Zika Virus

WHO declares Zika virus a Public Health Emergency of International Concern


On 1 February the Zika virus was declared a Public Health Emergency of International Concern (PHEIC) by the WHO Director-General, Dr Margaret Chan. The declaration was made on the advice of the Emergency Committee (EC) convened by the Director-General under the International Health Regulations.

The advice was given after clusters of microcephaly and Guillain-Barré Syndrome (GBS) were associated with Zika virus transmission in some settings, particularly in Brazil and a number of other countries in south and central America.

The Aedes aegypti mosquito is responsible for transmitting the virus.

On 18 February this year the WHO issued an ‘interim guidance’ for the general public and healthcare practitioners on the ‘Prevention of potential sexual transmission of Zika virus’ following reports of the sexual transmission of Zika virus in two cases – in Senegal in 2008 and in Texas, US, in February 2016 – and the presence of the Zika virus in semen in one additional case.

Over the past several months there have been hundreds of reports in Brazil of microcephaly and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant. However, according the US Centers for Disease Control and Prevention, more studies are needed to learn more about the risks of Zika virus infection during pregnancy. Currently, there is no vaccine to prevent or medicine to treat Zika.

Four in five people who acquire Zika infection may have no symptoms and illness from Zika is usually mild and does not require hospitalization.

Dr Ed Wright, Senior lecturer in Medical Microbiology, University of Westminster, said: “With [many] countries in the Americas now reporting human cases of Zika virus infection, a prediction of 3-4 million cases in the next 12 months and the WHO’s announcement that it considers this outbreak a ‘public health emergency of international concern’ due to the possible link to microcephaly in newborns, this gives some indication of the potential devastating impact this virus could have. This is especially alarming with the outbreak of Ebola in West Africa so fresh in our minds. However, it is important to note some key points.

“Towards the end of 2014 it was predicted that the number of Ebola cases could rise to over one million by 2015, but the true number was only a tiny fraction of that. Hopefully the prediction regarding the number of Zika virus cases will be an over estimation too.

“Further to this, the scientific evidence to-date suggest that the virus is only being transmitted by one type of mosquito. This not only naturally limits where the virus can circulate but for people living in these areas, simple strategies such as repellents, clothing that covers all exposed skin and sleeping under bed nets can greatly reduce their chances of becoming infected.

“Finally, the link between Zika virus infection of pregnant women and neurological and physiological development in a small proportion of their babies, is serious but so far unproven. The announcement by the WHO will enable more funding and resources to be used to answer this vital question.

“The fast reaction of global public health organisations to this outbreak and observation that pregnant women could be at greater risk of complications, and therefore given additional advice and support, should minimise the burden Zika virus has on populations where it has been found.”

Professor Trudie Lang, Director of the Global Health Network, University of Oxford, said: “It is excellent news that the WHO have taken this step to make this announcement. There are many key research questions that must now be addressed in order to understand, manage and ultimately treat and prevent this apparent effect that the Zika virus is having on foetal development during pregnancy. This essential research needs to be coordinated, supported and prioritised and this will require rapid international collaboration and strong leadership from a neutral organisation, and this surely must be the WHO rather than any one country?

No cases of Zika virus in WHO EMR, but countries warned to take precautions

As the Zika virus outbreak continues to spread reaching 24 countries in the Americas (as of 27 January), Dr Ala Alwan, WHO’s Regional Director for the Eastern Mediterranean Region (EMR), called on governments to work together to keep the Region protected.

“Zika virus is spread by the Aedes mosquito, the same type of mosquito that transmits dengue, yellow fever and chikungunya,” said Dr Ala Alwan. “No cases of the virus have been reported so far in this Region, but this type of mosquito exists in several countries here, so it is essential that government leaders take steps to prevent the virus from spreading if travellers returning from affected countries are infected with the virus.”

