Diagnostic challenges in a patient with dengue shock syndrome presenting with acute meningoencephalitis

Dengue is a systemic viral infection, and clinical findings vary from asymptomatic to life-threatening, including shock and neurological complications. Despite efforts in vector control, the disease continues to spread worldwide, and the number of annual dengue infections is estimated to be 390 million. For patients with severe dengue, early diagnosis is important; however, owing to the wide range of symptoms and severity, diagnosis can be difficult. Herein, we report the case of a 24-year-old man from Vietnam who was found to have dengue shock syndrome complicated by meningoencephalitis, even though he did not show the typical clinical manifestations of dengue infection. He was transported to our hospital by ambulance because of fever and altered mental status. Brain magnetic resonance imaging revealed hyperintensities in the bilateral thalamus and brainstem on the T2 sequence. After hospitalization, polymerase chain reaction testing of cerebrospinal fluid, serum, and urine revealed the presence of dengue virus serotype 2. This confirmed the diagnosis of dengue encephalitis. The patient was discharged on day 49 with impaired abduction of the left eye and urinary retention. In this case, the initial differential diagnosis was broad because the patient was unable to provide any medical history owing to altered mental status. In addition, the fact that he did not show the characteristic symptoms of dengue infection initially made the diagnosis very difficult. In conclusion, dengue fever should always be considered as a part of the differential diagnosis when a patient from an endemic area presents with fever and impaired consciousness.