What virus could cause nausea, diarrhea, cough, and bradycardia?

Viral Infection with Nausea, Diarrhea, Cough, and Bradycardia

The most likely viral etiology causing this constellation of symptoms—particularly the combination of gastrointestinal symptoms (nausea, diarrhea), respiratory symptoms (cough), and the distinctive finding of bradycardia—is typhoid fever caused by Salmonella typhi, though this is bacterial rather than viral; among true viral causes, COVID-19 (SARS-CoV-2) is the most probable diagnosis given its well-documented ability to cause both gastrointestinal and respiratory symptoms simultaneously. 1

Key Diagnostic Considerations

Typhoid Fever (Bacterial, Not Viral)

• Relative bradycardia is a classic and distinctive feature of typhoid fever, characterized by fever with a pulse rate that is inappropriately slow for the degree of temperature elevation 1
• The illness presents with insidious onset of sustained fever, headache, malaise, anorexia, constipation or diarrhea, and nonproductive cough 1
• This is the only common infectious disease in the differential that characteristically presents with bradycardia alongside gastrointestinal and respiratory symptoms 1

COVID-19 (SARS-CoV-2) - Most Likely Viral Cause

• COVID-19 can present with gastrointestinal symptoms (nausea, vomiting, diarrhea) that may precede respiratory symptoms, with up to 61% of outpatients experiencing GI manifestations 1, 2
• The most common gastrointestinal symptoms include poor appetite/anorexia, nausea/vomiting, diarrhea, and abdominal pain 3, 4
• Respiratory symptoms including cough are well-documented as primary manifestations 1, 5
• Cardiovascular complications including arrhythmias and conduction abnormalities have been reported, though bradycardia is less commonly emphasized than other cardiac manifestations 1

Norovirus and Other Viral Gastroenteritis

• Norovirus typically causes nausea, vomiting, and diarrhea with an incubation period of 12-48 hours, but respiratory symptoms are uncommon 6, 1
• In outbreak settings, 79% experience nausea, 71% abdominal cramps, 69% vomiting, and 66% diarrhea 1
• Respiratory symptoms (sore throat 18%, cough) are rare and not prominent features 1
• Bradycardia is not a recognized feature of norovirus or other common viral gastroenteritis agents 1, 6

Influenza

• Influenza presents with sudden onset of fever, myalgia, headache, and nonproductive cough 1
• Gastrointestinal symptoms (nausea, vomiting, diarrhea) can occur, particularly in children 1
• Bradycardia is not a characteristic feature; tachycardia is more typical with fever 1

Clinical Algorithm for Diagnosis

Step 1: Assess for relative bradycardia

• If present with sustained fever, gastrointestinal symptoms, and cough → strongly consider typhoid fever (bacterial) and obtain blood cultures 1

Step 2: Consider COVID-19 testing

• Obtain nasopharyngeal PCR for SARS-CoV-2, especially if GI symptoms preceded or accompanied respiratory symptoms 1, 2
• Consider stool PCR if nasopharyngeal testing is negative but clinical suspicion remains high, as viral RNA can persist in stool 5, 7

Step 3: Evaluate cardiac involvement

• Obtain ECG to document bradycardia and assess for conduction abnormalities 1
• Check cardiac biomarkers (troponin, BNP) if COVID-19 is suspected, as cardiovascular complications are common 1

Step 4: Rule out other causes

• If predominantly gastrointestinal with minimal respiratory involvement and no bradycardia → consider norovirus or other viral gastroenteritis 1, 6
• Stool studies for bacterial pathogens including Salmonella typhi if epidemiologic risk factors present 1

Critical Pitfalls to Avoid

• Do not dismiss gastrointestinal symptoms as unrelated to respiratory viral illness—COVID-19 frequently presents with GI symptoms that may precede respiratory manifestations 1, 2
• Do not overlook relative bradycardia—this is a distinctive clinical sign that should prompt consideration of typhoid fever even when other symptoms suggest viral illness 1
• Do not assume negative nasopharyngeal testing rules out COVID-19—viral shedding in stool may persist after respiratory clearance 5, 7
• Do not attribute all fever with bradycardia to viral causes—typhoid fever is bacterial and requires specific antibiotic therapy 1