Differential Diagnosis

The patient's symptoms and recent travel history to Southeast Asia, where he studied rodents, suggest a severe infectious disease. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Plague, pulmonary form: The patient's symptoms, such as severe headache, dizziness, chills, high fever, chest pains, shortness of breath, and cough with foamy sputum, are consistent with pulmonary plague. The recent exposure to rodents in Southeast Asia, a region where plague is endemic, further supports this diagnosis.
• Other Likely diagnoses
  • Ornithosis: Also known as psittacosis, this disease can cause similar respiratory symptoms, including pneumonia. However, the patient's exposure to rodents rather than birds makes this diagnosis less likely.
  • Yersiniosis, anginous form: Yersiniosis can cause a range of symptoms, including fever, chills, and abdominal pain. While it's possible, the patient's respiratory symptoms and exposure to rodents make plague a more likely diagnosis.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Hantavirus: This viral infection can cause severe respiratory symptoms, including hantavirus pulmonary syndrome (HPS). Although less likely, it's essential to consider hantavirus due to the patient's exposure to rodents and the potential for severe outcomes if left untreated.
  • SARS or other coronaviruses: While less likely given the patient's specific symptoms and exposure history, it's crucial to consider other viral respiratory infections, especially in a traveler returning from abroad.
• Rare diagnoses
  • Infectious mononucleosis: This diagnosis is unlikely given the patient's severe respiratory symptoms and exposure to rodents. Infectious mononucleosis typically presents with fever, sore throat, and lymphadenopathy.
  • Influenza: While influenza can cause severe respiratory symptoms, the patient's exposure to rodents and the combination of symptoms, including foamy sputum, make this diagnosis less likely.