Table of Contents

Oesophagostomiasis

Oesophagostomiasis is also known as Nodular worm of ruminants and pigs, and Pimply gut.

Oesophagostomiasis or Oesophagostomiosis is a major cause of enteritis in ruminants and pigs in tropical and subtropical areas and usually associated with nodule formation in the large intestine.

Etiology

*Oesophagostomiasis causing species, host, and location affected*

Morphology

Adult worm length: 1–2 cm.
Egg are thin shelled embryonated eggs (Blastomere 8–16 cell stage).

Life cycle

The infection occurs by ingestion of infective L₃ larvae. The L₃ larvae enter the mucosa of any part of small or large intestine. The L₃ moult to L₄ emerges on mucosal surface and migrates to colon and develops into adult stage. The prepatent period is about 45 days. On reinfection with most species, the larvae may remain arrested as L₄ in nodules for up to one year. However infection with O. Venulosum nodules are absent.

Pathogenesis

In the intestine Oe. Columbianum L₃ migrates deep into the mucosa of caecum, provoking an inflammatory response with the formation of nodules, which are visible to the naked eye (pimply gut).
On reinfection, this response is more marked, increase in size of nodules (upto 2.0 cm dia) containing eosinophilic greenish pus and L₄.
When larva emerges, there may be an ulceration of mucosa leads to diarrhoea one week after primary infection. In heavy it causes ulcerative colitis.

Clinical manifestation

Acute

Young lambs are highly susceptible.
Severe dark green diarrhoea, the faeces may contain excess mucus as well as streak of blood.
The sheep become weak, lose weight despite a good appetite, and show intermittent diarrhea and constipation.
Nodule formation usually is more pronounced in sheep than in cattle. Affected sheep walk with a stilted gait and often have a humped back.
Stenosis and intussusception may develop in severe cases.

Chronic

It occur primarily in sheep.
Inappetence, emaciation with intermittent diarrhoea.
Anaemia is the main clinical signs.

In Pigs

Pregnant sows show inappetence, become very thin following farrowing, reduced milk production, which indirectly affect the growth performance of litter.

Immunity

Prolonged survival of L₄ on nodules in the gut wall and the lack of an effective immunity, control is difficult.
In cattle good immunity developed against O.radiatum partly due to age and previous exposure.

Diagnosis

Based on clinical signs.
Post mortem examination-presence of nodules in the colon (pimply gut).
Acute case-eggs are not usually present.
Chronic cases- eggs are identified in faeces.
The L₃ identified in faecal culture.

Treatment

Benzimidazole compound at recommended dose.
Levamisole and morantel citrate at recommended dose.

Control

Prevent heavy exposure in susceptible hosts.
Reduce pasture contamination.
Minimize the effects of worm burden.
Encourage the development of development of immunity in the animals.