SITUATION REPORT ZIKA VIRUS MICROCEPHALY GUILLAIN-BARRÉ SYNDROME 10 MARCH 2017 DATA AS OF 9 MARCH 2017
KEY UPDATES Countries, territories and subnational areas reporting vector-borne Zika virus (ZIKV) infections for the first time in the past five weeks: o None Countries and territories reporting microcephaly and other central nervous system malformations potentially associated with ZIKV infection for the first time in the past five weeks: o Mexico, Saint Martin Countries and territories reporting Guillain-Barré syndrome cases associated with ZIKV infection for the first time in the past five weeks: o Curaçao, Trinidad and Tobago WHO, the United States Centers for Disease Control and Prevention and the European Centre for Disease Prevention and Control have developed a new Zika virus classification scheme.1 The classification serves to categorize the presence of and potential for vector-borne ZIKV transmission and to inform public health recommendations. Based on the defined criteria and expert review, some countries, territories and subnational areas were reclassified and some were classified for the first time. This is the final WHO Zika situation report. WHO will continue to update and publish the Zika classification table (Table 1) on a regular basis.
ANALYSIS Overall, the global risk assessment has not changed. ZIKV continues to spread geographically to areas where competent vectors are present. Although a decline in cases of Zika infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high.
SITUATION Eighty-four countries, territories or subnational areas with evidence of vector-borne ZIKV transmission (Table 1). o Sixty-one areas with ongoing transmission following new introduction reported from 2015 onwards or with reintroduction in an area where transmission has been 1
Link to guidance document.
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previously been interrupted (Category 1). o Eighteen areas with evidence of virus circulation before 2015 or with ongoing transmission that is no longer in the new or re-introduction phase, but where there is no evidence of interruption (Category 2). o Five areas where transmission has been interrupted, with the potential for future transmission (Category 3). Sixty-four areas where the competent vector is established but with no documented past or current transmission (Category 4). Thirteen countries have reported evidence of person-to-person transmission of ZIKV (Table 2). Thirty-one countries or territories have reported microcephaly and other central nervous system (CNS) malformations potentially associated with ZIKV infection, or suggestive of congenital infection (Table 3). Twenty-three countries or territories have reported an increased incidence of GuillainBarré syndrome (GBS) and/or laboratory confirmation of a ZIKV infection among GBS cases (Table 4).
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Table 1. ZIKV classification2,3 WHO Regional Office Country / territory / subnational area Total AFRO Angola; Cabo Verde; Guinea-Bissau 3 Anguilla; Antigua and Barbuda; Argentina; Aruba; Bahamas; Barbados; Belize; Bolivia (Plurinational State of); Bonaire, Sint Eustatius and Saba; Brazil; British Virgin Islands; Cayman Islands; Colombia; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; Ecuador; El Salvador; French Guiana; Grenada; Guadeloupe; Guatemala; Guyana; Honduras; Jamaica; Martinique; Mexico; Montserrat; Nicaragua; Panama; 47 Category 1: Area with AMRO/PAHO Paraguay; Peru; Puerto Rico; Saint Barthélemy; Saint Kitts and Nevis; new introduction or Saint Lucia; Saint Martin; Saint Vincent and the Grenadines; Sint re-introduction with Maarten; Suriname; Trinidad and Tobago; Turks and Caicos Islands; ongoing transmission United States of America; United States Virgin Islands; Venezuela (Bolivarian Republic of) SEARO Maldives 1 American Samoa; Fiji; Marshall Islands; Micronesia (Federated States WPRO of); Palau; Papua New Guinea; Samoa; Singapore; Solomon Islands; 10 Tonga Subtotal 61 Category 2: Area Burkina Faso; Burundi; Cameroon; Central African Republic; Côte AFRO 9 either with evidence d’Ivoire; Gabon; Nigeria; Senegal; Uganda of virus circulation AMRO/PAHO Haiti 1 before 2015 or area SEARO Indonesia; Thailand; Bangladesh 3 with ongoing transmission that is no longer in the new Cambodia; Lao People's Democratic Republic; Malaysia; Philippines; or re-introduction WPRO 5 Viet Nam phase, but where there is no evidence of interruption Subtotal 18 Category 3: Area with AMRO/PAHO ISLA DE PASCUA – Chile 1 interrupted transmission and with WPRO Cook Islands; French Polynesia; New Caledonia; Vanuatu 4 potential for future transmission Subtotal 5 Benin; Botswana; Chad; Comoros; Congo; Democratic Republic of the Congo; Equatorial Guinea; Eritrea; Ethiopia; Gambia; Ghana; Guinea; Kenya; Liberia; Madagascar; Malawi; Mali; Mauritius; Mayotte; AFRO 33 Mozambique; Namibia; Niger; Réunion; Rwanda; Sao Tome and Principe; Seychelles; Sierra Leone; South Africa; South Sudan; Togo; Category 4: Area with United Republic of Tanzania; Zambia; Zimbabwe established AMRO/PAHO Uruguay 1 competent vector but EMRO Djibouti; Egypt; Oman; Pakistan; Saudi Arabia; Somalia; Sudan; Yemen 8 no known Georgia; Região Autónoma da Madeira – Portugal; Russian Federation; documented past or EURO 4 Turkey current transmission SEARO Bhutan; India; Myanmar; Nepal; Sri Lanka; Timor-Leste 6 Australia; Brunei Darussalam; China; Christmas Island; Guam; Kiribati; WPRO Nauru; Niue; Northern Mariana Islands (Commonwealth of the); 12 Tokelau; Tuvalu; Wallis and Futuna Subtotal 64 Total 148 Category 1: Area with new introduction or re-introduction with ongoing transmission a. A laboratory-confirmed autochthonous,4 vector-borne case of ZIKV infection in a country /territory/subnational area where there is no evidence of virus circulation before 2015, whether it is detected and reported by the country /territory/subnational area where infection occurred, or by another country by diagnosis of a returning traveller; or
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Areas are classified according to country, territory, or subnational area Link to guidance document. 4 Autochthonous infection is considered to be an infection acquired in -country, i.e. among patients with no history of travel during the incubation period or who have travelled exclusively to non-affected areas during the incubation period.
