Differential Diagnosis

The patient's presentation with diarrhea, malaria, weakness, and a positive PAS (Periodic Acid-Schiff) test can be approached by considering various diagnoses based on the likelihood and severity of the conditions. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Whipple’s disease: This is a rare, systemic bacterial infection caused by Tropheryma whipplei. The positive PAS test is a key diagnostic clue, as it stains the bacteria in the intestinal mucosa. Diarrhea, weakness, and systemic symptoms like malaria (which could be a co-infection or a misdiagnosis of the systemic symptoms of Whipple’s disease) are consistent with this diagnosis.

• Other Likely diagnoses

  • Coeliac disease: An autoimmune disorder that primarily affects the small intestine, triggered by the ingestion of gluten. It can cause diarrhea and weakness due to malabsorption. However, the positive PAS test is not typically associated with coeliac disease, making it less likely.
  • Tropical sprue: A condition that affects the small intestines and is characterized by malabsorption, leading to diarrhea and weakness. It's more common in tropical regions and could be considered given the patient's history of malaria, suggesting exposure to tropical diseases.

• Do Not Miss diagnoses

  • Intestinal lymphoma: Certain types of lymphoma can cause malabsorption and diarrhea. A positive PAS test could be seen in some cases, especially if there's involvement of the intestinal mucosa. Given the potential severity of lymphoma, it's crucial not to miss this diagnosis.
  • Chronic infections (e.g., tuberculosis, HIV): These can cause chronic diarrhea, weakness, and systemic symptoms. While the positive PAS test is not directly indicative of these conditions, they are important to consider due to their potential severity and the need for specific treatment.

• Rare diagnoses

  • Abetalipoproteinemia: A rare inherited disorder that affects fat absorption and can cause diarrhea and weakness. It's characterized by the absence of beta-lipoproteins in the blood, but it would not typically be associated with a positive PAS test.
  • Other rare malabsorptive disorders: Conditions like alpha-heavy chain disease or immunoproliferative small intestinal disease could present with similar symptoms but are less common and might not directly correlate with the positive PAS test.