Lecture 23 : Assessment of Risks Overview

1. Lecture 23 : Assessment of Risks Overview EPIDEMIC DISEASES INFLUENZA

2. Epidemic Diseases • History shows that new diseases arriving as an epidemic can have a devastating impact. • New diseases are being discovered every year. • The threat posed by these new diseases is related to their means of transmission. • Diseases spread by person to person contact pose a risk, but they are generally containable. • Water- and food-borne infections can be contained with adequate public health measures. • Vector-borne diseases are dependent on the availability of vectors. It is becoming more difficult to control vectors. • Air-borne diseases pose the greatest threat.

3. Influenza(1) • Biggest threat may be influenza. • Influenza viruses are classified into A, B and C strains. The A strain is further classified by its haemagglutinin and neuraminidase antigens, which mutate. • 1957 Asian flu was A2 or H2N2, 1968 Hong Kong flu was A3 or H3N2. • Influenza is found in birds, pigs and horses. • The 1918 Spanish flu killed between 20 million and 100 million people worldwide. • SARS in 2003 was initially thought to be a flu.

5. Asiam Palm Civet

6. Influenza(2) • Avian flu H5N1 infected people in Vietnam in 2004. • Similar to the H5N1 strain in the Hong Kong outbreak in 1998, which was contained by culling the entire chicken population. • Human cases low, and at present confined to people in close contact with chickens. • Big fear is it could mutate into a human-human airborne infection. • Effective vaccines may not be deployed for six months. • With 63 per cent mortality, fear may cause all essential services to grind to a standstill.

8. H5N1 Influenza Deaths (Birds and Humans)

9. The End