Why does Zika Virus cause birth defects?

The virus uniquely exploits a cell surface molecule to act as a “secret passageway” directly to fetal circulation causing an increased probability of birth defects. The unique pattern of birth defects caused by the Zika virus is named congenital Zika syndrome. This may entail microcephaly, a condition where the circumference of a child’s head is smaller than normal due to abnormal (or lack of) development of the brain. Microcephaly can be caused if the mother abused alcohol or drugs or was infected with cytomegalovirus, rubella, or varicella during pregnancy. Congenital Zika syndrome can also lead to decreased brain tissue, damage to back of the eye, limited mobility of joints, excess muscle tone, damage to their eyes or brain causing a lack of visual development.  

Studies have shown that not all infected mothers had children with birth defects. During a Brazilian Zika outbreak in 2015, less than 10% of the children born from infection experiences birth defects. Yale scientists hypothesize that the chance of birth defects could be dependent on the mothers’ antibodies, and how her immune system reacts to the infection. Those who had children with birth defects were discovered to have specific antibodies that actually enhanced the transmission of the virus to the fetus.  

There is no treatment for microcephaly. The head will never return to a normal size so treatment is primarily concerned with decreasing other effects such as developmental delays and neurological disabilities. Physical, speech, and occupation therapy are essential in the child’s early life.  

There is currently no vaccine or treatment for the Zika virus. In order to avoid the dangers that come along with the Zika virus, pregnant women should avoid travel to areas where it is present. If it is essential to be in an area where an outbreak is present skin exposure should be limited and mosquito nets should be employed at night to avoid bites.