK) have reported 1 569 travel-associated Zika virus infections through The European Surveillance System (TESSy). Over the same time period, seven EU countries reported 79 Zika cases among pregnant women. 

EU’s Outermost Regions and Territories

As of 1 September 2016:

Martinique: 35 580 suspected cases have been reported, an increase of 230 since last week. The weekly number of cases is stable.

French Guiana: 9 565 suspected cases have been detected, an increase of 26 cases since last week. The weekly number of cases is stable.

Guadeloupe: 29 075 suspected cases have been detected, an increase of 405 suspected cases since last week. The weekly number of cases continues to decrease.

St Barthélemy: 595 suspected cases have been detected, an increase of 55 suspected cases since last week. The weekly number of cases has been decreasing during the past two weeks.

St Martin: 2 085 suspected cases have been detected, an increase of 95 suspected cases since last week. The weekly number of cases has been slightly increasing during the past week.

The USA

Five new autochthonous cases have been reported in Florida since the last CDTR, bringing the number of locally-transmitted cases to 47. As of 1 September, the number of autochthonous cases reported in Florida state is as follows: 40 cases in Miami-Dade, one in Broward, three in Palm Beach and one in Pinellas. The department is currently conducting an investigation into the other two cases to determine where exposure occurred. 

Update on microcephaly and/or central nervous system (CNS) malformations potentially associated with Zika virus infection

 
As of 1 September 2016, microcephaly and other central nervous system (CNS) malformations associated with Zika virus infection or suggestive of congenital infection have been reported by 20 countries or territories. Brazil reports the highest number of cases. Eighteen countries and territories worldwide have reported an increased incidence of Guillain-Barré syndrome (GBS) and/or laboratory confirmation of a Zika virus infection among GBS cases.

Since February 2016, 11 countries have reported evidence of person-to-person transmission of Zika virus, probably via a sexual route.

In the EU, Spain (2) and Slovenia (1) have reported congenital malformations associated with Zika virus infection after travel in the affected areas. Cases have also been detected in the EU’s Outermost Regions and Territories in Martinique, French Guiana and French Polynesia.
 
 

ECDC assessment

The spread of the Zika virus epidemic in the Americas is likely to continue as the vectors (Aedes aegypti and Aedes albopictus mosquitoes) are widely distributed there. The likelihood of travel-related cases in the EU is increasing. A detailed risk assessment is available here. As neither treatment nor vaccines are available, prevention is based on personal protection measures. Pregnant women should consider postponing non-essential travel to Zika-affected areas.

Table 1. Countries and territories with reported confirmed autochthonous cases of Zika virus infection in the past three months, as of 2 September 2016

  

Countries affected in past 3 months Areas (non-tropical countries only) Type of transmission
American Samoa   Widespread transmission
Argentina Tucumán Province Widespread transmission
Barbados   Widespread transmission
Belize   Widespread transmission
Bolivia   Widespread transmission
Bonaire   Widespread transmission
Brazil   Widespread transmission
Cape Verde   Widespread transmission
Colombia   Widespread transmission
Costa Rica   Widespread transmission
Curaçao   Widespread transmission
Dominica   Widespread transmission
Dominican Republic   Widespread transmission
Ecuador   Widespread transmission
El Salvador   Widespread transmission
Fiji   Widespread transmission
French Guiana   Widespread transmission
Guadeloupe   Widespread transmission
Guatemala   Widespread transmission
Haiti   Widespread transmission
Honduras   Widespread transmission
Jamaica   Widespread transmission
Martinique   Widespread transmission
Mexico   Widespread transmission
Micronesia, Federated States of   Widespread transmission
Nicaragua   Widespread transmission
Panama   Widespread transmission
Paraguay   Widespread transmission
Peru   Widespread transmission
Puerto Rico   Widespread transmission
Saint Lucia   Widespread transmission
Saint Martin   Widespread transmission
Saint Vincent and the Grenadines   Widespread transmission
Saint-Barthélemy   Widespread transmission
Samoa   Widespread transmission
Sint Maarten   Widespread transmission
Suriname   Widespread transmission
Thailand   Widespread transmission
Tonga   Widespread transmission
Trinidad and Tobago   Widespread transmission
US Virgin Islands   Widespread transmission
Venezuela   Widespread transmission
​​United States of America ​Florida (Miami-Dade county) Widespread transmission
​​​United States of America ​Florida (Broward, Palm Beach and Pinellas  counties) ​Sporadic transmission
Antigua and Barbuda   Sporadic transmission
Anguilla   Sporadic transmission
​Bahamas ​Sporadic transmission
​British Virgin Island (UK) ​Sporadic transmission
​Cayman Islands ​Sporadic transmission
​Cuba ​Sporadic transmission
Grenada   Sporadic transmission
Guinea-Bissau   Sporadic transmission
Indonesia   Sporadic transmission
Saba   Sporadic transmission
Sint Eustatius   Sporadic transmission
Turks and Caicos Islands   Sporadic transmission
​Vietnam ​Sporadic transmission

 
The classification of countries above is based on: 1) number of reported autochthonous confirmed cases; 2) number of countries who report a zika virus transmission or a country’s transmission status changes; 3) duration of the circulation.