Birds of Hong Kong - The Monster at Our Door: The Global Threat of Avian Flu - page 18

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Birds of Hong Kong
A new phase seems to have begun in the evolution of avian flu viruses. They have
found their way directly to man. 72
Jaap Goudsmit
In April 1997 Hong Kong issued a set of postage stamps celebrating the migratory birds that flock each
winter to the city's Deep Bay and the Mai Po marshes. Deep Bay's mangrove swamps are a freshwater/salt-
water interface “rich with pickings for birds,” while Mai Po, although now surrounded by the skyscraper
New Towns of Yuen Long and Tin Shui Wai, is such a luxuriant bird habitat that it has been designated
“a wetland of international importance.” 73 Hong Kong is proud of preserving so much avian diversity next
door to extraordinary urban density. Indeed it is a bird-crazy city: thousands of residents are avid bird-
watchers, and Kowloon's famed Bird Garden is one of the world's largest marketplaces for exotic birds of
all kinds. In 1997, moreover, the poultry industry was still thriving in the New Territories, supplying ducks,
geese, and chickens for sale in the live-poultry markets (also called “wet markets”) that are such colorful
parts of the urban mosaic. Birds of one kind or another seem to be everywhere.
One of the birds depicted on a new stamp is a handsome, medium-sized duck called falcated teal. The
drakes—somewhat larger than their North American cousins—have dark bills, white throats, and glossy
green heads and crests. The teals breed in eastern Siberia before their annual fall migration to the Pearl
River Delta and the Mai Po marshes. They like to forage in rice fields or float in freshwater ponds, where
they often come into contact with the domestic ducks that are such an integral part of south Chinese agri-
culture. The teals are treasured for their beautiful plumage and are frequently kept in captivity (again, often
alongside domesticated ducks and other birds). Like other wild ducks, they are also safe havens for influ-
enza. Amongst the flu subtypes identified in a Hong Kong teal is H5N1. That might well make the falcated
teal the duck of the apocalypse.
In March 1997, a month before the bird stamps were issued, chickens started dying on a farm near Yuen
Long and the Mai Po marshes; they displayed the unmistakable violent symptoms of Highly Pathogenic
Avian Influenza (HPAI). As Pete Davies explains in his account of the outbreak: “It's an ugly business.
The virus spreads through the bloodstream to infect every tissue and organ; the brain, stomach, lungs, and
eyes all leak blood in a body-wide hemorrhage until, from the tips of their combs to the claws on their feet,
the birds literally melt.” 74 The disease spread to two nearby poultry farms, and as is so often the case with
HPAI outbreaks, almost all the birds died. The virus was identified by Hong Kong University researchers
as H5N1, a subtype first isolated in 1959. Veterinary virologists had seen it on only two other occasions:
during a devastating outbreak in Pennsylvania in 1983 that forced authorities to cull 20 million chickens,
and, more recently, among English turkeys in 1991.
The gruesome pathology of so-called “fowl plague” was first described in 1878, but the pathogen was
not confirmed as influenza A until 1955. Episodic outbreaks in poultry farms along major migratory fly-