Strain-level variations of Dirofilaria immitis microfilariae in two biochemical assays.

BACKGROUND: The increase in reports of resistance to macrocyclic lactones in the canine heartworm, Dirofilaria immitis is alarming. While DNA based tests have been well-validated, they can be expensive. In a previous study, we showed that two biochemical tests adapted to a 96- well plate format and read in a spectrophotometer could detect differences among lab validated D. immitis isolates. The two tests- Resazurin reduction and Hoechst 33342 efflux-detect metabolism and P-glycoprotein activity respectively in microfilariae isolated from infected dog blood. METHODS: Our objective was to optimize the two assays further by testing various assay parameters in D. immitis isolates not tested previously. We tested microfilarial seeding density, incubation time and the effect of in vitro treatment with ivermectin and doxycycline in five other D. immitis isolates-JYD-34, Big Head, Berkeley, Georgia III and LOL. All assays were performed in 3 technical replicates and 2-4 biological replicates. To understand the molecular basis of the assays, we also performed qPCR for selected drug metabolism and elimination associated genes of the ABC transporter and cytochrome P450 gene families. RESULTS: Metabolism and ABC transporter activity as detected by these assays varied between strains. Anthelmintic status (resistant or susceptible) did not correlate with metabolism or P-gp efflux. Basal transcriptional variations were found between strains in ABC transporter and cytochrome P450 genes. CONCLUSIONS: These assays provide a greater understanding of the biochemical variation among isolates of D. immitis, which can be exploited in the future to develop in vitro diagnostic tests capable of differentiating susceptible and resistant isolates.

Comparative speed of kill provided by lotilaner (Credelio™), sarolaner (Simparica Trio™), and afoxolaner (NexGard™) to control Amblyomma americanum infestations on dogs.

BACKGROUND: Canine acaricides with rapid onset and sustained activity can reduce pathogen transmission risk and enhance pet owner experience. This randomized, complete block design, investigator-masked study compared the speed of kill of Amblyomma americanum provided by three monthly-use isoxazoline-containing products. METHODS: Eight randomized beagles per group were treated (day 0), per label, with sarolaner (combined with moxidectin and pyrantel, Simparica Trio™), afoxolaner (NexGard™), or lotilaner (Credelio™), or remained untreated. Infestations with 50 adult A. americanum were conducted on days - 7, - 2, 21, and 28, and tick counts were performed on day - 5 (for blocking), and at 4, 8, 12, 24, 48, and 72 h following treatment and subsequent infestations. Efficacy calculations were based on geometric mean live tick counts. A linear mixed model was used for between-group comparisons. RESULTS: On day 0, only lotilaner significantly reduced an A. americanum infestation by 12 h (43.3%; P = 0.002). Efficacy of lotilaner and afoxolaner at 24 h post-treatment was 95.3% and 97.6%, respectively, both significantly different from sarolaner (74%) (P = 0.002, P < 0.001, respectively). On day 21, at 12 h postinfestation, lotilaner efficacy (59.6%) was significantly different from sarolaner (0.0%) (P < 0.001) and afoxolaner (6.3%) (P < 0.001). At 24 h, lotilaner efficacy (97.4%) was significantly different (P < 0.001) from sarolaner and afoxolaner (13.6% and 14.9%, respectively). On day 28, at 12 h postinfestation, lotilaner efficacy (47.8%) was significantly different from sarolaner (17.1%) (P = 0.020) and afoxolaner (9.0%) (P = 0.006). At 24 h, lotilaner efficacy (92.3%) was significantly different from sarolaner 4.9% (P < 0.001) and afoxolaner (0.0%) (P < 0.001). Speed of kill for sarolaner and afoxolaner, but not lotilaner, significantly declined over the study period. Following reinfestation on day 28, neither sarolaner nor afoxolaner reached 90% efficacy by 48 h. By 72 h, sarolaner efficacy was 97.4% and afoxolaner efficacy was 86.3%. Only lotilaner achieved ≥ 90% efficacy by 24 h post-treatment and 24 h postinfestation on days 21 and 28. Time to ≥ 90% efficacy following new infestations consistently occurred 24-48 h earlier for lotilaner compared with sarolaner or afoxolaner. CONCLUSIONS: Credelio (lotilaner) has a more rapid onset of acaricidal activity against A. americanum than Simparica Trio (sarolaner-moxidectin-pyrantel) and NexGard (afoxolaner). Only lotilaner's speed of tick kill is sustained throughout the dosing period.

