The Immune System

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World declared free of smallpox in 1980

Slide 43

Smallpox

Eradication programme – why was it successful?

Variola virus stable -> cheap as everyone used same vaccine

Vaccine made from harmless strain of similar virus (vaccinia)

Vaccine could be used at high temperatures

Easy to identify infected people

Smallpox doesn’t lie dormant in body

Slide 44

Smallpox

Eradication programme – why don’t all work?

Political instability

Poor infrastructure

Unstable m-os

Slide 45

Measles

Caused by an airborne virus

9th leading cause of death worldwide

Causes rash and fever

Can have fatal complications

Passive immunity from mothers in infants under 8 months

Now quite a rare disease in developed countries due to vaccination

Slide 46

Measles

Transmitted easily in overcrowded, insanitary conditions

Mainly affects malnourished infants with vitamin A deficiencies

Responsible for many cases of childhood blindness and can cause severe brain damage

Herd immunity of 93-95% needed to prevent transmission within a population.

Slide 47

Allergies

When the immune system responds to harmless substances

Allergens – antigenic substances which do no real harm

Allergens include house dust, animal skin, pollen, house dust mite and its faeces

Slide 48

Slide 49

Allergies

Histamine causes blood vessels to widen and become leaky.

Fluid and white blood cells leave capillaries.

The area of leakage becomes hot, red and inflamed

Slide 50

Astha

Attacks can occur at any time

Genes play a role in who develops astha

Breathing becomes difficult, sufferers experience wheezing, coughing, a tightness about the chest and shortage of breath.

1/7 children in UK has astha, number is increasing.

>1000 people die each year from astha every year in the UK

Slide 51

Astha

Airways in asthatics are always inflamed, during an attack this worsens.

Fluid leaks from blood into airways and goblet cells secrete lots of mucus

Airways can become blocked

Muscles surrounding trachea and bronchioles contract which narrows airways further