Archive for February, 2016

Zika Virus, Microcephaly and Brazil

Sunday, February 14th, 2016

The first indications of a connection between Zika virus and the current outbreak of microcephaly in Brazil were picked up by the HealthMap System in Portuguese alerts on November of 2015. By Saturday, November 28th, the Ministry of Health in Brazil confirmed the connection that the increase in infants born with microcephaly could be contributed to transmission of the Zika virus in pregnant women. The link was first detected when Brazilian health authorities found traces of the Zika virus in a deceased infant born with microcephaly. And what is the Zika virus? How is it transmitted? The Zika virus is a mosquito-transmitted infection related to dengue, yellow fever and West Nile virus. It is transmitted by the Aedes Aegypti mosquito bites. Although it was discovered in the Zika forest in Uganda in 1947 and is common in Africa and Asia, it did not begin spreading widely in the Western Hemisphere until last year, when an outbreak occurred in Brazil. Few people have immune defenses against the virus, so it is spreading rapidly. Millions of people in tropical regions of the Americas may now have been infected. The possibility that the Zika virus causes microcephaly – unusually small heads and often damaged brains – emerged only in October, when doctors in northern Brazil noticed a surge in babies with the condition.  It may be that other factors, such as simultaneous infection with other viruses, are contributing to the rise; investigators may even find that Zika virus is not the main cause, although right now circumstantial evidence suggests that it is. It is not known how common microcephaly has become in Brazil’s outbreak (for more details check the NY Times article “Short Answers to Hard Questions About Zika Virus”). About three million babies are born in Brazil each year. Normally, about 150 cases of microcephaly are reported, and Brazil says it is investigating nearly 4,000 cases just from November of 2015 until now. Yet reported cases usually increase when people are alerted to a potential health crisis. A recent scientific report has shown strong indications that the Zika virus is present in the brain tissue combined with the clinical signs and symptoms such as microcephaly in a fetus (for more details check “Zika Virus Associated with Microcephaly”). In that case report, an expectant mother who had a febrile illness with rash at the end of the first trimester of pregnancy while she was living in Brazil was analyzed. Ultrasonography performed at 29 weeks of gestation revealed microcephaly with calcifications in the fetal brain and placenta. Microcephaly was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation. Zika was found in the fetal brain tissue using molecular biology tools, with consistent findings confirming the clinical observations. The complete genome of the Zika was recovered from the fetal brain and sequenced. Even though it is early to draw conclusions, the presence of the virus in combination with the clinical diagnosis in the babies is clear. However, cause and consequence is still very unclear. Brazil is in the epicenter of this epidemic caos, especially because the cases are increasing very fast. The government is taking measures to fight the mosquitoes that transmit the virus, but similarly to dengue fever, it has been difficult to eradicate viruses that are transmitted by this mosquito. In addition, further scientific research in Brazil and other countries are taking place to better understand the potential implications of these connections between the virus and the clinical findings. It is likely that the rapid spread of Zika virus around the globe will be a strong impetus for collaborative research on the biologic properties of the virus, particularly since the risk of neurotropic and teratogenic virus infections places a high emotional and economic burden on society. Brazilian scientists have a lot to learn and offer. Now it is time to collaborate and get more answers!

Image Source: National Geographic