The following timeline charts the origin and spread of the Zika virus from its discovery in Uganda nearly 70 years ago:

1947 - Scientists researching yellow fever in Uganda's Zika Forest isolate the virus in samples taken from a rhesus monkey

1948 - Virus recovered from Aedes africanus mosquito in the Zika forest

1952 - First human cases detected in Uganda and Tanzania

1954 - Virus found in young girl in Nigeria

1960s-1980s - Zika detected in mosquitoes and monkeys in band of countries stretching across equatorial Africa

1969-1983 - Zika is found in equatorial Asia, including India, Indonesia, Malaysia and Pakistan

2007 - Zika spreads from Africa and Asia to cause the first large outbreak in the Pacific island of Yap

More on this...

2012 - Two distinct lineages of the virus, African and Asian, are identified by researchers

2013-2014 - Zika outbreaks in French Polynesia, Easter Island, the Cook Islands and New Caledonia. Retrospective analysis shows possible link to birth defects and severe neurological complications in babies in French Polynesia

March 2, 2015 - Brazil reports an illness characterized by skin rash in northeastern states

Apr 29, 2015 - Brazilian samples test positive for Zika

July 17, 2015 - Brazil reports detection of neurological disorders in newborns associated with history of infection

Oct 5, 2015 - Cape Verde reports cases of illness with skin rash

Oct 22, 2015 - Colombia confirms cases of Zika

Oct 30, 2015 - Brazil reports unusual increase in cases of microcephaly - abnormally small heads - among newborns

Nov 11, 2015 - Brazil declares a national public health emergency

Nov 2015-Jan 2016 - Cases reported in Suriname, Panama, El Salvador, Mexico, Guatemala, Paraguay, Venezuela, French Guiana, Martinique, Puerto Rico, Guyana, Ecuador, Barbados, Bolivia, Dominican Republic, Nicaragua, Curacao, Jamaica

Feb 1, 2016 - World Health Organization declares a public health emergency of international concern

Source: World Health Organization