GI infections & diseases Flashcards
Case based PH management
(what to do when a case of a disease is reported)
- find out symptoms (make sure fits diagnosis)
- when did symptoms start
- place (of residence, travel, contact with someone with disease, been to a location where lots of people congregate (depends on how much exposure needed), shared cooking/food/utensils, sexual partners, school (if relevant),
- travel on plane (depends on condition - laminar flow in planes)
- vaccination history
- Risk assessment (how social are they etc.)
- Contacts: depends on incubation period (1 week for meningitis). Give high risk contacts chemoprophylaxis (for meningitis - coverage up to 28 days from contact)
What is the objective of a public health history
where did pt get disease from and who might they have given it to
Identify risk settings & high risk groups
What PH action to take following risk assessment
Initiate action for confirmed and probable cases (usually not for possible cases)
there is a difference between individual level case management and population level case management (therefore if high numbers of cases or if it is endemic response might be different - may have to cut corners)
How are GI infections defined
transmission route (faecal-oral) not presentation/symptoms (any infection whos source is in the GI tract)
Most common (globally) GI infections
Ecoli
Salmonella
Cholera
Shigella
Typhoid
Travellers Diarrhoea
Most common (UK) GI infections
Viral: norovirus (effects elderly), rotavirus (effects young) (rotavirus decreasing due to vaccine)
Bacterial: Campylobacter, salmonella
Shiga toxin
Dangerous
Produced by STEC (Shiga toxin producing E Coli (most common = E.coli0157) & shigella
Travels throughout body
Can cause haemolysis and kidney failure (HUS: Haemolytic Uraemic Syndrome)
Parasites that can cause GI infection
Cryptosporidium
Giardia - can cause long term malnutrition
Issues with diarrhoea surveillance
Cases reported = tip of the iceberg
Not all go to GP, not all that go to GP get tested
Often norovirus clears within 2 days whereas campylobacter lasts longer (2 weeks) - so numbers appear higher
What is the epidemiological triangle
Host (age, sex, race, genetics, previous disease, immune status, religion, customs, occupation, marital status, family background)
Environment (temperature, humidity, altitude, crowding, housing, neighborhood, water, milk, food, radiation, pollution, noise)
Agent (biologic (bacteria, viruses), chemical (poison, alcohol, smoke), physical (trauma, radiation, fire), nutritional (lack, excess)
Key aspects of agent in epidemiology triangle
An organisms transmissibility determines likelihood of spread
An organisms pathogenicity determines its likelihood of causing severe illness
Key aspects of host in epidemiology triangle
Susceptibility - likelihood of acquiring an organism & how severe the disease is likely to be
GI Risk groups
Group A: people who can’t practice good hygiene (mental illness, elderly, no WASH)
Group B: children before their 6th birthday party & attend childrens groups
Group C: food handlers
Group D: health and social care workers
(groups C&D generally won’t get very ill but risk transmitting to lots of people)
(Group B: concerning as can get it easily, pass it on easily and can get complications)
Standard diarrhoea exclusion advice
stay away from work/school for 48 hours after the diarrhoea stops (as when diarrhoea stops not all bacteria gone)
Diarrhoea exclusion in Risk Groups
need to test negative before go back to work – people who deal with food, work with immunocompromised etc. generally all healthcare workers and social workers
Key aspects of environment in epidemiology triangle
Faeco-oral transmission
- contaminated food (raw/unwashed)
- contaminated water (untreated)
- contaminated soil
- Contaminated hands after toilet/changing nappy, touching soil, animals
- from an infected person to an unaffected person.
What does incubation period depend on
Big dose - will get ill quicker
Weaker immune system - will get ill quicker
(since organism attacks cells and grows until body can’t cope –> show symptoms)
Clinical symptoms of GI infection
Fever
Vomiting
Diarrhoea
Abdominal cramps
Blood in stool (due to ulcers - never fresh blood)
Mucus in stool (cell material due to ulcers)
Clinical treatment of GI infections
Fluids
Medication to control fever
No meds for vomiting or bowel movements
No abx unless specifically indicated
admit to hospital where needed
Who is most at risk of getting STEC
Group A & B. Particularly at risk of acquiring & getting complications
Environment for STEC
Faeco-orally transmitted
- contaminated food/water
- direct contact with animals particularly cows
- secondary from infectious case
High risk settings: restaurant, petting farm, nursery
Most at risk people for STEC
<5 & elderly
STEC incubation period
2-4 day
Min 6 hours
Max 10 days
STEC symptoms & progression & complications
Diarrhoea progressing to bloody diarrhoea
Abdominal cramps
Occasionally fever
After 5 days either resolve or develop complications.
Complications: 5-10% of children & elderly: HUS
Diagnosis for STEC
Lab diagnosis
Stool sample –> culture (only alive)
PCR test for toxin (doesn’t indicate if organism is dead or alive so can’t tell if it is the issue - so following positive PCR do culture
Notification for STEC
Registered Medical Practitioners should notify based on clinical suspicion (don’t wait for lab)
Labs should notify
Indications for clinical suspicion: bloody diarrhoea, HUS
Public Health Management for STEC
- Verify diagnosis
- Source: identify & control
- Spread: stop/prevent
Information collection (to identify source): questionnaire to identify exposures in 10 days before onset of symptoms (exposures 2-4 days before - most likely)
Identify contacts: household, sexual (especially MSM), food handling, caring, shared exposure (make people aware if they are likely exposed), anyone else who is symptomatic (either secondary case or source), identify anyone in a risk group (may need different action)
Action:
- advise case and contact (personal & food hygiene, environmental cleaning) & STEC info leaflet
- Test case if not already tested
- Test symptomatic contacts
- Screen asymptomatic risk group contacts
- advise asymptomatic non risk group contacts to watch out for symptoms
- exclude case and contacts as appropriate (not in risk group: exclusion for 48 hours after diarrhoea stops; in risk group: exclusion until 2 stool samples 24 hours apart are negative (first 24 hours after diarrhoea stops then 24 hours later) <– 2 samples as potential intermittent excretion of bacteria
- decide whether to shut down source (balance pros and cons)
Cluster vs outbreak
Suspected outbreak >2 cases
Cluster: unsure if link between cases
Suspected outbreak: link between cases
If 100% on link & clear exposure & timeline fits = outbreak
What is the aim of outbreak control
to identify and control the source of infection & the route of transmission to prevent spread of infection (further cases)
