Epidemiology

Question 1

What are the types of parasites that cause disease?

Answer 1

Micro; small, multiply in host
Macro; big, multiply outside of host

Question 2

What are the 2 different classes of transmission?

Answer 2

1. Contact
2. Non-contact

Question 3

Describe 3 types of contact transmission

Answer 3

Direct:
- infected to colonised/susceptible host.

Indirect:
- Agent on surface, transfers to susceptible

Droplet:
- Contact, transmitted through air (more than 5 micrometers big).

Question 4

Describe 3 types of non-contact transmission

Answer 4

Airborne:
- Aerosols w organisms in nuclei, maybe via ventilation systems.

Vehicle:
- Single contaminated source spreads infection.

Vector-borne:
- Insect or animal vector transmission

Question 5

What is a DALY

Answer 5

Disability adjusted life year:
- No of healthy years of life lost due to premature death/disability

Question 6

What type of transmission is the plague?

Answer 6

Vector-borne via fleas

Question 7

What are the 3 types of plague?

Answer 7

• Bubonic
• Septicaemic
• Pneumonic

Question 8

Is plague fatal?

Answer 8

30-100% mortality but survival w treatment (antibiotic)

Question 9

Scheme of transmission of plague

Answer 9

1. Flea to Mammal
2. Mammal to Human
3. Flea to Human
4. Mammal to Flea
5. Flea or Mammal to Cat

Question 10

Arthropod vector-borne protozoan microparasite examples

Answer 10

1. Chagas disease -> Tryponosoma Cruzi
2. African sleeping sickness -> Tryponosoma Brunei
3. Malaria -> Plasmodium spp

Question 11

Symptoms of Chagas disease

Answer 11

Acute = inflammation, myocarditis
Chronic = kidney disease, myocarditis

Question 12

Chagas disease stats

Answer 12

Endemic to 21countries
6-7mil cases/year
10,000-14,000 annual deaths
100mil people at risk

Question 13

Chagas disease transmission

Answer 13

Vector-borne i.e. from “kissing bugs”
Vertical transmission in pregnancy to foetus
Accidental ingestion of infected material

Question 14

What are the features of macroparasites?

Answer 14

• Chronic and recurring (i.e. creates no immunity)
• Low mortality, high morbidity
• Direct contaminative transmission

Question 15

Typical life cycle of macroparasite

Answer 15

e.g. faecal-oral route.