Bird Flu in Vietnam - A Tale of Two Cities?
Recombinomics Commentary
February 2, 2005
>> A 24-year-old man from Hanoi was admitted to the city's Bach Mai hospital on Jan. 25 with a high fever and cough before testing positive for the H5N1 strain of the virus, said the hospital doctor on condition of anonymity. The doctor said the man had been removed from a respirator and was recovering.<<
The latest patient to test positive for bird flu appears to be recovering. Similarly, two other patients (30M and 66M) may be released this week. The first patient (42M) to recover for bird flu this season, was released last week.
When he was initially diagnosed, along with his brother (47M) and the 66 M, they seemed to represent a new demographic, The patients in the north were older and male, while most in the south were younger and female. As more cases were reported, the differences have blurred somewhat. However, the cases do appear to differ in the case fatality rate. Assuming that the 3 recovering patients in the north are discharged, the outcomes for the north would be two deaths in six confirmed cases, for a case fatality ratio of 33%, while there have been no discharges in the south. All 12 confirmed cases (Vietnam and Cambodia) with outcomes have died, for a case fatality rate of 100%
Earlier results had indicated that there were some genetic changes this season in isolates from Vietnam, and reports of H5N1 infected grey herons in Hong Kong identified additional change in those isolates also. A new season usually leads to H5N1 isolates with some genetic changes, and the clinical data suggests there may be differences in the H5N1 affecting the north and south.
Earlier WHO had issued a warning about asymptomatic ducks. These ducks had been infected with last season's H5N1 from both Vietnam and Thailand and although large amounts of virus were excreted, the ducks appeared to be healthy.
Most of the reports of asymptomatic ducks have been in the south, although more recent reports had indicated that the asymptomatic ducks were appearing in the Central Highlands. Thus it is possible that the H5N1 from these birds produces an infection with a higher case fatality rate in humans than isolates from the north. Initial reports indicated genetic changes were noted for isolates throughout the region, but the similarities and differences have not been made public.
Putting these sequences on deposit at GenBank and/or Los Alamos, two publicly accessible sequences databases, would be useful.
Media link