With its explosive spread and potential links to debilitating neurological disorders, the Zika virus has firmly grasped the world’s attention.
Earlier this month, WHO declared the recent spread of the Zika virus a ‘public health emergency’ of international proportion. Research into this relatively unknown virus has subsequently seen a boost in funding, and scientists are now racing to produce a vaccine.
We look at the background of the Zika virus to answer some common questions and compare the current epidemic to other internationally important viruses which can occur in the same area.
What parts of the world are affected by the Zika virus?
Until now, the Zika virus has maintained a pretty low profile – there were less than 20 reported cases of the virus worldwide before 2007.
The name ‘Zika’ comes from the Ugandan forest from which the virus was first reported in the 1940s. It then spread from equatorial Africa to Asia, Pacific Polynesia and now South America. The virus has spread explosively in Brazil since 2015, and 23 countries in the Americas are reporting transmission of the virus.
Closer to home, cases have been confirmed in Ireland, Spain, and the UK, as a result of travel to affected areas.
What are the health risks of the Zika virus?
The illness caused by the Zika virus is itself relatively mild. About 1 in 5 will get sick with fever, conjunctivitis, rashes, and joint pain, although this rarely leads to hospitalisation. The mortality risk posed by the virus is also very low.
The real pressing concern relates to the suspected link between the Zika virus and birth defects. An estimated 4,000 cases of microcephaly – a disorder where infants are born with abnormally small heads – have been registered in Brazil since October last year.
The virus has also been linked to Guillain-Barre Syndrome in some patients – a potentially paralysing nerve disorder – but this needs further research.
Is there anything unusual about this virus?
Other than the potential links to neurological disorders, the way the virus is transmitted has caused concern.
The first Zika virus case in the United States was reported as sexually transmitted. However, the risk of sexual transmission is currently thought to be very low.
The spread of the Zika virus seems pretty rapid. Should I be concerned?
The risk the Zika virus poses to the British public is extremely low. Despite rare sexual transmissions of the virus, Zika is a virus spread predominantly via a mosquito population which cannot survive in our temperate climate.
Obviously, if you are travelling to an area affected by the Zika virus, your risk of contracting it increases significantly.
Can I protect myself against the virus?
There is currently no vaccine against the Zika virus. However, this should not really concern you unless you are travelling to a Zika-infected area.
Public Health England (PHE) has advised pregnant women against travelling to areas infected with the Zika virus. It has also recommended that couples who have visited infected regions should not try for a baby for a month after leaving the endemic area.
Since the Zika virus may be spread via sexual contact, the PHE has also advised men in the UK to wear condoms during sex for a month after returning from an infected area.
If you do travel to an affected area you will not be able to give blood for four weeks after your return.
Putting the Zika Virus in Perspective
Whilst the Zika virus clearly needs increased research funding and support, it’s important to put it in perspective: the Zika Virus isn’t the only globally important mosquito-borne virus without a ‘cure’.
Whilst the Americas are currently witnessing an epidemic of the Zika virus, the need to educate and provide safe vaccination against several other high profile global viruses – which arguably carry a higher mortality risk to a larger portion of the global population – should not be overlooked.
Among these are the potentially fatal Dengue Fever, Yellow Fever and Chikungunya. Although not a virus, Malaria remains the mosquito-borne infection with the highest global mortality rate and is still awaiting a safe licenced vaccine.
Spread by: Aedis aegypti mosquitoes.
Global population at-risk: About 2.5 billion or 40% of the world’s population live in areas where there is risk of transmission. WHO estimates that 50-100 million infections occur each year.
Mortality risk: Dengue can manifest as a flu-like illness, with symptoms including fever, bleeding, abdominal pain, and shock. It is the leading cause of serious illness and death among children in some Latin American and Asian countries.
Areas affected: Endemic in more than 100 countries across Africa, the Americas, South-East Asia and the Western Pacific. It continues to spread, with the first European case being reported in 2010.
Vaccination available? Currently no vaccine – prevention remains the best ‘cure’.
Spread by: Species of the Aedes and Haemogogus mosquitoes.
Global Population at-risk: There are an estimated 200 000 cases of yellow fever worldwide each year, with 90% occurring in Africa.
Mortality risk: Yellow fever causes 30,000 deaths worldwide annually. Around 15% of those infected develop serious health problems, including kidney failure, jaundice and bleeding from the mouth, nose, eyes or stomach.
Areas affected: Found in tropical areas, and particularly South America, sub-Saharan Africa, and parts of Caribbean.
Vaccination available? Yes – the vaccine is safe, affordable and will provide life-long protection against the virus. Vaccination is mandatory for travellers visiting certain countries – particularly those in Asia.
Spread by: Anopheles mosquitoes.
Global population at-risk: Approximately 3.2 billion people – nearly half of the world’s population – were at risk of malaria in 2015.
Mortality risk: In its most dangerous form, malaria can prevent blood flow to vital organs, including the brain. There were an estimated 438,000 malaria deaths in 2015.
Areas affected: Malaria affects more than 100 countries, including Central and South America, South East Asia and the Pacific Islands. However, its impact is most concentrated in sub-Saharan Africa, where 89% of all malaria cases occur.
Vaccination available? No licenced malaria vaccination is currently available. Preventative anti-malarial tablets exist, but they don’t guarantee protection against malaria. Worryingly, parasites are becoming increasingly resistant to drugs and insecticides.
Spread by: Aedes aegypti and Aedes albopictus mosquitoes.
Global population at-risk: Available statistics relate to regional outbreaks rather than a global view of the virus. As an example, over 1 million cases of the virus have been confirmed in the Americas following a 2013 outbreak.
Mortality risk: Whilst it does not often result in death, Chickungunya symptoms can be severe. Joint pain can last for years and may lead to chronic pain and disability.
Areas Affected: Whilst it historically has occurred in Africa, Asia and the Indian subcontinent, Chikungunya has spread to the Americas and parts of Europe in recent years, as well as Australia.
Vaccination available? There is currently no vaccine – treatment is focused on relieving symptoms.