History and exam

Key diagnostic factors

common

presence of risk factors

Exposure to contaminated food or water sources

  • Noroviruses are the most common agents isolated from contaminated food or water sources.

Close contact with infected people

  • Cases tend to cluster, and airborne transmission can occur with noroviruses and coronaviruses.

    • Outbreaks on cruise ships and in childcare centres are thought to be due to close contact.

Poor hygiene

  • Viruses are spread by the faecal-oral route from person to person.

Extremes of age

  • Severe dehydrating diarrhoea occurs in very young children and older adults.

Comorbidities

  • Monitor people with multiple comorbidities as they are prone to serious complications, such as electrolyte imbalance, renal failure, hypo/hyperglycaemia, heart failure, cerebral oedema, pressure sores, and hospital-acquired pneumonia.

Immunocompromise

  • Organ transplant recipients and people with HIV tend to develop atypical and prolonged illness.

diarrhoea

Ask about onset, duration, severity, and frequency.[13] 

  • Character of the stool: watery, presence of blood or mucus.

    • Blood in the stool (or any rectal bleeding) is not a common feature of viral gastroenteritis.[13] Consider another cause, such as Shiga-toxin-producing Escherichia coli or Campylobacter, if blood is present.[13][17] Shigella and amoebic dysentery may also cause bloody diarrhoea.

vomiting

Ask about onset (usually acute), frequency, quantity, and character (i.e., the presence of bile or blood).

  • Vomiting occurs in around 80% of patients,[18] but absence does not rule out viral gastroenteritis. 

  • Usually self-limiting.

  • If severe, may contribute to dehydration.

nausea

A common symptom, which can occur on its own.

  • Malaise and loss of appetite may also occur.

abdominal pain

Cramping pain without much tenderness or rebound is typical.

  • Abdomen should be soft and only mildly tender.

    • If there is pain and guarding, investigate other diagnoses, such as pancreatitis, appendicitis, or inflammatory bowel disease.

Other diagnostic factors

common

malaise

Viral illness often causes body ache and malaise.

anorexia

The patient may report loss of appetite.

fever

About 40% of patients with norovirus have low-grade fever in the first 24 hours.[19] 

  • A high temperature might indicate a more severe diagnosis. Track to see whether it improves.

volume depletion

Signs include dry mucous membranes, tachycardia, hypotension, decreased urine output, and weight loss.

  • Note recent oral intake, urine output, prior weight, and associated symptoms, including fever or changes in mental status.

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