Introduction:
Zika virus or ZIKV, is a type of virus with a single strand of RNA that belongs to the Flaviviridae family. It was first discovered in 1947 when it was isolated from the blood of a monkey in the Zika forest of Uganda. In 2007, it became a concern when it affected around 75 percent of people in the Federated States of Micronesia, causing about 5000 infections in a short period of time. Before that, there were very few recorded cases of human infection over the previous 60 years. By November 2016, the virus had spread to more than 48 countries.
What Is Congenital Zika Syndrome?
Zika virus infection during pregnancy can cause a condition called microcephaly and other problems in the baby's development, like stiff limbs, tight muscles, eye issues, and hearing problems. These issues together are known as congenital Zika syndrome. It is not certain how often these problems occur when a pregnant woman contracts the Zika virus. Still, approximately 5 to 15 percent of babies born to infected mothers experience Zika-related issues. These issues can happen even if the mother does not have symptoms of a Zika virus infection.
Infections during pregnancy can also lead to other problems, like losing the baby before birth, having a stillbirth, or the baby being born too early. In adults and older kids, Zika virus infection can cause other problems like Guillain-Barré syndrome, issues with the nerves (neuropathy), and inflammation of the spinal cord (myelitis).
How Is Zika Virus Transmitted?
Zika virus is mainly spread by certain mosquitoes, especially Aedes aegypti and Aedes albopictus. It can also be passed from one person to another through blood transfusions, sexual contact, or during pregnancy. When a pregnant woman is infected, there is a higher risk of her baby developing congenital Zika syndrome (CZS), especially if the infection happens during the first trimester. This means the virus can cause birth defects and other health problems in the baby.
What Are the Symptoms of Congenital Zika Syndrome?
Many people who get infected with the Zika virus do not show any symptoms. However, for those who do, symptoms usually appear 3 to 14 days after infection. These symptoms are usually mild and include rash, fever, red eyes, muscle and joint pain, tiredness, and headache. They typically last for about two to seven days. Since these symptoms are similar to other diseases, diagnosing Zika virus infection requires lab tests.
What Are the Neurological Findings Seen in Congenital Zika Syndrome?
Children affected by CZS may experience severe symptoms, including significant delays in overall neurodevelopment, epilepsy, blindness, hearing loss, and low muscle tone. Among 48 infants with CZS, irritability was the most common symptom, affecting 85.4 percent of them, followed by upper motor neuron or extrapyramidal manifestations (56.3 percent), epileptic seizures (50 percent), and difficulty swallowing (14.6 percent). Muscle tone abnormalities may change over time; for example, low muscle tone can lead to spasticity. Extrapyramidal findings were mainly dyskinesia and dystonia.
Other findings observed in this infection include:
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Approximately 42 percent of cases had significant joint contractures, although arthrogryposis multiplex congenita was only observed in 10 percent.
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In children with epilepsy, the primary seizure types included infantile spasms (72 percent), focal motor seizures (21 percent), and tonic seizures (4 percent). The main electroencephalographic patterns were focal epileptiform discharges, multifocal epileptiform discharges, hypsarrhythmia, and burst-suppression.
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Microcephaly was present in 69 percent of children diagnosed with CZS, with 67 percent diagnosed at birth and 33 percent developing postnatal microcephaly, primarily during the first year of life. Diagnosis timing varied, with 46 percent of infants diagnosed at birth and 54 percent within the first ten months of life.
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A few babies with this infection might have a regular head size when they are born, but their heads may start becoming smaller (progressive microcephaly), during their first year of life.
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Even if prenatal and postnatal tests do not reveal any abnormalities, there remains a possibility of long-term neurocognitive deficits.
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Hyperactivity, severe irritability, and self-injurious behaviors have also been observed in infants with CZS.
How Can Congenital Zika Syndrome Be Diagnosed?
Testing for congenital Zika syndrome is not routine for every newborn. However, it is recommended that a baby undergo testing for Zika infection and related health issues in the following situations:
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If the baby displays birth defects associated with congenital Zika syndrome, there is a possibility of Zika exposure during pregnancy.
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If the baby does not exhibit birth defects linked to congenital Zika syndrome, laboratory tests suggest a potential Zika infection during pregnancy.
If a pregnant woman might have been around Zika, but tests do not show Zika, and the baby does not have Zika-related birth defects, talk to the baby's doctor about whether more tests are needed. Even if the baby seems fine when born, Zika problems might show up later. So, it is important to see the doctor regularly to watch for any issues and deal with them quickly.
The baby's doctor will suggest the following tests to check for Zika and related health problems:
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Blood and urine tests for Zika are ideally performed within the first few days after birth. Spinal fluid testing may also be considered, especially if blood and urine tests are negative for Zika, and no other cause for birth defects is identified.
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Physical examination to assess the baby’s head size, weight, and length.
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An eye examination is performed before the baby reaches one month of age to identify any vision problems.
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If not conducted during newborn screening, a hearing test known as automated auditory brainstem response (AABR) is administered before the baby turns one month old. AABR assesses how the baby’s brain nerves respond to sounds using electrodes and a computer.
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A head ultrasound is performed before the baby reaches one month of age to evaluate the skull and brain structure. It utilizes sound waves and a computer to generate images of the inside of the baby's head.
What Is the Treatment for Congenital Zika Syndrome?
The primary treatment protocols for ZIKV infection primarily focus on managing symptoms and providing rehabilitation. Currently, there are no targeted vaccines or therapies specifically designed for ZIKV.
Current treatment approaches are mentioned below:
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Antiviral Treatments: Some antiviral drugs used for treating hepatitis C, like Sofosbuvir, and other agents, such as Favipiravir, have been explored for their potential in treating ZIKV infection, primarily in animal studies.
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Antimalarial Drug Usage: Chloroquine (an antimalarial drug) has effectively inhibited ZIKV infection, particularly in pregnant mice. It has demonstrated the capability to limit vertical transmission of the virus and reduce the occurrence of fetal growth defects.
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ZIKV Vaccines: Numerous candidate vaccines targeting ZIKV are currently in various stages of development, with some already undergoing phase 1 clinical trials.
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Surgical Interventions: In cases where children experience progressive ventricular enlargement due to hydrocephalus, surgical procedures like ventriculoperitoneal shunt insertion may be recommended.
Conclusion:
Congenital Zika Syndrome serves as a serious reminder of how infectious diseases affect both mothers and children. The wide range of abnormalities in CZS affects many parts of the body. In the brain, common features include calcifications, developmental malformations, issues with the corpus callosum, and abnormalities in the brainstem and cerebellum. More research is needed to understand the different brain issues related to CZS fully. Preventing mosquito bites during the day and early evening is crucial to avoiding Zika virus infection, especially for pregnant women. women, women of reproductive age, and young children. This simple measure helps protect vulnerable groups from the virus.
