The Zika virus was first found in Africa, and was isolated in 1947. In 2015, cases of Zika began appearing in Brazil, and the virus soon spread rapidly across the Americas.
The Northeast Region of Brazil has been hard hit, as it is a region of great poverty, and has a tropical climate with chronic infestations of the Aedes aegypti mosquito which transmits the virus to humans.
Soon after the first cases of Zika appeared in Brazil, thousands of babies were born with a serious condition called microcephaly, i.e. an abnormally small head and impaired brain development. The Brazilian government declared a state of emergency, deploying over 200,000 troops going door-to-door to eradicate the Aedes mosquito (which also spreads dengue fever and chikungunya).
The Aedes aegypti mosquito thrives in human environments, breeding in stagnant water. In underprivileged districts, with raw sewage in open ditches and no proper garbage collection services, mosquitoes are part of ordinary living conditions.
The symptoms of the Zika virus are usually mild and short-lived, so most people do not realize that they have had the virus. Scientists have presented evidence to show that Zika infection during pregnancy can cause microcephaly and other severe forms of brain damage to the fetus. Pregnant women carrying fetuses with such conditions often miscarry; many babies die at birth or immediately after. Surviving infants need constant medical care, physical therapy and intellectual stimulation.
But in countries with inadequate health systems, such as Brazil, many families, particularly in the impoverished Northeast region, cannot afford medical treatment.