ZIKA VIRUS OUTBREAK: THE GLOBAL ENDEMIC TO PANDEMIC

*Prof. Dr. Dhrubo Jyoti Sen

ABSTRACT

Zika virus is a member of the Flaviviridae family and is transmitted to humans by mosquitoes. It is related to other pathogenic vector borne flaviviruses including dengue, West-Nile and Japanese encephalitis viruses but produces a comparatively mild disease in humans. Since 2007 Zika virus has caused several outbreaks in the Pacific and since 2015 it further spread in the Americas. These were the first documented transmissions outside of its traditional endemic areas in Africa and Asia. Zika virus is considered an emerging infectious disease with the potential to spread to new areas where the Aedes mosquito vector is present. Zika virus is related to the dengue, yellow fever, Japanese encephalitis and West Nile viruses. Since the 1950s, it has been known to occur within a narrow equatorial belt from Africa to Asia. From 2007 to 2016, the virus spread eastward, across to the Americas, leading to the 2015-16. The infection, known as Zika fever or Zika virus disease, often causes no or only mild symptoms, similar to a very mild form of dengue fever. While there is no specific treatment, paracetamol (acetaminophen) and complete rest may help with the symptoms. As of 2016, the illness cannot be prevented by medications or vaccines. Zika can also spread from a pregnant woman to her fetus. This can result in microcephaly, severe brain malformations and other birth defects. Zika infections in adults may result rarely in Guillain-Barré syndrome (demyelination). In January 2016, the United States CDC issued travel guidance on affected countries, including the use of enhanced precautions and guidelines for pregnant women including considering postponing travel. Other governments or health agencies also issued similar travel warnings, 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 non-segmented, single-stranded, 10 kilobase positive-sense RNA genome. It is most closely related to the Spondweni virus and is one of the two known viruses in the Spondweni virus clade.

Keywords: Aedes mosquito, Guillain-Barré syndrome, RT-PCR, Flavivirus, Capsid, Genome, CDC, Microcephaly, Zika fever.