My dear friend Robyn announced her anticipation and trepidation about her pregnancy. She is frightened that her child may be born with microcephaly, because of her recent trip to the southern United States. I had not heard of Zika, previously, but her concern drove me to find out more. The fear of Zika, a member of the virus family Flaviviridae has been attracting attention across the world as it has made its way to Peru and the United States.
The family of viruses Flaviviridae, includes members like Dengue fever, Japanese encephalitis, yellow fever and West Nile. Just like human families, the viruses in the Flavivirade have common traits like shape and encapsulation. Most are carried by an arthropod disease vector, (mosquitoes, sand fleas, lice, ticks, etc.) although one member of the group, Hepatitis C, is not transmitted through bug bites, but rather is often transmitted through needles or blood transfusions.
The rate at which Zika has expanded in Brazil and other South American countries is extraordinary. According to Dr. Anthony Fauci of the United States National Institute of Health, “up until now, South America and the Caribbean has been what we call immunologically naive to Zika virus. They have never had Zika virus in the Western Hemisphere or in the Americas.” He goes on to say in his NPR (National Public Radio) interview that because Zika has not been in the Western Hemisphere, we do not have a ‘background’ immunity towards the virus. Although it is closely related to Dengue, it is different enough to constitute a new virus to the area. (1)
The vector of infection is the mosquito Aedes aegypti, an African mosquito that spread to the tropics of the Americas, and as far north as the south-eastern portion of the United, with breeding populations emerging in California in 2013. (2) The mosquito lives in close proximity to human populations and given the pressure of population on areas that are mosquito infested, it is now estimated that there are millions of cases of Zika in 21 other countries in the Western Hemisphere. It is also feared that a similar mosquito Aedes albopictus may also be carrier, which could greatly increase the potential infection areas of Zika because if its adaptability to colder climes.
Zika is not the only virus to recently arrive in the New World. Chikungunya first appeared in the Caribbean in 2013. It is also a mosquito borne virus, similar to Dengue. (3) Chikingunya causes acute fever, eye pain, and joint pain that can last for months. (4)
The symptoms for Zika are usually unremarkable. A patient may be asymptomatic, or perhaps have a slight rash and muscle aches. “only about 20 percent of people who become infected actually show symptoms and become ill,” asserts Dr. Sankar Swaminathan, the Director of the Division of Infectious Diseases at University of Utah Hospital. “The main concern is, of course, with pregnant women becoming infected.” (5) The reason that Zika is being implicated in cases of microcephaly is that the virus is consistently found in the neonates.
Investigation continues as officials are still trying to determine if Zika definitively causes microcephaly in babies born to women infected with the virus, according to health reporting website Statnews. It is worried that the current rise in microcephaly babies in Brazil may be due to the Zika virus contracted during the first to second trimesters of pregnancy. Births rates of microcephaly prior to the outbreak were reported as .05 per 10,000 and after the outbreak the number has jumped to 20 per 10,000. (6)
It is while the cells are forming into the fetus that the virus can causes disruption at a cellular level. The neurological growth of fetus is particularly marked during the first and second trimester of pregnancy. The brain develops and skills such as movement, blinking and sleep cycles are exhibited. As the brain grows, it induces the skull to grow. If there isn’t sufficient brain growth, the skull doesn´t meet standard measurement parameters and that is the definition of microcephaly; insufficient head size. Babies with microcephaly are more likely to be stillborn, or have long term disabilities.
There are steps being taken around the world to control this outbreak of Zika. The health ministry of Peru installed over 20,000 ovitraps during the 2015 dengue outbreak to monitor mosquito infestations and infection rates. The same ovitraps will be used to monitor a potential Zika outbreak in Peru’s tropical regions . (7) Mosquitos will now be tested for Zika virus as well. Peruvian health minister Anibal Velasquez is promising more money for mosquito abatement after the heavy rains in Tumbes.
Brazil is taking more drastic measures. Beginning in 2014, Brazil agreed to release millions of genetically modified mosquitos. “The promise is to commercialize genetically modified mosquitoes that would end dengue, but results from field trials conducted in Bahia, Brazil have not been published to date and did not evaluate the relation between Aedes aegypti mosquito populations and the occurrence of dengue.” (8)
Hope is also being held out for a ‘chimeric vaccine’ that may be able to combat Dengue fever, Zika and other members of the Flavivirus family. But using several different viruses in concocting the vaccines, “results suggest that controlled exposure to multiple related Flavivirus vaccines may lead to enhanced protection against related Flaviviruses” (9)(10)
Viruses quick to adapt and change. We think of this as evolution. According to studies of the phylogenetic tree structures of the Flavivirus family, the virus is changing rapidly due to constant interaction between species as well as other pressures. These changes and mutations were a cause of concern, however the authors suggested, ¨The most serious implication of this work is that growing human populations are being exposed to an expanding range of increasingly diverse viral strains¨(11)
Until cures are found for Zika and other strains of the virus, some common sense measures are recommended:
Prevent Zika by avoiding mosquito bites (see below).
Mosquitoes that spread Zika virus bite mostly during the daytime.
Mosquitoes that spread Zika virus also spread dengue and chikungunya viruses.
When traveling to countries where Zika virus or other viruses spread by mosquitoes are found, take the following steps recommended by the Centers for Disease Control:
Wear long-sleeved shirts and long pants.
Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside.
Sleep under a mosquito bed net if you are overseas or outside and are not able to protect yourself from mosquito bites.
Use Environmental Protection Agency (EPA)-registered insect repellents. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breast-feeding women.
Always follow the product label instructions
Reapply insect repellent as directed.
Do not spray repellent on the skin under clothing.
If you are also using sunscreen, apply sunscreen before applying insect repellent.
If you have a baby or child:
Do not use insect repellent on babies younger than 2 months of age.
Dress your child in clothing that covers arms and legs, or
Cover crib, stroller, and baby carrier with mosquito netting.
Do not apply insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
Adults: Spray insect repellent onto your hands and then apply to a child’s face.
Treat clothing and gear with permethrin or purchase permethrin-treated items.
Treated clothing remains protective after multiple washings. See product information to learn how long the protection will last.
If treating items yourself, follow the product instructions carefully.
Do NOT use permethrin products directly on skin. They are intended to treat clothing.
Robyn’s baby is more than likely safe from the problems caused by Zika, but it is a concern to mothers everywhere.