Differential Diagnosis for Malabsorption in a Family Living in Mexico

The following differential diagnosis is organized into categories to help guide the thought process:

• Single most likely diagnosis

  • Giardiasis: This is a common cause of malabsorption, especially in individuals living in areas with poor sanitation, such as Mexico. Giardia lamblia is a protozoan parasite that can be difficult to detect in stool cultures and can cause chronic diarrhea, weight loss, and malabsorption in infected individuals.

• Other Likely diagnoses

  • Cyclosporiasis: This is another protozoan infection caused by Cyclospora cayetanensis, which can also be difficult to detect in stool cultures. It is known to cause prolonged diarrhea and malabsorption, especially in individuals living in or traveling to endemic areas like Mexico.
  • Cryptosporidiosis: Caused by Cryptosporidium species, this infection can lead to severe and prolonged diarrhea, particularly in immunocompromised individuals, but it can also affect immunocompetent people, causing malabsorption.
  • Tropical sprue: A condition of unknown etiology that can cause malabsorption, typically seen in individuals living in tropical regions. While its exact cause is not bacterial, it could be considered in the differential due to the geographic location and symptoms.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Cholera: Caused by Vibrio cholerae, this bacterial infection can lead to severe, life-threatening diarrhea. Although less common in a family setting without a clear outbreak, it's crucial to consider due to its high mortality rate if untreated.
  • Typhoid fever: Caused by Salmonella Typhi, this condition can present with gastrointestinal symptoms, including diarrhea, and can be severe if not properly treated. It's a significant concern in areas with poor sanitation.

• Rare diagnoses

  • Whipple's disease: A rare, systemic bacterial infection caused by Tropheryma whipplei, which can lead to malabsorption, diarrhea, and weight loss. It is extremely rare and usually affects middle-aged men, but it should be considered in cases where common causes have been ruled out.
  • Abetalipoproteinemia: A rare genetic disorder affecting fat absorption, leading to malabsorption. It's an unlikely cause for an entire family to be affected unless they are all carriers of the genetic defect, but it's worth mentioning due to the severity of malabsorption it causes.