In 2009, there were a total of 5 cases of H5N1 reported in humans in Vietnam. All of the patients died.
In 2010, as of today, there have been at least 9 reported cases of H5N1 in humans in Vietnam. Only 2 patients have died.
There are two significant differences with respect to H5N1 cases in Vietnam in 2010 as opposed to 2009. There are many more cases and the case fatality rate appears to be lower.
To understand what is going on, it may be worth considering the cases that have occurred this year.
A 3 year old girl from Khanh Hoa Province became ill on January 27, 2010 (WHO). A 38 year old woman from Tien Giang Province became ill on February 13, 2010. She died in Dong Thap Province on February 23, 2010 (WHO, Thanhnien). A 17 year old girl from Tuyen Quang Province became ill on February 19, 2010 (WHO). A 3 year old girl from Binh Duong province became ill on March 5, 2010. She died in Ho Chi Minh City on March 17, 2010 (WHO, Thanhnien). A 25 year old woman from Hanoi became ill on March 5, 2010. She was hospitalised on March 10, 2010 (Vietnam News, WHO). A 22 year old man from An Giang Province became ill on March 28, 2010 (VOVNews). A 2 year old girl from Bac Kan Province became ill on April 2, 2010. She was hospitalised on April 4, 2010. There are at least two additional confirmed cases in Bac Kan Province. There are large number of individuals, perhaps over 20, with symptoms similar to H5N1 in Bac Kan province, most in Cho Moi District [machine translation by Pixie at PFI_Forum].
The provinces with H5N1 in humans in Vietnam do not display any obvious pattern. Cases were found in both the South (An Giang, Tien Giang, Binh Duong and Khanh Hoa) and the North (Hanoi, Tuyen Quang and Bac Kan). The most recent outbreak in Bac Kan (Cho Moi District) is of particular concern due to the large number of confirmed and suspected cases. If all the patients with H5N1 symptoms were infected, this may represent the largest cluster of H5N1 cases ever recorded.
Many of us in Flublogia have been watching H5N1 for years, fearful of the day when large clusters may appear and not stop, despite the mass use of Tamiflu. We know that this antiviral is being used in Bac Kan. We don’t know, yet, whether this cluster will stop.
Is the H5N1 causing human disease in Bac Kan “different”? We don’t know. The fact that this large H5N1 cluster is occurring at the same time that an H1N1 pandemic is in full swing is not reassuring.
One might think that the WHO would have sent an investigative team to examine this large cluster in Vietnam. There is no indication that they have done so. Further, links to the 2010 cases in Vietnam have been removed from the WHO avian influenza web page.