Infectious- shigella, salmonella, campylobacter, E. Coli.
Noninfectious- Inflammatory bowel disease, ischemic colitis, diverticulitis, AV malformation.
Pyogenic abscess
Aerobic: Escherichia coli, Klebsiella, Pseudomonas
Anaerobic: Enterococcus, bacteroides, anaerobic streptococci
Echinococcosis<unk> 
Benign cysts/malignancy
Tuberculosis
Mycosis
Aerobic: Escherichia coli, Klebsiella, Pseudomonas
Anaerobic: Enterococcus, bacteroides, anaerobic streptococci
Normal causes of acute fever!
Malaria
Dengue
Leptospirosis
Typhoid fever
Typhus
Viral hemorrhagic fevers
Ebola virus disease
Marburg virus disease
Lassa fever
Crimean-Congo hemorrhagic fever
Chikungunya
Yellow fever
Rift valley fever
Q fever<unk> 
Zika virus
Ebola virus disease
Marburg virus disease
Lassa fever
Crimean-Congo hemorrhagic fever
Viral (e.g. rotavirus)
Bacterial
Campylobacter
Shigella
Salmonella (non-typhi)
Escherichia coli
E. coli 0157:H7
Yersinia enterocolitica
Vibrio cholerae
Clostridium difficile
Parasitic
Giardia lamblia
Cryptosporidium
Entamoeba histolytica
Cyclospora
Microsporidium
Toxin
Staphylococcus aureus
Bacillus cereus
Campylobacter
Shigella
Salmonella (non-typhi)
Escherichia coli
E. coli 0157:H7
Yersinia enterocolitica
Vibrio cholerae
Clostridium difficile
E. coli 0157:H7
Giardia lamblia
Cryptosporidium
Entamoeba histolytica
Cyclospora
Microsporidium
Staphylococcus aureus
Bacillus cereus
GI Bleed
Appendicitis
Mesenteric Ischemia
Diverticulitis
Adrenal Crisis
Thyroid Storm
Toxicologic exposures
Antibiotic or drug-associated
Enterotoxigenic E. coli (most common cause of watery diarrhea)
Norovirus (often has prominent vomiting)
Campylobacter
Non-typhoidal Salmonella
Enteroaggregative E. coli (EAEC)
Enterotoxigenic Bacteroides fragilis
Giardia lamblia
Cryptosporidiosis
Entamoeba histolytica
Cyclospora
Amebiasis
Infectious- shigella, salmonella, campylobacter, E. Coli.
Viral hepatitis
Noninfectious- Inflammatory bowel disease, ischemic colitis, diverticulitis, AV malformation.
Autoimmune hepatitis
Pyogenic abscess
Ischemic hepatitis
Aerobic: Escherichia coli, Klebsiella, Pseudomonas