Multispecific resistance of sheep trichostrongylids in Austria

Abstract

Anthelmintic overuse and failure to implement methods preventing the development and spread of anthelmintic resistance (AR) have led to an alarming increase of resistant ovine trichostrongylids worldwide. The aim of the present study was to determine whether the routine anthelmintic treatment strategy was effective, to obtain insights into the frequency of AR in trichostrongylids of sheep in Austria, and to determine the presence of different trichostrongylid genera. On 30 sheep farms, the faecal egg count reduction test (FECRT) was performed with the Mini-FLOTAC technique in two consecutive studies. In study 1, only fenbendazole and moxidectin were tested, while different compounds and products were used in study 2. Overall, 33 treatment groups were formed: 11 groups were treated with benzimidazoles (fenbendazole and albendazole), 2 groups with avermectins (ivermectin, doramectin), 18 groups with moxidectin, and two groups with monepantel. Reduced efficacy was detected in 64%, 100%, 28% and 50% of these groups, respectively. The most frequently detected genus in larval cultures was Haemonchus, which had been barely detected in Austria previously, followed by Trichostrongylus. Multispecific resistance of trichostrongylids in Austria seems to be on the rise and H. contortus was detected unexpectedly frequently in comparison to previous studies. There is an urgent need to develop efficient communication strategies aimed at improving the engagement of farmers and veterinarians in sustainable parasite control.

Parasitofauna and current status of anthelmintic resistance in Latvian sheep farms

“…In Lithuania, IVM resistance was detected in two of 16 sheep farms, and FBZ resistance was detected in three farms [29]. The situation is similar in similar studies in Belgium [4], the Netherlands [5], Denmark [6], Austria [30], France, Greece, and Italy [31].…”

Comparison of FECPAKG2, a modified Mini-FLOTAC technique and combined sedimentation and flotation for the coproscopic examination of helminth eggs in horses

“…egg is found [ 11 , 22 , 57 ]. In contrast, for a faecal egg count reduction test (FECRT) to identify drug-resistant nematode populations, a sensitive and precise quantitative method is required, and the Mini-FLOTAC method has been repeatedly shown to perform very well in FECRT studies [ 63 – 65 ], including studies on horses [ 32 , 66 – 68 ]. Reasons to consider when choosing a test based on convenience include access to the laboratories that offer tests and acceptable turnaround times for results.…”

Eprinomectin and Moxidectin Resistance of Trichostrongyloids on a Goat Farm in Austria

“…The observation of MOX resistance in our study indicates the progressed stage of a more generalized ML resistance on the investigated goat farm [ 9 ]. Since BZ resistance has previously been described in Austria in sheep trichostrongyloids [ 1 , 13 ], it is of the utmost importance to tightly monitor the development of AR in the field and to monitor changes in the use of anthelmintics and the effects of such changes in order to not maintain single- or multi-resistant populations under selection pressure, since AR is considered to be non-reversible [ 14 ].…”

“…The development of anthelmintic resistance (AR) in trichostrongyloids of ruminants is a serious threat to the health and productivity of livestock. In Austrian sheep, we can already observe a dramatic situation, with the failure of all anthelmintic classes available for this species to control trichostrongyloid infections [ 1 ].…”

“…Pasturing sheep together with goats is therefore considered to be a risk factor for AR development in sheep. Accordingly, our observation of a high level of anthelmintic resistance in ovine trichostrongyloids in Austria [ 1 ] indicates that AR in caprine parasites could be a considerable yet unreported problem.…”