Forty Cambodian children died of dengue fever in the first seven months of this year, an increase from 37 such deaths in whole last year, Minister of Health Mam Bunheng said Monday. From January to July this year, some 7,867 cases of dengue fever had been reported, exceeding the whole year 2010 of 5,497 cases, the minister told reporters during visit to dengue fever patients at the National Pediatric Hospital in Phnom Penh. \"The disease has claimed more Cambodian children\'s lives this year than in last year, so I\'d like to appeal to parents to let their children sleep under mosquito nets and if their kids have symptom that is suspicious of the disease, they should urgently send them for medical attention,\" he said. Dengue is an infectious tropical disease caused by the dengue virus. Symptoms include headache, fever, exhaustion, severe muscle and joint pain, swollen glands and rash. In Cambodia, the outbreak of dengue fever usually takes place in the rainy season from May to October.