Dengue shock syndrome occurs due to –
**Core Concept**
Dengue shock syndrome is a severe complication of dengue fever, characterized by plasma leakage, hemorrhage, and potentially life-threatening shock. This condition arises from the interaction between the dengue virus and the host's immune system, leading to an imbalance in vascular permeability and coagulation pathways.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of dengue shock syndrome, which involves the activation of the complement system and the release of cytokines. The dengue virus triggers an immune response that leads to the activation of C3 convertase, resulting in the cleavage of C3 and the subsequent activation of the complement cascade. This cascade causes the formation of membrane attack complexes (MACs), which increase vascular permeability and lead to plasma leakage. Additionally, the release of cytokines such as TNF-alpha and IL-1 beta contributes to the activation of endothelial cells and the disruption of the blood-brain barrier.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the pathophysiology of dengue shock syndrome. While platelet activation is a feature of dengue fever, it is not the primary cause of shock syndrome.
**Option B:** This option is incorrect because it refers to a different clinical condition altogether. Septic shock is a separate entity that arises from a bacterial infection and is characterized by a different set of pathophysiological mechanisms.
**Option C:** This option is incorrect because it is too broad and does not specifically address the pathophysiology of dengue shock syndrome. While inflammation is a feature of dengue fever, it is not the primary cause of shock syndrome.
**Clinical Pearl / High-Yield Fact**
The classic "tourniquet test" can be used to assess capillary fragility in patients with dengue fever. A positive test is defined as the appearance of 20 or more petechiae within 1 minute of applying the tourniquet.
**Correct Answer: D. Plasma leakage and hemorrhage.**