Which of the following can be a sign of severe dengue in patients?

Liver enlargement is an important clinical sign that can indicate severe dengue, a potentially life-threatening form of the disease caused by the dengue virus. In patients with severe dengue, the liver may be affected due to the increased inflammatory response and the effects of the virus on the organs. This enlargement, known as hepatomegaly, can be detected through physical examination or imaging studies and points to the severity of the infection, often correlating with other critical symptoms.

In contrast, the other options do not typically align with severe dengue. Maintaining normal activities is unlikely in cases of severe disease due to the significant symptoms and complications that arise. A low-grade fever as the only symptom does not usually reflect severe disease, as severe dengue often presents with higher fevers and more serious symptoms. Finally, having no symptoms at all would not indicate severe dengue; those infected typically exhibit some form of clinical manifestation, especially when the disease progresses to a severe state.