The Philippines' Department of Health has declared the country's outbreak of dengue a national epidemic. The agency says Health Secretary Francisco Duque III made the declaration on Tuesday to improve the response to the outbreak by allowing local governments to draw on a special Quick Response Fund. It says the Philippines has recorded 146,062 cases of dengue from January through July 20 this year, 98 per cent more than the same period last year. It says the outbreak has caused 622 deaths. Dengue is a mosquito-borne viral infection found in tropical countries. It can cause joint pain, nausea, vomiting and a rash, and can cause breathing problems, haemorrhaging and organ failure in severe cases. President Rodrigo Duterte is open to lifting the ban on the use of multinational pharmaceutical company Sanofi's controversial dengue vaccine Dengvaxia to deal with the epidemic, his spokesman said earlier. Concerns over dengue immunisation for nearly 734,000 children aged nine or older sparked two congressional inquiries, a criminal investigation and a sharp fall in the number of parents seeking routine vaccinations for their children. The Philippines stopped using Dengvaxia in late 2017 and ordered Sanofi to stop selling, distributing and marketing it after the company said the vaccine could worsen the disease in some cases.