Avian influenza: are our feathers ruffled?

Abstract

During the past century, three major influenza pandemics took place, leading to a devastating number of deaths. Pandemics occur through the emergence of a new strain of influenza virus that can infect humans, to which there is little pre-existing immunity and which spreads easily from human to human. The H5N1 influenza virus has the potential of becoming a pandemic virus, since it can infect humans and is highly pathogenic. All that remains is the final step of acquiring the genetic material to enable efficient human-to-human transmission. Therefore, the World Health Organization (WHO) has declared pandemic alert phase 3, the last phase before there is actual evidence of increased and efficient human-to-human transmission. In addition, every case of transmission of an avian influenza virus to humans is regarded by WHO as a cause for heightened alertness and surveillance. The circulation of highly pathogenic avian influenza viruses in large numbers among the poultry population in a growing number of countries is a major concern. Since the influenza viruses are highly unstable, the co-circulation of highly pathogenic animal viruses with human viruses may create opportunities for different species-specific viruses to exchange genetic material, giving rise to a new influenza virus to which humans would have little, if any, protective immunity. In this article, we highlight the current avian influenza situation from its different aspects with a special focus on the Hajj since we host over 2 million pilgrims a year in the holy cities of Mekkah and Medina.

Figure 1

Influenza virus epidemic and pandemic time line.

Figure 2

Genetic reassortment of the avian influenza virus.

Figure 3

Areas of the world reporting confirmed occurrence of H5N1 avian influenza in poultry and wild birds since 2003 and bird migration routes reaching Saudi Arabia (from the WHO, Public Health Mapping and GIS Map Library, adapted with permission)