The H7N9 avian influenza has two of the three characteristics of a pandemic virus. The new flu has infected 131 laboratory confirmed cases resulting in 32 deaths. It can clearly both infect humans and cause disease. Because H7N9 viruses have never been known to infect humans before, most people lack immunity to them. The missing link is the ability to spread easily among people. With the exception of two small clusters in China, most of the cases can be traced back to birds rather than to other people. The key question is can it become efficiently transmittable from person to person? And the simple answer is we don't know. Currently, the virus, like the highly pathogenic H5N1, is "hard to catch but dangerous for those who become infected". There have been more than 130 cases in 2 months of the H7N9 flu, compared with 628 H5N1 infections since 2003, suggesting that the novel flu is already more transmissible than H5N1, at least from poultry to humans. World Health Organization, in a new risk assessment of the outbreak, said that "further human cases should be expected." But tracing and monitoring of more than 2,000 contacts of infected people has only detected a few cases of probable transmission.
Human infection is linked to exposure to live poultry or contaminated environments:
The virus has been detected in poultry in live bird markets, and isolates from infected people are genetically similar.
About three-quarters of patients have a history of exposure to animals, mostly chickens.
The rate of new human cases appears to have slowed after live markets were closed.
One difficulty in tracking the H7N9 virus is that -- unlike the H5N1 influenza -- it doesn't appear to cause much illness in infected birds. The observed mortality rate of about 24% is likely to be an over-estimate, largely because milder cases might not be reported. But the WHO reported that Chinese officials tested more than 20,000 people with influenza-like illness in March and April and found only six carrying the H7N9 virus, suggesting that "milder cases of H7N9 infection are not occurring in large numbers." That would raise the stakes if the virus gained the ability to transmit efficiently; the mortality rate in the 1918-1919 flu pandemic, which killed millions worldwide, was only about 1%. The good news, is that surveillance systems are working well, health authorities in China are sharing data generously, and first steps toward developing a vaccine have already been taken. What's missing, are "rapid and accurate point-of-care assays" that could improve surveillance and detection of people infected by the virus. The virus currently appears to be sensitive to the neuraminidase inhibitors oseltamivir (Tamiflu) and zanamivir (Relenza). But drug resistance could develop rapidly. The public health and clinical infrastructure in the U.S. system is not prepared for the surge of patients that would come with a pandemic.
"Our public health departments have been decimated over the last 4 years,".
Source - ISTM discussion list
Human infection is linked to exposure to live poultry or contaminated environments:
The virus has been detected in poultry in live bird markets, and isolates from infected people are genetically similar.
About three-quarters of patients have a history of exposure to animals, mostly chickens.
The rate of new human cases appears to have slowed after live markets were closed.
One difficulty in tracking the H7N9 virus is that -- unlike the H5N1 influenza -- it doesn't appear to cause much illness in infected birds. The observed mortality rate of about 24% is likely to be an over-estimate, largely because milder cases might not be reported. But the WHO reported that Chinese officials tested more than 20,000 people with influenza-like illness in March and April and found only six carrying the H7N9 virus, suggesting that "milder cases of H7N9 infection are not occurring in large numbers." That would raise the stakes if the virus gained the ability to transmit efficiently; the mortality rate in the 1918-1919 flu pandemic, which killed millions worldwide, was only about 1%. The good news, is that surveillance systems are working well, health authorities in China are sharing data generously, and first steps toward developing a vaccine have already been taken. What's missing, are "rapid and accurate point-of-care assays" that could improve surveillance and detection of people infected by the virus. The virus currently appears to be sensitive to the neuraminidase inhibitors oseltamivir (Tamiflu) and zanamivir (Relenza). But drug resistance could develop rapidly. The public health and clinical infrastructure in the U.S. system is not prepared for the surge of patients that would come with a pandemic.
"Our public health departments have been decimated over the last 4 years,".
Source - ISTM discussion list
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