Four years on from London 2012 and the Olympic and Paralympic party has moved on to Rio de Janeiro, a breath taking setting for a wonderful sporting spectacle. However, over recent months anxiety about the outbreak of the Zika virus in Brazil and beyond has been growing due to the suspected link between the virus and cases of microcephaly and Guillan-Barré syndrome. Indeed, this has caused a number of high-profile athletes to withdraw from participating in the games. So, what should you know about Zika?
What is the Zika virus?
Well, firstly, the Zika virus is a mosquito-borne illness that is spread by the Aedes species of mosquito, which is also responsible for the transmission of the dengue, chikungunya and yellow fever viruses. It is now thought that the Culux mosquito may also transmit Zika. The Zika virus has been detected in blood, saliva, urine and semen.
The Zika virus was identified in 1947 in monkeys in Uganda and in 1954 the first case in humans was detected in Nigeria. Since then there have been regular but small outbreaks in Africa, South East Asia and the Pacific Islands. In May 2015 it was reported in Brazil and it has spread rapidly into many parts of central and south America. According to the World Health Organization (WHO), as of the end of July 2016 50 countries and territories across the globe have reported a first outbreak of Zika virus transmission since last year. In July of this year health officials reported that cases of Zika had been confirmed in Miami, Florida and furter cases are being reported.What are the concerns about the Zika virus?
The Zika virus has not previously been considered a major threat to human health. It is thought that only around one in five people infected by the virus go on to develop mild, flu-like symptoms and deaths from the virus occur only very rarely. However, the spread of the virus in Brazil has been accompanied by an unusual rise in the number of babies being born with the condition microcephaly. This is a neurological condition that causes a baby's head to be small and not fully developed and as a result the brain stops growing as it should. In addition, several countries including Brazil have reported a sharp increase in cases of Guillan-Barré syndrome, a rare neurological condition that can lead to paralysis and death.
As a result, in February 2016 an Emergency Committee of the World Health Organisation (WHO) met to consider Zika and agreed that although at that point not scientifically proven, a link between Zika infection during pregnancy and microcephaly was strongly suspected. They further declared that the cluster of microcephaly and other neurological cases constituted a global health emergency that required a coordinated international response to investigate and understand the link better.
The WHO has now developed a framework that sets out the key questions that need to be answered on the suspected link between the Zika virus and neurological complications so as to understand properly how Zika is implicated.
Unfortunately, experts now fear Zika infection during pregnancy may also cause limb joint deformities in babies. Brazilian researchers from Recife, the city at the centre of the Zika epidemic, have recently published details of seven cases of limb joint problems in newborn babies that might have been caused by Zika in the journal BMJ Open.
How can you protect against the Zika virus?
As the Zika virus spreads across the world efforts to develop a vaccine have intensified and progress is being made. Research carried out by the American military at the Walter Reed Army Institute of Research (WRAIR) in Maryland has demonstrated that a vaccine in development called ZIKV purified inactivated virus (ZPIV), offeres full protection against two strains of Zika virus in monkeys. Further clinical trials into the vaccine continue.
In the meantime, the most important ways of protecting against the virus are to control mosquito numbers and to prevent mosquito bites. Women who are pregnant or planning to become pregnant and their sexual partners should take extra care to protect themselves from the bite of mosquitoes that transmit Zika and pregnant women should think carefully about travelling to areas of ongoing Zika virus transmission.