Communicable Disease

• Define communicable disease.

  Illnesses caused by viruses or bacteria that people spread to one another through contact with contaminated surfaces, bodily fluids, blood products, insect bites, or through the air.

  Some communicable diseases require reporting to health departments or government agencies.
• What is the epidemiologic triad?

  Host, agent, environment

  In order for a disease to occur there needs to be interaction between these variables

  
• What is the cycle of infection?

  Agent

  Transmission

  Portal of entry

  Susceptible host

  Reservoir - acts a source of agent

  Portal of exit

  
• Define pathogenicity.

  The power of an infectious agent to produce disease
• Define virulence.

  Ability to produce severe pathological reaction

  Measured by the ratio of clinical to subclinical disease & case fatality rate
• What is inoculum?

  Dose of infection

  High probability of severe disease with higher dose of infection
• What is resistance, in terms of 'The Agent'?

  Viability of the organism

  Ability of the organism to live outside the body
• How does spore formation impact the survival of microorganisms?

  Maintain viability got a long period of time in an unfavourable environmental conditions
• What is the 'antigenic power' of an organsim?

  Ability to stimulate the immune system to produce antibodies or antitoxin with subsequent immunity

  Measured by the second attack frequency
• What is 'ease of communicability'?

  How easily the microorganism can spread

  Measure by the secondary attack rate -> number of secondary cases, within the range of incubation period following exposure to a primary cause expressed as a percentage of susceptible
• Define control, in terms of communicable disease.

  Activities conducted to bring a disease or health problem ar a very low level till it becomes no longer a public health problem
• Define elimination, in terms of communicable disease.

  Termination of all modes of transmission to a reduce the incidence of the disease to 0 in a confined or specific geographic locality

  Due to deliberate efforts yet, continued intervention methods are required
• Define eradication, in terms of communicable disease.

  Termination of all modes of transmission of infection by extermination of the infectious agent
• What are fomites?

  Inanimate objects or materials that can carry infectious agents.
• What measures can be taken to manage communicable disease that are directed to the agent?

  Sterilisation

  Disinfection

  Antiseptics

  Sanitisation
• What is sterilisation?

  Complete removal of all forms of living/infectious agent
• What is disinfection?

  A process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects
• What are anti-septics?

  Disinfectants for use on skin
• What is sanitisation?

  Cleaning or disinfection of an area or an item using heat or chemicals to reduce the number of microorganisms to safe levels
• What measures can be taken to manage communicable disease directed towards breaking transmission?

  Isolation

  Decontaminating of fomites

  Promote handwashing

  Modify ventilation & air pressure

  Control vector population

  Environment - sanitation of water, food, proper sewage handling
• What measures can be used to manage communicable disease directed towards the reservoir?

  Case finding - to apply control measures for contact, isolation for whole period of communicability & treatment, surveillance for incubation period

  Identify carriers - treat & exclude from activities (inc. work) until organism is eliminated

  Animal reservoir - adequate animal husbandry, immunization of animals, treatment of infected animals & killing if treatment is not feasible
• What measures can be used to manage communicable disease directed towards protecting portal of entry?

  Using bed-nets

  Wearing masks & gowns to prevent entry of infected body secretions or droplets through skin or mucous membranes

  Covering skin & using insect repellents
• What measures can be used to manage communicable disease directed to the host?

  Health education

  Adequate personal hygiene

  Sound nutrition

  Immunization

  Chemoprophylaxis
• How can modelling be used in communicable disease?

  Modelling is an important part of managing infection

  Can use data from a variety of different sources to construct possible values for parameters, that can then be used to generate predications to inform policy decisions

  
• How are infections managed in the community?

  Local authorities & UK Health Security Agency (former Public Health England) will contact cases to indetify & control the spread of infection

  
• What is the management of infection in hospitals?

  Director of Infection Prevention and Control (DIPC)

  Infection Prevention and Control Team

  Faster than in community, as there are many suseceptible patients
• What are the standards for managing outbreaks?

  Outbreak recognition

  Outbreak declaration

  Outbreak Control Team - management

  Outbreak investigation & control

  Communications - clarity about outbreak

  End of outbreak - outbreak report completed within 12 weeks
• What is the impact on practice of communicable disease?

  Understand the route of transmission

  Design of facilities

  Environment

  Understanding risk associated with various procedures (e.g. taking blood)

  Use of PPE

  Bodily fluids as source of infection

  Sanitisation
• Registered medical practitioners have a statuatory duty to notify the 'proper officer' at their local council or local health protection team (HPT) of suspected cases of certain infectious diseases.
• What makes communicable diseases notifiable?


  Significant mortality/morbitiy AND/OR ease of rapid spread
• Communicable vs non-communicable disease (definition).

  C - disease spread from person to another, they are 'catching' disease & can be spread through air, water, etc.

  NC - disease which does not spread from 1 person to another through any mode
• Communicable vs non-communicable disease (cause)

  C - by pathogens considered as highly infectious & vectors play the major role in spreading disease form one person to another

  NC - caused due to allergy, illness, malnutrition or abnormalities in cell proliferation, changes in lifestyle & environment play significiant role
• Communicable vs non-communicable disease (infecting agent)

  C - bacteria & virus

  NC - no infectious virus
• Communicable vs non-communicable disease (inheritance)

  C - disease cannot be inherited

  NC - can be inherited
• Communicable vs non-communicable disease (treatment)

  C - treated by conventional methods (meds)

  NC - treated conservatively or surgically
• Communicable vs non-communicable disease (type)

  C - acute

  NC - chronic
• Communicable vs non-communicable disease (precaution)

  C - wear mask, wash hands, avoid sharing belongings, stay away from infected person

  NC - regular checkups, exercise, proper sleep & rest
• What are the national strategies for communicable disease?

  Prevention, surveillance, containment, treatment

  
  

  Optimise vaccine provision

  Tackling antimicrobial resistance