0312 GMT April 20, 2018
The Red Cross also announced it was scaling up its emergency response to the country's worst-ever outbreak of the disease as the number of dengue cases topped 100,000, according to AFP.
That figure is nearly double the previous year, with doctors warning hospitals were beyond capacity as medics struggled to treat a new strain of the disease.
The education ministry said schools would shut from Friday for four days as tens of thousands of volunteers join government officials and soldiers in targeting mosquito breeding grounds.
"Instructions have gone out to all schools today to coordinate with local authorities and look for any mosquito breeding areas in their immediate neighborhood," a ministry official said.
Troops have already been spreading out across the island to help local councils drain pools of stagnant water to ensure mosquito larvae have nowhere to flourish.
Official figures show 290 people have died so far this year from dengue fever, nearly four times the fatalities recorded in all of 2016.
The number of cases has soared to above 105,000, a sharp jump from the 55,150 recorded last year.
About half those cases were reported from the island's west, including the capital Colombo.
"One reason for the dramatic rise in cases is that the virus currently spreading has evolved and people lack the immunity to fight off the new strain," Dr. Novil Wijesekara, head of health at the Sri Lanka Red Cross, said in a statement.
The humanitarian organization, which has increased its budget by $300,000 to cope with the outbreak, said infected patients were "streaming into overcrowded hospitals that are stretched beyond capacity and struggling to cope".
Last week Australia said it was donating $1.2 million to manage patients and help with research to contain the spread of the virus.
Humid monsoon weather, stagnant water from recent flooding and mounting piles of rotting garbage in Colombo have created perfect conditions for the rapid spread of mosquitoes.
Authorities have blamed a waste management crisis in the capital for the unusually large number of infections.
Sri Lanka's main rubbish tip collapsed in April, crushing dozens of homes and killing 32 people.