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.
Also called: Raillietina demerariensis, Raillietina celebensis, Inermicapsifer madagascariensis, Bertiella mucronata, Bertiella studeri
Quick facts
- Type
- Parasite · Cestodes (tapeworms)
- Gram / shape
- Small
- Spread
- Accidental swallowing · Children who crawl on floors
- Causes
- Intestinal tapeworm infection
- Treatment
- Cestocides
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) →
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:
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.
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.
Connections
← Back to the group: Cestodes (tapeworms)
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 (CDC, 2019); CDC - DPDx - Bertiella Infection (CDC, 2019).
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Representative model, for educational purposes only.