Influenza, Avian Influenza, and the Impacts of Past and Looming Pandemics
Avian influenza is a disease that has been wreaking havoc on human populations since the 16th century. With the recent outbreak in 1997 of a new H5N1 avian flu subtype, the world has begun preparing for a pandemic by looking upon its past affects. In the 20th Century, the world witnessed three pandemics in the years of 1918, 1957, and 1968. In 1918 no vaccine, antibiotic, or clear recognition of the disease was known. Killing over 40 million in less than a year, the H1N1 strain ingrained a deep and lasting fear of the virus throughout the world. Though 1957 and 1968 brought on milder pandemics, they still killed an estimated 3 million people and presented a new problem of vaccine manufacturing and production. The new avian flu in Asia now claiming 54 lives has the world rushing to find a vaccine and prevent another, even more deadly pandemic
Influenza is a pathogenic virus that has been the cause deadly pandemics throughout recorded history. Influenza is caused by an A or B virus, the more deadly of the two is influenza A which derives from the avian species and initiates pandemics in the human population (Levison, 2004). The genomes in influenza viruses are divided into eight parts of RNA. Influenza A viruses are named by the two sets of proteins that protrude from the surface of the cell. The first protein is haemaglottin, or HA, which determines binding and cell entry. There are fifteen HA subtypes with H1, H2, and H3 most common in human infection (WHO, 2005). The second of the two proteins is neuraminidase (NA) that presides over the release of virus DNA from infected cells into host cells. There are nine subtypes of the NA protein (WHO, 2005). The danger with influenza A is the mutation of the infection via multiple species and hosts where the virus can rearrange genes to form new viruses, “Highly unstable and prone to small mutational errors, influenza viruses have a segmented genome , consisting
Impacts of Past and Looming Pandemics 2
of eight genes, that allow easy swapping of genetic material – like the shuffling of cards” (WHO, 2005, 8). As stated by the World Health Organization, “all fifteen HA subtypes and nine DNA subtypes have been detected in free flying birds”. (WHO, 2005, 12) They, in turn, provide a huge and highly mobile pool of genetic diversity.
Wild aquatic fowl, ducks in particular, serve as a reservoir for the Influenza virus to transmit into poultry and then to humans. Infected birds shed flu viruses in their saliva, nasal secretions, and feces (CDC, 2004). The current virus seen in Asia is denoted as H5N1 and was first seen in terns in South Africa in 1961 (CDC, 2004). The first human seen infection of the avian H5N1 viruses was in 1997 in Hong Kong in a three- year old boy (Ruben, 2005). The outbreak involved 18 cases and killed 6, one third of the confirmed infected population (Rueben, 2005). In three days 1.5 million birds were killed...