Viral gastroenteritis (I) Flashcards
Define viral gastroenteritis.
Acute inflammation of the lining of the stomach and intestines caused by enteropathogenic viruses
What is the typical presentation of viral gastroenteritis?
Increased frequency of defecation lasting <14 days, which may be accompanied by nausea, vomiting, anorexia, abdominal cramps and fever
What causative viruses are there for viral gastroenteritis? (3)
Norovirus > sapovirus > rotavirus (most common in infants and children)
(Hepatitis A&E, caliciviruses, astroviruses, adenoviruses, parvoviruses)
What are some bacterial causes of gastroenteritis? (3)
- Campylobacter
- E. coli
- salmonella
What are some subtypes of E. coli in relation to gastroenteritis? (5)
- enterohaemorrhagic (EHEC): Shiga-toxin producing, O157 serogroup
- enterotoxic (ETEC): cholera-like toxin
- enteroinvasive (EIEC): shigella-like illness
- enteroaggregative (EAEC)
- enteropathogenic (EPEC)
Describe the incubation period for different pathogens for viral gastroenteritis.
- hours: preformed toxins (S. aureus) and non-infectious toxins (salmonella)
- days: most viruses (exc. Hep A&E), Campylobacter, Shigella, parasites
- weeks: Hep A&E, chronic exposure to heavy metals
What type of transmission is responsible for most cases of viral gastroenteritis?
Person-to-person transmission is responsible for infection in most sporadic cases
What is viral gastroenteritis mainly caused by?
Norovirus
However, most common cause of food poisoning in UK is Campylobacter jejuni (will present after a summer BBQ/in clusters)
What are the key clinical features of viral gastroenteritis?
- diarrhoea (sudden onset)
- blood/mucus in stool - indicates invasion of intestinal/colonic mucosa
- vomiting
- nausea
- loss of appetite
- abdominal pain
- fever and malaise
- signs of dehydration (dry mucous membranes, skin turgor, capillary refill, reduced urine output, tachycardia, hypotension, weight loss)
Describe different types of stool and their causative organisms in viral gastroenteritis.
- blood/mucus in stool - indicates invasion of intestinal/colonic mucosa
- blood more common in Shiga-toxin-producing E. coli (EHEC/EIEC)/Campylobacter/Shigella/amoebic
- rice-water stool - cholera
- watery stool - enterotoxigenic E. coli
What are the signs of dehydration in viral gastroenteritis? (7)
- dry mucous membranes
- skin turgor
- capillary refill
- reduced urine output
- tachycardia
- hypotension
- weight loss
When do symptoms set in for viral gastroenteritis caused by norovirus?
Abrupt onset, usually short-lived GI upset 24-48h after inoculation
What complication can viral gastroenteritis caused by norovirus cause and in which group?
Usually self-limiting in healthy people but can cause pre-renal AKI in frail population
How can we prevent viral gastroenteritis caused by norovirus?
Strict handwashing with soap and warm water to prevent spread
What can be seen on examination of viral gastroenteritis? (3 + 1)
- fever
- skin changes
- bloating, tenderness
Significant tenderness to palpation, guarding, rebound or point-specific tenderness should lead the clinician to consider other causes of symptomatology
What are some risk factors for viral gastroenteritis?
- exposure to contaminated food
- close contact with infected people
- poor hygiene
- extremes of age
- immunocompromised
- recent Hx of travel
- consumption of: undercooked meat, raw seafood, unpasteurised milk/juice, raw eggs
How is viral gastroenteritis diagnosed?
Clinical diagnosis based on Hx and examination; tests rarely needed to diagnose the pathogen
What are the 1st line investigations for viral gastroenteritis if we are starting IV fluids? (3)
- FBC - look for abnormally high/low WBC, Hb or platelets
- U&Es - urea, creatinine or ratio may be elevated –> because any diarrhoeal condition can lead to dehydration so important to monitor; IV rehydration may need to be tailored
- creatinine - abnormal result may indicate AKI
What investigation do we order for viral gastroenteritis if symptoms are atypical and you suspect a bacterial or parasitic aetiology?
Stool for culture, ova and parasites when there is:
- persistent diarrhoea (>14 days)
- blood/pus in stool
- tenesmus
- severe abdominal pain
- suspicion of non-viral gastroenteritis
- Hx of hospitalisation or Abx therapy in last 6 months
- Hx of recent foreign travel
What investigation is used to identify the causative virus for viral gastroenteritis?
Stool viral culture (rarely necessary)
What are some differential diagnoses for viral gastroenteritis?
- food poisoning (multiple people after eating same food/drink)
- C. difficile colitis (recent Abx use)
- non-infectious diarrhoea (caused by toxins/Abx side effects/post-infectious IB)
- IBD
- food allergies
- IBS
- microscopic colitis
- acute appendicitis / cholecystitis / pancreatitis / hepatitis
- malabsorption syndromes
- small/large bowel obstruction
- diverticulitis
- systemic vasculitis
How can you distinguish between bacterial and viral gastroenteritis?
- viral infection generally produces diarrhoea without blood or mucus + watery diarrhoea is a prominent symptom
- viral - fevers, headaches, arthralgia, cramps (more generalised and benign symptoms)
- bacterial - tenesmus
What is the first-line treatment for viral gastroenteritis with mild to moderate dehydration?
-
oral rehydration & fluids
- replace fluid and electrolytes lost through diarrhoea by solutions containing Na+, K+ and glucose
- use a reduced osmolarity oral rehydration solution (50-60mmol/L) over 3-4 hours
- CONSIDER anti-emetic (only if intractable vomiting and unable to tolerate oral fluids) –> ondansetron or cyclizine
- CONSIDER antidiarrhoeal (avoid in those with bloody diarrhoea or inflammatory cause) –> loperamide
What is the first-line treatment for viral gastroenteritis with severe dehydration or unable to tolerate oral fluids?
- IV fluids
- CONSIDER anti-emetics (ondansetron or cyclizine)
- CONSIDER antidiarrhoeal (loperamide)
