The public has been cautioned against outbreaks of dengue, influenza and other viral diseases with the onset of southwestern monsoon conditions.
Prof. Chandima Jeewandara has told BBC Sinhala Service that immunity among schoolchildren against the dengue virus was as low as 24.9 percent.
This has been revealed in a study conducted in all nine provinces by the health ministry in collaboration with the WHO, he said.
Dengue patients are mostly reported from the three districts in the western province, he said.
The details collected will be important in the development of a vaccine presently on experimental level, said Prof. Jeewandara.
According to him, a variant that was first reported in 2009 has now resurfaced.
Sri Lanka witnessed its worst dengue outbreak in 2017.
Meanwhile, influenza virus is also spreading mostly among children of school-going age, said pediatrician Deepal Perera.
He urged that medical advice be sought if symptoms persist for more than three days.
Wearing facemasks is also advisable, he added.
