Trichuris

Also known as:

whipworm

Trichuris ovis from sheep faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

Trichuris ovis in caecum - Supplied by Biomed Image Archive

Trichuris vulpis - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine

Overview

The Trichuris worms, part of the Trichuroidea superfamily, are so called due to their characteristic whip like structure. They have a broad posterior end tapering to a long and narrow neck which is inserted into the caecal mucosa. They have a direct life cycle, moving directly into the definitive host from the infective L1 egg stage. Once ingested the larva is freed from the egg casing due to digestion of the plugs at either end of the egg. The larvae then form mucosal nodules in which to develop before emerging into the lumen of the large intestine and caecum of the host.

Characteristics

Eggs
The eggs of Trichuris species are yellow/brown in colour and are bioperculated (have a plug in each end). They are hardy eggs and in the correct coonditions can survive on pasture for up to 12 years. The Trichuris embryo develops inside the egg and is infective as the 1st larval stage living within the egg.
Larvae
Hatch from the egg into the small intestine and there grow and moult until the reach adulthood.
Adult
Attach to the mucosa of the large intesitine.

Life Cycle

The life cycle is not a standard nematode life cycle as these species are infective within the egg at a very early stage of embryo development. This means infective eggs can be present on pasture within 10 - 14 days of adult patency. Eggs are transerred to pasture in the feaces of the host animal and then ingested by animals grazing on the pasture; feaco-oral spread. Thrichuris spp. have no tissue migratory period, living there entire lives in the small and large intestine of the host.

Important Species

There are several species of veterinary importance, each typically infecting a different host species;

• Trichuris vulpis; the dog whipworm
• Trichuris campanula (Europe) and Trichuris serrata (North America); cat whipworms, though these are only seen rarely.
• Trichuris suis; the pig whipworm

Clinical

• Adult buries its thin anterior half into the intestinal mucosa and feeds on tissue secretions (not blood).
  • The caecum and colon are the most commonly infected sites.
  • Causes eosinophilia.
• Signs may include:
  • Diarrhoea
    • Catarrhal enteritis
  • Anemia
  • Dehydration