Differential Diagnosis
- Single most likely diagnosis
- Viral hepatitis: The patient's elevated INR and fever, combined with a negative Quantiferon test and normal CD4 count, suggest a possible diagnosis of viral hepatitis. The patient's history of living in Vietnam and Hawaii, where hepatitis is more prevalent, also supports this diagnosis.
- Other Likely diagnoses
- Tuberculosis (despite negative Quantiferon): Although the Quantiferon test is negative, it is not 100% sensitive, and TB is a significant concern in immunocompromised patients or those from high-prevalence areas like Vietnam.
- Endocarditis: The patient's fever and elevated INR, combined with a history of incarceration (which may increase the risk of IV drug use), raise the possibility of endocarditis.
- Viral infections (e.g., influenza, COVID-19): The patient's symptoms of fever and headache, combined with a negative workup for other conditions, suggest a possible viral infection.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningitis: Although the CT head is negative, meningitis can present with non-specific symptoms like fever and headache, and is a medical emergency that requires prompt diagnosis and treatment.
- Sepsis: The patient's fever and elevated INR, combined with a history of incarceration and possible exposure to infectious diseases, raise the possibility of sepsis.
- Toxoplasmosis: Although the patient has a normal CD4 count, toxoplasmosis can still occur in immunocompetent individuals, and is a significant concern in patients with a history of exposure to undercooked meat or contaminated water.
- Rare diagnoses
- Melioidosis: The patient's history of living in Vietnam and Hawaii, where melioidosis is more prevalent, combined with symptoms of fever and headache, raise the possibility of this rare but serious infection.
- Leptospirosis: Although the patient has no known exposure to animals, leptospirosis can still occur through contact with contaminated water or soil, and is a significant concern in patients with a history of living in tropical or subtropical regions.
- Brucellosis: The patient's symptoms of fever and headache, combined with a history of living in Vietnam and Hawaii, raise the possibility of this rare but serious zoonotic infection.