# Ascaris and Hookworm

> Ascaris lumbricoides and hookworm for NEET-PG Microbiology, covering life cycles, lung migration, iron-deficiency anaemia, egg identification and albendazole.

- Canonical URL: https://prepelephant.com/topics/neet-pg/microbiology/ascaris-and-hookworm
- Exam / course: NEET-PG · Subject: Microbiology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Textbook of Medical Parasitology by K D Chatterjee; Park's Textbook of Preventive and Social Medicine
- How to cite: "Ascaris and Hookworm", PrepElephant, https://prepelephant.com/topics/neet-pg/microbiology/ascaris-and-hookworm

## Direct answer

Ascaris lumbricoides and hookworms are soil-transmitted helminths that infect the intestine after contact with contaminated soil. Ascaris is acquired by ingesting embryonated eggs, while hookworm larvae penetrate intact skin, usually of the feet. Hookworm is a major cause of iron-deficiency anaemia among intestinal nematodes, and albendazole given as a single dose is the usual treatment for both.

## What you must remember

- **Ascaris eggs:** Fertilised eggs have a golden, mammillated outer coat, while unfertilised eggs are elongated with a thinner or absent coat.
- **Löffler syndrome:** Larval migration through the lungs causes transient cough, fever and eosinophilia.
- **Ascariasis complications:** Intestinal obstruction, biliary colic and intestinal perforation occur with heavy worm burdens.
- **Hookworm species:** Necator americanus and Ancylostoma duodenale are the two species, and their eggs are thin-shelled.
- **Ground itch:** Penetration by filariform larvae produces an itchy, papular reaction at the entry site, usually the feet.
- **Anaemia:** Hookworm adults feed on blood, causing chronic blood loss and microcytic hypochromic anaemia.
- **Diagnosis:** Stool microscopy identifies eggs, and the Kato-Katz thick smear quantifies the egg load.
- **Treatment:** Albendazole 400 mg as a single dose is standard, and mebendazole 500 mg is an alternative.

## Two life cycles, two entry routes, two kinds of damage

Ascaris and hookworm are both soil-transmitted, but they enter the body differently and damage different organs. Tracing each cycle explains the symptoms that exam questions ask about, and it also explains why the lungs are involved in both.

1. **Ascaris ingestion:** Embryonated eggs are swallowed and hatch in the small intestine, releasing larvae that penetrate the gut wall.
2. **Pulmonary migration:** Larvae travel through the bloodstream to the lungs, are coughed up and swallowed, and then mature into adult worms in the small intestine. This lung phase explains the eosinophilia and cough.
3. **Hookworm penetration:** Filariform larvae penetrate intact skin, usually of the feet, and reach the lungs through the bloodstream before settling in the intestine.
4. **Adult attachment:** Hookworm adults attach to the small intestinal mucosa and feed on blood, so chronic blood loss and iron deficiency follow over time.
5. **Diagnosis and cure:** Stool microscopy identifies the helminth from its eggs, the Kato-Katz method counts egg load, and albendazole given as a single dose clears most adult worms.

## Where the exam tries to catch you

Most mistakes come from confusing the lung phase with the anaemia and the egg morphology of the two worms.

- **Trap:** Calling Ascaris eggs embryonated when they are passed in faeces — **Correct:** passed eggs are unembryonated and become infective in soil over several weeks.
- **Trap:** Attributing eosinophilia to hookworm alone — **Correct:** eosinophilia is most typical of the lung phase of Ascaris, as in Löffler syndrome.
- **Trap:** Choosing iron supplementation alone for hookworm anaemia — **Correct:** the worm must be cleared with albendazole, and iron is given to correct the deficiency.
- **Trap:** Missing the biliary complication — **Correct:** a worm moving into the bile duct causes biliary colic, cholangitis or pancreatitis and needs urgent review.

## Frequently asked questions

### What is Löffler syndrome in ascariasis?
Löffler syndrome is pulmonary eosinophilia caused by Ascaris larvae migrating through the lungs. It presents with transient cough, fever and eosinophilia, and the lung changes resolve over time.

### Which egg features identify Ascaris lumbricoides?
Fertilised Ascaris eggs have a golden brown, mammillated outer coat, while unfertilised Ascaris eggs are elongated with a thinner or absent coat. Both forms appear in stool and are distinct from hookworm eggs, which are thin-shelled.

### Why does hookworm infection cause iron-deficiency anaemia?
Hookworm adults attach to the small intestinal mucosa and feed on blood, causing chronic blood loss. This results in microcytic hypochromic anaemia, which responds to iron replacement once the worms are cleared.

### What dose of albendazole treats Ascaris and hookworm?
Albendazole 400 mg as a single oral dose is the standard treatment for Ascaris lumbricoides and hookworm infection. Mebendazole 500 mg as a single dose is an alternative option.

### Which skin lesion is linked to hookworm larvae?
Ground itch is the itchy, papular skin reaction at the site where hookworm filariform larvae penetrate, usually the feet. It appears when people walk barefoot on contaminated soil.