Vaccinations and Allergies

Passive vs. Active Immunity

1. Active Immunity“actively” producing antibodies to fight infection.Ex: You have a throat infection and you are actively creating antibodies to fight

it.

2. Passive Immunity

antibodies are given to a person from the blood of another person or animal.

This immunity only lasts for a short period of time.

ex: Breastfeeding mothers pass antibodies to their children through the milk.

Vaccination

A preparation containing antigenic material:Whole live microorganismDead microorganismAttenuated (harmless) microorganismToxoid (harmless form of toxin)Preparation of harmless antigens

Vaccination: An injection of a weakened strain of an infectious microbe (pathogen) that causes the body to undergo active immunity (produce antibodies).

Why aren’t they always effective?Immunosuppressed patientsMalnutrition, particularly proteinAllergy to latex or egg

Smallpox –Variola virus

Symptoms:Red spots containing transparent fluid all over bodySpots filled with pusEyelids swell and become glued together

Smallpox

Mortality:12-30%Survivors often left blind and disfigured with scars

Smallpox

Eradication:Started by WHO 1956Aimed to rid world of smallpox by 1977Involved aggressive vaccination and surveillance policiesOver 80% of populations at risk of disease were vaccinatedAfter any reported case, everyone in the household and 30 surrounding houses were vaccinated

Smallpox

Smallpox Last case reported in Somalia in 1977 World declared free of smallpox in 1980

Smallpox scars on 10,000BC mummy

Smallpox Why was eradication successful?Virus is stable, doesn’t mutateCheap vaccine made from harmless strain of similar virusVaccine can be used at high temperaturesEasy to identify infected peopleDoesn’t lie dormant in body

MeaslesAirborne virus9th leading cause of death worldwide

Symptoms:Rash and high fever (104⁰)

MeaslesTransmitted easily in crowdsAffects malnourished infants with vitamin A deficiencyCan cause severe brain damage, blindness, and sterilityHerd immunity of 93-95% needed to prevent transmission in a population

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

There are two types of allergic reactions.

a. Immediate – occurs within seconds and normally lasts for about 30 mins.

b. Delayed – takes longer to react and can last for a much longer time.

What happens during an allergic reaction?

During an allergic reaction antibodies cause histamines to be released from certain cells.

Histamines cause:

a. Swelling of tissues

b. Release of fluids (runny noses and eyes)

c. Muscle spasms (some cases)

Example: TB (Mantoux test)

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

Anaphylaxis or anaphylactic shock:This is the sudden and severe allergic reaction to a substance that can cause death.

-inherited tendency to over-produce IgE (evolved to protect against round and flat worm infection)

Treatments for Allergies1. Avoidance of material – especially food.2. Epinephrine – “epi – pen”3. Antihistamines -- benadryl

Autoimmune Disease

Autoimmune diseases are diseases where the immune system begins to attack itself.

◦ Ex: ◦ Rheumatoid Arthritis – crippling disease of the joints.◦ Lupus – disease of blood and organs.◦ Multiple Sclerosis – disease of nervous system

Cause(s): mostly unknown; virus alters proteins,T cells don’t differentiate properly; a nonself may resemble a self antigen

More common in females –fetal cells transport through circulation and cause later response

Cures/Treatments: No known cures. Usually treated with drugs.