In 2015, the Zika virus began spreading throughout the Americas and a potential link was seen between the virus and a significant increase in cases of fetal microcephaly, as well as other neurologic abnormalities. They used lab-grown human stem cells and exposed them to the original Zika virus strain found in Uganda that is nearly a replica of the current strain spread in the outbreak countries.
The findings released Friday are preliminary results from the first study tracking pregnant women in Brazil from the time they were infected, and do not prove that Zika is to blame.
The Zika Virus can attack tissues in developing fetal brains, regardless of when during pregnancy the infection occurs, a new study found. The World Health Organization (WHO) declared the Zika outbreak, which has spread in Latin America and in Caribbean nations, an worldwide health emergency on February 1.
The team studied 88 pregnant women who went to a clinic at the Oswaldo Cruz Foundation in Rio de Janeiro with the intention of being tested for the virus.
The women were at various stages of pregnancy.
Researchers report that the Zika virus may be linked to a wider variety of “grave outcomes” for developing babies than previously reported – threats that can come at any stage of pregnancy. But they also detected two fetuses that died in utero during the last trimester; poor growth even without microcephaly; problems with the placenta; and one case that prompted an emergency C-section because of low amniotic fluid, Nielsen said.
“The cell types responsible for forming the cortex are the target of the Zika virus”, said Hongjun Song, a neurologist at Johns Hopkins University School of Medicine and senior author of the study.
“There are case reports for the Zika virus where they show that certain brain areas appear to have developed normally, but it is mostly the cortical structures that are missing”, said Guo-li Ming from Johns Hopkins’ Institute for Cell Engineering.
Numerous cells died, and others showed changes in gene expression that impaired cell division.
The Zika virus has reached epidemic proportions in many parts of South America, prompting US officials to issue travel advisories.
Many other questions about the Zika virus also remain unanswered, the researchers said.
Besides Brazil, C. quinquefasciatus also exists in more temperate climes, including the southern USA, where it is known to carry the West Nile virus and can survive winters.
Scientists have linked the Zika virus to severe birth defects, both in the lab and out in the wild. Of the eight babies born so far, two were stillborn and three have microcephaly or brain calcifications, according to Nielsen.
“What we show is that the Zika virus infects neuronal cells in dish that are counterparts to those that form the cortex during human brain development”, he added. The virus infects a type of neural stem cell from where the brain’s outer layer called cerebral cortex emerges.
Most people who get the virus display no symptoms, and those who do generally avoid serious illness.
CDC Director Tom Frieden, MD, MPH, will travel to Puerto Rico March 7-9 to assess first-hand CDC’s support for the Zika response.