Haemonchus spp

From Cow
Haemonchus placei egg
haemonchus contortus adult on the intestinal wall

Haemonchus spp (barber's pole worm, large stomach worm, wire worm) are a common haematophagous parasitic nematode of cattle worldwide.

Haemonchus spp are a major cause of economic losses in the livestock industry because they impair weight gain and increases mortality in cattle, especially in tropical and subtropical areas[1].

Species recognised as pathogenic in cattle include:

  • Haemonchus placei
  • haemonchus contortus[2]

The life cycle of Haemonchus spp is relatively short with a prepatent period of 4 - 6 weeks. Eggs are passed in the feces and become infective third stage larvae in a few weeks but may be longer in cold weather. Dormancy occurs over cold winters. The infective larvae lie on pasture and are then ingested during grazing by cattle and complete the cycle.

Clinical signs with this parasite are usually related to chronic gastroenteritis, protein-losing enteropathy. Diarrhea and anemia are commonly observed signs. Heavy burdens can be fatal in young calves.

Treatment is effective with most oral and topical anthelmintics. Resistance to benzimidazoles and avermectins are commonly reported[3].

Vaccination of calves with a gut membrane glycoproteins obtained from H. contortus conferred protection against both H. placei and H. contortus[4].

References

  1. do Amarante AF (2011) Why is it important to correctly identify Haemonchus species? Rev Bras Parasitol Vet 20(4):263-268
  2. Brasil BS et al (2012) Genetic diversity patterns of Haemonchus placei and Haemonchus contortus populations isolated from domestic ruminants in Brazil. Int J Parasitol 42(5):469-479
  3. Canul-Ku HL et al (2012) Prevalence of cattle herds with ivermectin resistant nematodes in the hot sub-humid tropics of Mexico. Vet Parasitol 183(3-4):292-298
  4. Bassetto CC et al (2011) Protection of calves against Haemonchus placei and Haemonchus contortus after immunization with gut membrane proteins from H. contortus. Parasite Immunol 33(7):377-381