More Efficient Human Transmission of Bird Flu in Vietnam
Recombinomics Commentary
January 23, 2005
>>Samples from the patient named Hung, who is receiving treatment at the Tropical Disease Institute in Hanoi, were tested positive to H5N1, local newspaper Pioneer on Monday quoted Vietnamese Deputy Minister of Health Tran Chi Liem as saying.
Earlier, samples from Hung's two brothers were also tested positive to the virus. The tests were made by the National Hygiene and Epidemiology Institute. The three brothers ate duck and a dish made from duck's raw blood at a local market on Dec. 29, 2004, before exhibiting symptoms of bird flu>>.
The timing of the onset of symptoms strongly suggests three generations of infections by H5N1, which is the longest reported chain of transmission. Although the Dec 29, 2004 meal may have been the source of virus that led to symptoms on Jan 1 for the fatal case, the 42 year old brother did not develop symptoms until Jan 9, consistent with transmission from the fatal case to the 42 year old brother. The 36 year old brother was admitted a week after the 42 year old brother, consistent with another round of transmission.
In addition to these three H5N1 positive brothers in the north, the sister (22F) of a confirmed fatal case (17M) in the south has also been hospitalized with avian influenza symptoms. Thus, from the two clusters there have been 4 confirmed and 1 suspect case. In both clusters the relatives developed symptoms after each index case died.
These likely human to human transmission clusters account for 4 of the 11 confirmed bird flu cases this season, which suggests that H5N1 has become more efficient at human to human transmission.
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