[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Nematodes](https://durgical.com/en/microbiology/groups/nematodes/) › Capillaria (C. philippinensis, C. hepatica, C. aerophila)

# Capillaria (C. philippinensis, C. hepatica, C. aerophila)

- Parasite
- For completeness

Thread-thin worms related to whipworm. One lives in the gut after raw fish and can waste the body; others reach the liver or the lungs.

Updated Nov 13, 2026

Also called: Paracapillaria philippinensis, Calodium hepaticum, Eucoleus aerophilus, capillariasis

## Quick facts

**Type**
Parasite · [Nematodes](https://durgical.com/en/microbiology/groups/nematodes/)

**Gram / shape**
Very thin worms

**Spread**
C · C · C

**Causes**
Intestinal capillariasis · Hepatic capillariasis

**Treatment**
Benzimidazoles

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Life cycle
- In Colombia
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- C. philippinensis: raw fish → diarrhoea, malabsorption, protein-losing enteropathy.
- Autoinfection, like Strongyloides: long treatment and relapse risk.
- Eggs look like small whipworm eggs (two polar plugs, striated shell).
- C. hepatica lives in the liver; eggs in stool after eating liver are spurious.
- Marked eosinophilia with hepatitis suggests hepatic capillariasis.

## At a glance

**Shape**
Very thin worms; barrel-shaped eggs with two flattened polar plugs and a striated shell

**Family**
Capillariidae

**Type**
Trichuroid nematodes (roundworms related to Trichuris)

**Size**
C. philippinensis adults about 2–4.5 mm; its eggs 35–45 × 20–25 µm; C. hepatica eggs about 50–70 µm

## Morphology

- Eggs look like small Trichuris eggs: barrel shape, two polar prominences, striated shell.
- C. philippinensis eggs are passed unembryonated; some females release shell-less eggs that hatch inside the gut.
- C. hepatica eggs stay trapped in liver tissue and are not passed in the stool of an infected person.

## Transmission

- C. philippinensis: eating raw or undercooked small freshwater fish that carry larvae.
- C. hepatica: swallowing embryonated eggs from soil, food or water contaminated by dead rodents.
- C. aerophila: swallowing embryonated eggs, possibly earthworms, from the environment of foxes, dogs and cats.

**Reservoir:** C. philippinensis: freshwater fish (intermediate hosts); fish-eating birds proposed; C. hepatica: rats and other rodents; C. aerophila: foxes, dogs, cats and other carnivores

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- C. philippinensis eggs leave in stool and embryonate in water within days.
- Freshwater fish eat the eggs; larvae hatch and settle in the fish tissues.
- A person eats the raw fish; adults burrow into the small-intestine mucosa.
- Some larvae hatch inside the gut and reinvade it (autoinfection), so worm numbers can explode.
- C. hepatica: eggs freed when a rodent liver decays or is eaten embryonate in soil and are swallowed.
- In C. hepatica the adults live and lay eggs in the liver, which is why stool shows no true eggs.

## Virulence factors

- Autoinfection lets C. philippinensis build huge worm burdens without new exposure.
- Mucosal invasion causes malabsorption and protein-losing enteropathy with low albumin and potassium.
- C. hepatica egg deposits cause granulomas and liver necrosis.
- C. aerophila in the airways causes bronchitis and can form masses that mimic cancer.

## Diseases it causes

- Intestinal capillariasis: chronic watery diarrhoea, malabsorption and protein-losing enteropathy
- Hepatic capillariasis: acute or subacute hepatitis with fever, hepatomegaly and eosinophilia
- Pulmonary capillariasis: cough, mucoid or bloody sputum, fever (rare)

## Clinical picture

- Intestinal form: borborygmi, abdominal pain, weeks of diarrhoea, weight loss, oedema and cachexia.
- Untreated intestinal disease can be fatal through electrolyte loss, heart failure and wasting.
- Hepatic form: fever, enlarged liver, leukocytosis and marked eosinophilia.
- Eggs of C. hepatica in stool after eating animal liver are a spurious passage, not disease.

## Diagnosis

- C. philippinensis: eggs, larvae or adults in stool or small-bowel biopsy; repeated stool exams help.
- C. hepatica: worms or eggs in a liver biopsy or at autopsy.
- C. aerophila: eggs in sputum or stool, or worms in a lung or bronchial biopsy.
- No validated serology; eggs can be confused with Trichuris eggs.

## Treatment

Benzimidazoles (albendazole or mebendazole), given for a long course because autoinfection causes relapse, plus fluid, electrolyte and protein replacement in intestinal disease.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Albendazole](https://durgical.com/en/pharmacology/albendazole/)
- [Mebendazole](https://durgical.com/en/pharmacology/mebendazole/)

## Prevention

- Cook freshwater fish well; avoid raw small fish dishes in endemic areas.
- Hand hygiene and rodent control; wash vegetables grown near rodents.
- Treat a known case fully, since autoinfection keeps it going.

## In Colombia

These are rare in Colombia. C. philippinensis is mainly Asian (the Philippines and Thailand), with cases also in Egypt; C. hepatica lives in rats worldwide, so human cases are exceptional and usually liver findings.

## Memory aid

Capillaria = capillary-thin: a thread from a raw fish that keeps multiplying in the gut until the patient becomes thin too.

## Test yourself

Think of the answer, then tap the question to see it.

## How do people acquire Capillaria philippinensis?

By eating raw or undercooked small freshwater fish that carry the larvae.

## Which feature lets C. philippinensis cause massive infections?

Autoinfection: larvae hatch inside the gut and reinvade the mucosa without new exposure.

## What syndrome results from heavy intestinal capillariasis?

Chronic diarrhoea with malabsorption and protein-losing enteropathy, which can be fatal.

## Why do Capillaria hepatica eggs in a stool sample usually not mean disease?

In true infection eggs stay in the liver; eggs in stool usually come from eating infected animal liver (spurious passage).

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/capillaria/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 3

- [Trichuris trichiura](https://durgical.com/en/microbiology/trichuris-trichiura/)
- [Strongyloides stercoralis](https://durgical.com/en/microbiology/strongyloides-stercoralis/)
- [Trichinella spiralis](https://durgical.com/en/microbiology/trichinella-spiralis/)

[← Back to the group: Nematodes](https://durgical.com/en/microbiology/groups/nematodes/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [CDC - DPDx - Intestinal Capillariasis](https://www.cdc.gov/dpdx/intestinalcapillariasis/index.html) (CDC, 2020); [CDC - DPDx - Hepatic Capillariasis](https://www.cdc.gov/dpdx/hepaticcapillariasis/index.html) (CDC, 2019); [Molecular Detection of Capillaria aerophila, an Agent of Canine and Feline Pulmonary Capillariosis](https://pmc.ncbi.nlm.nih.gov/articles/PMC3372154/) (Journal of Clinical Microbiology (PMC), 2012).

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Representative model, for educational purposes only.

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