Differential Diagnosis for 2 y/o Infant

Single Most Likely Diagnosis

• Viral Gastroenteritis: The combination of fever, loose stool, and vomiting for 3 days in a 2-year-old infant, along with episodes of fitting (seizures), suggests a viral gastroenteritis with possible dehydration leading to febrile seizures. The seizures are brief and self-limiting, which is consistent with febrile seizures often seen in this age group.

Other Likely Diagnoses

• Bacterial Gastroenteritis: Similar to viral gastroenteritis but caused by bacteria. The presence of fever and gastrointestinal symptoms could suggest a bacterial cause, especially if the symptoms are severe or if there's blood in the stool.
• Urinary Tract Infection (UTI): UTIs can present with fever and nonspecific symptoms in young children. The fitting could be related to the fever, and UTIs are a common cause of febrile seizures in this age group.
• Meningitis: Although less likely given the absence of specific meningeal signs and the presence of gastrointestinal symptoms, meningitis can cause fever, seizures, and vomiting. It's crucial to consider this diagnosis due to its severity.

Do Not Miss Diagnoses

• Intussusception: A condition where a part of the intestine slides into an adjacent part, potentially causing bowel obstruction. It's a surgical emergency and can present with vomiting, abdominal pain, and sometimes seizures if the child becomes severely ill.
• Septicemia: Bacterial sepsis can cause fever, vomiting, and seizures. It's a life-threatening condition that requires immediate recognition and treatment.
• Hyponatremic Seizures: Severe dehydration or inappropriate antidiuretic hormone secretion (SIADH) can lead to hyponatremia, causing seizures. This is particularly concerning in the context of gastroenteritis with significant vomiting and diarrhea.

Rare Diagnoses

• Reye's Syndrome: A rare but serious condition that causes swelling in the liver and brain. It often presents with vomiting, seizures, and altered mental status, typically after a viral infection.
• Inborn Errors of Metabolism: Certain metabolic disorders can present with seizures, vomiting, and altered mental status during episodes of illness or fasting. These are rare but important to consider in the differential diagnosis of a child with recurrent or severe episodes of such symptoms.

Each of these diagnoses should be considered based on the clinical presentation, and further evaluation, including laboratory tests and imaging studies, may be necessary to determine the underlying cause of the infant's symptoms.