Allergic Proctocolitis: This condition is a common cause of loose stools with occult blood in infants, often due to a milk protein allergy (e.g., cow's milk protein allergy). It typically presents with blood in stool, which may be the only symptom, making it a leading consideration.

Infectious Gastroenteritis: Viral or bacterial infections can cause diarrhea and occult blood in infants. Common pathogens include rotavirus, norovirus, and bacterial infections like Salmonella or Shigella.
Intussusception: Although more commonly associated with abdominal pain and currant jelly stool, intussusception can sometimes present with occult blood and loose stools in infants.
Food Protein-Induced Enterocolitis Syndrome (FPIES): This is a non-IgE-mediated food allergy that can cause vomiting, diarrhea (which may be bloody), and abdominal distension after ingestion of the offending food protein.

Hirschsprung's Disease: While primarily associated with constipation, some infants with Hirschsprung's disease may have enterocolitis, leading to bloody diarrhea. Early diagnosis is crucial for management.
Intestinal Malrotation with Volvulus: This condition can cause ischemia to the bowel, leading to bloody stools. It's a surgical emergency and must be considered in the differential diagnosis of an infant with abdominal symptoms and bloody stools.
Meckel's Diverticulum: A congenital anomaly that can cause painless rectal bleeding due to the presence of ectopic gastric mucosa. Although it typically presents with gross blood, occult blood can also be a finding.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis are rare in infancy but can present with chronic diarrhea, blood in stool, and failure to thrive.
Congenital Infections: Such as congenital CMV infection, which can cause gastrointestinal symptoms including diarrhea and occult blood in stool in newborns.
Tumor: Although exceedingly rare, intestinal tumors (e.g., juvenile polyps) can cause rectal bleeding in infants.