Lecture 22 - Bacterial disease - Past, Present and Re-emerging

Question 1

What does it mean for a disease to be endemic?

Answer 1

The disease occurs regularly at low of moderate frequency.

Question 2

What are examples of endemic diseases in the UK?

Answer 2

Dental caries (tooth decay), caused by streptococcus mutans.
Mastitis (where a woman's breast tissue become enlarged and inflamed) is another example.

Question 3

What is an epidemic? Give an example of an epidemic that occurred in the last 25 years.

Answer 3

The sudden appearance of a disease, or increase above endemic level, an ‘outbreak’. For example the diphtheria epidemic in Russia in 1994, where nearly 40,000 cases were reported, up from the endemic rate of 1,200.

Question 4

What is a pandemic?

Answer 4

A epidemic on a global scale. For example, we are currently in the 7th/8th cholera pandemic.

Question 5

What forms of direct (human) horizontal transmission are there?

Answer 5

Sexual contact
Via respiratory tract
Contamination from own flora
Contact with skin, eyes

Question 6

Which bacteria can be transmitted by sexual contact?

Answer 6

Syphillis, gonorrhoea.

Question 7

Which bacteria can be transmitted via the upper respiratory tract?

Answer 7

Pharyngitis, scarlet fever, diphtheria.

Question 8

Which bacteria can be transmitted via the lower respiratory tract?

Answer 8

Whooping cough, TB, pneumonia, plague.

Question 9

Which bacteria can be transmitted by contamination from own flora?

Answer 9

UTIs from GI tract (more common in women than men for anatomical reasons).

Question 10

Which bacteria can be transmitted by contact with skin, eyes etc?

Answer 10

Boils, impetigo, fasciitis, conjunctivitis, leprosy, anthrax

Question 11

What forms of direct (human) vertical transmission are there?

Answer 11

Transplacental and during parturition.

Question 12

Which bacteria can be transmitted transplacentally?

Answer 12

Syphillis

Question 13

Which bacteria can be transmitted during parturition?

Answer 13

Gonorrhoea

Question 14

What forms of indirect (non-human) transmission are there?

Answer 14

By inanimate objects, food, water, animals and soil.

Question 15

What are nosocomial infections?

Answer 15

Hospital acquired infections.

Question 16

What are examples of nosocomial infections?

Answer 16

UTI following catheterisation, surgical wound, burn infections.

Question 17

What are nosocomial infections normally caused by? Give two examples of such bacteria.

Answer 17

'Opportunistic', often drug resistant pathogens.
Staphylococcus aureus (MRSA)
Pseudomonas aeruginosa

Question 18

Which bacteria can be transmitted by water (faeco-oral)?

Answer 18

Cholera, dysentery, typhoid

Question 19

Which bacteria can be transmitted by water (air-con, respiratory)?

Answer 19

Legionnaires’ disease

Question 20

What two effects can bacteria have on food? Which bacteria can be transmitted by each one?

Answer 20

Intoxication (ingesting a bacteria made poison) - staphylococcal food poisoning, botulism
Infection (ingesting a bacteria) - salmonellosis (chicken eggs), E.coli 0157 (beef)

Question 21

What are zoonoses?

Answer 21

Bacteria transmitted by animals.

Question 22

Which bacteria can be transmitted by livestock?

Answer 22

Brucellosis, leptospirosis, E.Coli 0157

Question 23

Which bacteria can be transmitted by wild animals?

Answer 23

Lyme’s disease via ticks.

Question 24

Which bacteria can be transmitted via a wound by spores in the soil?

Answer 24

Tetanus, gas gangrene.

Question 25

What are point source outbreaks of bacteria? Why can this occur with bacteria?

Answer 25

Origin of an outbreak from a single origin e.g. food poisoning, nosocomial infections. This can occur as bacteria can survive and replicate outside the host.

Question 26

What is Legionnaires’ disease and what is it caused by?

Answer 26

It is a pneumonic disease caused by Legionella pneumophila.

Question 27

When was Legionnaires’ disease first identified and how many cases did it reach in the US?

Answer 27

1976, 25,000 pa.

Question 28

What was Legionnaires’ disease typically contracted from?

Answer 28

Aircon units.

Question 29

What are continuous source outbreaks?

Answer 29

Cases where the source of a point source outbreak is not eradicated, especially in poor environments.

Question 30

What are examples of continuous source outbreaks?

Answer 30

Typhoid, traveller’s diarrhoea, hospital acquired Staphylococci, food-borne infections.

Question 31

What are propagated outbreaks?

Answer 31

Where host-to-host transmission results in ever greater numbers (exponential numbers) of infections e.g. whooping cough, TB, gonorrhoea, dysentry, cholera, typhoid.