Publication details
Haemonchus on the rise – a story about a Czech sheep farm
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| Year of publication | 2024 |
| Type | Conference abstract |
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| Description | Gastrointestinal nematode infections may have a large negative impact on both welfare and production efficiency in intensive sheep and goat farming systems. Without a doubt, the most important gastrointestinal nematode is Haemonchus contortus. This species has great pathogenic potential because the fourth-stage larvae and adults feed on host blood. High parasite load may result in sudden death, especially in lambs and goat kids. In the climatic conditions of the Czech Republic, Teladorsagia and Trichostrongylus were the most prevalent gastrointestinal nematodes for many decades, followed by H. contortus. However, the situation is changing, and many Czech sheep farmers have been frightened of haemonchosis in the last few years. Here, we present a case of one sheep flock located in the Krkonoše Mountains. Emaciation, poor body condition, ill thrift and even deaths have been identified in animals at this farm since 2022. Fatal haemonchosis (6000 and 8000 H. contortus adults recovered from the abomasa) was diagnosed based on necropsy of two dead ewes, and severe infection (3300 11980 eggs per gram) were detected in ten individual faecal samples using the Concentration McMaster technique. Evaluating the efficacy of all broad-spectrum anthelmintic classes was urgently needed to effectively reduce the parasite load in animals. Using the faecal egg count reduction test, both major anthelmintic classes, benzimidazoles (Panacur) and ivermectins – doramectin (Dectomax), failed to control gastrointestinal nematodes (efficacy -214.3% and 102.9%, respectively). Only levamisole (First Drench), which is not currently registered for use in sheep in the Czech Republic effectively reduced the parasite burden (faecal egg count reduction of 96.8%). Multiplex real-time PCR assay was used to identify the richness of the most important nematode genera directly in individual faecal samples. Haemonchus and Teladorsagia were resistant against benzimidazoles (average proportion in the post-treatment samples 60.2% and 17.4%, respectively), and Haemonchus was the sole genera detected in lambs drenched with doramectin. Although levamisole effectively reduced gastrointestinal nematode burden, Teladorsagia (average proportion 75.3%) and, to a lesser extent, Haemonchus (4.7%) were detected in the post-treatment samples. The farm thus poses a high risk of spreading multidrug resistant nematode strains (Haemonchus is particularly alarming) amongst other sheep farms because it produces ewe lambs and rams for replacements of breeding flocks. To maintain farm profitability, a change in current parasite control practices is necessary and has been strongly recommended. |