History and Introduction:

The Zika virus disease is an emerging disease that was first identified in 1947 in rhesus monkeys in Uganda. In 1952 it was identified in humans in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.

There are many gaps in our knowledge of the virus- for instance, we do not know the reservoir of infection, and the incubation period.

However, what we do know is that the virus

• belongs to the genus Flaviviridae (it is a flavivirus)
• is transmitted by infected aedes aegypti mosquitoes (these bite during the day time; and are the same mosquitoes that transmit yellow fever, dengue fever, dengue haemorrhagic fever, chikungunya fever and chikungunya haemorrhagic fever)

 

Signs and Symptoms:

The symptoms are similar to other arbovirus infections such as dengue, and include

• fever,
• skin rashes,
• conjunctivitis,
• muscle and joint pain,
• malaise, and
• headache

These symptoms are usually mild and last for 2-7 days.

Recently in Brazil, local health authorities have observed an increase in Zika virus infections in the general public as well as an increase in babies born with microcephaly in northeast Brazil. However, further investigation is needed before we understand the relationship between microcephaly in babies and the Zika virus. Other potential causes are also being investigated.

Transmission:

In the tropics, Zika virus is mainly transmitted via the bite of an infected aedes aegypti mosquito.

Diagnosis:

Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples.

Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.

Treatment:

There is no specific treatment for zika virus disease.

People sick with Zika virus should get plenty of rest, drink enough fluids, and treat pain and fever with common medicines.

If symptoms worsen, they should seek medical care and advice.

Prevention:

Prevention and control depends upon

• reducing breeding of mosquitoes (source reduction through environmental modification)
• personal protection from mosquito bites (use of mosquito repellents, wearing clothes that cover the entire body, using mosquito screens and sleeping under mosquito bed nets)
• spraying of insecticides during outbreaks

There is no vaccine available at present.

Useful Links:

Link to the WHO fact sheet on Zika virus:

http://www.who.int/mediacentre/factsheets/zika/en/

Link to the WHO zika virus Question & Answer page:

http://www.who.int/features/qa/zika/en/