Fatal Expanded Dengue Syndrome Mimicking Heat Stroke With Hyperpyrexia, Subarachnoid Hemorrhage, and Refractory Multiorgan Dysfunction: A Case Report.

Dengue is a major mosquito-borne viral illness affecting tropical and subtropical regions worldwide and remains an important cause of critical care admissions. Although most infections are self-limited, a subset progresses to severe dengue characterized by plasma leakage, shock, severe bleeding, and end-organ dysfunction. Neurological manifestations are uncommon but increasingly recognized under the spectrum of expanded dengue syndrome, including seizures, encephalopathy, cerebral edema, ischemic stroke, and intracranial hemorrhage. We report a fatal case of a 29-year-old previously healthy man with significant occupational and environmental heat exposure in a tropical setting. He presented after two generalized tonic-clonic seizures followed by profound unconsciousness. He had experienced four days of continuous fever, retro-orbital pain, myalgia, and arthralgia and had been diagnosed one day earlier with NS1-positive dengue fever without warning signs. On arrival, his temperature was 41°C, and his skin was hot and dry; shortly afterward, he developed respiratory arrest requiring emergency intubation, making environmental heat stroke an important initial differential diagnosis. Brain imaging demonstrated subarachnoid hemorrhage and diffuse cerebral edema. During intensive care, he developed progressive hemoconcentration, dengue shock syndrome, coagulopathy suggestive of disseminated intravascular coagulation, acute kidney injury, hepatic dysfunction, lactic acidosis, and refractory shock despite fluid resuscitation, vasopressor support, neurocritical care, and blood product replacement, ultimately resulting in death. This case highlights the diagnostic challenge posed by the overlap between severe dengue and heat-stroke-like presentations, particularly in individuals with significant exposure to environmental heat.