Weekly releases (1997–2007) - Volume 7, Issue 3, 16 January 2003

The Agriculture, Fisheries and Conservation Department (AFCD, http://www.afcd.gov.hk/) of the government of Hong Kong recently reported outbreaks of avian influenza in two chicken farms in Hong Kong (1), as well as sporadic infections in wild fowl found dead in Hong Kong (2). As a result, control measures have been implemented. These included the slaughter of around 16 000 chickens, closure and disinfection of one of the live poultry markets which had contact with the farms and the halting of imports of chickens from mainland China (3). The virus has been partially typed and found to be influenza A (H5). The virus is not the same strain of influenza A (H5N1) (4) that crossed over to humans in 1997, causing six fatalities (5). Outbreaks of avian influenza due to influenza A (H5N1) viruses occurred in poultry in Hong Kong in May 2001 and February 2002, resulting in culls of about one million chickens on each occasion. Neither of these outbreaks was associated with transmission to humans. The last reported incident of transmission of avian influenza (H9N2) to humans was in 1999 in two young children in Hong Kong and the resulting illness was reported to be mild and self limited (6).

As far back as the 1960s and 1970s, some countries in the world managed – at least temporarily – to interrupt transmission of measles by vaccination (1). In 1989, the 42nd World Health Assembly set a target for the global control of measles through a 90% reduction in incidence by 1995 (2). Measles elimination has been defined as the situation in a large geographical area in which there is no sustained transmission following the occurrence of an imported case (3). This is only possible if very high levels of population immunity are achieved and maintained. The World Health Organization (WHO) then targeted three regions for elimination. In 1994, the target elimination year for the Americas was set as 2000. This was successfully achieved by Jamaica and some other Caribbean countries (1,4). In 1997, the Eastern Mediterranean Region target year was 2010. Finally, in 1998, the WHO European Region measles elimination target was set at 2007. Finland is the first country in Europe to have documented measles elimination, and did so more than a decade in advance. There have been no indigenous cases reported since 1996, despite laboratory testing of all suspect cases since 1987 (when laboratory confirmation became a requirement for notification (5,6)).