Zika virus and complications: Questions and answers
Online Q&A
Updated 6 September 2016
Summary of the situation
The rise in the spread of Zika virus in Brazil has been accompanied by an unprecedented rise in the number of children being born with unusually small heads—identified as microcephaly. In addition, several countries, including Brazil, reported a steep increase in Guillain-Barré syndrome—a neurological disorder that could lead to paralysis and death. Based on research, there is scientific consensus that Zika virus is a cause of microcephaly and Guillain-Barré syndrome.
Zika virus
Updated! How do people catch Zika virus?
Zika virus is primarily transmitted to people through the bite of an infected Aedes mosquito, which also transmits chikungunya, dengue and yellow fever.
A study, conducted by Fiocruz Pernambuco, detected the presence of Zika virus in Culex quinquefasciatus mosquitoes. These samples were collected in Recife, Brazil, in houses where people had Zika. Recent laboratory studies have shown that Culex species were experimentally unable to transmit the Zika virus, and it is unlikely that they play a role in the current outbreak of Zika.
Zika virus can also be transmitted through sex and has been detected in semen, blood, urine, amniotic fluids, saliva as well as body fluids found in the brain and spinal cord.
Where does Zika virus occur?
Local transmission of Zika virus by Aedes mosquitoes has been reported on the continents of Africa, the Americas, Asia and the Pacific.
There are 2 types of Aedes mosquito known to be capable of transmitting Zika virus. In most cases, Zika is spread through the Aedes aegypti mosquito in tropical and subtropical regions. The Aedes albopictus mosquito also transmits the virus and can hibernate to survive regions with cooler temperatures.
Can El Niňo have an effect on Zika transmission?
The Aedes aegypti mosquito breeds in still water. Severe drought, flooding, heavy rains and temperature rises are all known effects of El Niño—which is the result of a warming of the central to eastern tropical Pacific Ocean. An increase in mosquitoes can be expected due to expanding and favourable breeding sites. Steps can be taken to prevent and reduce the health effects of El Niño.
Can the Aedes mosquito travel from country to country and region to region?
The Aedes mosquito is a weak flyer; it cannot fly more than 400 meters. However it may be possible for the mosquito to be transported from one place to another accidentally and introduce Zika virus to new areas.
What are the symptoms of Zika virus disease?
Zika virus usually causes mild illness. Symptoms most commonly include a slight fever or rash, appearing a few days after a person is bitten by an infected mosquito. Although many will not develop any symptoms at all, others may also suffer from conjunctivitis, muscle and joint pain, and feel tired. The symptoms usually last from 2 to 7 days.
There is no known difference in the symptoms of infected pregnant and non-pregnant women.
How is Zika virus disease diagnosed?
Diagnosis is based on symptoms and the person’s recent history (e.g. mosquito bites, or travel to an area where Zika virus occurs). Laboratory testing can confirm the presence of Zika virus in the blood. However, this diagnosis may not be reliable as the virus could cross-react with other viruses such as dengue, West Nile and yellow fever. A reliable, rapid point-of-care diagnostic test is a research and development priority.
How is Zika virus disease treated?
The symptoms of Zika virus disease can be treated with common pain and fever medicines, rest and plenty of water. If symptoms worsen, people should seek medical advice.
Olympic and Paralympic Games Rio, 2016
What are the risks facing athletes and visitors attending the Olympic and Paralympic Games in Rio, Brazil in 2016 with regard to the current Zika outbreak?
Athletes and visitors will face risks similar to residents of Brazil. They are at risk of being infected with Zika if bitten by an infected mosquito or through sexual transmission of the virus.
Zika virus usually causes mild symptoms1 and most people may not develop any symptoms at all.
However, there is scientific consensus that Zika virus is a cause of microcephaly (children being born with unusually small heads) and other brain malformations and disorders in babies born to women who were infected with Zika virus during pregnancy. Thus WHO advises pregnant women not to travel to areas where Zika is circulating.
Zika is also a cause of Guillain-Barré syndrome, a rare but serious neurological disorder that could lead to paralysis and death.
The Games will take place during Brazil’s wintertime, when there are fewer active mosquitoes and the risk of being bitten is lower.
1 Symptoms include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache.
What can athletes and visitors do to protect themselves?
While mosquitoes are the primary vectors, a person infected with Zika virus can also transmit the virus to another person through unprotected sex. Athletes and visitors to Rio de Janeiro, and other areas where Zika virus is circulating, are being encouraged to:
– Follow the travel advice provided by WHO and their countries’ health authorities, and consult a health worker before travelling;
– Whenever possible, during the day, protect themselves from mosquito bites by using insect repellents and by wearing clothing – preferably light-coloured – that covers as much of the body as possible;
– Use physical barriers such as regular or mesh screens or insecticide treated netting materials on doors and windows, or close doors and windows; and
– Avoid visiting over-crowded areas in cities and towns with no piped water and poor sanitation (ideal breeding grounds of mosquitoes) where the risk of being bitten is higher.