On Friday, the Centers for Disease Control and Prevention (CDC) issued a travel alert for Mexico, Central America, South America, and the Caribbean due to the outbreak of Zika virus in these regions and its association with birth defects. The alert is a level two (out of three), meaning the CDC advises travellers to practice enhanced precautions—in this case, protecting themselves from mosquito bites.
Zika is a mosquito-borne virus that is similar to dengue both in form and in symptoms, which can include rashes, fever, headaches, pain behind the eyes, and joint pain. However, while dengue can be so painful that it is sometimes called ‘breakbone fever,’ Zika is usually mild, according to the CDC, with only one in five people infected developing symptoms.
The urgency of this outbreak comes not from the severity of its symptoms, but from the fact that Zika has been linked to microcephaly—smaller-than-normal head size—in infants. This is typically a rare condition, and is associated with incomplete brain development. In Brazil, there were 20 times more microcephaly cases in 2015 than in 2014; the country saw its first case of Zika in May of last year.
And as Brazil, in particular, scrambles for a solution, a British company has released test results that show how genetically modified mosquitoes could help nations combat the Zika virus. On Tuesday, company Oxitec said tests that began in April 2015 have shown that releasing genetically modified sterile male mosquitoes succeeded in reducing a variety of disease-transmitting mosquito larvae 82% by year’s end.
The genetically modified mosquitoes don’t spread disease because only the females bite. The virus is carried by the Aedes aegypti mosquito, which also transmits dengue fever and chikungunya. The tests were carried out in the city of Piracicaba, in the province of São Paolo. The city’s health department confirmed the tests and results.
Joseph Conlon, a technical adviser for the American Mosquito Control Association, called the results ‘novel and potentially efficacious.’ Colon said the procedure was not 100% effective, but if allowed to proceed to full measure, it would ‘reduce the mosquito population below disease transmission levels with minimal effect on the environment.’
The US has reported its first case of a baby born with a birth defect linked to the virus. The Hawaii state department of health said the baby’s mother was likely to have contracted the disease while living in Brazil in 2015 and passed it on while her child was in the womb.
Most of the 3,530 babies the Brazil’s Health Ministry said had been born with microcephaly in the country since October 2015 had been concentrated in the country’s poorest regions, such as the north-east. But worries about Zika have prompted residents in wealthier cities such as Rio de Janeiro and Sao Paulo to stock up on mosquito repellent.