Though Zika was first discovered in 1947 (in the Zika Forest in Uganda), it hasn’t bothered humans much in all these years.
“There have only been about 14 or 15 cases documented until 2007,” said Dr Marcos Espinal, the director of communicable diseases at PAHO (the regional World Health Organization). That’s when the first big Zika outbreak was reported, in the Yap Island in Micronesia.
Other Pacific Islands — Fiji, Vanuatu — have had periodic outbreaks since.
Researchers currently believe the Zika virus is spread mainly through mosquitoes. A mosquito bites an infected person, draws blood, and contracts the virus. When it then goes and bites another person, the virus spreads.
Zika is an arbovirus, passed to people by insects. (More narrowly, it’s part of the flavivirus family, which includes West Nile, dengue, and yellow fever.)
Also the viral disease called chikungunya — which had never appeared in the Western Hemisphere until 2013 — has lately affected Central and South America, even making an appearance in Florida last year. (Its name comes from the Makonde language of Tanzania, where it was discovered in 1952; it means “that which bends up”, referring to the contorted physique of a person afflicted by the virus.)
Dengue fever, known as “breakbone fever”, has also seen new outbreaks in Puerto Rico, Florida, Gulf Coast states, and Hawaii — all places that hadn’t usually been affected. In 2015, Brazil reported nearly 1.6 million dengue cases, a big increase from 569,000 in 2014.
Zika, dengue, and chikungunya are all spread by a type of mosquito called Aedes (in particular the Aedes aegypti and Aedes albopictus mosquitoes). For reasons researchers don’t understand, these mosquitoes have been more effective at bringing diseases to new places lately, affecting fresh populations that don’t yet have the antibodies to fight off the viruses.
Now there’s evidence that Zika may lead to birth defects.
Over the past year, public health officials have found evidence that Zika may be linked to birth defects in newborns and neurological conditions in adults.
Consider Brazil: the country has seen an unusual surge of Zika cases over the past two years — possibly after the virus arrived with World Cup travellers in 2014.
Last year, more than 1.5 million people were affected.
And over that same period, Brazil has seen more and more newborns with microcephaly, a congenital condition that’s associated with a small head and incomplete brain development. Normally, Brazil gets several hundred cases a year, but since October, 2015, health officials have reported more than 3,500 cases.
No specific antiviral treatment is available for Zika virus disease. Treatment is generally supportive and can include rest, fluids, and use of analgesics and antipyretics. Because of similar geographic distribution and symptoms, patients with suspected Zika virus infections also should be evaluated and managed for possible dengue or chikungunya virus infection.
Aspirin and other non-steroidal anti-inflammatory drugs should be avoided until dengue can be ruled out to reduce the risk of haemorrhage. People infected with Zika, chikungunya or dengue virus should be protected from further mosquito exposure during the first few days of illness to prevent other mosquitoes from becoming infected and reduce the risk of local transmission.
–– MICHAEL RUDDER