**Question:** Convalescent case of cholera remains infective for

A. 24 hours
B. 48 hours
C. 72 hours
D. 7 days

**Core Concept:** Cholera is an acute diarrheal disease caused by the bacterium Vibrio cholerae. Convalescent cases refer to individuals who have recovered from acute cholera but still retain the bacterium in their intestines. These individuals can continue to transmit the disease to others due to the presence of Vibrio cholerae in their stool.

**Why the Correct Answer is Right:** Convalescent cases of cholera remain infective for a longer duration because the bacterium persists in their intestinal tract, even after the acute phase of the disease has resolved. Vibrio cholerae continues to produce cholera toxin, which leads to diarrhea and osmotic diarrhea, causing the bacterium to be shed in the stool for a longer period.

**Why Each Wrong Option is Incorrect:**

A. 24 hours: This option is too short, as convalescent cases can continue to transmit the disease even after a day.
B. 48 hours: This is also too short, as the bacterium may persist for longer periods in some individuals.
C. 72 hours: This is closer to the correct answer but still too short; convalescent cases can remain infective for much longer periods.
D. 7 days: This is the correct answer, as the duration of infectivity in convalescent cases is typically around 7 days, although it can vary depending on the individual's immune response and environmental factors.

**Clinical Pearl:** Convalescent cases of cholera are a significant public health concern due to their ability to transmit the disease to others. It is crucial for healthcare professionals, especially in endemic regions, to understand the infectivity period of convalescent cases to implement appropriate measures for disease control and prevention.

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**Correct Answer:** D. 7 days

**Core Concept:** Cholera is an infectious disease caused by Vibrio cholerae bacteria. Convalescent cases, individuals recovering from acute cholera, can remain infectious for a certain period after the acute phase, as they still harbor the bacteria in their gastrointestinal tract.

**Why the Correct Answer is Right:** The infectivity of convalescent cases is due to the persistence of Vibrio cholerae in the gastrointestinal tract, which continues to produce cholera toxin and cause osmotic diarrhea, leading to ongoing excretion of the bacteria in the stool.

**Why Each Wrong Option is Incorrect:**

A. 24 hours: This is too short, as the duration of infectivity can be longer due to the presence of Vibrio cholerae in the gastrointestinal tract.
B. 48 hours: This is too short compared to the actual duration of infectivity in convalescent cases.
C. 72 hours: This is too short for convalescent cases, as their infectivity can last significantly longer.