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A laboratory-confirmed autochthonous, vector-borne case of ZIKV infection in a country/territory/subnational area where transmission has been previously interrupted, whether it is detected and reported by the country where infection occurred, or by another country by diagnosis of a returning traveller. Category 2: Area either with evidence of virus circulation before 2015 or area with ongoing transmission that is no longer in the new or re-introduction phase, but where there is no evidence of interruption This category takes into account those countries with known historical laboratory evidence of ZIKV circulation prior to 2015, based on the literature as well as all ZIKV surveillance data whether detected and reported by the country where infection occurred or by another country reporting a confirmed case in a returning traveller. Countries in this category may have seasonal variations in transmission. These countries may also experience outbreaks of ZIKV disease. Laboratory criteria to ascertain the presence of ZIKV in past studies are: a. Detection of the virus in humans, mosquitoes or animals; and/or b. Serologic confirmation of ZIKV infection with tests conducted after 1980, and considered as confirmed infection on expert review based on testing for all appropriate cross-reactive flaviviruses and utilization of comprehensive testing methodologies. Because of testing and interpretation limitations with serological data antedating 1980, they were not used for classification purposes. Category 3: Area with interrupted transmission and with potential for future transmission The minimum timeline for determining transition to an interrupted state is 12 months after the last confirmed case, and no cases identified in travellers. For countries with a high capacity for diagnostic testing, consistent timely reporting of diagnostic results, a comprehensive arboviral surveillance system and/or a temperate climate or island setting, the interruption of vector-borne transmission is defined as the absence of ZIKV infection 3 months after the last confirmed case. Countries where interruption is epidemiologically likely to have occurred should provide surveillance data to WHO to support the assessment by expert review. Category 4: Area with established competent vector but no known documented past or current transmission All countries/territories/subnational areas where the main competent vector (A. aegypti) is established, but which have not had a documented, autochthonous, vector-borne case of ZIKV infection. This category also includes a subgroup of countries/ territories /subnational areas where ZIKV transmission may occur because of a shared border with a neighbouring Category 2 country, by belonging to the same ecological zone and having evidence of dengue virus transmission. In this subgroup, a first laboratory-confirmed, autochthonous vector-borne case of ZIKV infection may not necessarily indicate new introduction (Category 1), but rather previously unknown and undetected transmission (Category 2), and these countries/territories/subnational areas will be reclassified accordingly.
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Table 2. Countries reporting person-to-person ZIKV transmission since February 2016 WHO Regional Office Countries with evidence AMRO/PAHO of person-to-person EURO transmission of ZIKV, other than vector-borne WPRO transmission Total Country / territory Argentina, Canada, Chile, Peru, United States of America France, Germany, Italy, Netherlands, Portugal, Spain, United Kingdom of Great Britain and Northern Ireland New Zealand Total 5 7 1 13
Table 3. Countries and territories that have reported microcephaly and/or CNS malformation cases potentially associated with ZIKV infection WHO Regional Office Reporting country or territory AFRO Cabo Verde AMRO/PAHO Argentina, Bolivia (Plurinational State of), Brazil, Canada*, Countries and Colombia, Costa Rica, Dominican Republic, El Salvador, French territories that have Guiana, Grenada, Guadeloupe, Guatemala, Haiti, Honduras, reported microcephaly Martinique, Mexico, Nicaragua, Panama, Paraguay, Puerto Rico, and/ or CNS Saint Martin, Suriname, Trinidad and Tobago, United States of malformation cases America* potentially associated EURO Slovenia**, Spain*** with ZIKV infection SEARO Thailand WPRO French Polynesia, Marshall Islands, Viet Nam Total *Probable locations of ZIKV infection are undetermined. ** Probable location of ZIKV infection is Brazil. *** Probable locations of ZIKV infection are Colombia or Bolivarian Republic of Venezuela.
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Table 4. Countries and territories that have reported Guillain-Barré syndrome (GBS) potentially associated with ZIKV infection WHO Regional Office Reported increase in incidence of GBS cases, AMRO/PAHO with at least one GBS case with confirmed WRPO ZIKV infection No increase in GBS incidence reported, but at least one GBS AMRO/PAHO case with confirmed ZIKV infection Total Country or territory Brazil, Colombia, Curaçao, Dominican Republic, El Salvador*, French Guiana, Guadeloupe, Guatemala, Honduras, Jamaica, Martinique, Puerto Rico, Suriname**, Venezuela (Bolivarian Republic of) French Polynesia Total 14 1
Bolivia (Plurinational State of), Costa Rica, Grenada, Haiti, Mexico, Panama, Saint Martin, Trinidad and Tobago
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*GBS cases with previous history of ZIKV infection were reported by the United States of America. **One case living in continental Netherlands was diagnosed in January 2016 and reported by the Netherlands.
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