It took just 48 hours for Ben Lopman’s 18-month-old son to go from being an energetic toddler to totally listless. Lopman’s son Ruben was suffering from severe dehydration from rotavirus, one of the most common causes of diarrhea and vomiting in babies and children. He was so sick, he ended up in the hospital, desperately needing intravenous fluids to keep up his strength to battle the infection. Lopman, an infectious disease epidemiologist now at Emory University, was living in London when his