IMMUNITY © 2016 Paul Billiet ODWS

Active immunity Passive immunity Infection of pathogen or injection of vaccine Antibodies acquired from a host Mother ,via placenta or milk (colostrum) Immunised organism (e.g. horse) or monoclonal antibodies Immune response Antibodies produced and memory cells retained Infection destroyed No memory cells created because the body has not produced an immune response itself Infection destroyed Infection by the same pathogen New, rapid immune response Further infections possible by the same pathogen.

VACCINES AND VACCINATION Vaccination is a prophylactic treatment Some are used as post infection vaccination It stimulates the immune system by exposing it to harmless antigens The immune response leaves memory cells Response to a real infection is rapid and the body resists. © 2016 Paul Billiet ODWS

A typical immune response to vaccination Primary immune response, slow to build up and not very strong. Antibody response Time Secondary response stronger and more rapid than primary response Memory cells remain Infection by pathogen Vaccination © 2016 Paul Billiet ODWS

Vaccines Vaccines: Purified antigens from the pathogen Dead pathogens or parts of pathogens Live but attenuated (harmless) pathogens Memory is not perfect, booster vaccination may be necessary Vaccines are usually limited to those diseases that are endemic to the region because of complications. © 2016 Paul Billiet ODWS

The benefits and dangers of vaccination Vaccination has helped to cut infantile death rates in many parts of the world Some diseases (e.g. small pox) have been eliminated totally Others (e.g. polio) are programmed for elimination Vaccination has helped to contain the spread of a number of diseases Vaccines are a cheap form of prophylactic treatment. © 2016 Paul Billiet ODWS

The benefits and dangers of vaccination Live vaccines containing attenuated viruses may “jump” to another virus in the system e.g. attenuate live polio virus given to a person contaminated with HIV may develop polio Vaccines may lead to allergic responses or auto immune diseases e.g. Crohn’s disease Multiple vaccinations received by soldiers fighting in the Gulf War 1991 are associated with a number of health problems (The Gulf War Syndrome). © 2016 Paul Billiet ODWS

Vaccines: a victim of their own success Infectious diseases become rarer in a population The attention of parents tends to be focussed on the problems with vaccines They become reluctant to vaccinate their children or … they become complacent about the risk of infection 1990 in the United States, an outbreak of 28 000 cases of measles, 30 children died. © 2016 Paul Billiet ODWS

The small pox story Variolation Edward Jenner (1796) & cow pox Vaccination Eradication programme Polio next? © 2016 Paul Billiet ODWS

Small pox WHO global eradication plan 1966 © 2016 Paul Billiet ODWS

Polio WHO global eradication plan 1988 © 2016 Paul Billiet ODWS