Cystic echinococcosis in cattle and sheep caused by Echinococcus granulosus sensu stricto genotypes G1 and G3 in the USA.

BACKGROUND: Endemic domestic dog-ruminant cycles and human cystic echinococcosis caused by Echinococcus granulosus have been sporadically reported in the United States. However, there is a paucity of molecular data describing the genotypes and haplotypes of this important cestode in domestic ruminant hosts. METHODS: Ninety-four cysts from the lungs and/or livers of slaughtered beef cattle (76 samples), dairy cows (five samples) and sheep (13 samples) were collected from abattoirs in four states of the USA. Samples were genotyped at two mitochondrial loci, cox1 and nad5. Sequences were used to determine species, genotypes and haplotypes using median joining networks and Bayesian phylogenetic analyses. Cyst fertility was assessed in hematoxylin and eosin-stained sections. Additionally, previously reported autochthonous E. granulosus infections in the USA in various hosts were mapped. RESULTS: Based on cox1 sequences obtained from 94 cysts, 89 (94.7%) were identified as E. granulosus G1/G3, while five (5.3%) were Taenia hydatigena. Taenia hydatigena were only isolated from sheep. Based on nad5 sequences obtained from 89 hydatid cysts, 96.6% and 3.4% belonged to E. granulosus sensu stricto genotypes G1 and G3 respectively. Two haplotypes were found among E. granulosus cox1 sequences, neither of which was geographically unique. Six haplotypes were found among nad5 sequences in genotype G1, of which five were novel, while one haplotype was found in genotype G3. In the concatenated cox1-nad5 dataset, seven haplotypes were identified, of which six were geographically unique. All cysts from cattle were non-fertile. Four cysts from sheep were fertile. CONCLUSIONS: All genotyped samples belonged to E. granulosus s.s. This is the first study to our knowledge to confirm the presence of genotypes G1 and G3 in domestic cattle and sheep intermediate hosts in the USA and provide data for future diagnostic and epidemiological studies. Sequences have been deposited in GenBank (cox1 sequences: OR398494-OR398496, nad5 sequences: OR400695-OR400702).

Comparison of the initial and residual speed of Ixodes scapularis kill on dogs treated with a single dose of Bravecto® Chew (25 mg/kg fluralaner) or Simparica TRIO® (1.2 mg/kg sarolaner, 24 µg/kg moxidectin, 5 mg/kg pyrantel).

BACKGROUND: Compliant ectoparasiticide product use is a comprehensive way to control ticks and reduce the risk of tick-borne pathogen transmission to dogs. Because the systemically acting isoxazoline ectoparasiticides require tick attachment for drug delivery, fast speed of kill is essential to minimize tick-borne pathogen transmission risk. METHODS: Dogs of satisfactory tick-carrying capacity were randomly allocated to treatment groups and administered, per label instructions, Bravecto® Chews (minimum 25 mg/kg fluralaner), Simparica TRIO® (minimum 1.2 mg/kg sarolaner, 24 µg/kg moxidectin, 5 mg/kg pyrantel), or no treatment. Dogs were infested with approximately 50 unfed adult (35 female, 15 male) Ixodes scapularis on Day -2, 21 and 28. Live tick counts were performed at 4, 8, 12 and 24 h post-treatment (Day 0) and post-infestation on Day 21 and 28. Tick control efficacy was determined by comparing live tick means for each product-treated group to the untreated control group and each other at all time points using a linear mixed model. The percent of dogs free of live ticks was analyzed using the Fisher's exact test for treatment group comparison. RESULTS: The untreated control group maintained adequate tick infestations throughout the study. Using geometric means, an existing I. scapularis infestation was controlled by 99.7% and 93.0% 12 h post-treatment and by 100% and 99.5% 24 h post-treatment, for Bravecto® and Simparica TRIO®-treated dogs, respectively. Ixodes scapularis infestations were controlled more quickly for Bravecto®- compared to Simparica TRIO®-treated dogs on Day 21 at 8 h (efficacy 74.0% vs. 0.0%, p = 0.003) and 12 h (efficacy 99.2% vs. 39.4%, p < 0.001) post-infestation and Day 28 at 8 h (efficacy 92.2% vs. 0.0%, p < 0.001) and 12 h (efficacy 99.6% vs. 27.7%, p < 0.001) post-infestation. On Day 28 post-treatment, the efficacy of Bravecto® and Simparica TRIO® to control a new I. scapularis infestation was 100% and 96.6%, respectively, by 24 h post-infestation. Of product-treated dogs, 100% of Bravecto®-treated dogs were free of live ticks by 24 h post-treatment or post-infestation. No treatment-related adverse reactions occurred during the study. CONCLUSIONS: Ixodes scapularis infestations are controlled more quickly 21 and 28 days post-treatment for dogs administered a single dose of Bravecto® compared to dogs administered a single dose of Simparica TRIO®.

