Know About Zika Virus

The Zika virus was virtually unheard of until recently. But
links to birth malformations, and a prediction that 4
million people could be infected this year, have led to the
World Health Organization declaring it an international
public health emergency . We take a look at the risks, the
issues and whether there are any solutions.
What is the Zika virus?
Zika is a virus transmitted by Aedes mosquitoes, which
are found in tropical regions. Typical symptoms include a
fever, headache and rash lasting for up to a week. It can
also cause a mild form of conjunctivitis, which can help
distinguish the illness from dengue fever, another
mosquito-borne illness. In some cases it can lead to the
potentially fatal Guillain-Barre syndrome, a rare condition
that affects the nervous system. But with about 80 per
cent of people affected not showing any symptoms, the
infection is often undiagnosed.
Why is infection with the Zika virus so bad for pregnant
women?
The reason for such concern is that the virus seems to
affect fetuses . Since the virus arrived in Brazil last year,
cases of microcephaly – a congenital condition that
causes babies to be born with a small head and
sometimes brain damage – have increased 20-fold.
However, it isn’t yet known how many of the cases are
linked to Zika infection. Nutrition, environmental
conditions and additional infections, for example, could
also play a role.
It can affect fetuses at all stages of pregnancy, although
infection is thought to be most dangerous during the first
and second trimester. Women living in Zika hotspots are
being advised by governments to hold off getting
pregnant, in some countries for up to two years . Some
have suggested the impacts of the virus could challenge
anti-abortion policies in this region.
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Why have I never heard of Zika before?
Before 2000, Zika mostly infected forest animals. Human
infections were rare and the virus didn’t cause any of the
suspected complications we are seeing today. One theory
is that it has mutated , making it capable of hijacking
human cells more easily.
The Zika virus is also new to the Americas. Previously, it
was limited to Africa and South-East Asia, typically in
areas that are also hotspots for dengue fever. But after
first making its appearance in Brazil last May, Zika has
been spreading across the Americas, with 25 countries
now seeing active transmission of the virus. The World
Health Organization believes it will spread to all countries
in the region except for Canada and continental Chile.
And that could happen soon, helped by this year’s El Niño
potentially increasing mosquito populations.
On 4 February, Spain confirmed a case of Zika virus in a
pregnant woman – the first in Europe. The woman had
recently returned from Colombia. According to the
Spanish health ministry, “the diagnosed cases of Zika
virus in Spain… don’t risk spreading the virus in our
country as they are imported cases”.
How is the Zika virus spread?
Several species of Aedes mosquitoes are known to carry
the Zika virus, including Aedes aegypti , the species that
transmits dengue. Although previously limited to specific
tropical regions, they now seem to be taking up residence
in higher latitudes, which could be due to global warming.
Zika can also be passed on through sex . The virus has
been isolated from the semen of an infected individual
and has been confirmed as the transmission method for a
case of Zika on the US mainland .
Is there a vaccine for Zika?
There is currently no vaccine available. It could take years
to develop one, although some vaccine developers claim
they could have one ready this year .
Until then, efforts are focused on relieving symptoms, if
any are present, and advising against pregnancy in those
at risk. Protective measures include using insect
repellents and mosquito nets, wearing long-sleeved shirts
and long trousers, and staying indoors.
Have there been outbreaks of Zika before?
The biggest outbreak until now affected about 28,000
people in French Polynesia in 2013 and 2014, before
spreading to other Pacific islands. Following the outbreak
in French Polynesia there was an unusual increase in
babies born with microcephaly . In 2007, there was a
smaller outbreak in Yap Island, Micronesia, where about
185 cases were identified. The Zika virus was new to both
of these regions.
The virus that emerged in Brazil seems to be closely
related to the strain seen in French Polynesia. One theory
being debated is that travellers to the 2014 Football World
Cup in Brazil may have brought the virus with them .
What is being done to control the current outbreak?
The WHO has asked for international help to develop a
vaccine. Other anti-Zika initiatives involve learning more
about the virus, diagnosing cases more quickly and trying
to control mosquito populations with techniques including
the release of genetically modified insects.
With the Olympic Games set to take place in Rio this
summer, there are concerns the event could spread the
virus further around the world. While cooler, dryer weather
at that time of year should reduce the mosquito
population, organisers are also searching venues for
standing water where mosquitoes could breed.
What’s the advice to those visiting areas affected by
Zika?
Pregnant travellers are being advised to avoid countries
affected by Zika, while those returning from a trip should
see a doctor. Conceiving after the virus has cleared from
the blood, which takes about a week, is thought to be
safe, although it’s always best to seek medical advice.
Health authorities in the UK are advising men who have
travelled to affected regions to use condoms for a month
after they return, or six months after recovery if they
experience Zika symptoms.