Zika virus is transmitted to people through the bite of an infected Aedes mosquito. This is the same mosquito that transmits dengue and chikungunya.
The
Zika virus is “is now spreading explosively” in the Americas, the head
of the World Health Organization said Thursday, with another official
estimating between 3 million to 4 million infections in the region over a
12-month period.
“The level of concern is high, as is the level of uncertainty,” Dr.
Margaret Chan, WHO’s director-general, told her organization’s executive
board members. “We need to get some answers quickly.”
The lack of any immunity to Zika and the fact that mosquitoes spreading
the virus can be found most “everywhere” — explains the speed of its
transmission, said Dr. Sylvain Aldighieri, an official with the WHO and
Pan American Health Organization.
Some 80% of those infected with the Zika virus don’t even feel sick, and
most who do have relatively mild symptoms such as a fever, rash, joint
pain or pink eye. But there are major worries about the dangers pregnant
women and their babies face.
Chan said that, where the virus has arrived, there’s been a
corresponding “steep increase in the birth of babies with abnormally
small heads and in cases of Guillain-Barre syndrome.” Having small heads can cause severe developmental issues and sometimes death. Guillain-Barre is a rare autoimmune disorder that can lead to life-threatening paralysis.
Health authorities began to suspect a connection between Zika and
neurological ailments, especially in fetuses and newborns. Brazil alone
has reported more than 4,000 cases of microcephaly — a neurological
disorder resulting in the births of babies with small heads — in infants
born to women infected with Zika while pregnant.
“We expect more countries to be affected,” she said.
U.S.-based researchers Daniel Lucey and Lawrence Gostin urged the WHO
leader to “mobilize international resources to curb the rapid spread of
Zika worldwide, including aggressive mosquito control, active
surveillance, accelerated vaccine research and travel advisories for
pregnant women.”
“It is far better,” said the Georgetown University public health expert,
“to be overprepared than to wait until a Zika epidemic spins out of
control.”
What is Zika virus infection?
Zika virus infection is caused by the bite of an infected Aedes mosquito, usually causing mild fever, rash, conjunctivitis, and muscle pain.
The virus was isolated for the first time in 1947 in the Zika forest in
Uganda. Since then, it has remained mainly in Africa, with small and
sporadic outbreaks in Asia. In 2007, a major epidemic was reported on
the island of Yap (Micronesia), where nearly 75% of the population was
infected.
In May 2015, the public health authorities of Brazil confirmed the
transmission of Zika virus in the northeast of the country. Since
October 2015, many other countries have reported the presence of the
virus.
What are the symptoms?
The most common symptoms of Zika virus infection are mild fever and
exanthema (skin rash), usually accompanied by conjunctivitis, muscle or
joint pain, and general malaise that begins 2-7 days after the bite of
an infected mosquito.
One out of four infected people develops symptoms of the disease. Among
those who do, the disease is usually mild and can last 2-7 days.
Symptoms are similar to those of dengue or chikungunya,
which are transmitted by the same type of mosquito. Neurological and
autoimmune complications are infrequent, but have been described in the
outbreaks in Polynesia and, more recently, in Brazil. As the virus
spreads in the Americas, giving us more experience with its symptoms and
complications, it will be possible to characterize the disease better.
How is Zika virus transmitted?
Zika virus is transmitted to people through the bite of an
infected Aedes mosquito. This is the same mosquito that transmits dengue
and chikungunya.
What treatment is there?
There is no vaccine for Zika. Treatment
consists of relieving pain, fever, and any other symptom that
inconveniences the patient. To prevent dehydration, it is recommended to
control the fever, rest, and drink plenty of water. There is no vaccine
or specific drug for this virus.
Can it cause death?
It is a new virus that up until now has had a very limited geographical
and demographic distribution, and there is no evidence that it can cause
death. However, sporadic cases have been reported of more serious
manifestations and complications in patients with preexisting diseases
or conditions, causing death.
Who is at risk of Zika infection?
Anyone not previously exposed to the virus and who lives in an area
where the mosquito is present, and where imported or local cases have
been reported, may be infected. Since the Aedes mosquito is found
throughout the world, it is likely that outbreaks will occur in other
countries that have not yet reported any cases.
What is the difference between Zika, dengue, and chikungunya?
All these diseases present similar symptoms, but certain symptoms suggest one disease or another:
Dengue usually presents with higher fever and more severe muscle pain.
There can be complications when the fever breaks: attention should be
paid to warning signs such as bleeding.
Chikungunya presents with higher fever and more intense joint pain,
affecting the hands, feet, knees, and back. It can disable people,
bending them over so that they cannot walk or perform simple actions
such as opening a water bottle.
Zika does not have clearly characteristic features, but most patients
have skin rashes and some have conjunctivitis (inflammation of the
conjunctiva of the eye).
What causes rapid transmission of Zika virus?
There are two factors for rapid transmission – 1) Since this is a new
virus to the world, the entire population is susceptible, lacking
defenses to Zika virus 2) The Aedes mosquito is widespread in the world,
given the climatic conditions, temperature, and humidity in tropical
countries.
Is it advisable to travel to countries where Zika virus is circulating?
PAHO/WHO does not recommend any travel or international trade
restrictions related to Zika virus outbreaks. Travelers are advised to
take the suggested precautions to prevent mosquito bites.
What measures should be taken to prevent Zika virus infection?
Prevention involves reducing mosquito populations and avoiding bites,
which occur mainly during the day. Eliminating and
controlling Aedes aegypti mosquito breeding sites reduces the chances
that Zika, chikungunya, and dengue will be transmitted. An integrated
response is required, involving action in several areas, including
health, education, and the environment.
To eliminate and control the mosquito, it is recommended to:
- Avoid allowing standing water in outdoor containers (flower pots, bottles, and containers that collect water) so that they do not become mosquito breeding sites.
- Cover domestic water tanks so that mosquitoes cannot get in.
- Avoid accumulating garbage: Put it in closed plastic bags and keep it in closed containers.
- Unblock drains that could accumulate standing water.
- Use screens and mosquito nets in windows and doors to reduce contact between mosquitoes and people.
