American Board of Internal Medicine (ABIM) Certification Practice Exam

Why might diarrhea persist even after giardia has been eradicated?

1. Infection-induced lactose intolerance

2. Inadequate hydration

3. Excessive fiber intake

4. Use of medications

The correct answer is: Infection-induced lactose intolerance

Diarrhea may continue even after the successful treatment of a Giardia infection due to infection-induced lactose intolerance. Giardia lamblia can damage the intestinal lining and lead to a temporary inability to properly digest lactose, the sugar found in milk and dairy products. When the body is unable to digest lactose, it can result in symptoms such as diarrhea, bloating, and abdominal pain. This post-infectious lactose intolerance is relatively common and may persist for weeks to months after the infection has resolved, thereby leading to ongoing gastrointestinal symptoms. In contrast, inadequate hydration pertains to the management of diarrhea and could exacerbate symptoms but does not directly explain the persistence of diarrhea after eradication of Giardia. Excessive fiber intake may contribute to diarrhea in some cases, but it does not specifically relate to the aftermath of a Giardia infection. The use of medications, such as antibiotics, could disrupt the gut flora or lead to side effects, yet these would not typically result in a prolonged state of diarrhea following parasitic eradication.