The Zika virus has been in the news a lot lately because it’s been linked to a cluster of cases of microcephaly in Brazil and Columbia. Microcephaly is a rare birth defect where the fetus’ brain does not develop fully in utero, and as a result, the baby is born with an abnormally small head and multiple neurological disorders.
Public health officials have been aware of Zika for decades, however, it was only believed to only cause mild flu-like symptoms with few, if any, lasting negative outcomes. The virus is spread by mosquitoes and recently cases as far north as Mexico, Hawaii and Puerto Rico have concerned public health officials in North America.
On January 15, the Centers for Disease Control and Prevention (CDC) issued a level-two travel alert for Latin America and the Caribbean, with a special note for pregnant women to avoid those areas. Since then we’ve been asked about Zika by a number of readers. We reached out to Dr. Waleed Al-Salem, a tropical medicine specialist and father based in Liverpool, England, to have him answer your questions.
Why is this virus becoming a problem now? Why was it not identified as a problem decades ago?
Generally speaking, Zika is not a serious infection. Three-quarters of individuals with Zika are asymptomatic and of the one-quarter of individuals that do develop symptoms, the symptoms aren’t severe enough for them to go to the hospital.
We first became aware of Zika in humans in the late 1960s, but there was no correlation at that time between the virus and any severe symptoms or outcomes. Every region of the planet has some native strain of virus that causes flu-like symptoms, so because most people were asymptomatic or had mild flu-like symptoms there was no real cause for concern.
However, currently recent reports state that the Zika virus is highly correlated with microcephaly in infants in Brazil, specifically if it’s contracted by the mother during pregnancy. Because the impact is so severe, people have begun to panic. It’s understandable because all you need to do is look at the the map of Zika (see map below) and microcephaly cases in Brazil.
Why are more areas in the Northern Hemisphere being impacted by the virus now?
Any mosquito-borne disease can travel where certain mosquito species are found, regardless of hemisphere. Zika was identified in humans and monkeys in Africa, particularly in Zika forest in Uganda (which is where the disease gets its name), and then spread to several African and Asian countries, to the Pacific Ocean Islands, and finally to Latin America. If a person infected with the disease is infected in one area, say in Latin America, and then that person travels to another area, say, the United States, and is bitten by a mosquito, that mosquito has the ability to infect another person that it bites, and so on and so on. That’s how the disease spreads.
Aedes aegypti is the specific species of mosquito that that is known to transmit this virus, as well as the more commonly heard of yellow fever (a virus from the same family as the Zika virus). This species of mosquito is also widely distributed even in the United States. Due to the scale of the outbreak globally and how frequently people travel via airplane, this is why health officials are warning the public to be aware.
Can Zika be spread in ways other than mosquito bites? For example, through saliva if a child bites another child?
So far there are no reports that Zika can be transmitted through human saliva, so parents can relax a little about that. However, the disease could be transmitted from mother to child by trans-placental transmission (meaning the virus crosses the placenta) or during delivery if a mother is infected. Also, there have only been two cases noted where the disease was transmitted sexually.
If someone is bitten by an infected mosquito, what are the chances they will become infected with the virus?
It’s hard to know the answer to this question because the number of asymptomatic cases is so high. We don’t have all the data we need to answer this question right now, but generally speaking if someone is bitten by an infected mosquito it’s believed they will also become infected with the virus, either with symptoms or asymptomatic.
If a pregnant woman is infected with the virus, what are the chances that her child will suffer birth defects such as microcephaly?
I hate to say this again, but this is also hard to answer because we don’t have all the data as so many cases are asymptomatic. Currently most of the cases of microcephaly have been reported in Brazil. In Brazil more than 3,000 cases of microcephaly have been linked to the virus in the Zika transmission area. Other countries have not reported cases of pregnant women who have delivered babies with microcephaly even though they had the virus while pregnant. We need to study this situation more before we can make statements like that.
The bottom line is that women who are pregnant or intend to become pregnant soon should avoid travelling to Latin American countries to protect their babies from developing microcephaly.
If a woman is infected with Zika and is not pregnant, is there still a risk to a baby she may choose to conceive in the future?
It is good question. As far as I know virus would need to be actively circulated in the human body in order to be transmitted through the placenta, but to accurately answer the question we need to investigate more.
If a pregnant woman suspects she may have been exposed to Zika, what should she do?
If a woman is pregnant and has become infected with the virus there’s not much that can be done. The treatment being recommended now is similar to if she had the flu: rest and drinking fluids to avoid dehydration.
Right now prevention is what’s being recommended. Any pregnant woman should avoiding area with reported Zika transmission. However, if she does decide to travel or is living in area with Zika transmission she should consult her doctor. She can also avoid mosquitoes bites by wearing long sleeved shirts, long pants, a hat and a bednet at night. She can also use an EPA-approved insect repellent.
For more information about the Zika virus and pregnancy, please visit: http://www.cdc.gov/zika/pregnancy/question-answers.html
Dr. Waleed Al-Salem holds a PhD in Tropical Medicine, he’s the father of a gorgeous son and husband to the world’s best wife. He’s a researcher in the Department of Parasitology of the Liverpool School of Tropical Medicine and he is also working on the national vector-borne disease control program for the Saudi Ministry of Health. He loves to travel with his family whenever he can and is an amateur photographer.