TYPES OF IMMUNITY
Immunity is the ability of microorganisms to resist infection by protecting against disease causing microorganisms. When the body has enough antibodies (or can produce quickly enough) to fight infection.
- Active Natural: Exposed to foreign antigen by getting the disease – immune system is activated – body produces memory cells, making the body immune to the same disease in the future
- Active artificial: Vaccination – Injection of dead and weakened disease organisms, toxins or antigen fragments means the body is exposed to the antigen and produces memory cells – develops immunological memory – if exposed to same disease again, antibodies are quickly released
- Passive natural: A mother’s antibodies across the placenta or through breast milk – these antibodies protect the baby against any pathogens the mother has encountered – short-term as antibodies are broken down within a few days
- Passive artificial: Antibodies are formed in one individual, injected with antibodies that provide immediate protection against the invading pathogen they are specific for – then gradually broke down and not replaced
Active = body produces its own antibodies – catching a disease – long-term
Passive = body receives ready made antibodies – vaccination – short-term
Vaccinations:
Substance that stimulates immunity without getting the disease – it is non virulent. Antigens come from weakened, dead or fragmented pathogens. This stimulates memory cells to develop – ready to destroy the real pathogen if encountered.
Vaccinations need to be affordable, available, have few side effects and be able to provide herd immunity.
Types of vaccination: pathogenic, antigens, harmless toxins, live MOs
Vaccinations don’t eliminate disease if:
- Immune system is defective
- Disease develops before immunity is built
- Mutations arise (antigenic variability)
- If the pathogen hides/conceals itself
- May varieties of a pathogen
- Individuals don’t receive vaccination
Advantages of vaccination:
- Protects against disease
- Herd immunity
- Most common vaccinations are relatively cheap
Disadvantages of vaccination:
- Some may suffer from allergic reactions
- Minority of children become severely ill/death
- Linked to a rise in asthma and allergies
Ring vaccination: used for new cases of disease. Vaccinates people in immediate vicinity of the disease – e.g. surrounding people, can control livestock disease