A measles epidemic has killed 1,145 children in the Democratic Republic of Congo since January, the UN\'s Humanitarian Affairs mission in Kinshasa said Monday. The epidemic \"has already affected 115,600 children and killed 1,145\" between January and June, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said in a statement. This prompted the vaccination of 3.1 million children across five provinces, it added. The campaign swung into action on May 10 after the NGO Medecins Sans Frontiers - Doctors Without Borders (MSF) deplored \"the lack of reactivity\" of organisations like the World Health Organisation (WHO) to what it termed an \"uncontrollable\" epidemic. Vaccination is continuing in two provinces, the WHO said. Measles is extremely contagious and can cause severe diarrhoea, pneumonia and, in extreme cases, blindness and death. It is one of the leading causes of death among young children globally, despite a safe vaccine being available. In 2010, 5,407 cases were reported in DR Congo, leading to 82 deaths, up from 899 cases and 26 deaths the year before. DR Congo is also battling cholera and polio epidemics that have claimed 250 people since March, and is the country with one of the world\'s highest child mortality rates -- 148 out of every 1,000 live births. The WHO responded to MSF\'s criticism by calling for dialogue. \"If you have criticism, the best thing is to open dialogue to see what is not going well,\" WHO coordinator Ayigan Kossi told AFP.