Victoria : Credit Wikipedia
#18,071
The plot, as they say, thickens.
Overnight (here) the government of Victoria State in Australia announced (h/t FluTrackers) the detection of an imported case (of a child) infected with H5N1 from India, which apparently occurred in March of this year.
This begs a lot of questions. But first, the gist of the announcement from Victoria's Chief Health Officer.Details are disappointingly vague (no specific dates are provided), but it is revealed the child has recovered and contact tracing has uncovered no additional infections.
What is the issue?
A case of avian influenza A (H5N1) infection, also known as “bird flu”, has been reported in Victoria. This is the first human case of H5N1 avian influenza in Australia. The case occurred in a child, who acquired the infection in India and was unwell in March 2024. The avian influenza virus was detected through further testing of positive influenza samples that takes place to detect novel or concerning flu virus strains, as part of Victoria’s enhanced surveillance system. Contact tracing has not identified any further cases of avian influenza connected to this case.
There are lots of different subtypes (strains) of avian influenza. Most of them don’t infect humans. Some subtypes, including H5N1, are more likely to cause disease and death in poultry. These are known as highly pathogenic avian influenza (HPAI) viruses. Significant outbreaks of HPAI viruses are being reported in poultry and non-poultry birds and mammals overseas. The United States of America is currently experiencing outbreaks of HPAI (H5N1) in dairy cows, with one recent human case in a dairy worker. Whilst the Victorian case is HPAI (H5N1), it is not the same as the strains that have caused these outbreaks in the United States of America.
The rest is boilerplate and/or standard health advice. That said, there are are so many unanswered questions/problems with this report, I scarcely know where to begin.
- The absence of any dates at all make it impossible to know whether this case was only very recently discovered (through retrospective testing), or if they've known about this case for some time (weeks? ) and are just announcing it now.
- We discussed previously how difficult it can be to detect individual human infections, even in countries that are actively looking for cases (see UK Novel Flu Surveillance: Quantifying TTD). In Australia, which is one of the last regions of the world without H5N1, it would be understandably pretty far down the suspect list.
- The assurance that this `strain' is not the same as the strain in American cattle may well be true, but it doesn't tell us much. The clade is not given (presumably 2.3.4.4b, although from Asia others are possible), and there are no genomic details provided.
- There is no mention of the possible exposure of this case back in India, or even where in India this case came from. When was the Indian government notified? When was WHO?
- The child was described as experiencing a `severe infection', but no details of symptoms, treatment, or time to recover are provided.
- Contact tracing is mentioned, but no numbers or context is provided. Depending upon the time delay in diagnosing the index case, their tracing options could have been quite limited.
A quick check of the CSIRO site and the WHO DON list show no updates on this event. While the immediate risk from this imported case has likely passed, this absence of specific data does little to inspire confidence.
Hopefully more detailed information will be released sooner rather than later.
