Transmission Of Infectious Disease

Question 1

Define and give example

1. Pandemic
2. Epidemic
3. Endemic
4. Sporadic

Answer 1

1. Pandemic - TB, spread over several countries/worldwide
2. Epidemic - SARS outbreak, sudden increase in number above what is expected
3. Endemic - Malaria in africa, always present in a population/region
4. Sporadic - Legionnaires disease, occurs infrequently and irregularly

Question 2

List criteria for disease transmission (4+)

Answer 2

1. Survive in outside environment
2. Sufficient infective dose e.g. vibrio cholerae 10^5 vs mycoTB less than 10 organisms
3. Establish colonisation in host
4. Others: stability of microbes (desiccation, temperature, chemicals), host shedding/transmission, pathogen genetic factors

Question 3

List 3 types of transmission and 6 routes

Answer 3

Types: horizontal, vertical (in utero, intrapartum, postpartum), zoonoses

Routes: mucosal - respiratory, oral, venereal, skin, blood, vectors

Note: direct, indirect, aerosol (<5um) vs droplets

Question 4

List general prevention strategies infectious disease (8)

Answer 4

1. Eliminate source of infection
2. Reduce vectors
3. Vaccine
4. Food/water hygiene
5. Sufficiently cooking meat
6. Personal hygiene
7. Washing hands between patients
8. Safe sex

Question 5

Influenza methods of transmission (4) and prevention of transmission strategies (6)

Answer 5

Methods: droplets, aerosols, direct, indirect

Prevention: flu vaccine, antiviral drugs, washing hands, cleaning surfaces, educate patients (+ avoid contact/secretions)

Question 6

TB methods of transmission (1) and prevention of transmission (3)

Answer 6

Methods: Aerosols 1-5 micrometres

Prevention: identification and proper treatment, educate re. Cough etiquette and hygiene, BCG vaccine