US is currently battling a growing Cyclospora outbreak across the states. According to researchers, it is the largest outbreak of its kind in the country's history and health officials are yet to identify the source.

Nearly 7,000 cases of cyclosporiasis are either confirmed or under investigation in the US - the source is still unknown.

Why fresh produce is the perfect vehicle for a parasite that needs a week to mature, and what the US outbreak tells us about its spread.