Zika-linked abnormalities that occur in human foetuses are more extensive and severe than previously thought, according to scientists who found that microcephaly is not the most common congenital defect caused by the infection.
What the Study Suggests:
- The study suggests that damage during foetal development from the mosquito-borne virus can occur throughout pregnancy and that other birth defects are more common than microcephaly, when babies are born with very small heads.
- These defects may only be detected weeks or months after the baby is born.
- “This means that microcephaly is not the most common congenital defect from the Zika virus,” The absence of that condition does not mean the baby will be free of birth defects, because there are problems that are not apparent at birth and such difficulties may not be evident until the age of six months, she said.
- Researchers found that there were nine foetal deaths among women with Zika infection during pregnancy, five of those in the first trimester.
- Foetal deaths or abnormalities in the infants were present in 46 per cent of Zika-positive women, contrasted with 11.5 per cent of Zika-negative women.
Forty-two per cent of infants born to the Zika-infected mothers were found to have microcephaly, brain lesions or brain calcifications seen in imaging studies, lesions in the retina, deafness, feeding difficulties and other complications.
About Fetal Death/Still Born:
- Stillbirth is typically defined as fetal death at or after 20 to 28 weeks of pregnancy.
- It results in a baby born without signs of life.
- A stillbirth can result in the feeling of guilt in the mother.
- The term is in contrast to miscarriage which is an early pregnancy loss and live birth where the baby is born alive, even if it dies shortly after.
- Often the cause is unknown. Causes may include pregnancy complications such as preeclampsia and birth complications, problems with the placenta or umbilical cord, birth defects, infections such as malaria, and poor health in the mother.
- Risk factors include a mother’s age over 35, smoking, drug use, use of assisted reproductive technology, and first pregnancy.
- Stillbirth may be suspected when no fetal movement is felt.
- Microcephaly is a condition where a baby is born with a small head or the head stops growing after birth.
- Microcephaly is a rare condition. One baby in several thousand is born with microcephaly.
- The most reliable way to assess whether a baby has microcephaly is to measure head circumference 24 hours after birth, compare the value with WHO growth standards, and continue to measure the rate of head growth in early infancy.
- Babies born with microcephaly may develop convulsions and suffer physical and learning disabilities as they grow older.
- There are no specific tests to determine if a baby will be born with microcephaly, but ultrasound scans in the third trimester of pregnancy can sometimes identify the problem.
- There is no specific treatment for microcephaly.
Causes of microcephaly
There are many potential causes of microcephaly, but often the cause remains unknown. The most common causes include:
- infections during pregnancy: toxoplasmosis (caused by a parasite found in undercooked meat), Campylobacter pylori, rubella, herpes, syphilis, cytomegalovirus, HIV and Zika;
- exposure to toxic chemicals: maternal exposure to heavy metals like arsenic and mercury, alcohol, radiation, and smoking;
- pre- and perinatal injuries to the developing brain (hypoxia-ischemia, trauma);
- genetic abnormalities such as Down syndrome; and
- severe malnutrition during fetal life.
Based on a systematic review of the literature up to 30 May 2016, WHO has concluded that Zika virus infection during pregnancy is a cause of congenital brain abnormalities, including microcephaly; and that Zika virus is a trigger of Guillain-Barré syndrome.
Signs and symptoms
- Many babies born with microcephaly may demonstrate no other symptoms at birth but go on to develop epilepsy, cerebral palsy, learning disabilities, hearing loss and vision problems. In some cases, children with microcephaly develop entirely normally.
Treatment and care
- There is no specific treatment for microcephaly. A multidisciplinary team is important to assess and care for babies and children with microcephaly. Early intervention with stimulation and play programmes may show positive impacts on development. Family counselling and support for parents is also extremely important.