Tapeworm

 

 

  • Anoplocephala perfoliata is the most common species of tapeworm in the UK

  • No documented resistance to any of the effective tapeworm wormers

  • There is another species Anoplocephala magna found in the small intestine, this is longer and much rarer than Anoplocephala perfoliata

  • Tapeworms are asexual, each segment contains eggs

 

Lifecycle

 

The tapeworm lifecycle requires an intermediate host, the harvest mite. The harvest mite ingests the tapeworm eggs in the dung from ruptured tapeworm segments. The mite then crawls around forage in the pasture and is ingested by the horse. The harvest mite is also present in hay and haylage and can be ingested this way. Once ingested the eggs hatch, the mite is digested and the immature tapeworm migrate to the junction between the large and small intestine. They hook on here until mature and then drop off to be excreted in the dung. The cycle then starts again.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What do they look like?

 

When in the dung seen as cream segments 4-8cm in length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What damage can they cause?

 

  • Inflammation to the junction between the large and small intestine can cause impaction or intersusseption where a section of small intestine is pushed through the junction into the large intestine

  • Can also cause bowel irritation and twisting of the intestine

  • Presence of the tapeworm causes reduced intestinal motility

 

Clinical signs

 

  • Many tapeworm infections have no symptoms and mild to moderate infections may go unnoticed

  • Anaemia, mild diarrhoea and digestive disturbances may be associated with high tapeworm burdens

  • There is a correlation between high levels of tapeworm burden and spasmodic colic

  • Animals with high tapeworm burdens can show outward signs such as lack of condition and hair loss

 

Diagnosis and Detection

 

Tapeworm infection cannot be accurately detected by worm egg counts, however, there are three methods routinely used for diagnosing tapeworm burdens.

 

  • ScientifEQ offers a faecal flotation test to check for the presence of tapeworm eggs in a dung sample. The test result is reported as positive or negative.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Your vet can perform an ELISA test which measures the levels of tapeworm-specific antibody in a blood sample. Antibody is produced when the tapeworm antigen enters the horse's system. The antibody fights the antigen to kill this foreign body. The results of this test give a level of antibody to give an indication of the level of tapeworm burden.

  • The Equisal tapeworm test, launched in April 2014, identifies tapeworm specific antibodies in the saliva. Antibodies are measured using a combination of two laboratory tests to give a low, borderline or moderate/high result. This innovative test is available to buy from ScientifEQ and offers a simple alternative to the standard ELISA as samples can be collected yourself without the need for a vet.

 

The limitation of ELISA and Equisal tests are that they cannot always distinguish whether there is a current infection or whether the horse has been infected with tapeworm in the past 3 months. This is because it takes some time for the level of tapeworm antibody to drop after the infection is cleared. Furthermore, the immune system has memory. If your horse has previously been exposed to tapeworm there will always be a low level of antibody in the bloodstream, this allows the immune system to quickly fight further tapeworm infections. Therefore, after any exposure to tapeworm the test is always likely to come back low positive in the future, however, if the level of antibody increased this would be indicative of a tapeworm infection.

 

 

Treatment

 

  • Tapeworm infection can be cleared easily using either pyrantal (at a double dose) or praziquantel

  • As tapeworm diagnostics are not wholly reliable it is recommended to give 2 tapeworm treatments a year. This covers the parasite life cycle of 6 months

  • A minimum of 1 tapeworm treatment a year can be given to low risk horses

 

Preventative measures

 

Tapeworm cannot be prevented through chemical intervention. Tapeworm treatments only clear existing burdens and do not have any longevity. Worm control can be aided by good pasture management.

 

Current issues in 2015

 

  • Tapeworm is widespread in the UK

  • Infection is more prevalent in parts of the country with acidic soils as this favours the survival of the intermediate host, the forage mite

  • Approximately 30% of horses are estimated to have a tapeworm burden in the UK

  • There has been concerns over some cases of resistance to pyrantel