On the sixth floor of the modern, glass-fronted Max Institute of Medicine in New Delhi's upper-middle-class neighborhood of Saket, Dr. Sandeep Budhiraja is fielding calls on his iPhone from panicked patients, most of them members of India's elite. "I've treated at least five CEOs this week alone," he says.
Delhi's growing middle class and sliver of super-rich have ensconced themselves in the posh suburbs of south Delhi, where three-bedroom apartments sell for $1 million and tree-lined boulevards end at high-walled security gates. The maladies of the poor—malaria, tuberculosis, polio, and diarrhea—are rarely seen here. Every monsoon, though, south Delhi becomes the hub for dengue, a disease harbored in mosquitoes that flourish in the environment these entrepreneurs and executives crave—clean and lush, punctuated by public parks with pools and fountains.
"There's no doubt about it. In Delhi, dengue is a disease that spreads best in neighborhoods that only the upper middle class and rich live in," says Budhiraja, whose hospital is a stroll away from India's largest shopping mall. What makes south Delhi's suburbs more susceptible than the slums of north Delhi is that the Aedes aegypti mosquito, which transmits dengue, lays eggs almost exclusively in clean water that stands for days. That commodity, while rare in slums, is abundant in neighborhoods like Greater Kailash, Defence Colony, and Chanakyapuri, where residents store water in large tanks and cultivate gardens filled with flower pots.
Dengue causes fever, severe headaches, and muscle and joint aches for up to 10 days, according to the World Health Organization. It is the most widespread tropical disease after malaria. Dengue-related complications cause about 500,000 hospitalizations annually worldwide, mostly involving children. About 2.5 percent those hospitalized have a form of the disease that weakens blood cells and kills the patient through spontaneous bleeding and shock.
The Indian Health Ministry has confirmed 1,438 cases of dengue so far this season in Delhi. Budhiraja and other doctors say that number is low. Spokespeople and doctors at 15 hospitals contacted by Bloomberg News say they have already seen more than 3,300 cases. Indian newspapers have reported up to five deaths this season.
Unlike other diseases, dengue does not tend to decrease in incidence as tropical countries become wealthier. "Instead, the problem is often exacerbated," says Peter Ryan, head of the mosquito control laboratory at the Queensland Institute of Medical Research in Australia.
Research in Vietnam has shown that in areas without running piped water, the rich tend to hoard more water, says Ryan. People with 10 containers of fresh water in their houses are 10 times more exposed to dengue-carrying mosquitoes than poorer residents who may store water in a single bucket. In Delhi, where the municipal corporation supplies piped water for only two or three hours a day, the middle class and wealthy buy water pumps and tanks in which they store their daily requirements. In the slums of Jagdamba Camp and Sadar Bazaar, the congested living conditions, open sewers, and influx of migrants expose the residents to diseases like malaria, which breeds in filthy water.
Delhi's preparations for the Commonwealth Games, which will start on Oct. 3 and involve 71 countries, may have left south Delhi residents more vulnerable to dengue. The Indian government has spent at least $4.6 billion building or refurbishing subway routes, stadiums, and roads. "Construction sites with tarpaulins that collect rainwater, pipes lying around, or even buckets are perfect for dengue," says Scott Ritchie, a medical entomologist at the Tropical Public Health Unit in Cairns, Australia. Fear of dengue has prompted the U.K., Canada, Australia, and New Zealand to advise its athletes in the Games to wear protective clothing and use mosquito repellent.
On Sept. 9, Anjum Khan, a 19-year-old resident of the exclusive enclave of Greater Kailash sat in a New Delhi hospital room waiting to be discharged after a week of receiving platelet transfusions and painkillers. The fashion-school student, her skin still pale and her breathing shallow, had switched hospitals twice as clinics and dispensaries ran short of the platelets prescribed in extreme cases like hers. "I am not sure where I caught it," says Anjum, while her mother packed her belongings. "I didn't know that the mosquitoes only liked clean water."
The bottom line: India's rising affluence is creating new opportunities for infectious diseases such as dengue, which needs clean, standing water to spread.