Tricostrongylosis

Tricostrongylosis is a nematode parasitic disease of animals caused by Trichostrongylus species (Trichostrongylus Colubriformis, axei and tenius).

Etiology

Life cycle

• Infection of definitive host: Through passive ingestion.
• Exsheathment (abomasum or small intestine).

Pathogenesis

T. Axei

• It occurs in anterior part of small intestine
• In mucosa – formation of tunnels between epithelium and basement membrane
• Distortion and displacement of mucosal epithelium
• Loss of plasma protein into intestine results in  hypoalbuminaemia

T. colubriformis

• Similar to T. axei

In general Trichostrongylus species

• Intestinal parasitism – increased gastric secretion of cholecystokinin act on appetite centre in brain, leads to decreased appetite
• Loss of serum protein  is due to anorexia, reduced feed intake and reduced food conversion ratio
• Reduced absorption of calcium and phosphorus from intestine leads to retarded bone growth and osteoporosis

Clinical manifestation

Gastrointestinal disturbances like diarrhoea seen in Tricostrongylosis.

Acute cases

• Sudden death, such animal neither emaciated nor anaemic.
• Leg weakness and unable to stand.

Chronic cases

• variable in appetite, emaciation, rough and dry hair coat.
• alternatively constipation and diarrhoea, faeces is dark in colour, so the worm is called as “Black scour worms”.
• anemia is not well pronounced (mild one).

In avian species

• Haemorrhagic typhilitis with diarrhoea, loss of appetite, emaciation and anemia.

Immunity

• Infection induces immunity to reinfection (intake of infective larvae or presence of adult worm).
• Cross immunity is observed between Trichostrongylus spp, not at generic level.

Diagnosis

• Demonstration of eggs in faeces.
• Faecal culture.

Treatment

• Same as that of ostertagia.

Control

• Reduce pasture contamination.
• Minimize the antihelmintic resistance by rotational use of antihelmintics.
• Antihelmintic treatment ofweaned lambs before entered into the grazing area.
• Reduce the periparturient rise (PPR) of egg count in pregnant ewes by treating with antihelmintic aat the end of gestation and one month after lambing.
• Alternate ormixed grazing of animals with different host species and different age groups, immune and nonimmune animals.