Monday, April 15, 2013, Noon (Press Release)
Update on Bird Flu in China
Current Situation: On April 1, 2013, the World Health Organization (WHO) reported three human infections with a novel avian influenza A (H7N9) virus in China. These are the first known human infections with this avian influenza strain. The virus has also been detected in birds from poultry markets in eastern China, including chickens, ducks, and pigeons. As of this morning, a total of 63 human cases had been reported, aged from 4 to 87, mostly male. Most cases had severe respiratory illness, and 14 died. New cases continue to be reported and case counts are likely to increase (updates are available at the WHO website: http://www.who.int/csr/don/en/). At this time, no human cases of novel influenza A (H7N9) have been detected outside of China. While investigations are ongoing, no sustained person-to-person transmission or firm link between any of the cases has been identified thus far.
What we anticipate will happen
As of last week, cases had been reported from Shanghai, and the provinces of Jiangsu, Zhejiang, and Anhui. Over the weekend, cases were reported for the first time from the central province of Henan, and also from Beijing. Henan is just west of the 4 provinces previously affected, but Beijing is almost 600 miles away. It would not be surprising if we begin to see case reports from more provinces in China, as all 31 provinces now have the ability to test for the virus in over 400 labs. The poultry trade certainly crosses provincial borders, as well as wild birds and humans. Since there are daily non-stop flights from Shanghai to both Los Angeles and San Francisco, it is only a matter of time before suspect cases show up in the US.
There are 2 confirmed cases associated with possible family clusters, where additional family members developed severe pneumonia. Limited human-to-human transmission would not be surprising. No close contacts of cases have tested positive, although over 1,000 are being followed. No healthcare workers have become sick.
What we fear might happen
This new virus seems to derive from a reassortment of genes from wild birds in East Asia (Korea) and chickens in eastern China. Each time the virus infects a person, there is a fresh opportunity to mutate and to acquire the ability to spread rapidly between people. This potential ability to mutate into a form easily passed from human-to-human, known as sustained human-to-human transmission, is our greatest fear.
The fact that there were only a few cases reported a few weeks ago, and now we have many human cases over a wide area in a short time, is a very concerning situation. Humans have no immunity to this virus. There will not be a vaccine for many months. If human-to-human transmission becomes a reality, spread is inevitable, and the toll could be severe. Two other viruses come to mind: SARS, which quickly killed over 800 people, and the H5N1 bird flu, which has killed over 300 people over a number of years.
Another big question involves the origination of the virus. Where did it come from? The focus has been on the live poultry markets in the big cities such as Shanghai, where many birds have been culled, and the live poultry trade shut down. Many human cases have had a close association with the poultry trade. China has 6 billion domestic birds. It is estimated that the economic loss to the poultry industry during the first week was $1.6 BILLION alone. However, the ability to stop animal to human transmission by these reactive measures is virtually impossible. How big will the ultimate human and economic impact be?
How is it spread? It seems to have acquired an affinity for mammals (including humans), but are there other hosts, such as pigs? It has been found in poultry (chicken, ducks, and pigeons), but what about the role of wild birds? Certainly these populations intimately share their viruses. H7 viruses are usually found in wild birds such as ducks, geese, waders, and gulls, and occasionally jump to poultry flocks. A focus has been on the migratory birds in the Yangtze River Delta, and Chongming Island near Shanghai. This is the season for many migratory birds to pass through the affected areas on the way to their summer breeding grounds in the north including Alaska. Should that be a concern for us?
An issue that greatly complicates efforts to find the ultimate source is that the virus causes very mild to no disease in infected poultry. This is in contrast to the H5N1 bird flu virus, which has decimated millions of birds, and therefore its presence in the environment in a given geographic area can easily be recognized. This also raises the possibility that the virus already has a much larger geographic footprint than we realize.
There are 3 possibilities:
- The virus may rapidly fizzle out and never be heard from again, like SARS
- The virus may become established in animal hosts to fuel continued sporadic human outbreaks, like its cousin, the H5N1 virus
- The virus may morph into a virus that can spread easily between people and spark a deadly pandemic, like the 1918 Spanish flu pandemicSince scientists are just becoming acquainted with this latest virus, it is tempting, but too early to predict how events will unfold. This is a rapidly evolving situation, and information may change quickly. Only time will tell what the eventual scenario will look like. We will know a lot more in the next month.
What are we doing?
We are reviewing our plans to deal with any possible outbreak of influenza in our area. We have plans, have carried out exercises, and will be providing educational materials to staff of our healthcare partners. We will be assessing our current stocks of personal protective equipment and antiviral medication. We maintain 24/7 contact with our regional, state, and federal partners, and will keep you the public informed of the current situation and recommendations.
What should you be doing?
Stay informed! Go to the Centers for Disease Control and Prevention (CDC) Website for current information, especially if you are planning to visit China. If you have returned from a visit to China in the last 10 days, and get sick, be sure to inform your healthcare provider of your recent travel (always a good idea anyway!)