Assessment of in vitro efficacy for common surface disinfectants and antiseptics against Tritrichomonas foetus trophozoites.

The protozoan Tritrichomonas foetus causes early embryonic death in cattle, there are no legal options for treating this parasite in the United States, and there are few developed protocols for cleaning veterinary and obstetrical equipment that may have been contaminated with trophozoites. In this study, we evaluated bleach, ethanol, acetic acid, chlorhexidine gluconate, and hydrogen peroxide solutions for the ability to kill trophozoites in vitro. Our findings suggested that ethanol and bleach could adequately disinfect tools and equipment. Acetic acid, chlorhexidine, and hydrogen peroxide had applications as surface disinfectants in addition to potential as local topical treatments due to their past uses in veterinary theriogenology. Chlorhexidine gluconate demonstrated trophocidal effects by damaging parasite cell membranes and had the lowest effective concentration 50 (EC50) of any compound tested and was in the micromolar range. These findings, in conjunction with accepted clinical uses of chlorhexidine gluconate suggest that this is a convenient agent for disinfecting equipment. In addition, topical use of chlorhexidine is relatively common, setting the stage for further investigation of this compound as a topical therapeutic option for bovine trichomonosis.

Haplotypic analysis of cox1 from Toxocara canis demonstrates five distinct clades that are not geographically defined.

BACKGROUND: Toxocara canis is a cosmopolitan parasite of dogs that is transmitted transplacentally to puppies resulting in widespread shedding of eggs in the environment. However, it is not clear if there are dominant parasite genotypes that are more common, pathogenic, or likely to be zoonotic. METHODS/PRINCIPLE FINDINGS: Sequences of mitochondrial cox1 gene from adult worms were used to compare parasites from the United States with submitted sequences from parasites isolated from dogs in different countries. Our analysis revealed at least 55 haplotypes. While we expected the North American worms to form a distinct cluster, we found haplotypes of T. canis reported elsewhere existing in this population. Interestingly, combining the sequence data from our study with the available GenBank data, analysis of cox1 sequences results in five distinct clades that are not geographically defined. CONCLUSIONS: The five clades of T. canis revealed in this study potentially have unique life histories, traits, or host preferences. Additional investigation is needed to see if these distinct clades represent cryptic species with clinically useful attributes or genotypes with taxonomic value. Evaluation of common mitochondrial genes may reveal distinct populations of zoonotic T. canis.

Comparative Genomic Analysis and Species Delimitation: A Case for Two Species in the Zoonotic Cestode Dipylidium caninum.

Dipylidium caninum (Linnaeus, 1758) is a common zoonotic cestode of dogs and cats worldwide. Previous studies have demonstrated the existence of largely host-associated canine and feline genotypes based on infection studies, differences at the 28S rDNA gene, and complete mitochondrial genomes. There have been no comparative genome-wide studies. Here, we sequenced the genomes of a dog and cat isolate of Dipylidium caninum from the United States using the Illumina platform at mean coverage depths of 45× and 26× and conducted comparative analyses with the reference draft genome. Complete mitochondrial genomes were used to confirm the genotypes of the isolates. Genomes of D. caninum canine and feline genotypes generated in this study, had an average identity of 98% and 89%, respectively, when compared to the reference genome. SNPs were 20 times higher in the feline isolate. Comparison and species delimitation using universally conserved orthologs and protein-coding mitochondrial genes revealed that the canine and feline isolates are different species. Data from this study build a base for future integrative taxonomy. Further genomic studies from geographically diverse populations are necessary to understand implications for taxonomy, epidemiology, veterinary clinical medicine, and anthelmintic resistance.

Genomic differences and species delimitation: a case for two species in the zoonotic cestode Dipylidium caninum.

