Emerging Infections Flashcards
1
Q
Desribe food borne infection.
Give examples and state how it can be prevented / curtailed.
A
- Examples:
- Salmonella
- Shigella
- Listeria - increased recently because it can continue to grow at refrigerated temperatures.
- Food handlers spreading infection - hand washing and exclusion from work.
- Adequate decontamination through pasteurisation.
- Adequate cooking to kill pathogens.
2
Q
What are the main ways in which infections are transmitted?
A
- Aerosol
- Hands
- Sexual
- Faecal-oral
- Arthropod
3
Q
Give examples of water borne infections and state how to prevent their spread.
A
- Examples:
- Cholera
- Amoebiasis
- Cryptococcosis
- Aeparate sewage from water supply.
- Purify the water.
- Monitor water quality.
- Boiling water in emergencies.
4
Q
Describe how to manage preson-to-person spread of infection.
A
- Wide range of organisms transmitted by person-to-person spread.
- Identify cases.
- Isolate using appropriate methods.
- Treat to render non-infectious.
- BREAK THE CHAIN OF INFECTION.
5
Q
How do you break the chain of infection in a disease being transmitted by person-to-person spread?
A
- Contact tracing
- Isolation
- Early treatment
- Vaccination
- Antibiotic prophylaxis (e.g. meningitis)
6
Q
Describe zoonosis.
A
- A disease spread from animals to humans.
- Can be direct spread from animals or through vectors e.g. insects.
- Can arise through food.
- Can arise through animal husbandry.
- Can arise when humans invade new environment e.g. logging.
- Zoonotic diseases can be maladapted to the human host and cause severe symptoms - animal ringworm.
- Zoonotic infections can cause disease regularly e.g. salmonellosis.
- Some zoonotic diseases can ‘jump species’ and enter the human population.
7
Q
What is an endemic?
A
- A disease that is constantly present in a community.
- The numbers of cases may fluctuate from time to time.
- Endemic diseases are often sustained by a complex interaction between hosts, environment and ecosystems.
- Endemic diseases can be eradicated with complex interventions (vaccination).
- Examples cover a wide range if organisms and infectious disease entities:
- Malaria
- Influenza
- Meningococcal disease
8
Q
What is an epidemic?
A
- Epidemics occur when the number of cases is very large and significantly exceed the background.
- Epidemics can spread widely in the community.
- Epidemics may have a regular periodicity but do not need to.
- Influenza can become epidemic if the numbers of cases rise significantly. This is usually associated with antigenic change.
- In the pre-vaccination era, mumps, measles and chickenpox had regular periodicity related to the number of immune naïve hosts available to infect.
9
Q
What is a pandemic?
A
- A pandemic occurs when an infection spreads globally.
- This can be rapidly as in the case of influenza or cholera.
- It can occur slowly as in the case of HIV or tuberculosis.
- Examples:
- Cholera
- Plague
- Tuberculosis
- Influenza
- HIV
10
Q
Why do pathogens appear to emerge?
A
- We develop new methods to detect previously unrecognised pathogens e.g. molecular or better culture techniques.
- Pathogens jump from one species into the human species.
11
Q
How do new infections emerge?
A
- Between 60 and 80% of emerging infections spread from an animal source.
- Infectious disease emergence can be viewed operationally as a 2-step process:
- The agent must ‘jump’ into a new host population.
- Note: this may be a pathogen that originated in the environment or in another species or as a mutant of an existing human pathogen.
- Then it must establish itself in the new host range and disseminate in that new host population (adoption).
- The agent must ‘jump’ into a new host population.
12
Q
Why do new pathogens emerge?
A
- Depends on the interaction of microorganisms and the human population.
- Microbial change - constant; otherwise they would disappear.
- Ecological change
- Demographics and behaviour
- Technology and healthcare
- International travel
- Breakdown of public health measures
- Changing susceptibility
13
Q
What effect does microbial change have on emerging infection?
A
- Emergence of a new pathogenicity factor.
- Emergence of resistance.
- Mutation to vaccine resistance.
14
Q
What types of ecological change may cause emerging infections?
A
- Changing land use e.g. agriculture, forest clearance, dam building, irrigation.
- Climate change e.g. vector range (mosquitos)
- Short term weather conditions such as flooding.
15
Q
How do human demographics and behaviour affect emerging infections?
A
- Population pressure on food resources - invading new terriotory.
- Bush meat.
- Migration to towns - overcrowding.
- Changes in cultural norms - eating things that were never previously.
- War - overcrowding, malnourishment, stress. A perfect storm for invading infections.
- Increasing global tourism especially extreme holidays - exposure to things we would never have been before.
