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H5N1 Fatality in Hunan China Raises Vaccine Concerns
October 27, 2005
The death of a Chinese girl with flu-like symptoms in a village where a bird flu outbreak had been reported was caused by pneumonia acute respiratory difficulty, local health authority cited initial blood tests result as saying on Thursday.
Latest tests on the girl's blood sample have turned out negative for the avian influenza virus, and doctors said she had died of severe pneumonia with acute respiratory difficulty, according to the provincial center for disease prevention and control.
The 12-year-old He Yin died recently after eating a dead chicken in Wantang Village, in Xiangtan County of central China's Hunan Province, where the latest outbreak of H5N1 avian influenza was reported several days ago.
The above description provides additional evidence that the cause of the girl's death was H5N1. On Tuesday, China filed an OIE report indicating that H5N1 had been detected at Wantang Village and was killing chickens and ducks. The death and/or bird flu symptoms in two children that had eaten a dead chicken in the village strongly suggests the severe pneumonia was due to H5N1. Negative data means little if there is no positive data identifying the micro-organism that caused the pneumonia.
The outbreak in Wangtang follows reports of outbreaks in AnHui, Inner Mongolia, and Mongolia and strongly suggests that the H5N1 detected at each location was the H5N1 wild bird flu closely related to H5N1 from Qinghai Lake. This homology was subsequently found in Russia, Kazakhstan, Romania, Turkey, Croatia, and Moldova. Although human cases have not been confirmed. Boxun reports on the Qinghai outbreak described human cases and pneumonia cases in Russia and Kazakhstan have been described. Like the Hunan cases, the victims had pneumonia, H5N1 exposure, but tested negative for H5N1. Since these additional cases also cited pneumonia but offered no positive data on the etiological agent of the pneumonia, H5N1 remains highly suspect in all three countries.
Human infection by wild bird H5N1 is cause for concern. As the number of H5N1 versions that cause human infections increase, the likelihood that H5N1 in wild birds does not cause human infections descreases. In 2004, the only reported human H5n1 cases were in Vietnam and Thailand and isolates from the two countries were similar as were case fatality rates. However, in 2005 a milder version of H5N1 emerged in northern Vietnam, while a more lethal version was found in southern Vietnam and Cambodia. This there were two versions of H5N1 co-circulating in Vietnam.
Similarly, the first human cases in Indonesia were reported in 2005 and there may be milder version there also. Some reports have described two distinct versions of H5N1 in Indonesia. Therefore the number of H5N1's that are variations of the Z genotype continue to increase, which increases the likelihood that the Z genotypes in wild birds can infect humans. Indeed, the dramatic increase in human cases in Indonesia, including those linked to the Ragunan Zoo were blamed on H5n1 from wild birds and Thailand has Laos suggested that the sudden increase in human and poultry infections in Thailand are linked to wild birds.
This increase in versions of H5N1 raises serious questions about a pandemic vaccine effort that targets a 2004 version of H5N1 and ignores the emerging human versions that are linked to wild birds. The current strategy is to wait for a reassortment event, and there is little data to support such a prediction.
All 8 genes from the 1918 pandemic strain are now public, and there is no reassortment with a human gene. Similarly, the new versions of the Z genotype iof H5N1 do not involve reassortment. Rather the H5N1 is recombining to produce drifts that evade the earlier immune response on organisms infected with H5N1
Thus it is time to reconsider a pandemic vaccine effort that waits for a event of low probability and ignores the diversity in H5N1 infecting humans in 2005.