Because no specific treatment or vaccine is currently available, the best form of prevention is protection against mosquito bites. To protect people living in the Eastern Mediterranean Region, Dr Alwan urges all countries to:

  • enhance surveillance for early detection of Zika virus infection, particularly among travellers returning from countries where the virus is currently circulating;
  • be vigilant for any increase in the number of babies recently born with birth defects or neurological syndromes, where this is not a clear medical cause;
  • bolster surveillance in countries where the Aedes aegypti mosquitoes are present, to detect high density of mosquito populations;
  • scale up activities to reduce the source of mosquito populations, especially breeding sites like standing water, through indoor spraying and engage communities;
  • raise awareness among people living in high-risk countries where dengue, chikungunya and yellow fever are present, emphasizing personal protection measures to prevent mosquito bites, especially during day time when these types of mosquitoes tend to bite.

As agreed by international law, all countries must work together by reporting to WHO any suspected case of the disease so necessary actions can be taken to help prevent spread of the virus.

Guillain-Barre syndrome

Guillain-Barré syndrome is a rare condition where, the body’s immune system attacks part of the peripheral nervous system. The syndrome can affect the nerves that control muscle movement as well as those that transmit feelings of pain, temperature and touch. This can result in muscle weakness and loss of sensation in the legs and/or arms.

Around 3%-5% of GBS patients die from complications, which can include paralysis of the muscles that control breathing, blood infection, lung clots or cardiac arrest.


Symptoms typically last a few weeks and most individuals recover without longterm, severe neurological complications.

The first symptoms of Guillain-Barré syndrome include weakness or tingling sensations. They usually start in the legs, and can spread to the arms and face.

Severe cases of Guillain-Barré syndrome are rare, but can result in near-total paralysis. These cases are considered life-threatening, and affected individuals are typically treated in intensive-care units.


The cause of Guillain-Barré cannot always be determined, but it is often triggered by an infection (such as HIV, dengue, or influenza) and less commonly by immunization, surgery, or trauma.

Researchers are studying a potential, but unproven, link between the surge in GBS cases and Zika virus infection.


GBS patients are usually hospitalised so that they can be monitored closely.

There is no known cure for GBS. But treatments can help improve symptoms of GBS and shorten its duration.

Given the autoimmune nature of the disease, its acute phase is typically treated with immunotherapy, such as plasma exchange to remove antibodies from the blood or intravenous immunoglobulin.

Global scientific community commits to sharing data on Zika

Leading global health bodies including academic journals, NGOs, research funders and institutes, have committed to sharing data and results relevant to the current Zika crisis and future public health emergencies as rapidly and openly as possible.

Organisations including the Bill and Melinda Gates Foundation, Médecins Sans Frontières, the US National Institute of Health and the Wellcome Trust, along with leading academic journals including Nature, Science and the New England Journal of Medicine, have signed a joint declaration and hope that other bodies will come on board.

The statement is intended to ensure that any information that might have value in combatting the Zika outbreak is made available to the international community, free of charge, as soon as is feasibly possible. Journal signatories provide assurance that doing so will not preclude researchers from subsequently publishing papers in their titles.

It follows a consensus statement arising from a WHO consultation in September 2015, in which leading international stakeholders from multiple sectors affirmed that timely and transparent prepublication sharing of data and results during public health emergencies must become the global norm.

Lack of knowledge presents challenge to vaccine development

The development of a vaccine for the Zika virus faces a series of challenges because of the relatively poor knowledge of the virus. Because of this it’s estimated that large-scale vaccine trials are at least 18 months away. These remarks were made at a press conference in Geneva 12 February by Dr Marie-Paule Kieny, Assistant Director- General, Health Systems and Innovation at WHO. She was speaking about Research and Development (R&D) for the Zika virus.

However, despite these challenges she said that, based on WHO’s experience with R&D during the West Africa Ebola epidemic, WHO’s R&D response is proceeding very quickly for Zika.

“After Ebola, WHO began to draw up a master plan for R&D to both prepare for health emergencies and to be able to mount a fast R&D response in case of need. The R&D Blueprint – as the initiative is called – aims to accelerate the availability of medical countermeasures during epidemics and limit damage as much as possible. We now have established critical paths for coordinated action, and industry interest in providing platform technologies for the development of medical products,” Dr Kieny said.

“We have already identified a large number of manufacturers and research institutions either involved in the development of medical tools for Zika, or interested in embarking on such research.”

Date of upload: 15th Mar 2016


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