AH Biology - Unit 2 - KA5(f) - Challenges in Treatment and Control

What is epidemiology?

Epidemiology is the study of the outbreak and spread of infectious diseases.

What are vaccines?

Vaccines are a method of immunisation by which a weakened or altered form of the parasite or pathogen or its toxin is deliberately introduced into the body to act as an antigen of the pathogen to produce an immune response. For example, to produce lymphocytes for the pathogens antigens.

What do vaccines contain?

Vaccines contain the antigens to produce the immune response, but do not contain the harmful pathogen.

Why are vaccination programmes important?

Vaccination programmes are important as they allow vulnerable members of the population to gain herd immunity from the pathogen, without being vaccinated.

What is herd immunity?

Herd immunity is when the percentage of the population immune to the pathogen is high enough that the chances of an infected individual coming in contact with a non-immune individual is very low.

What is the herd immunity threshold?

The herd immunity threshold is the density of resistant hosts in the population required to prevent an epidemic.

What are some of the challenges in treatment and control of disease with drugs and vaccines?

Some of the challenges in treatment and control of disease with drugs and vaccines are:

• Host and parasite metabolisms may be so similar, that it is difficult to find a drug that targets only the pathogen.

• Antigen variation may make a vaccine ineffective when there are different variants of a pathogen. Vaccine programmes are now designed to reflect this.

• Some parasites are too difficult to culture in the lab, so it is difficult to design vaccines for them.

When do parasites spread more rapidly?

Parasites spread more rapidly when:

• The host population is overcrowded

• It is a warm and wet tropical climate. This means parasites can survive outside their hosts for longer.

What are two key examples of locations where overcrowding may take place and where disease is likely to spread?

Two key examples of locations where overcrowding may take place and where disease is likely to spread are:

• Refugee camps, which occur as a result of war or natural disasters.

• Less economically developed countries and rapidly growing cities.

What is it very difficult to achieve in overcrowded and/or tropical climates what is it very difficult to achieve?

In overcrowded and/or tropical climates, it is very difficult to achieve coordinated treatment and/or a control programme needed to control the spread of the disease.

Often, what does the only practical disease control strategy involve the combination of?

Often, the only practical disease control strategy involves the combination of:

• Civil engineering projects to improve sanitation

• Coordinated vector control

What are improvements in parasite control for children?

Improvements in parasite control for children are:

• Reduces childhood mortality

• Results in population wide improvements in child development and intelligence because the child will have more resources to grow and develop if they are not fighting parasitic infections.