Zika virus outbreak timeline

Spread of the Zika virus^[1]^[2]^[3]

This article primarily covers the chronology of the 2015–16 Zika virus epidemic. Flag icons denote the first announcements of confirmed cases by the respective nation-states, their first deaths (and other events such as their first reported cases of microcephaly and major public health announcements), and relevant sessions and announcements of the World Health Organization (WHO), and the U.S. Centers for Disease Control (CDC), as well as relevant virological, epidemiological, and entomological studies.

Timeline

The date of the first confirmations of the disease or any event in a country may be before or after the date of the events in local time because of the International Dateline.

1947–1983

Uganda The Zika virus is first isolated in 1947 in a rhesus monkey in the Zika Forest near Entebbe, Uganda, and first recovered from a Aedes africanus mosquito in 1948.^[4]^[5] Serological evidence indicates additional human exposure and/or presence in some mosquito species between 1951 and 1981 in parts of Africa (Uganda and Tanzania having the first detection of antibody in humans, in 1952,^[6] followed by isolation of the virus from a young girl in Nigeria in 1954 during an outbreak of jaundice,^[7] and experimental infection in a human volunteer in 1956.^[8] The virus was then found variously in Egypt, Central African Republic, Côte d'Ivoire, Senegal, Sierra Leone, and Gabon;^{[citation needed]} Between 1969 and 1983, Zika was found in equatorial Asia including India, Indonesia, Malaysia and Pakistan.^[9] Zika is generally found in mosquitoes and monkeys in a band of countries stretching across equatorial Africa)^[10] and Asia (Malaysia, Philippines, Thailand, Vietnam, and Indonesia).^[11]^[12]^[13] The first confirmed case of Zika fever in a human occurs in Uganda during 1964 in a field researcher, who experiences a mild, non-itchy rash.^[4]

2007

Federated States of Micronesia The first major outbreak is identified outside of Africa and Asia, on Yap Island. Previously only 14 cases of Zika fever had been documented since the virus had first been identified in 1947.^[11]^[14] Approximately 5,005 people, more than 70% of the population of 7,391, were infected with Zika, and generally exhibited mild symptoms; no cases of microcephaly were reported.^[12]

2008

United States The first case of sexual transmission is reported, that of a scientist who had fallen ill in Senegal who thereafter infected his wife.^[4]

2012

Researchers identify two distinct lineages of the Zika virus, African and Asian.^[10]^[4]^[15]^[16]^[17]

2013–2014

French Polynesia In October 2013, an independent outbreak of the Zika virus occurred in the Society, Marquesas and Tuamotu Islands of French Polynesia.^[18] The outbreak abated in October 2014, with 8,723 suspected cases of Zika reported. The true number of Zika cases was estimated at more than 30,000.^[19] An unusual rise in neurological syndromes is reported, including 42 cases of Guillain–Barré syndrome (GBS);^[20] typically five cases are reported in a three-month timeframe.^[21]

French Polynesia On 20 March, researchers discover that two mothers and their newborns test positive for Zika, perinatal transmission confirmed by polymerase chain reaction performed on serum collected within four days of birth during the outbreak.^[4]^[22]

French Polynesia On 31 March, researchers on Tahiti report that 2.8% of blood donors between November 2013 and February 2014 tested positive for the Zika virus, of which 3% were asymptomatic at the time of blood donation.^[23] This indicated a potential risk of transmission of the Zika virus through blood transfusions, but there were no confirmed cases of this occurring.^[24]

French Polynesia On 13 December, a patient recovering from Zika infection on Tahiti seeks treatment for bloody sperm. Zika virus is isolated from his semen, adding to the evidence that Zika can be sexually transmitted.^[4]^[25]

Japan In December 2013, a Japanese tourist returning to Japan was diagnosed with Zika virus infection by the National Institute of Infectious Diseases after visiting the French Polynesian island of Bora Bora, becoming the first imported case of Zika fever in Japan.^[26]

New Caledonia In January 2014, indigenous cases of Zika virus infection were reported in New Caledonia.^[27] The outbreak peaked in April, with the number of confirmed cases reaching 1,400 by 17 September.^[20]

Cook Islands In February 2014, an outbreak of Zika started in the Cook Islands. The outbreak ended on 29 May, with 50 confirmed and 932 suspected cases of Zika virus infection.^[20]^[28]

Easter Island In March 2014, there were one confirmed and 40 suspected cases of Zika virus infection on Easter Island.^[29]

Bangladesh On 22 March 2016, Bangladesh's health ministry announced that they had detected Zika virus in human blood sample which they obtained in 2014.^[30]

2015

February

Solomon Islands An outbreak of Zika begins on the Solomon Islands, with 302 cases reported by 3 May.^[31]

March

Brazil On 2 March, an illness in Northeastern Brazil characterized by a skin rash is reported.^{[citation needed]}

April

Vanuatu On 27 April, the Vanuatu Ministry of Health reports that blood samples collected before March were confirmed to contain the Zika virus.^[32]

Brazil On 29 April, samples first test positive for the Zika virus.^[10]

May

Brazil On 15 May, the Ministry of Health reports the presence and circulation of the Zika virus in the states of Bahia and Rio Grande do Norte after testing 16 people for Zika.^[33]

July

Brazil On 17 July, neurological disorders in newborns associated with history of infection are reported.^[10]

September

Brazil A sharp increase in the number of microcephaly cases is reported. The state of Pernambuco used to register 10 cases of microcephaly annually,^[34] whereas in 2015 over 140 cases were registered.^[35]

October

Colombia 27 cases of Guillain-Barre syndrome are reported in the region around Cucuta; 27,000 cases of Zika are reported nationwide.^[36]

Cabo Verde On 21 October, Cabo Verde confirms, by PCR, its first outbreak of Zika.^[37]

November

Brazil On 11 November, the Ministry of Health declares a national public health emergency.^[34]^[38]

United Nations On 17 November, the Pan American Health Organization (PAHO), under the aegis of the WHO, issues an Epidemiological Alert regarding the increase in microcephaly cases in northeastern Brazil.^[34]

French Polynesia On 24 November, French Polynesian authorities announce that there had been an unusual increase in the number of cases of central nervous system malformations in fetuses and infants, including microcephaly, following the 2013–2014 outbreak.^[39]^[40]

Guatemala On 26 November, Guatemala confirms, by PCR, its first local cases of Zika.^[41]

Samoa, American Samoa and Tonga Local transmission of the Zika virus by mosquitoes is reported in the Polynesian islands of Samoa, American Samoa and Tonga.^[42]

December

United Nations On 1 December, PAHO releases a report noting the possible connection between the Zika virus and the rise in neurological syndromes. Three deaths are reported, and autochthonous circulation of the virus is reported in Brazil, Chile (on Easter Island), Colombia, El Salvador, Guatemala, Mexico, Paraguay, Suriname, and Venezuela.^[43]

Puerto Rico On 31 December, the Puerto Rico Department of Health reported the first locally acquired case of Zika virus infection in Puerto Rico. Zika was confirmed in a resident of Puerto Rico with no known travel history.^[44]

2016

January

United States On 17 January, a baby is born in Hawaii with the Zika virus and microcephaly, the first such case reported in the U.S.; the mother had lived in Brazil in May the previous year.^[45]

Taiwan On 19 January, a man from Thailand becomes the first imported case of Zika virus in Taiwan.^[12]

Samoa On 26 January, Samoa is added to the CDC travel advisory.^[46]

Curacao On 31 January, Curacao reports its first confirmed autochthonous case of Zika.^[47]