<p>It seems like eons ago because of COVID, but Zika was one of multiple viral panics we experienced in the last decade or so. </p> <p>What famously sets Zika apart is its terrifying effects on unborn children: the babies of pregnant mothers infected with the virus can contract an array of potential birth defects, most notably, microencephaly (where the head is much smaller than normal). Between 2015 and 2017, outbreaks of Zika spread across the Americas, with limited local outbreaks reaching Florida and Texas in the US.</p> <p>Since 2019, there have been no reported cases of Zika reported in US territories, but it does persist as a problem in many parts of the world. We don’t have a vaccine available yet, and that makes traveling risky for pregnant women (depending on their destination).</p> <p>Attempts are being made, however. Newly reported data from the LION/repRNA vaccine platform showed “robust” findings in the immune responses of adult pregnant rabbits that transferred Zika to their offspring. </p> <h2>Understanding congenital Zika syndrome</h2> <p>Zika is primarily spread by an <em>Aedes</em> species mosquito (<em>aegypti</em> and a<em>lbopictus</em>) carrying the virus. It can also transmit through sex with an infected individual. </p> <p>Most people infected by Zika don’t show symptoms and are therefore unaware, though if they do manifest, they’re usually mild and last between 2 and 7 days. A fever, rash, joint or muscle pain, and headache are possible symptoms. </p> <figure> <figure><img alt="Zika fever - Symptoms | Source: Beth.herlin" src="https://cdn.storymd.com/optimized/RdaeN9FXdl/thumbnail.jpg" /> <figcaption>Symptoms of Zika Virus. <em>Source: Beth.herlin/Wikimedia</em></figcaption> </figure> </figure> <p>Congenital Zika syndrome (CZS) is a group of birth defects connected to the Zika virus. In pregnant women, the virus can pass through the placenta and reach the baby. Infection before birth increases the odds of developing these birth defects, but not all babies go on to experience them.</p> <p>Birth defects alter the shape or functionality of body parts and may cause all sorts of problems with your overall health or development. Pregnant women who contract Zika in their first trimester are more likely to have a baby with birth defects than those who contract it later on.</p> <p>Other infections during pregnancy can cause some of the features of CZS, but there is a particular pattern that characterizes CZS:</p> <ul> <li>Severe microencephaly</li> <li>Diminished brain tissue with identifiable patterns of brain damage</li> <li>Damage to the back of the eye, like scarring </li> <li>Limited range of motion in joints</li> <li>Restrictions in body movement soon after birth</li> </ul> <figure> <figure><img alt="Microcephaly | Source: CDC" src="https://cdn.storymd.com/optimized/Rdax1vSXol/thumbnail.jpg" /> <figcaption>Microcephaly. <em>Source: CDC</em></figcaption> </figure> </figure> <p>The risk for birth defects following infection during pregnancy is not yet known, but 5%–15% of children born to infected mothers have evidence of Zika-related issues, according to the WHO. Birth defects can happen whether the mother was symptomatic or not. A Zika infection during pregnancy can also trigger complications like stillbirth and preterm birth.</p> <p>Based on what we currently know, a Zika virus infection in a woman who is not pregnant doesn’t pose a risk for future pregnancies after the virus has been expelled from the body. Infection likely also offers protection against future infections. </p> <p>The virus continues to be studied for its effects on mothers and children as well as to understand the full spectrum of health disorders that infection during pregnancy can cause.</p> <h2>Globetrotting in a world with Zika virus</h2> <p>Following the height of the outbreaks in the mid-2010s, Zika cases began declining globally in 2017, but low-level transmission persists in several countries in the Americas and elsewhere. Europe received its first case of local mosquito-transmitted Zika virus in 2019, and an outbreak was recorded in India in 2021. The WHO reported that 89 countries to date have recorded the presence of Zika transmission, but surveillance remains limited around the world.</p> <p>For travelers, the CDC has a dedicated page for country-by-country updates on the status of Zika (see link in references). Their interactive map allows you to select any country and offers information pertaining to transmission as well as guidelines for pregnant women or those planning on becoming pregnant.</p> <p>The CDC recommends that pregnant women and couples planning on conceiving within the next three months contact a healthcare provider if they plan on going to a country with a known transmission risk. They will be able to brief you on steps to protect against mosquito bites and sexual exposure to the virus.</p> <p>Travel decisions are complicated and personal. The safest option is to not travel, but if you must go to an area with evidence of transmission, make sure to cover up your skin with appropriate clothing, stay indoors as much as feasible, and use insect repellant. If you are not yet pregnant, you should consider delaying attempts to conceive for a few months after your return.</p> <figure> <figure><img alt="Prevention of Zika virus | Source: UNIMAS Sarawak - WHO" src="https://cdn.storymd.com/optimized/RoeBrmcadv/thumbnail.jpg" /> <figcaption>Prevention of Zika. <em>Source: UNIMAS Sarawak - WHO</em></figcaption> </figure> </figure> <h2>Status of a vaccine</h2> <p>Vaccines for Zika have proven to be elusive. Momentum was strong at the height of the 2016 outbreaks across the Americas, but interest waned as the epidemic began to resolve. </p> <p>A recently published study in <em>Molecular Therapy</em> describes how scientists used HDT Bio’s vaccine platform (LION/repRNA) to immunize rabbits against HIV-1 and Zika virus. Before birth, both the mothers and their offspring produced strong levels of antibodies against the viruses. </p> <p>The authors wrote that the fetuses likely received antibodies from their mothers passively while in the womb, but the generation may also have been triggered directly by the vaccine itself. Litter size was not impacted, nor were there any notable effects on the health of the offspring.</p> <p>As explained by senior author Amit Khandhar in conversation with Fierce Biotech, the HDT Bio vaccines are different from the mRNA vaccines used for COVID in that they involve self-amplifying replicon RNA (repRNA). This is a type of mRNA that encodes for proteins that form a complex known as a replicon. Once inside a cell, the replicon starts creating new copies of the repRNA so that it expresses at exponentially higher levels, and lower doses are ultimately needed to spark an immune response.</p> <p>“Preventing mother-to-child transmission is a major goal for reducing disease burden in newborns,” said Khandhar in a press release. “With mRNA vaccines attracting global attention, there is a need to evaluate their safety and immunogenicity in preclinical models that inform maternal and childhood vaccination.”</p> <p>So, there’s cause for optimism with these findings but still a long way to go. Researchers will need to assess the durability of antibody responses to maximize their passive transfer to newborns, as well as safety signals before going ahead with clinical trials.</p> <h2>More on Zika</h2><ul><li><a href="https://soulivity.storymd.com/journal/wzvn3g6tlj-zika-and-pregnancy" target="_blank">Zika During Pregnancy: How to Protect Yourself and Your Baby</a></li><li><a href="https://soulivity.storymd.com/journal/bmp69o3f6w-congenital-zika-syndrome" target="_blank">Congenital Zika Syndrome (CZS)</a></li><li><a href="https://soulivity.storymd.com/journal/lw233rkh8m-zika-virus" target="_blank">Zika Virus Infection</a></li></ul>