GENEVA, Twenty-one people have died from diphtheria in the Rohingya camps in Bangladesh, the World Health Organization said Tuesday, adding that it had started a second vaccination drive to rein in the outbreak. According to the UN health agency, 1,571 suspected cases of the bacterial disease were registered in the Rohingya refugee camps of southeast Bangladesh between November 10 and December 17. More than 655,000 Rohingya Muslims have poured into these camps after fleeing a brutal crackdown in Myanmar in recent months. "Twenty-one deaths have been reported among the Rohingya population in Cox's Bazar," WHO spokeswoman Fadela Chaib told reporters in Geneva, adding that about 20 percent of the suspected cases were children under the age of five. Diphtheria is a highly contagious disease that mainly affects the nose and throat and can cause breathing problems, and can be fatal if left untreated, but has become increasingly rare in recent decades because of high vaccination rates. Bangladesh authorities began an initial vaccination campaign on December 12, targeting children aged six weeks to six years. Chaib said the second campaign was launched on Sunday, targeting children aged seven to 15.