Chapter 14 - Immunology and Disease. Flashcards
What bacterium causes Cholera and when can it reproduce?
Vibrio cholerae and it can only reproduce when its inside its human host.
What does Endemic mean?
Disease occurring frequently, at a predictable rate, in a specific location or population.
How do people become infected with Cholera?
They become infected by contaminated food or water.
How does Vibrio cholerae affect the body?
It releases a toxin in the small intestine which affect the chloride channel proteins. Water and many important ions aren’t absorbed into the blood stream which causes the patient to have very severe, watery diarrhoea. Causes dehydration.
How can Cholera be prevented?
With good hygiene and sanitation. Better sewage treatment, water purification, safe food handling and regular hand washing have all reduced the incidence of cholera. A temporary vaccine is also available.
How is Cholera treated?
Two strands- Water and ions replaced by giving patients electrolytes. The bacteria are also treated with antibiotics.
What bacteria causes Tuberculosis?
Mycobacterium tuberculosis.
How is TB spread?
By aerosol transmission (the inhalation of bacteria-laden droplets from the coughs and sneezes of infected people. It spreads very rapidly in crowded conditions. Increase in TB cases has been linked with HIV.
What are the symptoms of TB and how is it treated?
It mainly infects the lungs so patients develop chest pain and they cough up phlegm (often containing blood). Its treated with a long course of antibiotics but tuberculosis has shown some antibiotic resistance. A vaccine can be provided but its only given to those at risk.
What virus causes smallpox?
Variola major.
How is the smallpox virus transmitted?
It is inhaled or transmitted in saliva or from other bodies if there is close contact with an infected person.
What symptoms does smallpox produce?
Causes a rash and then fluid-filled blisters which will cause scars in survivors. People have also suffered from blindness and limb deformities.
How is smallpox prevented and what can be done for infected patients?
Prevented by a vaccine which produces a strong immune response. Infected people given fluids, drugs to control the fever and pain and antibiotics but 60% die.
Why are humans immune system not able to provide adequate protection when a new strain of influenza appears?
Because this new strain has new proteins on the virus surface which means that a pandemic occurs.
Where is influenza’s surface membrane derived from and what are the proteins that act as antigens?
Phospholipid envelope from the host’s cell surface membrane. The two proteins are Haemagglutinin (H) and Neuraminidase (N).
What symptoms does influenza cause and how is it transmitted?
Attacks mucous membranes causing sore throat, cough and fever. Transmitted in aerosol transmission. Reduced by regular hand washing and using and discarding tissues.
What is an antigenic type?
Different individuals of the same pathogenic species with different surface proteins, generating different antibodies.
What are the two ways of a new antigenic type appearing?
Antigenic drift - No proofreading enzymes so each round of replication produces a new mutation.
Antigenic shift - If a cell is infected with different combinations of H and N the separate strands can recombine giving rise to new virus types. These new types can cause epidemics.
What protoctistan causes malaria?
Plasmodium.
What kind of mosquitos transmit malaria?
Female anopheles mosquito
How is malaria transmitted?
The mosquito takes blood from an infected person so they take the plasmodium in the sexually reproducing stage. These then develop into an infective stage which migrate from the mosquitos gut to the salivary glands. When another blood meal is taken, the plasmodium is injected into the human which then travel to the liver and reproduce asexually. Merozoites are then produced which are released into the blood and infect RBC where they undergo more reproduction.
