Lecture 37 Flashcards
What stages do all mechanisms of transmission have?
Escape from the host, travel and entry into the new host. Could be direct or indirect.
What are the sources of infection and mechanisms?
Animal reservoirs, nonliving reservoirs or human carriers/cases.
Mechanisms include: contact (direct, indirect (contaminating a surface) or droplets (e.g sneezing or coughing), vectors (mechanical e.g flies carrying diseases passively or biological (e.g zika virus is hosted by mosquitoes).
Where can pathogens be found in the body?
All parts of our body can carry pathogens.
What is a nosocomial infection?
An infection acquired in health care facilities, these can be exogenous, endogenous(e.g via catheters) or latrogenic (doctor or other health professional accidentally transfers an infection).
What is important for preventing pathogen spread in hospitals?
Good hygiene and use of antiseptics (sterile equipment).
What are the stages of infectious disease?
Incubation period (no signs or symptoms, low amount of microorganisms), prodromal period (vague, general symptoms, normally short length of time, still not a huge amount of microorganisms), illness(most severe signs and symptoms, amount of microorganisms is about to reach the peak), decline (declining signs and symptoms as the amount of microorganisms decreases), convalescence (no signs or symptoms, a relatively low amount of microorganisms).
What does the incubation period length depend on?
The virulence, dose of microorganism, immune defences, pathogen characteristics and the site of the infection.
Why can the prodromal period be important for differential diagnosis?
the length of time can be different for different diseases despite the symptoms being the same.
What are the main characteristics of the illness stage?
The characteristic signs and symptoms of the disease become evident and the immune response is not yet helpful. At this stage the disease is normally most infectious.
What is the decline stage associated with?
The immune response or medical intervention leads to decrease in pathogen numbers and the symptoms subside. The immune parameters generally peak at this point and the pathogen may enter a latent phase.
What is the convalescence stage associated with?
The patient recovers and the tissues repair, the amount of time will depend on the amount of damage, the nature of the pathogen, infection site and the patient health.
How can diseases be classified?
Based on body system (e.g respiratory, enteric or renal).
Based on the taxonomic group (staphylococci, salmonella).
Based on the longetivity and severity (e.g acute, chronic, subacute (between chronic and acute) or latent).
What terms can be used to describe the epidemiology of a disease?
Epidemic: occurs in a large number of people in a population at the same time
Pandemic: widespread disease, usually worldwide
Endemic: constantly present in a population, usually at low incidences.
Sporadic: only involves a few scattered cases.
How are epidemiological studies done?
Reporting of clinical cases, diagnostic follow up to confirm the disease incidence, monitoring the disease incidence following therapy/vaccination. Monitoring case histories/patient records can also be done.
Why is prevalence normally higher than incidence?
Incidence refers to the number of new cases, prevalence refers to the number of total cases. Once infected individuals will keep the disease (particularly if latent like HIV).
