The following timeline summarizes the spread of Zika infection, country by country, from the earliest discovery in 1947 to the latest information as of 7 February 2016.
Figure 1 provides a chronological map of the presence of Zika only in those countries for which there is evidence of autochthonous or indigenous transmission by mosquitos, excluding the many countries that have notified imported Zika infections.1964: A researcher in Uganda who fell ill while working with Zika strains isolated from mosquitoes provides the first proof, by virus isolation and re-isolation, that Zika virus causes human disease.
In October 2015 Brazil reported an association between Zika virus infection and microcephaly. In February 2016, as infection moved rapidly through the range occupied by Aedes mosquitos in the Americas, WHO declared that Zika infection associated with microcephaly and other neurological disorders constitutes a Public Health Emergency of International Concern (PHEIC).
By the start of February 2016, local transmission of Zika infection had been reported from more than 20 countries and territories in the Americas, and an outbreak numbering thousands of cases was under way in Cabo Verde, western Africa.
In South America, the first reports of locally transmitted infection came from Brazil in May 2015.
In July 2015 Brazil reported an association between Zika virus infection and GBS.
Zika, a flavivirus transmitted mainly by mosquitos in the genus Aedes, was discovered in 1947 in Uganda.
From the 1960s to 1980s, human infections were found across Africa and Asia, typically accompanied by mild illness.
EIS contains information about public health events of potential international concern notified to WHO as required by the International Health Regulations.
No deaths or hospitalizations are reported, and seroprevalence studies consistently indicate widespread human exposure to the virus.1969–1983: The known geographical distribution of Zika expands to equatorial Asia, including India, Indonesia, Malaysia and Pakistan, where the virus is detected in mosquitos.
As in Africa, sporadic human cases occur but no outbreaks are detected and the disease in humans continues to be regarded as rare, with mild symptoms.
House-to-house surveys among the island’s small population of 11 250 people identify 185 cases of suspected Zika virus disease.
Of these, 49 are confirmed (RNA identified by PCR or a specific neutralizing antibody response to Zika virus in the serum) and 59 are classified as probable (patients with Ig M antibody against Zika virus who had a potentially cross-reactive neutralizing-antibody response).