Pathogens

Question 1

What is the difference between endemic, epidemic, and pandemic?

Answer 1

› Endemic is when a disease is always present in low numbers
› Epidemic is where there is a significant increase in the usual number of cases of a disease
› Pandemic is when a disease is present across continents or worldwide

Question 2

Describe smallpox, what causes it, and how it is prevented and controlled

Answer 2

› Causes high temperature, headaches, muscle pains, and blisters
› Spread by airborne droplet infection (through coughing) or direct contact
› Caused by DNA virus known as variola
› Preventable by vaccine

Question 3

Describe cholera, what causes it, and how it is prevented and controlled

Answer 3

› Gut lining is affected by toxins, leading to watery diarrhoea, dehydration, and possible death
› Water supplies can become contaminated, and drinking contaminated water and eating contaminated food spreads the disease
› Caused by Vibrio cholerae, a gram negative bacterium
› Vaccine provides temporary protection, antibiotics can be used, and water supply should be well treated

Question 4

Describe tuberculosis, what causes it, and how it is prevented and controlled

Answer 4

› Lungs and neck lymph nodes infected, causing a bad cough, chest pain, and fever
› Transmitted via airborne droplet infection, through sneezing and coughing
› Caused by Mycobacterium tuberculosis, a rod shaped bacterium
› Prevented by vaccinating as a child, or antibiotics as an adult

Question 5

Describe influenza, what causes it, and how it is prevented and controlled

Answer 5

› Cells of upper respiratory tract infected, leading to sore throat, coughs, and fevers
› Transmitted via airborne droplet infection, through sneezing and coughing
› Caused by an RNA virus surrounded by a lipoprotein coat
› Vaccine is available but not effective due to many new strains emerging, hence good hygiene and quarantine should be used

Question 6

Describe malaria, what causes it, and how it is prevented and controlled

Answer 6

› Infects the liver and then the red blood cells, causing severe bouts of fever, and possibly coma and convulsions
› Transmitted by a vector (adult female mosquitoes), that inject saliva containing the protoctist
› Caused by the protoctist Plasmodium, which is parasitic
› Preventable by nets, insecticide, draining swamps, spraying oil on water, using anti-malarial drugs

Question 7

What are the four stages in viral replication?

Answer 7

› Attachment to a host cell
› Penetration into the cell
› Replication (via the genome acting as either mRNA or DNA providing code for synthesis of mRNA)
› Release of new viral particles

Question 8

Explain the two methods by which release of new viral particles occurs

Answer 8

› The lytic cycle, where cells lyse allowing virions to be free to infect more cells (destroys cells, causing more harm)
› Lysogeny, where the virus exists in a latent form within the host cell, usually integrated into the host DNA

Question 9

What are the two types of antibiotics?

Answer 9

› Bacteriocidal, which kill microbes directly

› Bacteriostatic, which prevent growth of microbes

Question 10

What can cause antibiotic resistance?

Answer 10

› Random mutations (can only happen in the presence of the antibiotic)
› Plasmid transfer between different bacteria species
› Overuse of antibiotics in agriculture and by over-prescription