Months before the 2016 Summer Olympics the host country Brazil had to face…

Correct answer: Zika virus

Why this is correct: Months before the 2016 Summer Olympics, Brazil was experiencing a large Zika virus outbreak. The virus raised particular safety concerns because infections during pregnancy were suspected to cause microcephaly and other neurological problems in newborns, prompting international health alerts.

• Large outbreak in Brazil in 2015–2016.

• Suspected link between Zika infection during pregnancy and microcephaly and other neurological disorders.

• Transmitted by Aedes mosquitoes, raising concerns for visitors and pregnant women.

• WHO declared a Public Health Emergency of International Concern in early 2016, and travel advisories followed.

Why the other diseases are not the best choice:

• Chikungunya: This is also a mosquito-borne disease and present in the region, but it did not drive the same level of international pregnancy-related safety concern as Zika.

• Dengue: Endemic in Brazil and a real health risk, yet the headline global safety issue before the Games focused on Zika because of its suspected teratogenic effects.

• Herpes simplex: A common non-mosquito-borne virus that was not related to the outbreak concerns tied to hosting the Olympics.