The appearance of haemonchus contortus, or Barber’s pole worm has quickly become a problem on some sheep farms recently.
Signs of the gastrointestinal worm infection in a sheep include the presence of elevated faecal egg counts (over 1,000 eggs/g) and clinical signs including poor thrive, anaemia, general weakness, bottle jaw, with little or no diarrhoea.
Figures provided by the Department of Food, Agriculture and the Marine (DAFM) have shown that since January to October 31, 2023, there has been 37 deaths across all ruminant species where haemonchus contortus, or Barber’s pole worm was identified as the cause of death.
When compared to the number of deaths in 2022 (which was 14), since then there has been a 164% increase in deaths to-date, from figures provided following post mortems of ruminants in DAFM Regional Veterinary Laboratories (RVL).
According to the “perception” from the department labs is that “haemonchus contorus is increasing in Ireland and the geographic area it has been diagnosed in is expanding”.
This, according to the DAFM, is “largely in accordance with the industry perception that this parasite is becoming more widespread and impactful in Ireland”.
This table shows the number of post mortems across all ruminant species where haemonchus contortus, or Barber’s pole worm, was identified as the cause of death.
RVL 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 to Oct. 31 Athlone – – – – 1 4 – 1 1 4 13 Cork – – – – 1 – – – – 1 3 Dublin – – – – 2 – – – – 1 3 Kilkenny – 1 – – 5 – 4 2 1 7 16 Limerick – – – – – – – – – – 1 Sligo – – – – – – – – – 1 1 Annual totals 0 1 0 0 9 4 4 3 2 14 37
While these data show an increase in the diagnoses of death due to haemonchus, this is a simple count of post mortems and some of may represent multiple submissions from a single farm.
Haemonchus contortus produces eggs that are very similar in size and shape to those produced by other roundworms such as ostertagia and cooperia.
The department is currently working on a test to differentiate haemonchus contortus eggs from those of other common roundworm eggs.
A definitive diagnosis of haemonchus contortus, or Barber’s pole worm, can only be reached currently via post mortem examination when these roundworms, measuring up to 30mm, are observed in the abomasum (fourth stomach).
In contrast to haemonchus contortus, the maximum size of ostertagia ostertagi roundworms, which are also located in the abomasum, is 10mm.
All RVL post mortems are carried out voluntarily, and the caseload is largely selected by the referring veterinary practitioners.
While the observed increase in the involvement of haemonchus in mortalities investigated by RVL post mortems may reflect an increased prevalence, some part of the increased numbers may be a result of heightened awareness of the disease as a cause of illness.
The findings of a report earlier this year suggested that the increase in temperature caused by global warming could cause a higher outbreak of haemonchus contortus as it is found in regions where conditions of high humidity coincide with high temperatures.