Differential Diagnosis for Severe Thrombocytopenia in a 40-year-old from India after Visiting Austria

• Single most likely diagnosis:
  • Dengue Fever: Given the patient's origin from India, a region endemic for dengue fever, and the presentation of severe thrombocytopenia, dengue fever is a highly plausible diagnosis. Although Austria is not typically endemic for dengue, the patient could have been infected before leaving India or potentially in another travel destination before returning to Austria.
• Other Likely diagnoses:
  • Malaria: Another common infection in India that can cause thrombocytopenia. The patient could have been exposed during their time in India before traveling to Austria.
  • Viral infections (e.g., HIV, Hepatitis C): These infections can cause thrombocytopenia and are relevant considerations given the patient's travel history and potential exposure risks.
  • Immune thrombocytopenic purpura (ITP): An autoimmune condition that can cause severe thrombocytopenia, though it's less directly linked to travel history.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Thrombotic Thrombocytopenic Purpura (TTP): A rare but life-threatening condition requiring immediate treatment. It presents with thrombocytopenia, microangiopathic hemolytic anemia, renal failure, and neurological symptoms.
  • Hantavirus infection: Although less common, hantavirus can cause severe thrombocytopenia and is found in Europe, including Austria. It's a critical diagnosis to consider due to its severity and the need for specific management.
  • Severe sepsis or disseminated intravascular coagulation (DIC): These conditions can lead to thrombocytopenia and are medical emergencies. They might not be directly related to travel but could be secondary to an infection acquired during travel.
• Rare diagnoses:
  • Tick-borne illnesses (e.g., Tick-borne encephalitis, Anaplasmosis): These could be considered if the patient had exposure to ticks during outdoor activities in Austria. They are less common causes of thrombocytopenia but relevant given the travel history.
  • Leptospirosis: Another infection that can cause thrombocytopenia, though it's less likely unless the patient had specific exposures (e.g., water sports in contaminated water) during their travel.
  • Bartonellosis: Caused by Bartonella species, this infection can lead to thrombocytopenia among other symptoms, but it's relatively rare and typically associated with specific vectors like ticks or fleas.