Going to the Olympics this year? The incidence of zika virus in the state of Rio de janeiro in the last 6 months is close to 1 in 500 of the population; Travax notes
Pregnant women (in any trimester) from non-affected areas should not travel to this country. WHO states that there is strong scientific consensus that Zika virus is a cause of Guillain-Barré syndrome, microcephaly, and other neurological disorders. Zika virus infection should be considered in any traveler (especially pregnant women) who reports Zika-like illness during or within 2 weeks of returning from this country.
There are other suggestions for travellers who go to Rio about using condoms and not conceiving for a period of time after return-see handout.
People have the impression it wont be an issue but the Aedes mozzy that spreads it is quite at home in urban areas, and there is currently a dengue outbreak in Rio as well.