Updated

Updated · bbc.co.uk · Jul 23

Sri Lanka Deploys Drones Against 77,000 Dengue Cases as 56 Die in Worst Outbreak in 10 Years

Updated

Updated · bbc.co.uk · Jul 23

Sri Lanka Deploys Drones Against 77,000 Dengue Cases as 56 Die in Worst Outbreak in 10 Years

Q: Why does dengue's most lethal stage begin only after the patient’s fever seems to have broken?

Dengue becomes most dangerous just after the fever falls because that is when the illness can shift into its “critical phase,” driven less by the fever itself than by damage to blood vessels and an intense immune reaction. In many patients, the high-fever stage lasts several days while the virus is actively circulating. As the fever breaks, usually around days 3 to 7, the body’s immune response can surge. Researchers point to inflammatory chemicals and the virus’s NS1 protein as key triggers. Together, they can disrupt the lining of blood vessels, making them abnormally permeable. That leakiness allows plasma, the fluid part of blood, to escape into surrounding tissues. The result is a drop in circulating blood volume, thicker blood, and in severe cases shock, organ stress, or internal bleeding. This is why a patient may appear to be improving because the temperature is lower, while in fact the most life-threatening complications are just beginning. Doctors watch especially closely during the 24 to 48 hours after defervescence. Warning signs include severe abdominal pain, persistent vomiting, bleeding gums, black or bloody stools, unusual drowsiness or restlessness, and rapid breathing. People with a second dengue infection from a different strain are at higher risk of severe disease because immunity is strain-specific and can worsen the immune response. So in dengue, a broken fever is not always reassurance; it can be the point when urgent monitoring matters most.

3 articles · Updated · bbc.co.uk · Jul 23

Military drones are scanning rooftops, schools and construction sites across Sri Lanka as authorities intensify mosquito-control efforts during the country’s worst dengue outbreak in nearly a decade.
More than 77,000 infections and 56 deaths have been recorded this year, with over a quarter of cases reported in July alone and about 75% tied to a more virulent strain.
Health officials link the surge to a cyclone last December that left debris and stagnant water breeding grounds; nearly 11,000 sites have been cleared this month and more than 4,000 premises fined.
Hospitals have added beds and extended hours, but capacity strains have led doctors to tell mild cases to recover at home while public health workers are stretched to their limit.
The outbreak reflects a wider global rise in dengue, with WHO-reported cases climbing from about 500,000 in 2000 to 14.4 million in 2024 as warming temperatures expand mosquito habitats.