Dipylidium caninum (Linnaeus, 1758) is a common zoonotic cestode of dogs and cats worldwide. Previous studies have demonstrated the existence of largely host associated canine and feline genotypes based on infection studies, genetic differences at the nuclear 28S rDNA gene and complete mitochondrial genomes. There have been no comparative studies at a genome-wide scale. Here, we sequenced the genomes of a dog and cat isolate of Dipylidium caninum from the United States using the Illumina platform and conducted comparative analyses with the reference draft genome. Complete mitochondrial genomes were used to confirm the genotypes of the isolates. D. caninum canine and feline genomes generated in this study had mean coverage depths of 45x and 26x and an average identity of 98% and 89% respectively when compared to the reference genome. SNPs were 20 times higher in the feline isolate. Comparison and species delimitation using universally conserved orthologs and protein coding mitochondrial genes revealed that the canine and feline isolates are different species. Data from this study builds a base for future integrative taxonomy. Further genomic studies from geographically diverse populations are necessary to understand implications for taxonomy, epidemiology, veterinary clinical medicine, and anthelmintic resistance.

Repertoire of P-glycoprotein drug transporters in the zoonotic nematode Toxocara canis.

Toxocara canis has a complex lifecycle including larval stages in the somatic tissue of dogs that tolerate macrocyclic lactones. In this study, we investigated T. canis permeability glycoproteins (P-gps, ABCB1) with a putative role in drug tolerance. Motility experiments demonstrated that while ivermectin failed to abrogate larval movement, the combination of ivermectin and the P-gp inhibitor verapamil induced larval paralysis. Whole organism assays revealed functional P-gp activity in larvae which were capable of effluxing the P-gp substrate Hoechst 33342 (H33342). Further investigation of H33342 efflux demonstrated a unique rank order of potency for known mammalian P-gp inhibitors, suggesting that one or more of the T. canis transporters has nematode-specific pharmacological properties. Analysis of the T. canis draft genome resulted in the identification of 13 annotated P-gp genes, enabling revision of predicted gene names and identification of putative paralogs. Quantitative PCR was used to measure P-gp mRNA expression in adult worms, hatched larvae, and somatic larvae. At least 10 of the predicted genes were expressed in adults and hatched larvae, and at least 8 were expressed in somatic larvae. However, treatment of larvae with macrocyclic lactones failed to significantly increase P-gp expression as measured by qPCR. Further studies are needed to understand the role of individual P-gps with possible contributions to macrocyclic lactone tolerance in T. canis.

Mitochondrial Genomes of the American Dog Tick (Dermacentor variabilis) Isolated from Horses in the Midwestern United States.

Here, we report two complete and three partial mitochondrial genome sequences of Dermacentor variabilis specimens collected from horses in the United States. The complete genomes are 14,837 bp long and contain 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. The sequences have been deposited under GenBank accession numbers ON052120 to ON052124.

A comparison of Mini-FLOTAC and McMaster techniques, overdispersion and prevalence of parasites in naturally infected North American bison (Bison bison) in the USA.

Several quantitative diagnostic techniques are available to estimate gastrointestinal parasite counts in the feces of ruminants. Comparing egg and oocyst magnitudes in naturally infected samples has been a recommended approach to rank fecal techniques. In this study, we compared the Mini-FLOTAC (sensitivity of 5 eggs per gram (EPG)/oocysts per gram (OPG)) and different averaged replicates of the modified McMaster techniques (sensitivity of 33.33 EPG/OPG) in 387 fecal samples from 10 herds of naturally infected North American bison in the Central Great Plains region of the USA. Both techniques were performed with fecal slurries homogenized in a fill-FLOTAC device. In the study population, prevalence of strongyle eggs, Eimeria spp. oocysts, Moniezia spp. eggs and Trichuris spp. eggs was 81.4%, 73.9%, 7.5%, and 3.1%, respectively. Counts of strongyle eggs and Eimeria spp. oocysts obtained from 1 to 3 averaged technical replicates of the modified McMaster technique were compared to a single replicate of the Mini-FLOTAC. Correlation between the two techniques increased with an increase in the number of averaged technical replicates of the modified McMaster technique used to calculate EGP/OPG. The correlation for Moniezia spp. EPG when averaged triplicates of the modified McMaster technique were compared to a single replicate of the Mini-FLOTAC count was high; however, the correlation for Trichuris spp. eggs was low. Additionally, we used averaged counts from both techniques to show the overdispersion of parasites in bison herds.

Survey of U.S. based veterinarians' knowledge, perceptions and practices about canine giardiasis.

