Acute gastrointestinal illness Flashcards
Symptoms
Vomiting - especially for intoxifications - nausea Diarrhoea - Acute watery (rice water stools) - Blood (dysentry) - severe (6+ unformed stools per day) Abdominal pain and cramping Fever
Microbial causative agents
Viral
Bacterial
- colonisation of intestines and production of toxins
- Colonisation if intestines and invasion of intestinal tissue
- Toxin produced in food and ingested, no infection, food poisoning
Protozoan
Viral Symptoms
Watery diarrhoea not bloody Abdominal cramps Muscle ache Low grade fever Headache
Viral, things to know
Colonisation of small intestine
- norovirus, +ve strand ssRNA
- Rotavirus, dsRNA, produces enterotoxin stimulating Cl- secretion
Generally self limiting, over in 48 hours
Effective rotavirus vaccines available
Supportive treatment with effective rehydration is sufficient
Be aware of outbreaks and potential for outbreaks
Bacterial, types that colonise intestines and produce toxins
Clostridium difficile (noscominal diarrhea)
*Shiga (or vero) toxin producing Eshericha coli (STEC/VTEC)
*Shigella dysenteriae
Enterotoxigenic E coli
Vibrio cholera
- Dysentery common
Bacterial, colonisation of intestines invasion of intestinal tissue
campylobacter jejuni
Non-typhoid salmonella
Yersinia enterocolitis
Enteroinvasive E coli
Bacterial, toxin produced in food and ingested, no injection, food poisoning
staph aureus Clostridium perfrinigens Bacillus cereus Vomiting within 2-7 hours Symptoms cleared within 1-2 days identification most likely from remaining food
Protozoan
Colonisation of small intestine
- guardia lamblia
- cryptosporidium
Food / water contaminated by human / animal faeces
- at risk, tramper, farmer, pet owner, child carer
Incubation period of 1+ weeks
Symptoms may last 4-6 weeks
Diarrhoea, flatulance, fowl smelling stools, abdominal cramps
Mostly self limiting, but antimicrobials may be necessary (e.g. metronidazole for giardia)
May cause serious illness in immunocompromised (esp. cytosporidium)
Cysts are resistant to disinfectants e.g. chlorine, this is why you have to boil water to get rid of giradia!!!
Diarrhoea disease in developing countries
the 2nd leading cause of death in children under 5
kills 1.5M children/year
Globally 2 billion cases every year, eat 5 million cases of cholera
Mainly affects children under 2 years old
Define and outbreak and how can it be spread?
2 or more cases linked to a common source, community wide or person to person spread
Course of AGI
animal or human GI tract / faeces Animals Infected people / carriers Contaminated food Contaminated water
Routes of transmission
fecal / oral route
indirect
Risk factors
Consume food from retail premises Consume 'at risk'produce e.g. soft cheese for listeria Contact with farm animal Untreated water Feral matter contact Contact with symptomatic people Contact with recreational water Overseas travel with incubation period sick animals
If watery diarrhoea and possibly seafood involved test for?
Vibrio
Test for what if bloody diarrhoea
STEC
stool culture sample numbers?
1 sample unless you want to confirm not a carrier e.g. for food worker 3 negative tests aren’t required
Why don’t you microscopy instead if stool culture?
Microscopy of limited value because of large numbers of bacteria in faeces
Give some examples of agar types used for stool cultures
Sheep blood agar - growth of most pathogens, including listeria that don't grow on other media MacConkey agar with lactose - E coli ferment lactose Salmonella, shigella,
Protozoa and viruses: diagnostic tests
- outbreak
- Stool culture
- 4+ weeks of diarrhoea, not bacterial
- Antigen test
- Norovirus, rotavirus
- Antibody or PCR based test, EIA for rotavirus
- Giardia, cytosporidium
- possibly microscopy for ova ect
Complications of AGI
Dehydration
Bacteremia - salmonella, campylobacter
Haemolytic ureic syndrome - STEC toxin effects on kidneys
Gillan Barre syndrome - autoimmune attack of motor neurone sheath, campylobacter
Reactive arthritis
- autoimmune
- yersinia enterocoliticia
Treatment of symptoms
Fluid and electrolyte replacement - mix of clean water, salt and sugar - absorbed in the small intestine and replaces water and electrolytes lost in faces - Presumes access to safe, clean water Easily digestible food Anti-motility drugs - Reduce stool rate for acute watery diarrhoea - concentrate toxins
Treatment of microbial cause
antibiotics usually not required, may have small effect on duration and severity of symptoms
May reduce numbers shed, an important consideration for cholera and outbreaks
NOT RECOMMENDED for STEC as antibiotics can cause an increase in toxin production in vitro, although no evidence to support this if it happens in the human body
Prevention
Vaccines - not routine, limited efficacy, outbreak control Sanitation - Sewerage and clearwater Hygiene Effective cooking Food safety regulations for retail food outlets avoid risky food and drinking water
