With the Olympic Games well under way, there is renewed interest in the possible effects of the Zika virus on athletes and visitors to Brazil. But the focus of concern for public health experts has moved to the United States with news of the first cases of local transmission of the virus.
A mosquito-transmitted infection originally discovered in the Zika forest of Uganda in 1947, the virus began to spread westward in May of last year. Until now cases of Zika infection in the US and Europe have primarily occurred in people who travelled to countries in South America and Polynesia and who were bitten by mosquitoes while abroad.
Having entered the height of the breeding season for mosquitoes in Florida, we can expect to see an increasing number of human infections from mosquito bites sustained locally.
The Department of Foreign Affairs has extended its travel warning to Florida: women who are pregnant or planning to become pregnant should consider postponing their travel. A definite association between Zika virus infection and the birth defect microcephaly has been declared by the the Centres for Disease Control and Prevention (CDC). Women who are infected during the first trimester of pregnancy are likely to deliver babies who have been brain damaged in utero.
Ongoing research has shown that Zika can be transmitted sexually via semen. It is also present in saliva, urine, and breast milk, but transmission via these fluids has not been documented to date.
However scientists in Brazil have identified at least two cases of Zika transmission through blood donation. Sexual transmission of the virus means that for men who travel to endemic areas and who have a pregnant partner, abstinence or condom use for at least the duration of pregnancy is recommended.
According to the latest World Health Organisation assessment there is, as yet, no overall decline in the Zika virus outbreak. With no human vaccine on the horizon, the key to managing spread lies firmly in the realm of personal lifestyle modification.