zika virus geographic expansion

Since initial discovery of Zika virus, early virological and serological studies from the 1950s to 1980s showed that Zika virus infection is predominantly limited to African and Asian countries.

In Asia, endemic circulation of the virus (clinical disease and/or seroprevalence studies) has been reported in Indonesia, Cambodia, Thailand, The Philippines, Peninsular Malaysia, and Borneo, and among travelers returning from endemic areas.

The first major epidemic outside Africa occurred in Yap Island of the Federated States of Micronesia (in the western Pacific Ocean, north to Papua New Guinea) in 2007. Since then, Zika, dengue, and chikungunya viruses became rampant in the Pacific islands. Another major epidemic occurred in the western Pacific islands of French Polynesia and New Caledonia in 2013-2014.

The outbreak in Easter Island in 2014 heralded the incursion of the virus to mainland Latin America. Since early 2015, Brazil reported the first autochthonous case in the city of Natal and this was quickly followed by another large epidemic in Brazil and neighbouring countries in Latin America.

As of 12 February 2016, there were over 2,000 confirmed and over 118,000 suspected cases in the Americas. The exact time and route of spread of the virus to Brazil is unknown, but importation during the 2014 World Cup has been postulated.

Table 3 Outbreaks of human Zika virus infection since 2007.

Year Location Estimated number of cases Notable features
2007 Yap Island,
49 confirmed, 59 probable, and 72 suspected
cases in one study. Estimated over 900 clinical
cases, 73% of population infected in 4 months.
Aedes hensilli implicated as the main vector.
2007 Gabon Detected in 5 archived human samples; total
number of cases unknown.
Retrospective study of a concurrent outbreak
of dengue and chikungunya; detection of virus
in patient sera and Ae. albopictus pools.
2013-2014 French
8,723 suspected cases, over 30,000 sought
medical care.
Derived from the Asian lineage, closely related
to Cambodia 2010 and Yap state 2007 strains.
Association with Guillain-Barre´ syndrome and
other neurological complications suspected.
2014 The Cook Islands 932 suspected, 50 confirmed cases.  
2014 New Caledonia 1400 confirmed cases (35 imported).
2014 Easter Island 51 confirmed out of 89 suspected cases from
Jan e May 2014.
Infecting strain closely related to viral strain
found in French Polynesia.
2015 Latin America Estimated 1.5 million cases in Brazil. Association with microcephaly and maculopathy
a As of 10 February 2016. Includes Barbados, Bolivia, Colombia, Commonwealth of Puerto Rico, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Saint Martin, Suriname, U.S. Virgin Islands, Venezuela.

Zika virus geographic expansion related reference

Wong SS-Y, et al., Zika virus infectiondthe next wave after dengue?, Journal of the Formosan Medical Association (2016), http://dx.doi.org/10.1016/j.jfma.2016.02.002