Nurse to Nurse Transmission of Bird Flu in Thai Binh?
Recombinomics Commentary
March 12, 2005
The hospitalization of a second nurse with bird flu symptoms extends the transmission chain and suggests the 41 year-old nurse was infected by the 26 year-old nurse. The latest patient is linked to four confirmed H5N1 cases. The index case (21M) developed symptoms on February 14. His sister (14F) developed symptoms on February 21. The nurse (26M) caring for the brother developed symptoms on or about February 26. The second nurse (41F) was hospitalized in Hanoi March 10 after developing symptoms in Thai Binh.
Since the brother was transferred February 20 from Thai Binh to Hanoi, he is an unlikely source for H5N1 infection of the second nurse. However, the first nurse, who developed symptoms later and was not transferred to Hanoi until March 1, may have infected the second nurse since they worked at the same hospital and both cared for the brother.
Although the precise order of the transmission chain remains to be proven, the chain has now involved four patients who have developed symptoms over a three week time period which may have involved four generations of cases. This extended transmission chain suggests human-to-human transmission of H5N1 in Thai Binh has become more efficient.
This increased efficiency may have come at the expense of some virulence. All four members in the chain are still alive, and only the index case is in critical condition. In addition, the grandfather of the index case has also tested positive for antibodies to H5N1. However, it is not clear if these antibodies are from a family member, since H5N1 has been isolated in northern Vietnam and adjacent Guangxi Province in China for the past several years. A rising titer in the grandfather would link his H5N1 antibodies to the current infections.
Antibodies to the 1918 pandemic strain were detected in patients in 2004, showing that antibodies against influenza A can persist for many decades.
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