What is the best course of treatment for a patient with viral gastroenteritis, particularly in vulnerable populations such as the elderly, young children, and those with compromised immune systems?

Treatment of Viral Gastroenteritis

Oral rehydration therapy (ORT) is the cornerstone of treatment for viral gastroenteritis across all age groups and should be initiated immediately based on clinical assessment without waiting for laboratory confirmation. 1

Rehydration Strategy by Severity

Mild to Moderate Dehydration

• Administer oral rehydration solutions (ORS) as first-line therapy, which is equally effective as intravenous therapy for preventing hospitalization and correcting dehydration 1, 2
• For children with mild illness, half-strength apple juice followed by preferred liquids is an acceptable alternative to traditional ORS 2
• Nasogastric ORS administration may be considered in patients who cannot tolerate oral intake or are too weak to drink adequately 1
• Continue ORS until clinical dehydration is corrected, then maintain with ongoing replacement of stool losses until symptoms resolve 1

Severe Dehydration

• Initiate isotonic intravenous fluids (lactated Ringer's or normal saline) immediately for patients with shock, altered mental status, or failure of ORS therapy 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS for remaining deficit replacement 1
• In patients with ketonemia, initial IV hydration may be necessary to enable tolerance of oral rehydration 1

Nutritional Management

• Continue breastfeeding throughout the illness without interruption, as human milk has protective effects 1
• Resume age-appropriate diet immediately after rehydration or during the rehydration process—early feeding decreases intestinal permeability and reduces illness duration 1, 3
• Consider lactose-free diet for 10-14 days post-rotavirus infection in children under 5 years, as this reduces diarrhea duration by approximately 18 hours 3

Symptomatic Medications

Antiemetics

• Ondansetron may be administered to children >4 years and adolescents with vomiting to facilitate oral rehydration tolerance, but only after adequate hydration is ensured 1, 2
• This is not a substitute for fluid and electrolyte therapy 1

Antimotility Agents

• Loperamide is absolutely contraindicated in all children <18 years of age 1, 4
• In immunocompetent adults with acute watery diarrhea, loperamide may be considered, but avoid in any patient with fever or inflammatory diarrhea due to risk of toxic megacolon 1, 4
• Avoid loperamide in patients taking QT-prolonging medications or those with cardiac risk factors 4

Adjunctive Therapies

• Bismuth subsalicylate provides modest benefit, reducing illness duration by approximately 7 hours 3
• Probiotics may be offered to reduce symptom severity and duration in immunocompetent patients 1
• Oral zinc supplementation (20 mg daily) reduces diarrhea duration in children 6 months to 5 years in areas with high zinc deficiency prevalence or malnutrition 1

Special Population Considerations

Elderly Patients

• Exercise heightened vigilance for dehydration, particularly in those taking diuretics, as they have increased risk of adverse outcomes from mild illness 1, 3
• Waning antibody levels with age increase susceptibility to infections that younger adults resist 1

Immunocompromised Patients

• For patients with AIDS or primary immunodeficiencies experiencing chronic diarrhea with rotavirus or adenovirus, consider persistent viral shedding as the etiology 1
• CMV gastroenteritis in hematology/oncology patients requires specific antiviral therapy: ganciclovir 5 mg/kg IV twice daily for 2-3 weeks (induction), followed by maintenance 3
• Diagnosis requires CMV detection in endoscopic biopsy specimens, not peripheral blood or stool 3

Pregnant Women

• No specific threat beyond standard dehydration risks, as viremic states do not occur with typical gastroenteritis viruses 1, 3
• Maintain adequate hydration to prevent electrolyte imbalance that could affect pregnancy 1

Neonates

• Full-term infants have maternal antibody protection for the first 3-6 months, making rotavirus infection typically mild or asymptomatic 1
• Premature infants lack adequate maternal antibody and are at increased risk for symptomatic infection 1
• Oral immunoglobulin may protect against disease during nursery outbreaks 1

Critical Pitfalls to Avoid

• Never delay ORT while awaiting laboratory results—begin rehydration immediately based on clinical assessment 3
• Bloody diarrhea is not typical of viral gastroenteritis and mandates investigation for bacterial or other causes 1, 5, 3
• Do not use rectal swabs for viral diagnosis, as they have minimal diagnostic value 3
• Discontinue loperamide immediately if constipation, abdominal distention, or ileus develops 4
• Stool microbiological testing is unnecessary when viral gastroenteritis is the likely diagnosis in mild illness 2

Infection Control Measures

• Hand hygiene with soap and water after toilet use, diaper changes, before food preparation, and before eating is essential 1
• Exclude symptomatic staff from patient contact for at least 2 days after symptom resolution, particularly food handlers 1, 3
• Use gloves and gowns when contamination with fecal material is possible 1
• Clean environmental surfaces thoroughly, especially areas soiled by feces or vomitus 3
• Alcohol-based sanitizers are less effective against norovirus—soap and water handwashing is preferred 1