[15][16] Other governments or health agencies also issued similar travel warnings,[17][18][19] while Colombia, the Dominican Republic, Puerto Rico, Ecuador, El Salvador, and Jamaica advised women to postpone getting pregnant until more is known about the risks.

Like other flaviviruses, Zika virus is enveloped and icosahedral and has a nonsegmented, single-stranded, 10 kilobase, positive-sense RNA genome.

This protein is the flavivirus envelope glycoprotein, that binds to the endosomal membrane of the host cell to initiate endocytosis.

[32] Phylogenetic studies indicate that the virus spreading in the Americas is 89% identical to African genotypes, but is most closely related to the Asian strain that circulated in French Polynesia during the 2013–2014 outbreak.

[35] The vertebrate hosts of the virus were primarily monkeys in a so-called enzootic mosquito-monkey-mosquito cycle, with only occasional transmission to humans.

[36] Though the reason for the pandemic is unknown, dengue, a related arbovirus that infects the same species of mosquito vectors, is known in particular to be intensified by urbanization and globalization.

[42] At that time, the Pan American Health Organization published a list of countries and territories that experienced "local Zika virus transmission" comprising Barbados, Bolivia, Brazil, Colombia, the Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, and Venezuela.

Zika has been detected in many more species of Aedes, along with Anopheles coustani, Mansonia uniformis, and Culex perfuscus, although this alone does not incriminate them as vectors.

A much cheaper and faster method involves shining a light at the head and thorax of the mosquito, and detecting chemical compounds characteristic of the virus using near-infrared spectroscopy.

[53] A. aegypti distribution is now the most extensive ever recorded – on parts of all continents except Antarctica, including North America and even the European periphery (Madeira, the Netherlands, and the northeastern Black Sea coast).

[54] A mosquito population capable of carrying Zika has been found in a Capitol Hill neighborhood of Washington, DC, and genetic evidence suggests they survived at least four consecutive winters in the region.

[56][57] Research into its ecological niche suggests that Zika may be influenced to a greater degree by changes in precipitation and temperature than dengue, making it more likely to be confined to tropical areas.

[39][59][60] As of April 2016, sexual transmission of Zika has been documented in six countries – Argentina, Australia, France, Italy, New Zealand, and the United States – during the 2015 outbreak.

[63] Since October 2016, the CDC has advised men who have traveled to an area with Zika should use condoms or not have sex for at least six months after their return as the virus is still transmissible even if symptoms never develop.

Eleven of the positive donors reported symptoms of Zika fever after their donation, but only three of 34 samples grew in culture.

[77] Specifically, Link et al. reported in 2019 that NS4A disrupted the asymmetric division of neuronal precursors by the third larval instar in Drosophila fruit flies, and that these defects could be suppressed by heterologous expression of human ANKLE2, which NS4A interacts with, or by reducing expression of the VRK1 homologue Bällchen or the LLGL1 homologue lethal (2) giant larvae.

[82][85] Diagnosis is by testing the blood, urine, or saliva for the presence of Zika virus RNA when the person is sick.

[80][83] In 2019, an improved diagnostic test, based on research from Washington University in St. Louis, that detects Zika infection in serum was granted market authorization by the FDA.

[89] If the patient affected is already taking treatment for another medical condition it is advisable to inform your attending physician before taking any other drug or additional treatment;[90] The World Health Organization has suggested that priority should be to develop inactivated vaccines and other nonlive vaccines, which are safe to use in pregnant women.

This vaccine consists of a small, circular piece of DNA, known as a plasmid, that expresses the genes for the Zika virus envelope proteins.

[95] The virus was first isolated in April 1947 from a rhesus macaque monkey placed in a cage in the Ziika Forest of Uganda, near Lake Victoria, by the scientists of the Yellow Fever Research Institute.

[105] Subsequent serological studies in several African and Asian countries indicated the virus had been widespread within human populations in these regions.

[107] A study published in 2017 showed that the Zika virus, despite only a few cases were reported, has been silently circulated in West Africa for the last two decades when blood samples collected between 1992 and 2016 were tested for the ZIKV IgM antibodies.

[110] In April 2007, the first outbreak outside of Africa and Asia occurred on the island of Yap in the Federated States of Micronesia, characterized by rash, conjunctivitis, and arthralgia, which was initially thought to be dengue, chikungunya, or Ross River disease.

[112] After October 2013 Oceania's first outbreak showed an estimated 11% population infected for French Polynesia that also presented with Guillain–Barre syndrome (GBS).

In January 2016, the WHO said the virus was likely to spread throughout most of the Americas by the end of the year;[114] and in February 2016, the WHO declared the cluster of microcephaly and Guillain–Barré syndrome cases reported in Brazil – strongly suspected to be associated with the Zika outbreak – a Public Health Emergency of International Concern.

[6][120] Several countries took the unusual step of advising their citizens to delay pregnancy until more was known about the virus and its impact on fetal development.

[20] With the 2016 Summer Olympics hosted in Rio de Janeiro, health officials worldwide voiced concerns over a potential crisis, both in Brazil and when international athletes and tourists returned home and possibly would spread the virus.

[123] On 22 March 2016, Reuters reported that Zika was isolated from a 2014 blood sample of an elderly man in Chittagong in Bangladesh as part of a retrospective study.

After the first confirmed case, 19 other people who had previously presented symptoms were tested, and 13 of those had positive results, showing that Zika had been circulating in Kerala since at least May 2021.