U2) KA5) treatment and control of parasites

Question 1

what is epidemiology and what can it be used for

Answer 1

• study of the outbreak and spread of infectious disease
• info gained from epidemiology surveys can be used to plan and evaluate strategies to help prevent the spread of the parasite in the future

Question 2

how does herd immunity prevent spread of disease

Answer 2

• one way to prevent spread of disease is to use vaccinations, which increases the number of resistant hosts in the population, creating herd immunity
• it means susceptible hosts are too dispersed for the parasite to continue to spread

Question 3

what is the herd immunity threshold

Answer 3

• the herd immunity threshold is the density of resistant hosts required in a population to prevent an epidemic
• ( how many people need to be vaccinated in order to prevent an epidemic)

Question 4

who does the herd immunity programme protect in particular

- where is this particularly useful

Answer 4

• vaccination programmes aim to reach herd immunity threshold as this protects many individuals who cannot have vaccinations for health reasons
• particularly important in ledcs , where poorer nutrition weakens the health of individuals so they are more susceptible to disease

Question 5

how does a vaccination work

Answer 5

vaccinations exposes the immune system to a non infectious source of parasite antigens
- this triggers an immune response and develops immunological memory to these antigens and so protects against infection by the real parasite

Question 6

problems with vaccinations

Answer 6

• antigenic variation has to be reflected in the design of vaccines ( the parasite may use rapid antigen change as means of evading the immune system)
• some parasites are difficult to culture in the lab, as they have a very narrow range of conditions, as well as specific host signals making it hard to make the vaccines

Question 7

problems with developing drugs against parasites

Answer 7

• the similarities between the host and parasite metabolism make it difficult to find drug compounds that only target the parasite
• drugs that work to kill the parasite in the host could have detrimental effects on the host
• drugs provide a selection pressure ,leading to the evolution of resistant strains of parasites

Question 8

challenges arise where parasites spread ____ _____ as a result of….

Answer 8

more rapidly

- as a result of overcrowding or tropical climates

Question 9

where does this overcrowding often occur

Answer 9

• in refugee camps that result from war or natural disasters
• rapidly growing cities in ledcs

Question 10

overcrowded conditions make _____________________________ difficult to achieve

Answer 10

co ordinated treatment and control programmes

Question 11

what may be the only practical parasite control strategies

Answer 11

• civil engineering projects to improve sanitation

- co ordinated vector control

Question 12

what are the benefits of parasite control

Answer 12

• reduce child mortality
• population wide improvements of child development and intelligence as individuals have more resources for growth and development