# 3018
The ECDC (European Centre For Disease Control) has weighed into the discussion over the perceived changes being observed among recent H5N1 cases in Egypt.
As you are probably aware, there have been 13 non-fatal infections with the bird flu virus in that country since the first of the year. The latest case, however, is reportedly in `very serious condition’.
Last year, Egypt saw 8 cases of the virus, and 50% were fatal.
This isn’t the first time that Egypt has seen a series of `mild’ H5N1 cases.
In March of 2007 there were 9 non-fatal cases.
Still, it is a bit of a mystery, and it has prompted some scientists to ask whether or not something has changed with the virus?
Reported Cases In Egypt. Red=Fatal Green- Non-Fatal
(From the ECDC webpage)
The ECDC website has a discussion, posted yesterday, on these recent `mild’ cases, and what they may (or may not) signify.
It is a bit long, so I won’t try to post the entire page. By all means, follow the link to read it in its entirety. (Note: I’ve reformatted some of the paragraphs for readability)
A hat tip to Ironorehopper, editor of A Times Memory, and a member of Flutrackers for posting this link.
The low Case Fatality Ratio (CFR) for human infections with Highly Pathogenic Avian Influenza (HPAI) H5N1 virus in Egypt is most welcome. However it was noted at a WHO global review two years ago.(2) Therefore, what is being described now is not entirely new, except that there have been a series of 12 cases in 2009 with no deaths.
Clinically, mild illness with HPAI H5N1 virus infection has been reported in children in several countries apart from Egypt i.e. Turkey, Indonesia and Bangladesh and it should be noted that Egypt seems to be testing more children with milder illness soon after onset than any other countries.
This could be because children are brought to medical care for H5N1 testing early in their illness. Moreover, testing and care (including early commencement of the antivial oseltamivir as recommended by WHO and ECDC (3,4)) seems to be relatively available in Egypt.
It is noticeable in the recent reports how soon after onset dates treatment with oseltamivir seems to have started. The occurrence of so many cases late in 2008 and early in 2009 is not in itself unusual. It was also the pattern in the 2007-8 period.(Figure) (5)
Despite the above speculation, it is not yet known how to explain the commendable low CFR being achieved in Egypt with a virus that overall has been observed to have a CFR of around 60-70%.(5)
Various hypotheses have to be tested. It could reflect a further adaptation of the virus to humans and a lessening of its virulence but equally it could be the result of good local surveillance, or that the clade 2.2 virus infections in Egypt has a lower CFR, or that its because early oseltamivir and other treatment has a better outcome.
There are no reports as yet of a change in the virological sequences and it is commendable that the Egyptian authorities have been sharing viruses with the global community as evidence from the WHO A(H5N1) Tracking Mechanism.(6)
The clade hypothesis theory seems unlikely since in nearby Turkey the same clade of H5N1 cases in 2005/6 resulted in a CFR for Turkey of 4 out of 12 in circumstances where it was difficult to achieve early treatment (a rural areas in then middle of a severe winter).(5)
Hence the good surveillance / early treatment theory seems the strongest hypothesis. However uncertainty remains and it will be important to investigate further. It is very welcome that the Egyptian authorities have invited WHO to send senior staff to Egypt next week to assess the current epidemiological situation.
It is especially reassuring that despite the low CFR and apart from two of the cases in the most recent report there have been no clusters in the cases suggesting more easy human to human transmission.
However it would be hoped that this would be investigated in Egypt with serological surveys to look for milder and asymptomatic cases and any suggestion of clustering since even though the seeming lack of significant change in the sequence of the virus is reassuring the changes can be subtle and its how the viruses behave that is most important.(7)
A good example of such investigations were recently published in the Weekly Epidemiological Report of joint National / WHO work done in Pakistan in 2007.(8)
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