The mosquito-borne disease, which typically spreads during the island nation’s monsoon season, has intensified following Cyclone Ditwah, which struck Sri Lanka in late November and left behind widespread debris that created favorable breeding conditions for mosquitoes.

Data released by the National Dengue Control Unit (NDCU) showed infections nearly doubled from 5,651 cases in April to 10,638 cases recorded during the first two weeks of June alone.

“We noticed this increase after the cyclone,” said Dr. Prashila Samaraweera, consultant community physician and spokesperson for the NDCU. “A lot of debris was in our environment, so we noticed a lot of mosquito breeding places, and our entomological indices were high from that time.”

Sri Lanka recorded approximately 51,000 dengue cases throughout 2025, but the pace of infections this year has accelerated significantly. Health officials expect case numbers to continue rising for at least another two weeks before showing signs of easing.

Health Minister Nalinda Jayatissa warned on Thursday that a further increase in patient admissions could place severe strain on public hospitals already managing growing caseloads.

More than half of all reported infections have been concentrated in the country’s western region. Colombo, Sri Lanka’s commercial capital, has reported 9,429 cases since January, while eight other districts have each registered more than 2,000 infections.

The fatalities recorded this year include five children, underscoring concerns among health authorities about vulnerable populations.

Officials have warned that the outbreak could approach levels seen during Sri Lanka’s last major dengue epidemic in 2019, when the country reported more than 105,000 cases.

In response, authorities have launched a nationwide cleanup campaign involving schools, residential neighborhoods, construction sites and public institutions. The program, coordinated by health agencies and local government bodies, is scheduled to continue through next week as officials seek to eliminate mosquito breeding grounds and slow transmission.

The campaign, led by the health ministry with support from UNICEF, the World Health Organization and Gavi, the Vaccine Alliance, has been rolled out across 18 high-risk districts, according to a joint statement.

Government data shows 17 confirmed deaths linked to measles so far, alongside 113 suspected fatalities and more than 7,500 suspected infections across the country. The outbreak has now spread to 56 of Bangladesh’s 64 districts, raising concerns over further transmission.

Authorities said the vaccination drive is prioritising children aged between six months and five years, particularly those who missed routine immunisation and are at higher risk of severe complications. Health officials described the campaign as a critical intervention to address immunity gaps exposed by the surge in infections.

UNICEF representative Rana Flowers said the agency was alarmed by the sharp rise in cases, warning that thousands of children, especially the youngest and most vulnerable, face heightened risk.

She said the resurgence underscored significant gaps in population immunity.Hospitals in several high-burden areas are operating beyond capacity, with limited resources to manage the influx of patients, officials said, adding to concerns about the outbreak’s trajectory.

The World Health Organization said the outbreak is likely to continue spreading in the coming days but could be brought under control following the large-scale vaccination effort. WHO representative Dr Ahmed Jamsheed Mohamed said the campaign would be key to preventing further child deaths.

Officials said the emergency drive is intended to complement existing routine immunisation programmes as authorities work to contain the outbreak and stabilise public health conditions.