Micro-parasites of the ruminant abomasum

Authors: Scott I, Pernthaner T, Simpson HV
Publication: New Zealand Veterinary Journal, Volume 55, Issue 1, pp 49-50, Feb 2007
Publisher: Taylor and Francis

Animal type: Cattle, Deer, Livestock, Production animal, Ruminant, Sheep
Subject Terms: Abdomen, Alimentary system/gastroenterology, Bacterial, Parasites - internal
Article class: Abstract

---

Abstract: A cursory examination of the conditions of the ruminant abomasum reveals a highly acidic environment that should discourage colonisation by invading organisms. Yet, ample species have adapted to this ecological niche and some are extremely successful, e.g. the nematode (macro-) parasites of ruminants Haemonchus contortus, Ostertagia ostertagi and Teladorsagia circumcincta, but nematodes are not the only organisms to make gastric mucus their home. Helicobacter pylori is one of a group of bacteria (as micro-parasites) that has also successfully invaded the gastric environment. In 2004, in order to investigate the immune response of sheep to T. circumcincta, recently-weaned lambs were drenched then held indoors for approximately 2 months before some were infected with T. circumcincta larvae; others were kept as worm-free controls. Histological examination of the stomachs of nematode-free animals revealed large numbers of bacteria present within the gastric pits, but only minimal gastritis, if any. Although these animals were ostensibly ‘healthy’ their immune function was not. Whilst worms promoted expression of the cytokine interleukin 1-beta (IL-1β), the presence of the bacteria favoured interleukin 6 (IL- 6) and tumour necrosis factor alpha (TNFα). In other studies, IL-1β, IL-6 and TNFα have been shown to be extremely important in influencing the behaviour of sick animals, promoting the classical signs of sickness behaviour, viz anorexia, fever and depression. Although the bacteria have yet to be properly identified, their appearance and distribution was consistent with a helicobacter-like organism, and the isolation of H. pylori from sheep in Italy was recently reported. Questions exist as to whether the unidentified bacteria have any impact on the health of their ovine hosts and whether infection with nematodes prevents or limits bacterial colonisation, based on the absence of bacteria from sheep infected with the larger parasite.

---