The history of the Zika virus

Zika virus identified in a captive rhesus monkey in the Zika forest of Uganda in routine surveillance for yellow fever.

The first human cases of virus infection are detected in Uganda and the United Republic of Tanzania.

Brazil is declared free of Aedes aegypti (the main vector for dengue, yellow fever, chikungunya and Zika) following an extensive eradication programme using DDT to control a yellow fever outbreak.

Two more Zika virus strains are isolated from Aedes africanus mosquitoes in the Zika forest area.

The first proof that the Zika virus causes human disease. A researcher in Uganda falls ill while working with Zika strains isolated from mosquitoes.

The first large outbreak of Zika in humans on the Pacific island of Yap, in the Federated States of Micronesia. Prior to this event only 14 cases of human Zika virus disease had been documented worldwide. An estimated 73% of Yap residents over three years of age were infected with Zika virus. No deaths, hospitalizations, or neurological complications are reported.

Analysis of Zika virus strains collected in Cambodia, Malaysia, Nigeria, Senegal, Thailand and Uganda, show two geographically distinct lineages of the virus in Africa and Asia. The outbreak on Yap Island was confirmed to have originated in South East Asia.

Zika outbreak in four other groups of Pacific islands: French Polynesia, Easter Island, the Cook Islands, and New Caledonia. The outbreak in French Polynesia causes thousands of suspected infections. The first reports of a possible association between Zika virus infection and congenital malformations and severe neurological and autoimmune complications, in particular, Guillain-Barré syndrome.

A dengue outbreak in Brazil reached 1.5 million cases, showing the extent of the Aedes aegypti re-emergence.

Brazil notifies WHO of outbreak of unknown illness characterized by skin rash with or without fever in north eastern states — 13% tested positive for dengue.

Brazil reports neurological disorders associated with patients having infection of Zika, chikungunya or dengue. 49 cases confirmed as Guillain-Barré syndrome.

Zika reported in Suriname.

Brazil reports Zika virus in amniotic fluid of two pregnant women whose foetuses have microcephaly (confirmed by ultrasound). Suspected microcephaly cases reach 739 cases across nine states.

The United States reports the first locally acquired Zika infection, in the Commonwealth of Puerto Rico.

The first diagnoses of intrauterine transmission of the Zika virus in two pregnant women in Brazil whose foetuses were diagnosed with microcephaly. Zika virus is detected in amniotic fluid even though the mothers tested negative.

The Unites States issues travel guidance for pregnant women which, “out of an abundance of caution”, advises them to consider postponing travel to areas with Zika outbreak or to take precautions against mosquito bites if they must travel. Creates worldwide interest in Zika.

21 July: The Oswaldo Cruz Foundation in Brazil reported it had detected the Zika virus in Culex quinquefasciatus mosquitoes collected in Pernambuco State.

26 July: Inovio Pharmaceuticals and GeneOne Life Science announced the dosing of the first subject in its multi-center phase I trial to evaluate Inovio’s Zika DNA vaccine (GLS-5700).

29 July: US reported the first cases of mosquito-borne virus transmission of Zika, in Florida.

WHO declared an end to Public Health Emergency of International Concern (PHEIC) for microcephaly, other neurological disorders and Zika virus. The WHO Emergency Committee recommended that the Zika programme should be escalated into a sustained programme of work.

65 countries had reported an outbreak or possible transmission in 2015 and 2016.

The Zika virus RNA is found in Aedes albopictus mosquitoes in Brazil. Male mosquitoes were also found with the virus RNA, which means it must have passed from the mother to the egg, as males do not feed on blood (research conducted by University of Florida Institute of Food and Agricultural Sciences).