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Excellent article for those trying to understand the many complex reasons why cases may be being under detected/ unreported. Well worth reading in full
01:03 PM ET
China's bird flu mystery
By Laurie Garrett, Special to CNN
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But the disease drama now is unfolding in five large eastern China cities with a combined population of 48 million. This is a decidedly urban flu, its human victims identified to date span from ages 4 years to 87, and [B]for most of the cases there is no obvious explanation for how they contracted their infections, or why their loved ones, co-workers and neighbors apparently did not.
Information released to date by Chinese health and agricultural authorities boils down to:
- Four of the flu viruses found in deceased Shanghai, Anhui and Hangzhou patients have been fully genetically sequenced, and those details have been posted on a transparent website for all the world to scrutinize.
- Those flu virologists that have examined the sequences say H7N9 – which for millennia has only infected birds – has now mutated into a mammalian virus. There are stretches of RNA genetic material that are exclusively found in flu viruses that infect mammals.
- But the Chinese insist those thousands of bloated pig carcasses that were floating down Shanghai’s Huangpu River when this outbreak began were coincidental occurrences – the animals did not have H7N9 flu. No satisfactory explanation for the pigs’ deaths has been offered.
- Some pigeons, doves, ducks and chickens caged for sale in the Shanghai poultry markets tested positive for the virus, but showed no signs of illness. Yesterday in Shanghai some 20,000 of them were killed, in hopes of stopping putative spread from birds-to-people.
- There is no indication that H7N9 is spread from person-to-person, or that a lot of Chinese are carrying the virus without outward symptoms of flu.
None of this is making sense.
Looming over all other questions in this outbreak is the Denominator Problem. Typically, when a dangerous disease breaks out in people for the primary time it’s noticed first in hospital emergency admissions, as deathly ill individuals gasp for air. These acute cases are counted, and [B]as their numbers climb it’s possible to get a dangerously distorted view of disease severity. As I write these words, Chinese authorities have reported 16 confirmed cases of H7N9 infection, all critical; six have proven fatal. And no infected-but-mild flu cases or asymptomatic individuals have been identified. So it seems this H7N9 produces life-threatening illness in 100 percent of infected humans, killing nearly half of them.
But those numbers must be wrong. When H1N1 swine flu broke out in Mexico authorities were terrified by a sudden wave of critically ill and dying pneumonia patients that swamped emergency rooms all over the country.
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As it turned out, the denominator was enormous, so that for every seriously ill swine flu case there were thousands of mild and asymptomatic infections.
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So far, China has not provided any genuine denominator. This is most likely due to one of three things.
First, the actual blood test used to identify infections is overly specific, missing infections. So infected, but not ailing, people that are controlling the viruses in their bodies so well that very few microbes are present in each tested droplet, may be missed.
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The most recent announcements from WHO and Chinese authorities indicate most of the “testing” of close contacts of ailing or deceased H7N9 patients has featured interviews, not actual blood tests. I
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There are three reasons why many Chinese might choose to hide an illness if it weren’t obviously life-threatening.
First, during the SARS epidemic the People’s Liberation Army took control of most patient care outside of the initial Guangzhou outbreak of December 2002, placing all fever patients in confinement. Those not held in military facilities were quarantined for weeks either inside key hospitals or their homes. For some the isolation and fear was so great that they leapt from high story windows to escape, or bribed their ways out of confinement if they were wealthy enough to do so.
Though the government has announced that patient care for H7N9 should be free, healthcare can be bankrupting in China.
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During the SARS epidemic I spoke with many patients’ families that had been assured the government would cover the costs for their loved ones’ care, but wept openly as they described doctors and nurses demanding huge payments, or else. Typically, the threat was without more money, your loved one will simply be left on his own in isolation, without medicine, without food. These stories circulated widely in 2003, and resonate today.
A final, perhaps more complicated reason family, co-workers and friends of the 16 H7N9 sufferers may not admit to experiencing flu-like symptoms is China’s air pollution.
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It would be easy to miss a mild flu when feeling lousy, and flu-like, day after day, thanks to the pollution.
This Denominator Problem is the key to understanding what is going on.
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My Council on Foreign Relations Colleague Yanzhong Huang argues that, “the post-Mao policy process has witnessed a shift from ‘bandwagon’ to ‘buck-passing,’ which encourages strategic disobedience and policy shirking. For this reason, China’s response to public health emergencies may continue to be bedeviled by lingering problems of under-reporting, misinformation, and inaction.”
On March 19 a Chinese government agency issued the following statement, which ended up on the social media site, Weibo: “The Shanghai Huangpu River dead pig incident is already being dealt with effectively. Related follow-up coverage should follow Xinhua wire copy and information issued by authoritative local departments. The media are not to send journalists to Jiaxing or similar locations to investigate, nor to sensationalize or comment on the issue.”
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