Control of communicable diseases

What are communicable diseases?

Bacterial, viral, fungal and parasitic infections that can be passed from human to huma

What do communicable diseases cause and in what countries

• significant morbidity (ill health) and mortality

• particularly in low- and middle-income countries

• pandemic infections - economic, social and security impacts

Name 3 control measures to control communicable diseases

• social distancing

• mask wearing

• isolation period

What are reservoirs in the chain of infection and name them

• where infectious agent lives

• animals, humans, environment

Draw the chain of infection

What are the 3 paths from reservoir to human being infected in chain of infection

• direct (faecal-oral and direct contact)

• indirect (vector-borne and vehicle-borne)

• airborne (respiratory infection)

Most important part of chain of infection

susceptibility to infection

4 factors that affect susceptibility to communicable disease

• susceptible host (immunosuppression, extremes of age, medical treatment)

• genetics

• lifestyle factors

• socio-economic factors (pop density, sanitation, vaccination coverage, deprivation, access to healthcare and travel)

4 definitions of outbreak (of infectious disease)

• 2+ people experiencing a similar illness are linked in time or place

• greater than expected rate of infection compared with usual background rate for place and time where outbreak has occurred

• single case of certain rare diseases (polio, rabies)

• suspected, anticipated or actual event involving microbial or chemical contamination of food or water

4 outbreak identifications

• lab reports (whole genome sequening, microbiolgoy)

• clinical notifications (NOIDs)

• public concerns

• demand for related products/ services (NHS111 data for given sxs)

define surveillance

collecting data to identify or monitor trends in communicable disease incidence or distribution

what can surveillance provide information on

• incidence of disease

• geographical distribution

• seasonal distribution

• age and sec distribution

(provide early warning signals and help detect outbreaks)

Name 4 types of surveillance

• passive

• active

• sentinel

• enhanced

• syndromic

describe passive surveillance

• routinely collected data (lab reports/ clinician notifications)

describe active surveillance

• specifically collected data

• aims for completeness - usually reserved for rare/ highly contagious infections

describe sentinel surveillance

provides rough estimate of disease incidence and uses a sample of reporting units (e.g. GP practices)

descrive enhanced surveillance

• a form of active surveillance

• usually limited to particular time/ place/purpose (monitoring vaccine effectiveness)

5 most common HAIs (Hospital acquired infections)

• clostridium difficile

• MRSA

• CPE

• Legionella pneumophila

• norovirus

Why are HAIs common in pts, staff and visitors

• high density setting

• immunosuppression

• illness (diabetes)

• invasive procedures (IV lines, catheters)

5 ways to prevent HAIs

• education

• sreening

• isolation/ cohorting

• environmental cleaning

• learning from previous events (root causes analyses (RCA), audits)

3 (groups of) people that manage HAIs

• infection prevention and control team

• director of infection prevention and control - board level representation

• public health england - health protection team/ field epidemiology team

• staff - responsibility to prevent infections

• visitors

• local authority - responsible for community IPC

Draw the chain of infection and label how it can be targeted to prevent HAIs

name 3 bacterial communicable diseases

• pneumococcal infection

• Legionnaire’s disease

• Meningococcal disease

name 3 viral communicable diseases

• influenza

• Measles

• HIV

name 3 fungal communicable diseases

• candidiasis

• ringworm

• aspergillosis

name 3 parasitic communicable diseases

• malaria

• giardiasis

• tapeworm

define pandemics

outbreak of disease that spread across the world

Name a (indirect) vector-borne pathogen

malaria

Name an (indirect) vehicle-borne pathogen

Hepatitis B

Name 2 airborne respiratory pathogens

• TB

• legionella

Name a (direct) faeco-oral pathogen

viral GE

name 2 (direct) direct contact pathogens

• STIs

• scabies

What are vehicle-borne diseases transmitted through

through objects (e.g. needles)

describe syndromic surveillance

• based on sxs of pts in GP practices, A+E rather than definite diagnosis

• can serve as an early warning system

Most important HAIs pathogens in terms of outbreak potential

• C.difficile

• MRSA

• CPE

Define R number

• average number of new individuals who will contract an infectious disease from a single infected person

R0

R number in a pop that is highly susceptible to infection (no immunity)

Re

R number in pop with some level of immunity (vaccinated or where measures to limit spread have been taken e.g. self isolation)

What causes the R number to differ for different pathogens

• innate infectiousness of pathogen

• measures to limit transmission

List the steps of an outbreak management

Which members of MDTs manage outbreaks

• outbreak control teams (OCTs)

• incident management teams (IMTs)