A pilot study on the prevalence of lice in Irish beef cattle and the first Irish report of deltamethrin tolerance in Bovicola bovis

Parasitological examination results of zoo animals in Germany between 2012 and 2022

Parasitic infections in zoo animals are a critical concern for both animal health and management. The aim of this study was to assess the occurrence of endo- and ectoparasites among zoo animals in Germany. A retrospective analysis of the submitted samples of a diverse range of zoo animals (5768) from a ten-year period (2012-2022) was conducted. Overall, 31.1% of those samples tested positive for at least one parasite. In the examined samples, helminths (28.4%) were found more often than protozoans (10.3%) or ectoparasites (0.8%). Among the various animal groups the following parasites were found most commonly: Artiodactyla: Coccidia (34.6%), Strongylida (23.4%); Perissodactyla: Strongylida (19.3%), Ascaridida (12.0%); Carnivora: Ascaridida (16.6%), Coccidia (8.1%); Rodentia: Oxyurida (18.2%), Coccidia (10.5%); Marsupialia: Coccidia (9.4%), Oxyurida (5.9%); Primates: Trichuris spp. (9.7%), Oxyurida (2.2%); Aves: Capillaria (7.8%), Ascaridida (7.6%); Reptilia, Amphibia, Insecta: Oxyurida (18.7%); Pisces: Ciliates (6.2%). Furthermore, potentially zoonotic parasites were identified, including Toxoplasma gondii (0.1%), Cryptosporidium sp. (0.1%). By examining the occurrence of specific parasites, these findings demonstrate the importance of parasites in the context of zoo animal health. They also highlight the need for effective strategies to control parasite burden to improve the overall welfare of zoo animals.

Effectiveness of a fixed-dose combination injectable (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) against Rhipicephalus microplus and sucking lice infesting cattle

Unmanaged tick and sucking lice infestations negatively impact the health and production potential of cattle. Described herein are two non-interference dose confirmation studies evaluating the efficacy of a single administration of a new fixed-dose combination injectable (FDCI) endectocide consisting of 0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride, against either laboratory-induced Rhipicephalus microplus infestations in Australia or naturally acquired sucking lice (Linognathus vituli) infestations in the US. This FDCI is available as Dectomax V® in Australia and New Zealand and as Valcor® in the United States. To evaluate therapeutic efficacy against R. microplus, 12 calves were each exposed to 10 infestations of ∼5000 larvae per infestation between Days -24 and -2. Calves were either treated on Day 0 with the FDCI or left untreated (control). Additional R. microplus infestations of ∼5000 larvae were conducted on Day 2 and then three times weekly to also evaluate persistent efficacy of the FDCI. Tick collections were conducted daily from Day -3. Group mean live tick counts, egg production, and egg viability were analyzed for significant differences between the two groups. To determine efficacy of the FDCI against lice, 24 cattle with active sucking lice infestations based on Day -7 counts were allocated to two groups and treated on Day 0 with either saline (control) or the FDCI. Lice counts were conducted weekly from Day 14 through 42 and again on Day 56. Mean group lice counts on each count day were compared between treatment groups. In the R. microplus study presented here, cattle in Queensland, Australia treated with the FDCI (Dectomax V®) showed > 90 % reduction in tick counts based on arithmetic means within 48 h of treatment when compared to untreated cattle, and counts were > 95 % reduced from post-treatment Day 5 through Day 30. In the sucking lice study conducted in the US, the FDCI (Valcor®) displayed 100 % efficacy against sucking lice infestations (L. vituli) from first count day (Day 14 post-treatment) through Day 35 and then 99.9 % efficacy through Day 56 post-treatment. No treatment-related adverse events were reported for cattle in either study. Using R. microplus and sucking lice as representative ectoparasites, these studies demonstrate the ectoparasite activity of doramectin is retained in the new FDCI.

Detection of pyrethroids resistance alleles in goat biting louse Bovicola caprae (Phthiraptera: Trichodectidae) in west and northwest of Iran

Pyrethroid insecticides target voltage-gated sodium channels (VGSCs) that are essential for electrical signaling in the nervous system of insects. Three-point mutations at the corresponding amino acid sequence positions M815I, T917I, and L920F located in domain II conferring the knockdown resistance (kdr) are the most important mutations in pyrethroid-resistant lice worldwide. In addition, six new mutations have been reported in the extracellular loops IIS1-2 (H813P) and IIS5 (I927F, L928A, R929V, L930M, L932M) in the α- subunit of the sodium channel in lice. The aim of this study was to detect alleles resistant to pyrethroids in the domain II (S5-S6) of the VGSC gene in goat biting louse. Goat biting lice were collected from five provinces in the west and northwest of Iran. Genomic DNA was extracted from goat biting lice and Bovicola (Damalinia) caprae species was confirmed by amplifying the cytochrome oxidase subunit I (COXI) gene. A fragment in the domain II (S5-S6) of the VGSC gene was amplified using the specific primers and the resultant polymerase chain reaction products were sequenced. Substitutions T917I, L920F, I927F, L928A, R929V and L930M were identified in the examined sequences. The results showed that all the examined lice had at least one mutation in their VGSC gene associated with pyrethroid resistance or new mutations. The presence of these mutated alleles in the VGSC gene may be due to the long-term and multiple use of pyrethroids against arthropods. Thus, the molecular detection of resistance to pyrethroid insecticides in goat chewing lice can help plot a kdr frequency map to enact effective policies to control caprine pediculosis.

The current status and outlook for insecticide, acaricide and anthelmintic resistances across the Australian ruminant livestock industries: assessing the threat these resistances pose to the livestock sector

The Australian ruminant livestock industries are faced with the need to control parasitic infectious diseases that can seriously impact the health of animals. However, increasing levels of resistance to insecticides, anthelmintics and acaricides are substantially reducing the ability to control some of these parasites. Here we review the current situation with regard to chemical resistances in parasites across the various sectors of the Australian ruminant livestock industries and assess the level of threat that these resistances pose to the sustainability of these sectors in the short to long terms. We also look at the extent to which testing for resistance occurs across the various industry sectors, and hence how well-informed these sectors are of the extent of chemical resistance. We examine on-farm management practices, breeding of parasite-resistant animals, and non-chemical therapeutics that may act as short to long term means to reduce the current reliance on chemicals for parasite control. Finally, we look at the balance between the prevalence and magnitude of current resistances and the availability and adoption rates of management, breeding and therapeutic alternatives in order to assess the parasite control outlook for the various industry sectors.