--- title: "Ancylostoma Doudenale | Microbiology" description: "Ancylostoma doudenale is a human hookworm that infects the small intestine, causes blood loss and iron-deficiency anemia, and is traced by stool eggs." canonical: "https://fiveable.me/microbio/key-terms/ancylostoma-doudenale" type: "key-term" subject: "Microbiology" unit: "Unit 24" --- # Ancylostoma Doudenale | Microbiology ## Definition Ancylostoma doudenale is an Old World hookworm in Microbiology that infects the human small intestine. It penetrates skin, migrates through the lungs, and can cause blood loss, abdominal symptoms, and iron-deficiency anemia. ## What It Is Ancylostoma doudenale is a parasitic nematode, better known as an Old World hookworm, that lives in the human small intestine and feeds on blood from the intestinal wall. In microbiology, you study it as a helminth, not a bacterium or virus, because it is a multicellular worm with a complex life cycle and tissue migration. The infection usually starts when larvae in contaminated soil penetrate bare skin, often through the feet. After entering the body, they move through the bloodstream to the lungs, then crawl up the airways, get swallowed, and finally settle in the small intestine. That migration pattern is a big clue in hookworm biology, because the organism does not stay in one place from exposure to symptoms. Once in the intestine, the worm attaches to the mucosa and draws blood. That attachment is what leads to chronic blood loss and, in many cases, iron-deficiency anemia. People can develop fatigue, weakness, abdominal pain, diarrhea, and weight loss, especially if the infection lasts a long time or the worm burden is high. The life cycle has both free-living and parasitic stages. Eggs leave the human host in stool, hatch in soil, and develop into infective larvae under warm, moist conditions. That is why sanitation, footwear, and soil exposure matter so much in transmission, and why hookworm is tied to environmental conditions as well as host biology. In the lab, you usually connect Ancylostoma doudenale to stool microscopy. The adult worms are not normally seen in routine specimens, but their eggs are. That makes stool examination a practical diagnostic step in microbiology, especially when a case history includes anemia plus possible soil exposure. ## Why It Matters Ancylostoma doudenale shows up in microbiology because it ties together parasitology, transmission, pathogenesis, and diagnosis in one case. If you can trace how the larvae enter, migrate, and attach in the intestine, you can explain why the disease causes both GI symptoms and anemia instead of just saying it is a worm infection. It also helps you separate hookworm infection from other intestinal parasites. Some helminths are spread by fecal-oral transmission, but A. doudenale is acquired through skin penetration from contaminated soil. That difference matters when you are comparing diseases, building transmission chains, or deciding which prevention step actually breaks the cycle. The organism is also useful for reading clinical patterns. A patient with fatigue, pallor, abdominal discomfort, and a history of walking barefoot in areas with poor sanitation points you toward hookworm disease faster than a vague stomach bug. In that way, the term helps you move from symptoms to a likely parasite and then to the right diagnostic test. ## Connections ### [hookworm infection](/microbio/key-terms/hookworm-infection) This is the disease pattern caused by hookworms such as Ancylostoma doudenale. The term is broader than the species name, so you use it when discussing the clinical syndrome, symptoms, and the intestinal blood loss that leads to anemia. It is the umbrella label for the infection itself. ### Necator americanus This is the other major human hookworm and the closest comparison to A. doudenale. Both infect the small intestine and can cause iron-deficiency anemia, but they are different species. In microbiology, this comparison comes up when you are identifying hookworms or comparing parasite geography and disease burden. ### Stool Examination Stool examination is the usual lab step used to detect hookworm eggs. You are not looking for the adult worm in most routine samples, so the diagnosis depends on microscopic identification of eggs in feces. This makes specimen collection and microscope recognition part of the practical workflow. ### Helminthiasis Helminthiasis is the general term for infection with parasitic worms. Ancylostoma doudenale is one example within that broader category, specifically a nematode infection. The connection matters because it places hookworm in the larger framework of parasite classes, transmission routes, and chronic disease patterns. ## On the AP Exam A quiz question may ask you to identify the organism from a case of anemia plus barefoot soil exposure, or to match the parasite with its route of infection. In a lab practical, you might need to recognize hookworm eggs on a stool slide and connect that finding to intestinal blood loss. In a written response, the useful move is to trace the sequence: skin penetration, lung migration, swallowing, intestinal attachment, then chronic iron deficiency. If a question compares parasites, point out that A. doudenale is a soil-transmitted helminth, not a fecal-oral organism, so prevention depends on sanitation and footwear as much as treatment. ## Ancylostoma doudenale vs Necator americanus These are both human hookworms, so they get mixed up a lot. The big idea is that both can cause hookworm infection and anemia, but they are different species. If the question only cares about the disease pattern, either may be discussed under hookworm disease, but if it asks for the exact species, you need the specific name. ## Key Takeaways - Ancylostoma doudenale is a hookworm nematode that infects the human small intestine. - Infection starts when larvae in contaminated soil penetrate skin and migrate through the lungs before reaching the gut. - The worm attaches to the intestinal wall and feeds on blood, which can cause iron-deficiency anemia. - Stool examination is a common way to detect infection because eggs are shed in feces. - The term matters most when you are tracing transmission, symptoms, and diagnosis in a parasite case. ## FAQs ### What is Ancylostoma doudenale in Microbiology? It is an Old World hookworm, a parasitic nematode that infects the human small intestine. In microbiology, it is studied as a helminth with a soil stage, lung migration, and intestinal blood feeding that can lead to anemia. ### How does Ancylostoma doudenale infect humans? The infective larvae usually penetrate the skin from contaminated soil. They travel through the bloodstream to the lungs, move up the airways, get swallowed, and then mature in the small intestine. ### How is Ancylostoma doudenale different from fecal-oral parasites? It is not spread by swallowing contaminated food or water the way many fecal-oral parasites are. Instead, the larvae enter through skin contact with soil, so exposure to bare ground is the big transmission clue. ### How do you diagnose Ancylostoma doudenale infection? The usual first step is stool examination under the microscope. The adult worms are rarely seen directly, but their eggs can be identified in fecal samples, which helps connect the parasite to chronic blood loss and GI symptoms. ## Related Study Guides - [24.6 Helminthic Infections of the Gastrointestinal Tract](/microbio/unit-24/6-helminthic-infections-gastrointestinal-tract/study-guide/ffzHSrFhtGFKKoUS) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/microbio/key-terms/ancylostoma-doudenale#resource","name":"Ancylostoma Doudenale | Microbiology","url":"https://fiveable.me/microbio/key-terms/ancylostoma-doudenale","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/microbio/key-terms/ancylostoma-doudenale#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:23:45.862Z","isPartOf":{"@type":"Collection","name":"Microbiology Key Terms","url":"https://fiveable.me/microbio/key-terms"},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/microbio/key-terms/ancylostoma-doudenale#term","name":"Ancylostoma doudenale","description":"Ancylostoma doudenale is an Old World hookworm in Microbiology that infects the human small intestine. 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