Differential Diagnosis of Prolonged Fever with Diarrhea and Abdominal Pain

Primary Diagnostic Considerations

The American College of Physicians suggests that enteric fever should be at the top of the differential diagnosis given the prolonged fever preceding diarrhea onset, as diarrhea is actually uncommon in enteric fever but can occur 1, 3
The Infectious Diseases Society of America recommends considering enteric fever-endemic areas in the patient's travel history, as this presentation is particularly concerning if the patient has traveled to or had contact with travelers from these areas 3
The combination of persistent fever with systemic manifestations and subsequent gastrointestinal symptoms is classic for Salmonella typhi or paratyphi, according to the Centers for Disease Control and Prevention 1
Persistent abdominal pain and fever lasting 2 weeks strongly suggests Yersinia enterocolitica or Y. pseudotuberculosis, which characteristically cause prolonged symptoms and can mimic appendicitis, as stated by the American Gastroenterological Association 2, 4
Other bacterial pathogens causing fever with abdominal pain include Salmonella (non-typhoidal), Campylobacter, Shigella, and non-cholera Vibrio, according to the World Health Organization 2, 4

Recent international travel with fever ≥38.5°C or signs of sepsis warrants immediate empiric antimicrobial therapy while awaiting diagnostic results, as recommended by the Centers for Disease Control and Prevention 6, 7
Travel to enteric fever-endemic regions makes typhoid/paratyphoid the leading diagnosis, according to the World Health Organization 3
Immunocompromised patients require a much broader differential including opportunistic pathogens like Mycobacterium avium complex, cytomegalovirus, microsporidia, and Cystoisospora, as stated by the Infectious Diseases Society of America 1, 2, 4
Recent antibiotic use within 8-12 weeks mandates C. difficile testing, as this is the most common cause of healthcare-associated infectious diarrhea, according to the Society for Healthcare Epidemiology of America 1, 8, 5

Blood cultures must be obtained given the prolonged fever, as this presentation suggests possible bacteremia or enteric fever, as recommended by the American College of Physicians 1, 3
Stool testing should include culture for Salmonella, Shigella, Campylobacter, Yersinia, Shiga toxin or genomic assays for STEC, and parasitic examination or antigen testing for Giardia, Cryptosporidium, Cyclospora, Entamoeba, according to the Centers for Disease Control and Prevention 1, 2, 4, 6

Patients with clinical features of sepsis suspected of having enteric fever should receive empiric broad-spectrum antimicrobial therapy immediately after cultures are collected, then narrow therapy based on susceptibility results, as recommended by the Infectious Diseases Society of America 6, 7
Empiric therapy for suspected bacterial enterocolitis with fever ≥38.5°C and travel history should be either fluoroquinolone (ciprofloxacin) or azithromycin (depending on local resistance patterns and travel history), according to the American College of Physicians 6, 7
Never use loperamide or other antimotility drugs in patients with fever and inflammatory diarrhea, as they can precipitate toxic megacolon or worsen outcomes, as stated by the American Gastroenterological Association 9
If STEC is suspected (bloody diarrhea, abdominal pain, minimal fever), avoid antibiotics as they may increase risk of hemolytic uremic syndrome, according to the Centers for Disease Control and Prevention 6, 7