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H5N1 Wild Bird Flu Victims of the Evil Empire
September 3, 2005
As put elegantly in previous moderator comments, dead birds don't migrate -- i.e., waterfowl species typically identified in recent outbreaks appear to be victims rather than effective carriers of the disease.
The above commentary on ProMed adds to growing list of their curious statements. Characterizing migratory birds as "victims" because of H5N1 infections is not very precise or scientific. Any organism that is fatally infected with a virus could be considered a victim, but ProMed seems to be making up some definition that is based on the inability of some researcher to meet some preconceived level of infectivity to move migratory birds from the "victim" category to the H5N1 "aiding and abetting" category. Although some might call the birds victims, H5N1 would call the birds a free ticket to ride. If the birds are "victims" then H5N1 must be the embodiment of the "evil empire". Unfortunately, the evil empire appears to be destined to take over the world in the next 12 months.
Artificial characterizations aside, it is quite easy to see that migratory birds efficiently transport and transmit H5N1. Birds are the natural reservoir of influenza A and they clearly have been moving influenza A around the world for hundreds if not millions of years. The birds have been moving H5N1 sequences around the world for some time, but such movement was first clearly obvious in 2002 and 2003 when new sequences flew into Hong Kong and ultimately ended up in the pandemic H5N1 that exploded across eastern and southern Asia in 2004.
The outbreak at Qinghai Lake however, made the H5N1 movement clearer. It was not necessary to do detailed genetic analysis. A cursory look at H5N1 at Qinghai lake showed that the virus was like other Asian H5N1 isolates, but clearly distinct. A few notable markers, such as the PB2 polymorphism E627K or the three PB2 polymorphisms previously identified in European swine distinguished H5N1 wild bird flu from earlier isolates.
However, the increased virulence and lethal infections in waterfowl also made the H5N1 wild bird flu stand out. The die-off at the Qingahi Lake nature reserve was unprecedented and the trail of dead bodies was easy to follow. The Qinghai outbreak was reported in May (see May map) and that was quickly followed by outbreaks in Xinjiang province in June (see June map). In July there was an outbreak at the Chany Lake nature reserve in Russia (see July map), which was followed by outbreaks in August in Kazakhstan and Erhel Lake in Mongolia (see August 15 map).
The ProMed commentary above was in response to the OIE update from Mongolia indicating that the H5 isolated from bar headed geese or whooper swans, was H5N1. The sequential outbreaks clearly showed the efficient transmission and transport of H5N1 by migratory birds and the role of the migratory birds was clearly stated in the OIE reports.
However, in spite of this very clear-cut dataset, ProMed seems intent on creating a "victim" category because H5N1 was not detected in some birds. The trail of H5N1 wild bird flu clearly shows that migratory birds are efficient at moving the virus long distances. That is not a surprise because many of these birds migrate long distances. The bar headed geese can fly 1000 miles in 24 hours. Most of the dead birds at Qinghai Lake were bar headed geese, but the additional dead birds at Qinghai Lake showed that H5N1 had little trouble jumping to additional bird species.
The nature reserves offer the opportunity of transmitting H5N1 to many species. Because the H5N1 can be quite virulent, a low level of virus may be quite sufficient to effectively move the infections from location to location. These lower levels may not be detected by some of the assays designed to screen for H5N1. However, the movement is well defined by the fatal infections. Prior to 2005, H5N1 had not been reported at Qingahi Lake, Russia, Kazakhstan, or Mongolia. As the weather cools in these areas, H5N1 is expected to greatly expand its geographical range. The overlapping nature of migratory bird routes strongly suggests that H5N1 will soon be present worldwide.
This dramatic geographical spread is cause for concern. Although sequences at GenBank go back to 1902, H5N1 was not isolated until 1959. It was not isolated in Asia until 1996. The Asian version is easily identified by the HA cleavage site, and the sequence of basic amino acids has become widespread and endemic in southern and eastern Asia. This same seqquence has been found in the H5N1 wild bird flu isolates at Qinghai Lake and Chany lake. A similar sequence is expected in the isolates from Kazakhstan and Mongolia.
The evil empire is alarmingly growing in size and geographical range, negative data from Mongolia not withstanding. H5N1 has recently expanded its range across Mongolia, Kazakhstan, and Russia (see current map). There is no reason to not expect a dramatic expansion in the upcoming months.
Migratory birds are expanding the geographical range of H5N1, regardless of the ability of scientists to detect H5N1 under a limited set of experimental procedures. The unprecedented geographical expansion is cause for significant concern.