[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Cestodes (tapeworms)](https://durgical.com/en/microbiology/groups/cestodes/) › Rare tapeworms (Raillietina, Inermicapsifer, Bertiella)

# Rare tapeworms (Raillietina, Inermicapsifer, Bertiella)

- Parasite
- For completeness

Small tapeworms of rats and monkeys that sometimes infect young children. Parents notice white segments like rice grains in the nappy.

Updated Nov 13, 2026

Also called: Raillietina demerariensis, Raillietina celebensis, Inermicapsifer madagascariensis, Bertiella mucronata, Bertiella studeri

## Quick facts

**Type**
Parasite · [Cestodes (tapeworms)](https://durgical.com/en/microbiology/groups/cestodes/)

**Gram / shape**
Small

**Spread**
Accidental swallowing · Children who crawl on floors

**Causes**
Intestinal tapeworm infection

**Treatment**
Cestocides

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

- Young child + rice-grain proglottids in stool: think Raillietina or Inermicapsifer.
- Humans are infected by swallowing an arthropod, not eggs.
- Armed scolex = Raillietina; unarmed = Inermicapsifer.
- Bertiella: monkey tapeworm, mite intermediate host.
- Praziquantel treats them.

## At a glance

**Shape**
Small, white, barrel-shaped gravid proglottids full of egg capsules or eggs

**Family**
Davaineidae (Raillietina); Anoplocephalidae (Inermicapsifer, Bertiella)

**Type**
Cyclophyllidean cestodes of rodents (Raillietina, Inermicapsifer) and primates (Bertiella)

**Size**
Raillietina adults 15–60 cm; Bertiella 10–40 cm; proglottids a few millimetres

## Morphology

- Raillietina and Inermicapsifer proglottids and egg capsules look almost the same.
- The scolex separates them: armed with hooks in Raillietina, unarmed in Inermicapsifer.
- Bertiella eggs have a pear-shaped (pyriform) apparatus around the six-hooked embryo.
- Proglottids may be confused with Dipylidium caninum.

## Transmission

- Accidental swallowing of an infected arthropod: presumed insects for Raillietina (related species use ants and beetles), mites for Bertiella.
- Children who crawl on floors or play outdoors are most at risk.
- Bertiella: close contact with pet or wild monkeys, or contaminated fruit.

**Reservoir:** Raillietina demerariensis: Neotropical rodents and occasionally monkeys; Raillietina celebensis: peridomestic rats in Asia and the Pacific; Inermicapsifer: rodents; Bertiella: non-human primates

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- Gravid proglottids leave in the faeces of a rodent or monkey and release egg capsules or eggs.
- An arthropod (insect or mite) swallows the eggs; a cysticercoid develops inside it.
- The rodent or monkey eats the infected arthropod and the adult grows in its small intestine.
- A child swallows the arthropod by accident; the tapeworm matures and sheds proglottids in stool.

## Virulence factors

- Adults attach to the intestinal mucosa by the scolex and absorb nutrients; little tissue damage.
- Most infections are mild or asymptomatic.

## Diseases it causes

- Intestinal tapeworm infection in young children, often only the passage of proglottids [Intestinal tapeworm infections (taeniasis, hymenolepiasis, diphyllobothriasis) →](https://durgical.com/en/conditions/intestinal-tapeworm-infections/)

## Clinical picture

- Usually discovered when white, motile, rice-grain-like proglottids are seen in stool.
- Sometimes abdominal pain, irritability, poor appetite or nausea.
- Nearly all known Raillietina and Inermicapsifer cases are in young children.

## Diagnosis

- Proglottids, egg capsules or eggs in stool; proglottids can be pressed to release eggs.
- Genus identification needs expert morphology; the rarely recovered scolex settles Raillietina versus Inermicapsifer.
- Results are often reported as Inermicapsifer/Raillietina when the scolex is missing.
- Eggs passed in stool are not infectious to people.

## Treatment

Cestocides: praziquantel; niclosamide is an alternative.

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

In Pharmacology:

- [Praziquantel](https://durgical.com/en/pharmacology/praziquantel/)

## Prevention

- Rodent and insect control in and around the home.
- Hand hygiene and clean floors where small children crawl.
- Avoid close contact with monkeys kept as pets; wash fruit.

## In Colombia

Raillietina demerariensis is a New World species reported mainly from Ecuador, plus Central America and the Caribbean. Bertiella mucronata occurs in South America and Cuba in howler and titi monkeys. Inermicapsifer infections in children are best documented in Cuba.

## Memory aid

Rice in the nappy, rat in the house: the child ate the beetle the rat had shared.

## Test yourself

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

## What usually brings a child with Raillietina or Inermicapsifer infection to medical attention?

The parents see small white, rice-grain-like proglottids moving in the stool.

## How does a child acquire Raillietina?

By accidentally swallowing an infected arthropod intermediate host (presumed insects such as beetles or ants) carrying the cysticercoid.

## Which structure distinguishes Raillietina from Inermicapsifer?

The scolex: armed with hooks in Raillietina, unarmed in Inermicapsifer.

## What is the intermediate host of Bertiella?

Mites, usually oribatid soil mites.

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

## 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

- [Hymenolepis nana](https://durgical.com/en/microbiology/hymenolepis-nana/)
- [Dipylidium caninum](https://durgical.com/en/microbiology/dipylidium-caninum/)
- [Taenia saginata](https://durgical.com/en/microbiology/taenia-saginata/)

## Related conditions 1

- [Intestinal tapeworm infections (taeniasis, hymenolepiasis, diphyllobothriasis)](https://durgical.com/en/conditions/intestinal-tapeworm-infections/)

[← Back to the group: Cestodes (tapeworms)](https://durgical.com/en/microbiology/groups/cestodes/)

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

Sources: [CDC - DPDx - Raillietina infection](https://www.cdc.gov/dpdx/raillietina/index.html) (CDC, 2019); [CDC - DPDx - Bertiella Infection](https://www.cdc.gov/dpdx/bertiella/index.html) (CDC, 2019).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/rare-tapeworms/