Confirmed and suspected cases of the neurological condition microcephaly in Brazil continue to rise.
The Health Ministry revealed on March 29 that cases of the birth defect strongly linked with the mosquito-borne Zika virus now number 5,235 in the week through March 25, up from 5,200 just a week earlier.
Confirmed cases rose from 907 a week earlier to 944 while suspected cases slightly dropped to 4,291 from 4,293 over the same period.
Children born with microcephaly are characterized by smaller than normal heads, which can be attributed to the baby's brain not developing properly during pregnancy.
Microcephaly may be caused by changes in the babies' genes. Children at a higher risk of getting the condition are those born to a mother who had certain infections, such as cytomegalovirus and rubella during pregnancy, suffered from severe malnutrition, or exposed to harmful substances such as drugs, alcohol and other toxic chemicals.
The surge in microcephaly cases in Brazil, though, is strongly linked to Zika virus, which currently batters the South American country.
Although there is no definitive scientific proof that microcephaly is caused by Zika virus, many health experts believe the mosquito-borne disease is responsible for the increasing number of microcephaly in Zika-affected regions.
WHO Director-General Margaret Chan has said that patterns suggest a link between Zika and microcephaly. Initial detection of Zika is followed by cases of fetal abnormalities as pregnancies of women infected by the virus come to term.
"Concerning the link with fetal malformations, the virus has been detected in amniotic fluid. Evidence shows it can cross the placental barrier and infect the fetus. We can now conclude that Zika virus is neurotropic, preferentially affecting tissues in the brain and brain stem of the developing fetus," Chan said. "Zika has been detected in the blood, brain tissue, and cerebrospinal fluid of foetuses following miscarriage, stillbirth, or termination of pregnancy."
No local transmission of Zika has occurred yet in the U.S. albeit 273 individuals have acquired the virus after travelling to countries where it is active.
Microcephaly is supposedly a rare condition. In the U.S., estimated cases of microcephaly range from two babies per 10,000 live births to about 12 babies per 10,000 live births.
