A small Australian maker of bug sprays became an unlikely beneficiary of the mosquito-borne Zika virus outbreak this week when the country's Olympic team signed it up as its first official insect repellent sponsor.

As many countries scramble to contain the virus declared a global emergency by the World Health Organization, Melbourne-based Juno Laboratories Pty Ltd said it would supply 1,000 tubes of its Bushman "Heavy Duty" repellent gel for Australians at the Rio de Janeiro games in August.

The move points to the unpredictable nature of health planning for the first Olympic Games in a tropical location since Mexico City in 1968. Six months before they begin, doctors have yet to confirm a suspected link between the virus and thousands of birth defects in Brazil, let alone stop it spreading.