The transmission of communicable disease

Question 1

What is direct transmission?

Answer 1

When an individual comes into direct contact with a reservoir of pathogens which are on or in their host

Question 2

What is indirect transmission?

Answer 2

When an individual comes into contact with a pathogen which is outside its host. These pathogens will have to withstand the harsh environment of being away from their host. (Have to overcome risk of drying out)

Question 3

Explain 3 examples of disease transmitted through direct methods

Answer 3

1. Influenza= droplet infection where small droplets of mucus or saliva that contain the pathogen are expelled from the nose and mouth and land on mucus membrane or are immediately breathed in
2. Gonorrhoea= sexually transmitted
3. Hepatitis B= sharing needles

Question 4

Explain 3 examples of diseases that are transmitted indirectly

Answer 4

1. Malaria= spread by bite of a female mosquito= insect is vector
2. Athletes foot= spread by sharing towels or socks= are fomites
3. Cholera= water is vector

Question 5

Explain how ‘living conditions such as overcrowding’ is a factor that affects transmission.

Answer 5

• droplet infection and airborne transmission spread disease as either fall on to new hosts, or are inhaled sometime later
• poor ventilation makes spread more likely as everyone breaths and re-breathes same infected air
• sharing of beds, towel and utensils increase risk of catching disease, as skin to skin contact more likely

Question 6

Explain how ‘social factors such as financial income, education, occupation, and where a person lives’ are factors that affects transmission.

Answer 6

• good health care for early diagnosis and treatment of disease reduces spread of pathogen.
• education about safe sex practices can provide information to stop the spread of HIV virus
• both of these things are sometimes only accessible to those who can pay for it

Question 7

Explain how ‘climate such as temperature and humidity’ is a factor which affects transmission

Answer 7

• malaria is most common in tropical countries, as mosquitos can’t survive cold winters and therefore can’t colonise in the uk
• also need still water to lay their eggs