The following timeline charts the origin and spread of the Zika virus:

1947: Scientists researching yellow fever in Uganda's Zika Forest identify the virus in a rhesus monkey

1948: Virus recovered from Aedes africanus mosquito in Zika Forest

1952: First human cases detected in Uganda and Tanzania

1954: Virus found in Nigeria

1960s-80s: Zika detected in mosquitoes and monkeys across equatorial Africa

Source: b'A female Aedes aegypti mosquito is seen in a test tube in a laboratory. Reuters\xc2\xa0'

1969–83: Zika found in equatorial Asia, including India, Indonesia, Malaysia and Pakistan

2007: Zika spreads from Africa and Asia, first large outbreak on Pacific island of Yap

2012: Researchers identify two distinct lineages of the virus, African and Asian

2013–14: 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 illness characterized by skin rash in northeastern states

July 17: Brazil reports detection of neurological disorders in newborns associated with history of infection

Oct. 5: Cape Verde has cases of illness with skin rash

Oct. 22: Colombia confirms cases of Zika

Oct. 30: Brazil reports increase in microcephaly, abnormally small heads, among newborns

Nov. 11: Brazil declares public health emergency

November 2015-January 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: World Health Organization (WHO) declares public health emergency of international concern

Feb. 2: First case of Zika transmission in United States; local health officials say likely contracted through sex, not mosquito bite

Feb. 5: U.S. Centers for Disease Control and Prevention says virus being actively transmitted in 30 countries, mostly in the Americas

Feb. 8: U.S. President Barack Obama requests $1.8 billion to fight Zika

Feb. 12: Brazil investigating potential link between Zika infections and 4,314 suspected cases of microcephaly. Of those, 462 confirmed as microcephaly and 41 determined to be linked to virus

Feb. 17: Brazil investigating potential link between Zika and 4,443 suspected cases of microcephaly. Of those, 508 confirmed as microcephaly and most of those cases are linked to the virus. WHO seeks $56 million to fight Zika.

Feb. 18: CDC adds Aruba and Bonaire to countries and territories with active outbreaks, bringing total to 32.

Feb. 23: CDC investigating 14 cases of possible sexual transmission of Zika. CDC also adds Trinidad and Tobago and Marshall Islands to countries and territories with active outbreaks, bringing total to 34.

Feb. 25: Brazil says confirmed microcephaly cases number more than 580 and considers most of them to be related to Zika infections in the mothers. Brazil is investigating an additional 4,100 suspected cases of microcephaly.

Feb. 27: France detects first sexually transmitted case of Zika.

Feb. 29: CDC adds St. Maarten, and Saint Vincent and the Grenadines to countries and territories with active outbreaks, bringing total to 36.