Obese exposed as swine flu collides with epidemic of overweight
An unexpected characteristic has emerged among many swine flu victims who become severely ill: They are fat.
Doctors tracking the pandemic say they see a pattern in hospital reports from Glasgow to Melbourne and from Santiago to New York. People infected with the bug who have a body mass index greater than 40, deemed morbidly obese, suffer respiratory complications that are harder to treat and can be fatal.
The World Health Organization says it's gathering statistics to confirm and understand this development. Drugmaker Roche Holding AG is combing through studies to determine whether heavier people should get bigger doses of its Tamiflu antiviral.
"Morbid obesity is one of the most common findings turning up in severely ill patients," said Nikki Shindo, who is leading the investigation of swine flu patients at the WHO in Geneva. "It's a huge problem."
In Canada's Manitoba province, three out of five people treated for the new flu strain in intensive care units are obese, said Ethan Rubenstein, head of infectious diseases at the University of Manitoba in Winnipeg. Patients with flu symptoms should be considered at risk of complications if they carry excess weight, according to Rubenstein.
So far, the evidence is anecdotal. No global or national data have been reported. Scotland, where deep-fried foods such as Mars bars and pizzas contribute to the highest obesity rate in Europe, reported the continent's first two deaths from H1N1 and has experienced a fifth of the region's fatalities.
"We do seem to have more than our fair share of people in intensive care," said Hugh Pennington, 71, emeritus professor of bacteriology at the University of Aberdeen.
No deaths or severely ill patients have been recorded from among the 2,146 laboratory-confirmed cases in Japan, said Yasuyuki Abe, a health ministry spokesman in Tokyo. Only 1.6 percent of adults in Japan are obese, according to the WHO.
"You don't have to go to Scotland or Japan to figure this out," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland. "About 75 percent of patients have underlying conditions, and clearly obesity stands out as a statistically significant factor involved in the seriousness of the disease."
It's the first time that the prominence of obesity has been noticed among severely ill flu sufferers, Fauci said. "It's very likely that if we went back retrospectively and looked at people who did poorly during seasonal flu, what would shake out is that obesity would be one of the risks," he said.
Last year, 26.1 percent of adults in the U.S. were obese, up from 25.6 percent in 2007, the CDC said in a July 8 statement.
The bug is reported to have killed 429 people worldwide since its discovery in the U.S. and Mexico in April. The infection, which has now spread as far as New Zealand and Norway, causes little more than a fever and cough in most cases. The majority of those who died were pregnant, had asthma, diabetes or other chronic diseases, according to the WHO.
Scientists don't yet know whether extremely overweight people get sicker because of associated conditions like heart disease and asthma, or whether the excess fat itself makes them more vulnerable. Both may be to blame.
Fat cells secrete chemicals that cause chronic, low-level inflammation that can hamper the body's immune response and narrow the airways, says Tim Armstrong, a doctor working in the WHO's chronic diseases department in Geneva.
What's more, excess fatty tissue compresses the chest, and the fatty infiltration of the chest wall causes a decrease in lung function and an increase in the pulmonary blood volume, Armstrong said. "If you are obese, you tend to be less physically active and have an associated shallower breathing pattern. All these compound, leading to breathing difficulties."