Anthelmintic resistance in gastrointestinal nematodes of alpacas (Vicugna pacos) in Australia

Abstract

BackgroundGastrointestinal nematodes (GINs) can cause significant economic losses in alpacas due to lowered production of fibre and meat. Although no anthelmintics are registered for use in alpacas, various classes of anthelmintics are frequently used to control parasitic gastroenteritis in alpacas in Australia and other countries. Very little is known about the current worm control practices as well as the efficacy of anthelmintics used against common GINs of alpacas. This study aimed to assess the existing worm control practices used by Australian alpaca farmers and to quantify the efficacy of commonly used anthelmintics against GINs of alpacas.MethodsAn online questionnaire survey was conducted to assess current worm control practices on 97 Australian alpaca farms, with an emphasis on the use of anthelmintics. Of this group of 97 alpaca farms, 20 were selected to assess the efficacy of eight anthelmintics and/or their combinations (closantel, fenbendazole ivermectin, monepantel, moxidectin and a combination of levamisole, closantel, albendazole, abamectin) using the faecal egg count reduction test (FECRT). A multiplexed-tandem PCR (MT-PCR) was used to identify the prevalent nematode genera/species.ResultsThe response rate for the questionnaire was 94% (91/97). Almost half of the respondents kept alpacas with sheep and cattle, and 26% of respondents allowed alpacas to co-graze with these ruminants. Although only 63% respondents perceived worms to be an important health concern for alpacas, the majority of respondents (89%) used anthelmintics to control GINs of alpacas. The commonly used anthelmintics were macrocyclic lactones, monepantel, benzimidazoles, levamisole, closantel and their combinations, and they were typically administered at the dose rate recommended for sheep. The FECRT results showed that a combination of levamisole, closantel, albendazole and abamectin was the most effective dewormer followed by single drugs, including monepantel, moxidectin, closantel, fenbendazole and ivermectin. Haemonchus spp. were the most commonly resistant nematodes followed by Trichostrongylus spp., Camelostrongylus mentulatus, Ostertagia ostertagi and Cooperia spp.ConclusionsThis is the first study aimed at assessing worm control practices and efficacy of commonly used anthelmintics in alpacas in Australia. Our findings document the extent of anthelmintics resistance on Australian alpaca farms and identify those anthelmintics that are still effective against GINs of alpacas.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2949-7) contains supplementary material, which is available to authorized users.

Current anthelmintic treatment is not always effective at controlling strongylid infections in German alpaca herds

“…We confirm that H. contortus is a common strongylid species of South American camelids, and we further hypothesize that this high representation of the Barber’s Pole worm in the examined samples was promoted by the presence of resistant worms of this species. To a lesser extent this also applies to Cooperia and Trichostrongylus which have also been inferred in anthelmintic resistance in camelids [11, 12, 14, 68]. Since H. contortus is not only pathogenic in small ruminants but also in South American camelids [8, 26, 40], the presence of this species and its response to anthelmintic treatment should be monitored thoroughly, especially in view of cross-transmission between ruminants and alpacas as described to be considerable in recent studies from Australia [26].…”

“…After the first case report of ivermectin resistance of H. contortus in an alpaca herd in Australia [11], a recent systematic study described resistance to several anthelmintics (ivermectin, moxidectin, fenbendazole, closantel) in strongylids of Australian alpacas [12]. The large Australian sheep population may have contributed to the transfer of resistant nematodes to alpacas [12] since cross-transmission of a number of strongylid species (including H. contortus ) between these hosts is common [13]. In Europe, resistance to doramectin has been reported on a Belgian alpaca farm and confirmed in a controlled field trial, and the main strongylid species involved was H. contortus [14].…”

Anthelmintic resistance in small ruminants in the Nordic-Baltic region

“…In addition, domestic interactions through contacts with "exotic" livestock, such as alpacas, may also be a contributing factor. It has been documented in some countries that imported camelids are sometimes infected with Haemonchus that are refractory to anthelmintic treatments [61,62].…”

Quantitative Analysis of Abamectin, Albendazole, Levamisole HCl and Closantel in Q-DRENCH Oral Suspension Using a Stability-Indicating HPLC-DAD Method

“…Gastrointestinal infection with nematodes is one of the main causes of financial losses in sheep breeding [ 1 , 2 ]. Due to the increased rate of parasite resistance, a combination therapy of many anthelmintic drugs has been used to achieve fast animal curing [ 2 ].…”