Scientists identify a new virus in a rhesus monkey in the Zika forest of Uganda – named as the Zika virus.
Zika Virus (I). Isolations and serological specificity
(1) The isolation of what is believed to be a hitherto unrecorded virus is described. The first isolation was made in April 1947 from the serum of a pyrexial rhesus monkey caged in the canopy of Zika Forest. The second isolation was made from a lot of A. africanus taken in January, 1948, in the same forest. The virus has been called Zika virus after the locality from where the isolations were made.
(2) Cross neutralization tests indicate that Zika virus is not related to yellow fever, Hawaii dengue nor to the FA and GD VII strains of Theiler’s mouse encephalomyelitis virus. Neutralization tests with Zika virus and the antisera of some other viruses which are neurotropic in mice gave no evidence of any identity of these with Zika virus.
The first human cases of Zika are detected in Uganda and the United Republic of Tanzania.
Neutralizing antibodies against certain recently isolated viruses in the sera of human beings residing in East Africa.
1960s – 1980s
Human cases are confirmed through blood tests. No deaths or hospitalizations are reported, but studies consistently show widespread human exposure to the virus.
The disease is mapped as it moves from Uganda to western Africa and Asia in the first half of the 20th century.
First large Zika outbreak in humans in the Pacific Island of Yap in the Federated States of Micronesia.
Prior to this, no outbreaks and only 14 cases of human Zika virus disease had been documented anywhere in the world.
An estimated 73% of Yap residents are infected with Zika virus.
The Yap Island outbreak also suggests a lack of immunity in the island’s population. Regular exposure to infection by populations in Africa and Asia may have prevented the large outbreaks seen on Pacific Islands and in the Americas. Under-reporting, due to the clinical similarities of (mild) illness symptoms associated with Zika, dengue, and chikungunya infections might also account for previous Zika outbreaks being overlooked.
Researchers identify 2 distinct lineages of the virus, African and Asian.
20 March 2014
During the outbreak of Zika virus in French Polynesia, 2 mothers and their newborns are found to have Zika virus infection within 4 days of birth. The infants’ infections appear to have been acquired by transplacental transmission or during delivery.
31 March 2014
During the same outbreak of Zika virus in French Polynesia 1,505 asymptomatic blood donors are reported to be positive for Zika by PCR. These findings alert authorities that Zika virus can be passed on through blood transfusion.
17 July 2015
Brazil reports neurological disorders associated with a history of infection, primarily from the north-eastern state of Bahia. Among these reports, 49 cases were confirmed as Guillain–Barré syndrome. Of these cases, all but 2 had a prior history of infection with Zika, chikungunya or dengue.
30 October 2015
Brazil reports an unusual increase in the number of cases of microcephaly among newborns.
6 November 2015
Zika virus is highlighted in WHO’s Weekly Epidemiological Record:
“Recent outbreaks of ZIKV infection in different regions of the world underscore the potential for the virus to spread further in the Americas and beyond, wherever the vector is present.”
17 November 2015
WHO/PAHO issue an epidemiological alert asking countries to report increases of congenital microcephaly and other central nervous system malformations. Brazil reports the detection of Zika virus in amniotic fluid samples from 2 pregnant women, whose fetuses were confirmed by ultrasound examinations to have microcephaly.