The Zika virus is a recent concern that affects many people, including pregnant women and their unborn children.
What is the Zika Virus?
The Zika virus (ZIKV) is transmitted by mosquitoes, particularly the Aedes variety, which is active during the day. The name of the virus comes from the Uganda Zika Forest, where the virus was found in 1947. This virus is related to Japanese encephalitis, West Nile, yellow fever, and dengue. The infection itself is called Zika fever, and the symptoms are more like a mild dengue fever. Treatment has generally been rest, acetaminophen, and fluids. Common symptoms include headaches, rash, malaise, fever, joint pains, and conjunctivitis. The Zika virus had been only located in Africa and Asia, near the equator, but it spread across the Pacific around 2013. By 2015, the virus was found in the Caribbean, Central America, South America, and Mexico, at “pandemic levels”. There has been no vaccine or medication to prevent the Zika virus, as of 2016, but there are vaccines for “several flaviviruses”. In adults, there is a link between the virus and particular neurologic conditions, such as Guillain-Barré syndrome. Zika fever is a particular problem for pregnant women in that it restricts intrauterine growth, causing “abnormal brain development in their fetuses through mother-to-child transmission of the virus”. The resulting problems include the possibilities of miscarriage and microcephaly. The Centers for Disease Control and Prevention (CDC) issued a “travel guidance” for affected countries, including precautions and information for pregnant women, who were advised to postpone travel.1
Vector and Transmission
Before the 2007 pandemic, the Zika virus was known to only rarely cause “‘spillover’ infections in humans”. Primarily, the virus had impacted monkeys. But, like yellow fever, dengue fever, and chikungunya viruses, eventually the “mosquito-human-mosquito” cycle became established. The mosquitoes, active during the day, transmit the virus. They are, therefore, the vector. Generally the female mosquito transmits the virus to lay eggs. The “extrinsic incubation period in mosquitoes (is) about 10 days”. The reason that the Zika virus is spreading is because of global travel and trade. The types of mosquitoes able to transmit the virus have been found in parts of Europe and North America, and they are adapting to live in northern climates. As of February of 2016, there were a few cases reported of the Zika virus potentially being transmitted sexually. In one case, for example, a biologist who traveled to Senegal returned home and had unprotected sex with his wife, who had not left the US since 2008. She and her husband were both confirmed to have Zika antibodies after having Zika fever. It is unknown whether or not females can transmit the virus to male partners. Every case of potential sexual transmission thus far has been from men to women. The CDC, therefore, has recommended that those who travel to active Zika transmission areas should either abstain from sex or use condoms for all forms of sexual relations for the duration of the partner’s pregnancy, at the very least, and those without pregnant partners “might consider” condoms or abstinence. According to the World Health Organization (WHO), in March 2016, “a causal link between the Zika virus and microcephaly was ‘strongly suspected but not yet scientifically proven’”. The CDC is updating guidelines for women of reproductive ages and pregnant women to include “serologic testing” for those “who have returned from areas with ongoing Zika virus transmission”, even if they do not have symptoms. The WHO recommends that “the priority should be to develop inactivated and other non-live vaccines…for…pregnant women and those of childbearing age”.2
Since there is no vaccine for Zika virus, the CDC focus has been on prevention. Avoiding mosquito bites is the top priority. When traveling to Zika virus-impacted countries, travelers should wear long pants and long sleeves, stay in air-conditioning and/or use door and window screens, sleep under mosquito netting, and use insect repellants (checking for safety during pregnancy). For babies under two months old, insect repellants should be avoided. Children should be dressed in clothing that covers the legs and arms, or the baby carrier should have mosquito netting. Insect repellant should never be sprayed onto irritated or cut skin, or into a child’s face or on their hands. Instead, adults should spray the insect repellant onto their own hands and then apply it to the child’s face. Clothing and gear should be treated with permethrin, but this product should not be applied to the skin. If a person develops Zika virus, there are ways they can protect others from getting the disease. First, it is important to “avoid mosquito bites during the first week of illness”. The virus is present in the semen longer than the blood, so condoms should be used, although abstinence from all forms of sex is preferred, especially if the partner is pregnant.3 The CDC recommends that women who are pregnant should “receive blood tests two to 12 weeks after travel to an affected area”. If there is exposure, the women may consider “having extra ultrasounds to look for birth defects”. Unfortunately, ultrasounds do not show microcephaly.4 Zika virus can be confirmed by laboratory testing for the RNA of the virus in the blood, saliva, urine, or other body fluids.5
About Microcephaly and Guillain-Barré Syndrome
Guillain-Barré syndrome is a rare disorder. With it, the immune system attacks the nerves. Adult males most commonly get this syndrome, but anyone of any age can be impacted. Most recover fully, but in about ¼ of the people, it becomes hard to breathe due to the chest muscles being affected. Although severe cases of Guillain-Barré syndrome are rare, paralysis can result. As for microcephaly, this literally means the baby’s head is smaller than expected for sex and age. This is a result of an in utero issue in which the baby’s brain stops growing. It can also occur after birth, in a situation in which the head does not grow properly. For children with microcephaly, there are often developmental challenges, although some may develop normally. Some of the causes of microcephaly are genetic, such as Down syndrome, and others are environmental, including toxins, alcohol, drugs, and rubella infection.6 With regard to the Zika virus, early in the pregnancy seems to be the most dangerous time, often when a woman does not even realize she is pregnant. It is still unknown how the Zika virus is able to enter the placenta and damage the fetal brain. Other similar viruses (dengue, West Nile, yellow fever) do not normally do this, although German measles (rubella) and cytomegalovirus can. It is recommended that newborns of mothers who have traveled to affected countries be tested. This is especially true if the mother’s tests are inconclusive or positive. The virus can be linked to other birth defects, such as vision and hearing issues, even if microcephaly does not occur. These guidelines are directed towards mothers who reported Zika symptoms, such as joint pain, red eyes, fever, or rash while traveling to, or living in, a Zika-affected area. It is impossible to prevent all mosquito bites, but precautions should be taken in Zika-impacted regions, and pregnant women, or women considering pregnancy, should consult healthcare professionals before traveling there. Zika-suspected microcephaly has thus far impacted Brazil and possibly French Polynesia.7 According to the CDC, in April 2016, there is a causal link between Zika and microcephaly and “other neurological abnormalities”.8
Find out more about other vector-borne illnesses.