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Zika virus outbreaks in the Americas

Sunday, 17th of January 2016

Zika virus outbreaks in the Americas

 

Also at http://www.who.int/wer/2015/wer9045.pdf?ua=1

 

Background

Until 2007, Zika virus (ZIKV) was described as causing only sporadic human infections

in Africa and Asia. In 2007, an outbreak was reported from the Federated States of Micronesia (Yap), marking the first detection of ZIKV beyond Africa and Asia. The emergence of ZIKV outside its previously known geographic range prompted awareness of the potential for the virus to spread to other Pacific islands. Since then, it has spread to French Polynesia, New Caledonia, Cook Islands, Easter Island (Chile), and subsequently to Brazil and Colombia.

 

ZIKV is an emerging mosquito-borne Flavivirus related to dengue, yellow fever, Japanese encephalitis, and West Nile viruses, and is transmitted by Aedes spp. mosquitoes. It was first isolated in Uganda in 1947 in rhesus monkeys from the Zika Forest and was first reported in humans in 1952.

 

Following the bite of an infected mosquito, symptoms may appear after an incubation period of a few days. Symptoms can last for up to a week, with a clinical presentation similar to that of other arbovirus infections such as chikungunya and dengue, including fever, headache, malaise, arthralgia, myalgia, maculopapular rashes, and conjunctivitis.

 

ZIKV had not been known to cause severe disease until an outbreak in French Polynesia in 2013–2014, when there were reports of neurological and auto-immune complications, such as Guillain-Barre syndrome in the context of co-circulating arboviruses (chikungunya and dengue).

 

Zika virus in the Americas

 

Autochthonous circulation of ZIKV has been detected in the Americas since 2014.

In February 2014, the national authorities of Chile confirmed the first case of autochthonous transmission of ZIKV in Easter Island located in the south-eastern Pacific Ocean.

 

In May 2015, the Ministry of Health of Brazil confirmed autochthonous transmission of ZIKV in the north-eastern part of the country. This was the first documented outbreak in Brazil and in the Americas. As of October 2015, 14 states have confirmed autochthonous virus transmission: Alagoas, Bahia, Ceará, Maranhão, Mato Grosso, Pará, Paraíba, Paraná, Pernambuco, Piauí, Rio de Janeiro, Rio Grande do Norte, Roraima, and São Paulo.

 

In October 2015, the Ministry of Health of Colombia reported the first autochthonous case of ZIKV infection in the Department of Bolivar. As of 16 October 2015, ZIKV was laboratory confirmed in 9 of 98 samples from Bolivar.

 

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. Given the worldwide spread of chikungunya and dengue, associated with urbanization and globalization, there is a potential risk of outbreaks of urban ZIKV infection in urban settings in any part

of the world where the mosquito vector is present or may become established in future.

WHO encourages countries at risk to:

 

• strengthen laboratory capacity to confirm cases of ZIKV infection as clinical diagnosis is unreliable due to the clinical similarity of ZIKV and other arbovirus infections;

 

• establish a surveillance system for the detection of neurologic and auto-immune complications;

 

• implement social communication strategies to engage the community in reducing the population of the mosquito vectors.