Doctors are investigating the causes of a marked increase in cases of dengue fever in Indonesia. According to the Department of Health, in 1994 the disease afflicted 18,783 people, killing 471 of them. Last year, the figure rose to 35,102 with 885 deaths, department spokesman Mulyani said. In both years, 2.5 per cent of victims died and 20 per cent of all cases occurred in Jakarta. The disease has shown signs of continuing its spread this year. Newspapers quoted the Health Ministry as saying 1,880 cases and 28 deaths were reported in May alone, and there was a total of 3,024 cases and 43 deaths up to June 17. The disease causes severe muscle and joint aches and a fever. Without proper treatment it can kill people who are under-nourished or ill. 'It [dengue fever] is indeed on the increase,' said a spokesman for the Indonesian Medical Association, Jamfi Naswil. 'Whenever we have a season with a lot of rain like this one, the Aedes aegypti mosquito, the carrier of the disease, breeds more rapidly. 'The best solution is to fight the disease by wiping out the breeding grounds of the mosquitoes.' A spokesman for the World Health Organisation's office in Jakarta said the body was unable to comment on the causes of the increase in cases of the disease but said it had a specialist examining the problem. Mr Mulyani warned against panic, saying the disease was treatable provided adequate medical help was available. The country lacks eye doctors, the official Antara news agency yesterday quoted Indonesian Eye Specialists Association chairman Dr Mardiono Marseto as saying. In West Java alone, 266,000 out of a population of 35 million people were blind, a government official said at the eighth congress of the association in Bandung, outside Jakarta. Indonesia reportedly has one of the highest rates of blindness in Asia - recorded at 1.2 per cent of the population in a 1982 survey.