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Asymptomatic H5N1 Positive Exotic Birds at Ragunan Zoo
Recombinomics Commentary
September 19, 2005
The 19 were from a sample of 27 birds that were randomly tested earlier this month.
The above comment indcating that the 27 birds tested were randomly selected is cause for concern. This would indicate that the exotic birds were asymptomatically infected and the infections were widespread. In addition to the 19 that were H5N1 positive, 4 more were inconclusive, which is commonly found for low levels of infection. Thus, only 4 of the 27 tested were negative.
Thus, the percent positive was high and the positive birds included peacocks, mynahs, wild ducks, pigmy chickens, eagles and herons. These species suggest that the H5N1 at the zoo could grow asymptomatically in water and terrestrial birds. H5N1 commonly produces asymptomatic infections in waterfowl. In southern Vietnam's Mekong Delta, 70% of waterfowl are H5N1 positive. The percentage of chickens positive has grown to 21%, indicating H5N1 is adapting to asymptomatically infect a wide range of species. The results cited above indicates that this broadened host range in birds in Vietnam is continuing in Indonesia
This is particularly alarming because two of the zoo workers have tested positive for H5N1. It is inclear if the H5N1 is similar to the H5N1 that killed three family members in July. That H5N1 was similar to H5N1 in domestic poultry in Java, Indonesia.
However, since wild ducks in the zoo are positive, the H5N1 infections could have been brought in via migratory birds. Although there have been third party reports of H5N1 infections in Qinghai Province, there have been no official human cases. Similarly, there were no confirmed reports of H5N1 infections in humans in Russia, Kazakhstan, or Mongolia. Thus, if the zoo workers are positive for wild bird flu sequences, they would be the first confirmed human cases.
In addition, the sequences could be recombinants between the endiginous H5N1 sequences and those brought by migratory birds. Thus sequencing of the H5N1 in birds and poultry workers will be important.
Treating the exotic birds may be a problem. In Vietnam, H5N1 that is lethal to humans can be found in the intestines of ducks that appear healthy. The excreted H5N1 is uncommonly stable. A similar situation may exist with the zoo birds. Therefore, a vaccine may not have a major effect on the H5N1 levels.
Treatment with anti-virals may also create problems, because the H5N1 could become resistant. This would create a new version of H5N1 that would be even harder to control.
The finding of widespread H5N1 in exotic birds at the Ragunan Zoo on Jakarta, Indonesia creates a number of problems. Further testing and sequencing can help sort out options, but at this time most options are not attractive.
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