Q.One of the common symptoms observed in people infected with Dengue fever is

Dengue fever is well known for causing a significant decrease in platelet count, a condition called thrombocytosis's opposite, thrombocytopenia. Since platelets are the formed elements responsible for triggering blood coagulation, this drop in their numbers is what makes dengue patients prone to abnormal bleeding and bruising, which is why platelet counts are closely monitored in dengue cases.

Note: this specific dengue fact is general medical knowledge and is not detailed in this chapter's own notes, though it does not conflict with anything the chapter describes about platelets.

Platelets, or thrombocytes, are cell fragments produced from megakaryocytes in the bone marrow, and blood normally contains about 150,000 to 350,000 of them per cubic millimetre. Platelets release substances that are central to triggering the coagulation (clotting) of blood, and if their number falls too low, clotting disorders result, which can lead to excessive loss of blood from the body.

Dengue fever is a well-known infection in which platelet counts drop significantly, sometimes severely, which is why patients are monitored closely for bleeding risk during the illness and why platelet counts are among the routine tests ordered when dengue is suspected.

Method: Applying a Core Concept to a Clinical or Real-World Scenario

Use this approach whenever a question describes a real disease/condition and asks which basic physiological fact explains a symptom.

Steps

Step 1: Identify which core blood-component fact the scenario is really testing

A dengue-and-bleeding scenario is testing your understanding of platelets and coagulation, even though the word "platelet" appears only in the options.

Step 2: Recall the normal role and normal range of that component

Knowing platelets are cell fragments that trigger clotting, and that a normal count sits in a defined range, lets you recognise what a rise or fall would actually mean physiologically.

Step 3: Match the described clinical effect to the direction of change that would explain it

A bleeding/bruising risk implies impaired clotting, which implies FEWER platelets, not more — work from effect back to cause rather than guessing the direction.

Step 4 (Applying to this problem): When the fact tested is genuine applied/clinical knowledge rather than something stated word-for-word in the syllabus text, it is still fair game as long as it doesn't contradict what the chapter teaches about that component's core function — treat it as an extension of the concept, not a separate unrelated fact to memorise.