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This is an interim report on the WHO-led global response to the emerging threat posed by Zika virus. It summarises the background to the Strategic Response Framework and Joint Operations Plan published in February 2016, provides an update on some key activities conducted by WHO and its partners since, and sets out the current funding gap for critical activities until the end of June 2016, as well as the approach to setting a new strategy from July 2016 onwards.

Background

Zika virus is an emerging viral disease that is transmitted through the bite of an infected mosquito, primarily Aedes aegypti, the same vector that transmits chikungunya, dengue and yellow fever. Zika has a similar epidemiology, clinical presentation and transmission cycle in urban environments as chikungunya and dengue, although it generally causes milder illness.

Zika virus was first identified in 1947 in a monkey in the Zika forest of Uganda, and was first isolated in humans in 1952 in Uganda and the United Republic of Tanzania. Zika virus has been causing sporadic disease in Africa and Asia. Outbreaks were reported for the first time from the Pacific in 2007 and 2013 in Yap Island (Federated States of Micronesia) and French Polynesia, respectively. There was subsequent spread of the virus to other Pacific islands, including Cook Islands, Easter Island (Chile), Fiji, New Caledonia, Samoa, Solomon Islands and Vanuatu. The geographical range of Zika virus has been steadily increasing ever since.

In February 2015, Brazil detected cases of fever and rash that were confirmed to be Zika virus in May 2015. The last official report dated 1 December 2015, indicated 56 318 suspected cases of Zika virus disease in 29 States, with localized transmission occurring since April 2015. Due to the magnitude of the outbreak, Brazil has stopped counting cases of Zika virus. Today the Brazilian national authorities estimate 500 000 to 1 500 000 cases of Zika virus disease. In October 2015, both Colombia and Cabo Verde, off the coast of Africa, reported their first outbreaks of the virus. As of 19 March 2016, Colombia had reported 56 477 suspected cases of Zika virus, while Cabo Verde reported 7499 suspected cases as of 6 March 2016.

An International Health Regulations (IHR 2005) Emergency Committee met on 1 February 2016, and WHO declared the recent clusters of microcephaly and other neurological disorders in Brazil, following a similar cluster in French Polynesia in 2014, constitutes a Public Health Emergency of International Concern. In the absence of another explanation for the clusters of microcephaly and other neurological disorders, the IHR Emergency Committee recommended enhanced surveillance and research, and aggressive measures to reduce infection with Zika virus, particularly amongst pregnant women and women of childbearing age.