Zika virus becomes the 4th Public Health Emergency of International Concern

Tuesday, 2 February, 2016

The Emergency Committee of the World Health Organization (WHO) was convened under the International Health Regulations on 1 February to consider the increased incidence of microcephaly and Guillian-Barre syndrome (GBS) associated with Zika virus (ZIKV). The Committee has decided that the current outbreaks in the Americas justify declaration of a Public Health Emergency of International Concern (PHEIC). This is the fourth PHEIC; the first being the H1N1 influenza pandemic (2009); the second, the reverse in polio eradication in African and middle East countries (2014); and the third, the West African Ebola outbreak (2014). Three of the four PHEICs have been due to emerging infectious diseases (EID).

Read the Committee's decision at WHO.

Although there is still much uncertainty about the incidence of foetal infection with abnormalities and GBS after ZIKV infection, the virus has such a high attack rate in a new population (in some cases >70%) that it threatens public health globally. Zika is a mild disease producing headache, malaise, rash, myalgia, conjunctivitis and arthralgia with self-cure in 4-7 days. Only 1 in 5 of those infected with ZIKV show clinical signs. Hence, it is the life-long effects on the foetus and the serious neurological disease in others that make Zika a potentially serious disease.

Zika is spread by Aedes mosquitoes, with A. aegypti and A. albopictus, the dengue mosquitoes, being the major vectors. Hence, in Australia north and central Queensland, down to but not quite reaching Brisbane, are receptive areas. See the map of A. aegypti distribution at Queensland Health. Unfortunately, the capacity of native Australian Aedes species to act as vectors for ZIKV is unknown. Hence, ZIKV could possibly transmit outside the areas with A. aegypti.

Much research is needed very quickly to answer a whole suite of questions about ZIKV and the disease. Although a significant problem is the lack of a commercial test for ZIKV, Australian health departments do have tests to diagnose Zika.

WHO under the PHEIC makes the recommendations listed below:

Zika virus transmission

  • Surveillance for Zika virus infection should be enhanced, with the dissemination of standard case definitions and diagnostics to at-risk areas.
  • The development of new diagnostics for Zika virus infection should be prioritized to facilitate surveillance and control measures.
  • Risk communications should be enhanced in countries with Zika virus transmission to address population concerns, enhance community engagement, improve reporting, and ensure application of vector control and personal protective measures.
  • Vector control measures and appropriate personal protective measures should be aggressively promoted and implemented to reduce the risk of exposure to Zika virus.
  • Attention should be given to ensuring women of childbearing age and particularly pregnant women have the necessary information and materials to reduce risk of exposure.
  • Pregnant women who have been exposed to Zika virus should be counselled and followed for birth outcomes based on the best available information and national practice and policies.

Longer-term measures

  • Appropriate research and development efforts should be intensified for Zika virus vaccines, therapeutics and diagnostics.
  • In areas of known Zika virus transmission health services should be prepared for potential increases in neurological syndromes and/or congenital malformations.

Travel measures

  • There should be no restrictions on travel or trade with countries, areas and/or territories with Zika virus transmission.
  • Travellers to areas with Zika virus transmission should be provided with up to date advice on potential risks and appropriate measures to reduce the possibility of exposure to mosquito bites.
  • Standard WHO recommendations regarding disinsection of aircraft and airports should be implemented.

Data sharing

  • National authorities should ensure the rapid and timely reporting and sharing of information of public health importance relevant to this PHEIC.
  • Clinical, virologic and epidemiologic data related to the increased rates of microcephaly and/or GBS, and Zika virus transmission, should be rapidly shared with WHO to facilitate international understanding of the these events, to guide international support for control efforts, and to prioritize further research and product development

A problem that is not discussed is which countries pose a risk for ZIKV? This virus has been transmitting for decades in Africa and Asia with minimal issues being apparent. In some surveys up to 40% of the population in these areas have been exposed. The current focus is on Central and South America and the Caribbean. ZIKV is widespread in many Pacific island nations and is spreading so quickly and effectively across national borders that it will soon be a pandemic. A tricky problem for physicians advising patients about travel!

Travel advice for Australians is available at SmartTraveler.

Image of Zika Forest, near Entebbe, Uganda. ZIKV was isolated from a sentinel rhesus monkey (Rhesus 766) on 20 April 1947 placed in a cage in the canopy of the forest by Dr GWA Dick.. See Dick et al. Zika virus. I. Isolations and serological specificity. Trans R Soc Trop Med Hyg 1952;46(5):509-520. Image from http://www.ndtv.com/world-news/into-zikas-heart-the-ugandan-forest-where...

Posted by Rick Speare