Another three people in the United Arab Emirates are sick with the Middle East Respiratory Syndrome (Mers) virus and two people infected with it in Qatar have died. The new cases in UAE involved a family in Abu Dhabi - a mother, father and an eight-year-old boy - the World Health Organisation said in a disease outbreak update. The parents are both in a critical condition in hospital, while the boy has mild respiratory symptoms. The WHO said the mother gave birth while in hospital, adding the baby, other close family contacts and hospital staff were being monitored and tested for signs of the virus. Mers, which emerged last year and can cause coughing, fever and pneumonia, has killed almost 40 per cent of the people it has infected around the world, with cases in countries across the Middle East as well as in Europe and north Africa. The Geneva-based WHO says it has been informed of 163 laboratory-confirmed cases of infection and at least a dozen probable cases, and 70 people have died. Patients diagnosed and reported to date have had respiratory disease as their primary illness, the WHO says. Diarrhoea is also commonly reported among patients and severe complications include renal failure and acute respiratory distress syndrome. Scientists have been trying to work out the animal source of infections since the first human cases were found late last year. Qatari health officials said last week scientists had found cases of Mers in camels, fuelling speculation that camels might be the "animal reservoir" of the virus that is passing into humans.