The total number of suspected cholera cases in Yemen this year hit the half a million mark on Sunday, and nearly 2000 people have died since the outbreak began to spread rapidly at the end of April. Yemen’s cholera epidemic, currently the largest in the world, has spread rapidly due to deteriorating hygiene and sanitation conditions and disruptions to the water supply across the country. Millions of people are cut off from clean water, and waste collection has ceased in major cities.
— source who.int 2017-08-16