Acute gastrointestinal illness

Question 1

Symptoms

Answer 1

Vomiting
- especially for intoxifications 
- nausea 
Diarrhoea 
- Acute watery (rice water stools) 
- Blood (dysentry) 
- severe (6+ unformed stools per day)
Abdominal pain and cramping 
Fever

Question 2

Microbial causative agents

Answer 2

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

Question 3

Viral Symptoms

Answer 3

Watery diarrhoea not bloody 
Abdominal cramps 
Muscle ache 
Low grade fever 
Headache

Question 4

Viral, things to know

Answer 4

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

Question 5

Bacterial, types that colonise intestines and produce toxins

Answer 5

Clostridium difficile (noscominal diarrhea)
*Shiga (or vero) toxin producing Eshericha coli (STEC/VTEC)
*Shigella dysenteriae
Enterotoxigenic E coli
Vibrio cholera

• Dysentery common

Question 6

Bacterial, colonisation of intestines invasion of intestinal tissue

Answer 6

campylobacter jejuni
Non-typhoid salmonella
Yersinia enterocolitis
Enteroinvasive E coli

Question 7

Bacterial, toxin produced in food and ingested, no injection, food poisoning

Answer 7

staph aureus 
Clostridium perfrinigens 
Bacillus cereus 
Vomiting within 2-7 hours 
Symptoms cleared within 1-2 days 
identification most likely from remaining food

Question 8

Protozoan

Answer 8

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!!!

Question 9

Diarrhoea disease in developing countries

Answer 9

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

Question 10

Define and outbreak and how can it be spread?

Answer 10

2 or more cases linked to a common source, community wide or person to person spread

Question 11

Course of AGI

Answer 11

animal or human GI tract / faeces 
Animals 
Infected people / carriers 
Contaminated food 
Contaminated water

Question 12

Routes of transmission

Answer 12

fecal / oral route

indirect

Question 13

Risk factors

Answer 13

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

Question 14

If watery diarrhoea and possibly seafood involved test for?

Answer 14

Vibrio

Question 15

Test for what if bloody diarrhoea

Answer 15

STEC

Question 16

stool culture sample numbers?

Answer 16

1 sample unless you want to confirm not a carrier e.g. for food worker 3 negative tests aren’t required

Question 17

Why don’t you microscopy instead if stool culture?

Answer 17

Microscopy of limited value because of large numbers of bacteria in faeces

Question 18

Give some examples of agar types used for stool cultures

Answer 18

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,

Question 19

Protozoa and viruses: diagnostic tests

• outbreak
• Stool culture
• 4+ weeks of diarrhoea, not bacterial
• Antigen test

Answer 19

• Norovirus, rotavirus
• Antibody or PCR based test, EIA for rotavirus
• Giardia, cytosporidium
• possibly microscopy for ova ect

Question 20

Complications of AGI

Answer 20

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

Question 21

Treatment of symptoms

Answer 21

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

Question 22

Treatment of microbial cause

Answer 22

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

Question 23

Prevention

Answer 23

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