Lecture 23: Diarrhoea and Acute Gastrointestinal Illness Flashcards
What are the general signs and symptoms of acute gastrointestinal illnesses?
Acute gastrointestinal illness can exhibit:
-
Vomiting (esp. strap. aureus)
- intoxications,
- nausea
- Abdominal pain
-
Diarrhoea
- __acute;
- watery;
- bloody (dysentery)
- severe (6+ times day))
- Fever (invasive infection)
What are the features of the different microbial causative agents for AGI?
****Important***
1) Onset
2) Diarrhoea
3) Vomitting
4) Fever/Pain
5) Rehydration?
6) Antibiotics?
Viral
- Faster (hrs/day)
- Porbably have diarrhoea
- Vomit
- Need rehydration
Bacteria
- Diarrhoea
- Possibly vomitting
- Abdominal pain
- Soemtimes give antibiotics
- Need rehydration
Protozoa
- Slower (day/week)
- Diarrhoea
- Possibly vomitting
- Abdominal pain
- Probably give antibiotics
- Need rehydration
Describe Viral caused AGI
Viral (Norovirus; Rotavirus)
Symptoms include:
- Nausea and Vomiting.
- Watery diarrhoea (not bloody).
- Abdominal cramps.
- Muscle ache.
- Low grade fever.
- Headache.
-
Colonisation of small intestine include
- (1) norovirus (+ve strand ssRNA);
- (2) rotavirus (dsRNA, produces enterotoxin stimulating Cl- secretion)
- Generally s_elf-limiting_, over in 48 hours
- Effective rotavirus vaccines available
- Supportive treatment with effective rehydration is sufficient
Be aware of outbreaks and potential for outbreaks (e.g. contaminated food)
What are the 2 viruses that can cause AGI?
Norovirus
Rotavirus
How can bacteria cause acute GI illness?
Bacteria can cause acute GI illness by:
-
Colonisation of intestines and production of toxins, or
- Cholera
- Colonisation of intestines and i_nvasion of intestinal tissue,_ or
- Toxin produced in food and ingested, no infection, i.e. food poisoning.
What are the Bacteria involved in colonisation of intestines and production of toxins?
- Clostridium difficile (nosocomial diarrhoea)
- Shiga (or vero) toxin-producing escherichia coli (STEC/VTEC) (damage to GI tract, bleeding, dysentery common)
- Shigella dysenteriae (damage to GI tract, bleeding, dysentery (bloody diarrhoea) common)
- Enterotoxigenic escherichia coli
- Vibrio cholerae
(bolded) = Dysentery common. All will most likely begin with acute watery diarrhoea.
Describe the Bacteria involved in colonisation of intestines and invasion of intestinal tissue
- Campylobacter jejuni
- Non-typhoid Salmonella
- Yersinia enterocolitica
- Enteroinvasive escherichia coli
Symptoms:
- May see blood in stool.
- Abdominal cramping common.
Describe Bacteria involved in toxin produced in food and ingested, no infection, i.e. food poisoning:
- Staphylococcus aureus
- Clostridium perfringens
- Bacillus cereus
Vomiting likely within 2-7h of consumption. Symptoms cleared within 1-2 days. Identification most likely from remaining food.
Describe Protozoa and AGI
Protozoa involved in c_olonisation of small intestine_ are giardia lamblia; cryptosporidium.
- Food/water contaminated by human/animal faeces (at risk groups include tramper, farmer, pet owner, child carer)
- Incubation period of 1+ weeks.
- Symptoms may last 4-6 weeks, including diarrhoea, flatulence, foul smelling stools, abdominal cramps.
- Mostly self-limiting, but antimicrobials may be necessary (e.g. metronidazole for giardia)
- May cause serious illness in immunocompromised (esp. cryptosporidium).
- Cysts are resistant to disinfectants (e.g. chlorine). Therefore, boil water!
Describe the epidemiology of diarrhoeal diseases in developing countries
Diarrhoeal disease is the second leading cause of death in children under five years old.
- Diarrhoeal disease kills 1.5 million children every year. Estimated 120,000 due to cholera.
- Diarrhoeal disease mainly affects children under two years old (dehydrate quickly, rehydration does not work as well).
What constitutes as an “outbreak”
- Outbreak is when 2 or more cases linked to a common source.
- AGI is associated with outbreaks of disease
What are the 6 sources of contamination?
- Animal GI tract/faeces
- Human GI tract/faeces
- Animals
- Infected people and carriers
- Contaminated food
- Contaminated water
Describe the 2 possible faecal/oral routes of transmission of AGI (Direct; Indirect)
** Learn diagrams **
What are some prevention strategies for faecal/oral route (direct and indirect) route of transmission
** learn diagrams **
What are some risk factors for AGI?
Categories from surveillance reports:
- Consume food from retail premises
- Consume ‘at risk’ produce, e.g. soft cheese for Listeria
- Contact with farm animal
- Consume untreated water
- Contact with faecal matter
- Contact with symptomatic people
- Contact with recreational water
- Overseas travel within incubation period
- Contact with sick animals
Describe the diagnositic tests for bacterial - caused diarrhoea
1) Severe diarhoea
2) Stool culture
* Stool culture uses one sample unless want to confirm not a carrier, e.g. for food worker where 3 negative tests are required (need to make sure they are cured).
3) Toxin tests
- Antibody
- PCR of toxin gene
