Over the past several months, new reports in the US have focused on a “new” threat: the zika virus. Until recently, zika was believed to be transmitted only by mosquitoes, but there is now new evidence for sexual transmission.
The zika virus has been around at least since the 1950s. It was originally found in rhesus monkeys in the equatorial regions of Africa and Asia. Very rarely it was spread to humans in the region. Sometime in the early 2000s it made the jump to humans as a preferred host and began spreading. Between 2007 and 2014 the virus spread through Micronesia and Oceania before appearing in the South America in 2014. From South America it spread north, and the first cases appeared in the US in 2015.
Zika fever, caused by the virus is usually very mild. Headache, rash and fever are common symptoms. It is estimated that 1 in 5 people infected with the zika virus develop zika fever.
Long Term Complications
Since the zika virus appeared in Brazil there has been spike in cases of microcephaly. Microcephaly is defined as a skull that is within less than 2 standard deviations of normal for size and age. In other words, a skull that is too small for the brain to develop properly. Children with microcephaly frequently suffer from neurological disorders and shorter lifespan.
We do not know if zika causes microcephaly. At this time, scientists have proven that it is possible for zika to be transmitted from mother to fetus. This means that zika may be the cause of these birth defects. Other possible causes have been proposed. It is notable that increases in microcephaly are not being reported in other areas with the zika virus. For the time being, governments in South American countries with zika infections are advising their people to avoid pregnancies until the epidemic is under control.
Zika fever also appears to be connected to the development of Guillain–Barré syndrome in adults.
TransmissionUpdate May 12, 2016
Scientists have recently determined how the zika virus causes birth defects. We can now say with certainty that zika causes birth defects, and is most damaging during the early stages of pregnancy.