Reservoir of hookworm –
**Core Concept**
Hookworm infection is a parasitic disease caused by hookworms (Ancylostoma duodenale and Necator americanus). The lifecycle of hookworms involves a complex process of infection, migration, and establishment in the human host. The reservoir of hookworms refers to the source of the infection, which is crucial for understanding the epidemiology and transmission dynamics of the disease.
**Why the Correct Answer is Right**
The reservoir of hookworms is primarily the human host, specifically those individuals who are infected and harbor the parasites in their intestines. This is because the adult hookworms live in the small intestine of humans, where they attach to the mucosa and feed on blood. The human host serves as a reservoir for hookworms because it provides a suitable environment for the parasites to grow, multiply, and produce eggs, which are then shed in the feces and contaminate the soil. This perpetuates the lifecycle of hookworms and allows them to infect new hosts.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because while dogs and other animals can act as reservoirs for certain types of hookworms, they are not the primary reservoir for the hookworms that infect humans.
* **Option B:** This option is incorrect because the soil itself is not a reservoir for hookworms, but rather a medium through which the eggs and larvae of hookworms are transmitted to new hosts.
* **Option C:** This option is incorrect because while the feces of infected individuals can contain hookworm eggs and larvae, the feces themselves are not considered a reservoir of hookworms.
**Clinical Pearl / High-Yield Fact**
The human host serves as the primary reservoir for hookworms, highlighting the importance of good hygiene and sanitation practices in preventing the transmission of this disease.
**Correct Answer:** D.