# 2709
The World Health Organization has updated their avian influenza chart, and issued their 3rd update of the year on China.
Included are the three new cases reported over the weekend.
As you'll probably note, the total number of cases now exceeds 400, with 254 deaths.
That's a case fatality ratio (CFR) of 63% among known cases.
No one seriously believes that these 403 known infections make up all of the cases that have occurred around the world. These are the lab confirmed cases.
Just as with any other disease, there are cases that are never identified and are therefore never counted.
We strongly suspect, for example, that the mother of the 2-year-old who is currently recovering from the bird flu virus died of the disease in early January.
But she was never tested, and so she is not counted.
Additionally, testing for the H5N1 virus is difficult and not available in many parts of the world. Problems are also known to exist with the accuracy of these tests.
And the big unknown is whether there are mild, or asymptomatic infections out there. Many observers feel that this is likely, although very little actual testing for antibodies to the H5 virus has been done.
The few seroprevalence studies to date have not turned up evidence of mild cases. More work is needed.
As distressing as all of this may be, we don't know how many people get infected with West Nile Virus, or Lyme Disease each year in the United States either.
Medical surveillance and reporting is an inexact science.
Lab confirmed infections are a measurement tool, and while imperfect, they are still a pretty good indicator of how fast infection rates are growing, and where cases are occurring around the world.
Avian influenza – situation in China - update 3
27 January 2009 -- The Ministry of Health in China has announced three new confirmed human cases of H5N1 infection. The first, a 31-year-old female from Urumqi, Xinjiang Autonomous Region had onset of symptoms on 10 January. She received treatment in hospital but died on 23 January. Investigations into the possible source of her infection indicate recent visits to a live poultry market. The local authorities are currently conducting epidemiological investigations and close contacts are being monitored. To date, no clinical symptoms have been reported among the contacts.
The second case is a 29-year-old male from Guiyang city, Guizhou. He had onset of symptoms on 15 January and remains in a critical condition. Investigations into the source of his infection indicate possible exposure at poultry market.
The third case is an 18-year-old male from Beiliu City, Guangxi Province. He had onset of symptoms on 19 January and died on 26 January. Investigations into the source of his infection indicate a recent history of exposure to sick and dead poultry. Close contacts of the case are being monitored and to date all remain well.
Of the 37 cases confirmed to date in China, 25 have been fatal.
Updated as of 1/29/09 - Click to Enlarge
