Islands devise plans to counter bird flu

Mark Smaalders
Increased international travel and trade are two benefits of globalisation, but they also increase the likelihood that isolated countries, such as the Pacific Islands, will be impacted by pandemic, or worldwide, disease outbreaks.

The 1918 influenza pandemic—which involved a strain of avian influenza (or bird flu) that mutated and became more easily transmissible between people—proved devastating to several Pacific Islands, killing around 25% of the population in Samoa, 15% in French Polynesia (Tahiti), and 5% in Fiji and Guam.

A key message of the 2006 session of the World Health Organisation (WHO) Regional Committee for the Western Pacific was that avian influenza remains the top threat to global public health.

Scientists classify influenza viruses into three categories—A, B and C—with only type A capable of causing a pandemic. In recent years several countries have experienced outbreaks of avian influenza, a type A influenza for which wild birds are the natural hosts.

The virus responsible for most of these outbreaks is H5N1, a highly pathogenic strain. Although not normally associated with human disease, over 290 people were infected with H5N1 between 2003 and April 2007, and over 170 died.

Most cases of avian influenza infection in humans are thought to have resulted from direct contact with infected poultry or contaminated surfaces, and sustained human-to-human transmission has not yet occurred.

But given the potential for influenza A viruses to change—and possibly develop the ability to spread easily between people—the threat of an influenza pandemic is very real.

How ready are PICTs for an influenza pandemic?

National pandemic influenza preparedness plans are being developed. A few Pacific Islands countries and territories (PICTs) have completed and endorsed their plans, while others are fine-tuning their drafts.

The Secretariat of the Pacific Community (SPC), in conjunction with WHO, has supported the ability of the region to prepare for epidemics through the Pacific Public Health Surveillance Network (PPHSN), which was established in 1996. 

Work by SPC to support influenza preparedness in the region expanded significantly in 2006 with the start of the Pacific Regional Influenza Pandemic Preparedness Project (PRIPPP).

The four-year, A$10.5 million project is funded by AusAID and NZAID, and will cover all 22 Pacific islands countries and territories.

PRIPPP will provide technical assistance to support finalisation and testing of PICT pandemic influenza preparedness plans, and increase the surveillance and response capacity of the region’s animal and human health ministries. 

Most existing viruses that affect humans originate in animals. However, there has been limited cooperation in the past between animal and human health services on issues such as zoonotic disease surveillance and animal health services in PICTs are of uneven quality.

There is now much greater awareness of the need for improved animal health services and coordination with human health specialists has increased over the last few years.

PRIPPP staff will include three sub-regional animal heath specialists to be based in Fiji, Papua New Guinea and the Federated States of Micronesia.

PRIPPP will work with animal health and production authorities to build effective surveillance systems, improve biosecurity on farms and in live bird markets, and explore the role of preventive vaccination.

The skills, techniques and approaches useful in influenza epidemics can also be applied to other diseases, and PRIPPP’s broader goal is to develop and strengthen surveillance and response capacities.

The Pacific Avian and Pandemic Influenza Taskforce held its first meeting in March 2007, providing a consultative forum on avian and pandemic influenza for Pacific Islands professionals working in the area.

How new influenza viruses emerge Influenza A viruses infect different animals (e.g. ducks, chickens, pigs, whales, horses, and seals). Some influenza A subtypes are specific to certain species, but birds are hosts to all known subtypes. Influenza A viruses that normally infect one species can cause illness in another species; viruses from humans have caused widespread disease among pigs, and viruses from horses have crossed over and caused outbreaks in dogs. Avian influenza A viruses may be transmitted to humans in two ways: directly from birds or from avian virus-contaminated environments to people, and through an intermediate host, such as a pig. Influenza A viruses from different species can mix and create a new virus if viruses from two different species infect the same person or animal at the same time; the new virus would contain a mix of genetic information and could possibly be capable of infecting humans. Such a major change in an influenza A virus is termed an antigenic shift, and if the new influenza A subtype - to which most people would have little or no immunity - causes illness in people and is easily transmitted from person to person, an influenza pandemic can occur. The same emergence could happen if avian influenza viruses frequently infect mammals (including humans): by adapting to the new hosts, an avian influenza virus could acquire the capacity to generate a new pandemic.

• Mark Smaalders is a SPC consultant.