**Question:** Hectic picket type of fever with rigor is important feature in

A. Dengue fever
B. Typhoid fever
C. Hepatitis
D. Malaria

**Core Concept:**
The question is asking about a specific type of fever characterized by a "hectic" pattern and the presence of rigor. This combination of symptoms is characteristic of a particular group of febrile illnesses.

**Why the Correct Answer is Right:**
The correct answer, D. Malaria, is the correct response because it is known to present with a hectic pattern of fever, characterized by rapid fluctuations of body temperature. Additionally, rigors are common symptoms in malaria, particularly in severe cases. Malaria is caused by Plasmodium parasites that infect red blood cells and lead to fever as the body attempts to eliminate the parasites.

**Why Each Wrong Option is Incorrect:**
A. Dengue fever typically presents with a high fever (>39°C) without a specific pattern, although some cases can have a biphasic pattern. Rigors are not a common feature in dengue fever.
B. Typhoid fever is characterized by a slow, progressive fever pattern without a specific hectic pattern. Rigors can occur, but they are not as prominent or common as in malaria or typhoid fever.
C. Hepatitis is a group of diseases characterized by inflammation of the liver and may present with fever, but the fever pattern is usually subfebrile or intermittent, not hectic. Rigors are also uncommon in hepatitis cases.

**Clinical Pearl:**
Malaria is a globally distributed disease with significant global health implications. The hectic pattern of fever (rapid fluctuations) and the presence of rigors are key clinical features that help differentiate malaria from other febrile illnesses, such as dengue, typhoid fever, and hepatitis. A thorough history taking, including travel history and exposure to endemic areas, can provide further clues to the diagnosis.

**Correct Answer:**
D. Malaria

**Correct Answer Explanation:**
The correct answer is malaria because it is known to present with a hectic pattern of fever and rigors, which are not common in the other options. In malaria, the fever pattern is caused by the uncontrolled multiplication of Plasmodium parasites in the red blood cells, leading to fever responses from the body's immune system. The term "hectic" refers to the rapid fluctuations in body temperature. Rigors are also common in severe malaria cases as the body's attempt to expel the parasites.