Scientists have received direct evidence of the harmful effects of the Zika virus: the complete genome of the pathogenic microorganism was found in the tissues of the embryo with microcephaly. Reported by the New England Journal of Medicine.
The child was conceived by a Slovenian citizen during her stay in Brazil. Returning home at the 28th week of pregnancy, the woman underwent an ultrasound examination. There were so many abnormalities in brain development that the Slovenian decided to terminate the pregnancy and transfer the fetus to researchers.
In addition to the complete genome of the Zika virus, scientists have found viral RNA in high concentrations in brain cells, as well as virions. No other harmful microorganisms capable of causing damage to the brain were found. Other organs were also found to be intact by the virus. That is, there is strong evidence of the penetration of the Zika virus into the brain of the embryo during the mother's pregnancy.
Scientists do not yet know how the virus crosses the placenta into the child's body and how often it leads to brain damage. It is unlikely that all cases of infection with the virus lead to intrauterine infections - otherwise there would be much more cases of microcephaly in epidemic-affected countries.
In addition to detecting the virus in the amniotic fluid of two Brazilian women whose unborn babies have been diagnosed with microcephaly, only statistics point to the link between Zika fever and dangerous brain damage. In 2014, Brazil recorded 150 cases of congenital microcephaly, in 2015 - 4783. However, the Ministry of Health's investigation linked only 404 cases to the Zika virus. It can take months or even years for the virus to be involved in congenital disorders of the nervous system to be undeniable, doctors say.
The Zika virus was first identified in 1947 in Uganda, but until recently it was considered harmless to humans. In 2015, it came from Africa and Asia to South America, after which it spread very quickly across the mainland. Infection occurs through mosquito bites. Considered a relatively harmless microorganism that causes the disease, it has been associated with numerous cases of microcephaly (congenital decrease in the size of the brain and skull, which leads to mental retardation).
The World Health Organization (WHO) recognized on February 1 that the rapidly spreading Zika virus is a global threat and declared a state of emergency. She previously warned that the virus will soon spread to all countries of the New World, with the exception of Canada and Chile. According to WHO forecasts, Zika virus can become ill from three to four million people in the Americas.