Communicable diseases Flashcards
What has Public Health England been replaced with?
UK Health Security Agency
Office for Health Improvement and Disparities.
Define communicable disease
Illness caused by infectious microbes normall bacteria or viruses that spread from one individual to another via contact with a contaminated object e.g surface, bite or air droplet
What is the key difference between what a communicable and non-communicable disease are?
Communicable - spreads, caused by infective agents or pathogens, highly infectious or rely on vectors. Examples - TB, COVID-19. Can not be inherited. Tend to be acute
Non-communicable - does not spread, caused by allergy, illness, malnutrition, combination of environmental or genetic factors. No infectious agent. Examples include cancer, rickets. Can be inherited. Tend to be chronic
What are the key difference in the management of communicable and non-communicable disease?
Communicable - conventional methods, antibiotics etc. Prevent further spread by wearing masks, PPE, hand hygiene, isolation of infected individuals
Non-communicable - conservative or surgical treatment, precautino through regular check ups, maintain proper diet, daily exercise, taking proper sleep and rest.
What is the epidemiological triad of infectious disease?
Agent of infection - the pathogen
Environment - mechanism of transmission or reservoir
Host - susceptible to infection
These can all be linked by a vector - acts as a intermediate for survival and transmission.
What are the different stages in the chain of infection?
Agent of infection - virus, bacteria parasite etc
Mechanism of transmission - water born, air droplets etc
Portal of entry - cuts in skin, mucous membranes
Susceptible host - influenced by lifestyle, genetics, risk factors
Reservoir of infection - replicates and survives
Portal of exit - vomit, diahorrea.
Define pathogenicity
The power of an infective agent to cause disease
Pathogenic or not.
Define virulence of a microbe
The ability to produce severe pathological reactions
Measured by the rate of clinical to subclinical disease and the case fatality rate
Describe a property, how nasty, the disease caused by pathogenic microbes is.
Define dose of infection (inoculum)
Inoculum - amount of mircobe given to a patient.
MID - The size of the population of the microorganism required to cause disease.
Higher probability of severe disease with higher dose infection.
Define viability of the organism (resistance)
The ability of an organism to surive outside the host body.
Ability to persist during transmission between hosts.
A viable organism is living and able to reproduce.
How does spore formation affect viability of an organism?
Spore formation - maintains viability for a long period in unfavourable environmental conditions
Spores - resistant to death in harsh environmental conditions, dormant bacteria with minimal metabolism or respiration.
What is meant by the antigenic power of an organism?
The ability of an organism to stimulate the immune system to produce antibodies or antitoxins with subsequent immunity
Measured by second attack frequency (second occurrence of same pathogen in individual)
What is second attack rate?
The probability that an infection occurs within susceptible individuals within a specified time after close contact with infected individual.
What is meant by the ease of communicability of an organism?
Measured by the second attack rate
Indicates the number of secondary cases likely to occur within the range of the incubation period following exposure to a primary case
Often given as a percentage of the susceptible population.
May be represented by the R-value - which is the number of people that an infected individual is expected to pass the disease on to.
How can we break the chain of infection at the reservoir stage?
Ensure environmental sanitation
Disinfection and sterilisation
Water hygiene methods - filtering
Employee health in healthcare environments - using antivirals/antibiotivs when appropriate
How can we break the chain of infection at the portal of exit stage?
Hand hygiene
Control of excretions and secretion
Trash and waste disposal effectively
How can we break the chain of infection at the mean of transmission stage?
Isolate infected individuals
Ensure correct food handling
Airflow control (ventilation in hospitals)
Standard precautions - PPE when taking bloods etc
Sterilisation of surfaces/fomites
Hand hygine
How can we break the chain of infection at the portal of entry stage?
The aseptic technique when handling clinical examinations/material e.g blood
Catheter care - insertion technique and replacement when/if needed
Wound care - wear waterproof plaster, clean around the area,
Examples - bed nets, covering skin to prevent entry through skin or mucous membranes, using insect repellents
How can we break the chain of infection at the susceptible host?
Recognition of high risk patients - additional safety mechanisms e.g vaccines etc
Treatment of underlying diseases for example effective flu management to reduce risk of pneumonia, management of HIV to reduce risk of infection in AIDs.
Health education
Adequate personal hygiene
Sound nutrition
Immunixsation
Chemoprophylaxis
How can we break the chain of infection at the infectious agent stage?
Rapid and accurate identification of organsisms - targeted and effective treatment
Sourcing and linking cases to identify source of infection an dhow to eradicate