Is anaemia in sheep caused by Haemonchus contortus?

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By Lucas Reynolds

Anaemia is a common disorder in sheep that can cause significant economic losses in livestock production. It is characterized by a decrease in the number of red blood cells or haemoglobin concentration in the blood, leading to weakness, lethargy, poor growth, and ultimately death. One of the most common causes of anaemia in sheep is the parasitic infection caused by Haemonchus contortus, commonly known as the barber’s pole worm.

What is Anaemia?

Anaemia is a condition in which the body does not have enough red blood cells or haemoglobin to carry oxygen to the body’s tissues. This can result in a variety of symptoms, such as fatigue, weakness, shortness of breath, dizziness, and pale skin. Anaemia can be caused by a variety of factors, including iron deficiency, chronic disease, and blood loss.

What is Haemonchus Contortus?

Haemonchus contortus is a blood-sucking parasite that affects small ruminants, including sheep and goats. It is commonly known as the barber’s pole worm due to its distinctive appearance, with two different-coloured bands resembling a barber’s pole, wrapped around its body. This parasite lives in the abomasum, or the fourth stomach compartment, of infected animals, where it feeds on blood and causes significant damage to the host’s gastrointestinal tract.

The Relationship Between Haemonchus Contortus and Anaemia

Haemonchus contortus is a significant cause of anaemia in sheep, particularly in areas with warm and humid climates. The parasite feeds on the host’s blood, leading to a decrease in the number of red blood cells and haemoglobin concentration in the blood, resulting in anaemia. The severity of anaemia depends on the number of parasites present in the host’s abomasum, the duration of infection, and the host’s immune response.

The Life Cycle of Haemonchus Contortus

The life cycle of Haemonchus contortus is complex and involves both sheep and free-living stages. The adult worms in the abomasum lay eggs that are passed out in the faeces of the host. These eggs hatch into infective larvae that can survive for several weeks in the environment under favourable conditions. When sheep graze on contaminated pasture, they ingest these infective larvae, which then migrate to the abomasum, where they mature into adult worms and start feeding on blood.

Transmission of Haemonchus Contortus

Haemonchus contortus is transmitted through the faecal-oral route. The parasite eggs are passed out in the faeces of infected animals and can contaminate the pasture. When healthy sheep graze on this pasture, they ingest the infective larvae, which then migrate to the abomasum, where they mature into adult worms and start feeding on blood.

Diagnosis of Haemonchus Contortus in Sheep

Diagnosis of Haemonchus contortus in sheep is based on clinical signs, faecal egg counts, and post-mortem examination. Clinical signs of infection include lethargy, weakness, poor growth, and anaemia. Faecal egg counts can be used to estimate the level of parasite infection in the flock. Post-mortem examination can be used to confirm the diagnosis and assess the severity of damage caused by the parasite.

Treatment of Haemonchus Contortus in Sheep

Treatment of Haemonchus contortus in sheep includes the use of anthelmintic medicines, such as benzimidazoles, imidazothiazoles, and macrocyclic lactones. These medicines kill the adult worms and/or inhibit their egg production, reducing the parasite burden in the host and preventing further damage to the abomasum. In severe cases of anaemia, blood transfusions may be required to restore the red blood cell count.

Prevention of Haemonchus Contortus in Sheep

Prevention of Haemonchus contortus in sheep includes good management practices, such as rotational grazing, pasture management, and strategic use of anthelmintics. These practices reduce the level of parasite contamination on the pasture, minimize the risk of infection, and reduce the development of anthelmintic resistance in the parasite population. Genetic selection for resistance to Haemonchus contortus can also be used to reduce the incidence of infection in sheep.

Economic Impact of Haemonchus Contortus on Sheep Production

Haemonchus contortus has a significant economic impact on sheep production, particularly in tropical and subtropical regions. The parasite can cause reduced weight gain, poor wool quality, reproductive failure, and death, leading to significant losses in productivity and profitability for the farmer. The cost of treatment and prevention of the parasite infection can also be high, further reducing the farmer’s income.

Conclusion

Haemonchus contortus is a major cause of anaemia in sheep, leading to significant economic losses in livestock production. Prevention and treatment of the parasite infection can help reduce the burden of the disease on the farmer and improve the productivity and profitability of sheep production. Good management practices, genetic selection, and strategic use of anthelmintics are essential for controlling the parasite infection and minimizing the economic impact of the disease.

References

  1. Kaplan RM. Anthelmintic resistance in nematodes of cattle, sheep and goats in the United States. Vet Parasitol. 2004;125:167-94.
  2. Sargison ND. Control of Haemonchus contortus in sheep. Vet Clin North Am Food Anim Pract. 2011;27:217-27.
  3. van Wyk JA, Bath GF. The FAMACHA system for managing haemonchosis in sheep and goats by clinically identifying individual animals for treatment. Vet Res. 2002;33:509-29.
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Lucas Reynolds

Lucas Reynolds, the mastermind behind TravelAsker's compelling content, originates from the charming Sedona, Arizona. A genuine local, he shares deep insights into the region, unveiling its enchanting attractions, tranquil resorts, welcoming accommodations, diverse dining options, and engaging pastimes. Lucas invites readers to explore captivating experiences within the stunning landscapes of Sedona and beyond, ensuring unforgettable adventures.

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