Avian Influenza in Hong Kong 1997–2002

Abstract

In 1997, a high-pathogenicity H5N1 avian influenza virus caused serious disease in both man and poultry in Hong Kong, China. Eighteen human cases of disease were recorded, six of which were fatal. This unique virus was eliminated through total depopulation of all poultry markets and chicken farms in December 1997. Other outbreaks of high-pathogenicity avian influenza (HPAI) caused by H5N1 viruses occurred in poultry in 2001 and 2002. These H5N1 viruses isolated had different internal gene constellations to those isolated in 1997. No new cases of infection or disease in man due to these or other H5N1 viruses have been reported. This paper provides an overview and chronology of the events in Hong Kong relating to avian influenza, covering the period from March 1997 to March 2002.

Effect of Interventions on Influenza A (H9N2) Isolation in Hong Kong’s Live Poultry Markets, 1999–2005

“…Indeed, we observed that the effect of 1 rest-day in chickens became larger and more signifi cant statistically after quails were removed. The sales of live ducks and geese in LPMs had already been banned since 1998 in Hong Kong, and the sales of live quails were banned in 2002 (7).…”

“…The previous day, all remaining birds are sold or slaughtered, and the next day the stalls, free of poultry, are cleaned and disinfected. This rest-day has been synchronized with 1 of 3 standing monthly rest-days in the wholesale market (Cheung Sha Wan; Figure 1) (7). Since infl uenza A (H9N2) viruses found in quail were identifi ed as the donor of the internal genes of the (H5N1) virus that caused human disease in Hong Kong in 1997 and because isolation rates of these viruses from quail were particularly high (8), the sale of live quails, together with any other live poultry at the same premises, was banned effective February 2002.…”

“…Since infl uenza A (H9N2) viruses found in quail were identifi ed as the donor of the internal genes of the (H5N1) virus that caused human disease in Hong Kong in 1997 and because isolation rates of these viruses from quail were particularly high (8), the sale of live quails, together with any other live poultry at the same premises, was banned effective February 2002. Episodic reappearance of (H5N1) viruses in the LPMs in late 2002 and early 2003 led authorities to introduce a second rest-day on day 10 of each month beginning March 2003 (7).…”

Characterization of Avian Influenza Viruses A (H5N1) from Wild Birds, Hong Kong, 2004–2008

“…The Kowloon Park outbreak was concurrent with outbreaks caused by this virus in several live poultry markets and on some chicken farms in Hong Kong (14). Measures to improve biosecurity on farms, changes in the poultry marketing system, the introduction of rest days in poultry markets, and vaccination for all poultry entering Hong Kong markets have prevented subsequent HPAI (H5N1) outbreaks in farmed poultry in Hong Kong (15). No further cases of infection in live poultry markets were detected from November 2003 through June 2008, when live bird market surveillance detected incursion of a new HPAI (H5N1) virus (2).…”

A review on human influenza A H5N1 infections in Hong Kong

“…After learning from the traumatic experience of H5N1 outbreaks in poultry and humans in 1997, an intensive surveillance system for H5N1 in live poultry was established [19] (Figure 5). In May 2001, eight poultry markets were found to have large numbers of chickens dying from H5N1 infection.…”