At dusk, the foggers come out to spray their sticky-sweet clouds of diesel smoke and insecticide across the Indian capital. Mothers scold their children for wearing short sleeves. Posters glued to signposts warn about the perils of neighborhood puddles.

Such efforts to stop mosquitoes from spreading dengue fever in New Delhi have failed to keep the city from its biggest outbreak in almost two decades: more than 10,190 registered cases, including 32 deaths. Experts say it didn’t need to be this way, and blame health officials for being slow on both prevention work and medical response.

They say, for example, that the Delhi municipal government should have started much sooner and anticipated a longer-than-usual mosquito-breeding season months ago, when weather forecasters predicted this year’s monsoon would extend beyond September.

“If they clean up in time, if they have those anti-mosquito, anti-larval measures on time, they can contain dengue,” general physician Devendra Jain said in the small single room, crammed with patients, where he operates his private practice in south Delhi. Details