Zika Virus — Key Questions

Since the Zika virus was first discovered in Uganda in 1974, it has slowly spread around the world, first to other African countries, then to some countries in southeast Asia, then across the Pacific (including a major outbreak in French Polynesia) and now finally to the Americas. Now, 60 countries have reported people infected with the Zika virus. South Korea and China are the latest to report cases in travellers returning from countries where there are outbreaks of this virus. However, the virus being spread by locally infected mosquitoes in 33 countries and territories in the Americas. Cuba and Dominica are the latest to report transmission by local mosquitoes.

So, What’s the Current Situation?

The geographical distribution of Zika virus has steadily widened since the virus was first detected in the Americas in 2014. The two hardest hit countries have been Brazil and Colombia. Other countries like Jamaica, the US Virgin Island and Puerto Rico have reported a handful to several hundred cases.

But how widespread is it really?

Countries have a problem counting all the people with this infection. Most people who are infected with this virus (about 80%) don’t get sick at all. They don’t go to get medical care, and therefore, they are not reported to health authorities to be counted. So, no one can say how many people have actually been infected in any country. It is likely that this virus is pretty widespread throughout all the countries of the Americas except for Canada and Chile (where the right kind of mosquito to carry the virus is not present). The absence of reports of transmission of this virus in other countries does not mean that it isn’t there. To complicate matters, there are no approved commercially available laboratory tests for rapid confirmation of an infection. Certain tests can be done to detect the presence of the virus in someone who is actually ill, but even these have some limitations. Sometimes the test can be confused with dengue fever and chikungunya viruses that are circulating in the population at the same time.

But This Virus is NOT Trivial

The symptoms caused by this virus are not particularly severe (fever, muscle aches, mild rash), and people generally recover in a few days. There is no special treatment for this infection. Deaths due to Zika infection are rare and may occur in persons with serious pre-existing health conditions. But this virus is not harmless.

Microcephaly

Microcephaly (abnormally small brain) is a condition found in newborn infants. It is caused by many conditions that occur during pregnancy, including certain well known infections like German measles (rubella). As the outbreak of Zika virus grew in Brazil, physicians began to notice a dramatic increase in this condition in newborn infants. Over the last year, there has been mounting evidence from various studies to indicate that Zika virus is highly likely to be a cause of microcephaly. More studies are underway to confirm this. In the meantime, as a precautionary measure, pregnant women and women who are planning to become pregnant are advised to avoid travel to areas where this virus is actively circulating.

Guillain-Barré Syndrome (GBS)

With the spread of this virus, 12 countries or territories have reported an increase in people affected by the Guillain-Barré Syndrome (GBS). GBS is a condition that often follows some time after an infection. The symptoms include the rapid-onset of changes in sensation or pain, often in the hands or feet, followed by muscle weakness. The symptoms develop over half a day to two weeks. During the acute phase, this illness can be life-threatening with about a quarter of the patients developing weakness of the breathing muscles. Evidence is mounting that Zika virus is a new cause of GBS.

Sexual Transmission

Several countries (United States, France and Italy) have reported that a man infected with Zika transmitted the infection to his female sexual partner. It is not known if this is a frequent or unusual means of transmission of this virus.

Questions

Pregnancy

If a pregnant woman is exposed

• We don’t know how likely she is to get Zika. Many women who have been infected deliver normal babies.

If a pregnant woman is infected

• We don’t know how the virus will affect her or her pregnancy.

• We don’t know how likely it is that Zika will pass to her fetus.

• We don’t know if the fetus is infected, if the fetus will develop birth defects.

• We don’t know when in pregnancy the infection might cause harm to the fetus.

• We don’t know whether her baby will have birth defects.

• We don’t know if sexual transmission of Zika virus poses a different risk of birth defects than mosquito-borne transmission.

Sexual Transmission

• The virus is present in semen longer than in blood, up to 2 months or maybe longer.

• We don’t know how long the virus will persist in semen.

• We don’t know how often virus in semen will infect a sex partner. A female partner of a man who has visited areas with active Zika virus transmission should use birth control measures for at least 2 months.

• A man who has visited areas with active Zika transmission should use condoms if having sex with a pregnant woman.

• We don’t know if a woman can pass the virus to a man through sex. We don’t know if the virus be transmitted through anal, oral or other forms of sexual contact

Testing

• All pregnant women who have visited areas with active Zika transmission should have a blood test for the virus, whether or not they have symptoms.

• All pregnant women who have visited areas with active Zika transmission should have careful follow-up testing during their pregnancy to detect any malformations in the fetus.

• People who have visited areas with active Zika transmission should be tested if they had or if they develop symptoms of the disease.