Giardia spp. is a protozoal parasite capable of causing diarrhea in mammals. Certain Giardia assemblages are potentially zoonotic. As part of a public health study, a questionnaire-based cross-sectional web survey was distributed among U.S. small and mixed animal veterinarians to assess the perceived prevalence, the preferred testing and treatment methods, the recommended control measures, and the information communicated about the zoonotic potential of canine giardiasis. Between February and June 2021, over 123 veterinarians from 31 U.S. states participated in the survey. 77% of surveyed veterinarians indicated that they are aware of the prevalence of canine giardiasis in their areas of practice. 52% of veterinarians reported that they test all symptomatic dogs for Giardia, while 42.4% test dogs only some of the time. The preferred confirmatory tests were in the following order: commercial diagnostic lab > in-clinic SNAP® Test > in-clinic Direct Smear > in-clinic Fecal Flotation > state/university diagnostic lab. Several combinations of tests are frequently used to confirm diagnosis. Although there are no labelled products available for treating canine giardiasis in the U.S., 54% of respondents preferred using both fenbendazole and metronidazole simultaneously, 15% reported using fenbendazole only, and 20% reported using metronidazole only. 77.0% of respondents indicated they have dealt with treatment refractory cases often or rarely. 92.6% of veterinarians reported mentioning environmental control to pet owners sometimes or always, which included bathing the infected pet, cleaning toys/bowls/bedding, cleaning floors, and bathing other pets. 73.6% of veterinarians communicated to their clients that Giardia was potentially zoonotic. There are conflicting opinions on the importance of zoonotic transmission between humans and canines available to the general veterinary practitioner. Given that children are at a higher risk of developing Giardia infections, it is important for veterinarians to preserve the health of canine companions to protect their human owners. Thus, the contributions of veterinarians in managing canine giardiasis within the framework of One Health initiatives should not be overlooked.

Characterization of a P-glycoprotein drug transporter from Toxocara canis with a novel pharmacological profile.

P-glycoproteins from the ATP-binding cassette transporter family are responsible for drug evasion by bacterial pathogens and neoplastic cells. More recently, these multidrug resistance transporters have been investigated for contributions to drug resistance in nematode parasites. In this study, we cloned and characterized the P-glycoprotein Tca-Pgp-11.1 from Toxocara canis, the canine intestinal ascarid. Large numbers of Tca-Pgp-11 transcripts were observed in the intestine of adult male and female worms. Heterologous expression studies confirmed sensitivity to known P-glycoprotein inhibitors. Interestingly, the competitive inhibitor verapamil had lower IC50 values than newer generation inhibitors that are designed to allosterically modulate mammalian P-glycoprotein. Consistent with other nematode P-glycoproteins, Tca-Pgp-11.1 was sensitive to ivermectin and selamectin but not moxidectin. Taken together, our data suggests that T. canis P-glycoproteins represent nematode-specific drug targets that could be exploited to enhance efficacy of existing anthelmintics.

Global prevalence of Mesocestoides infections in animals - A systematic review and meta-analysis.

Mesocestoides spp. are zoonotic cestodes found as adults in carnivorous domestic and wild definitive hosts and as metacestodes in several taxa of intermediate hosts. Although several regional studies record its occurrence in different host populations, the global prevalence and patterns of occurrence of Mesocestoides spp. are not fully understood. The objective of this study was to conduct a systematic review and meta-analysis of published literature to estimate the global prevalence of Mesocestoides spp. in major definitive and intermediate host taxa. Records published in English were collected from NCBI PubMed, Science Direct, Web of Science and Google Scholar databases, with 364 papers being included in the meta-analysis. The overall pooled prevalence estimates show that 21.72 % (95 % CI: 18.49-25.14) of terrestrial carnivore definitive hosts and 7.09 % (95 % CI: 5.79-8.51) of intermediate hosts are infected. Among definitive hosts, opossums and foxes were most commonly infected with pooled global prevalence of 48.16 % (95 % CI: 14.62 - 82.69) and 35.97 % (295 % CI: 9.54 - 42.66) respectively. Pooled global prevalence in domestic dogs and cats were 7.97 % (95 % CI: 5.67 - 10.63) and 8.32 % (95 % CI: 3.78 - 14.41) respectively. Among intermediate hosts, birds and snakes were most commonly infected with pooled global prevalence of 16.19 % (95 %CI: 5.9 - 30.31) and 15.74 % (95 % CI: 10.59 - 21.69) respectively. Our analysis demonstrates that prevalence of Mesocestoides spp. is variable across the world. The sylvatic cycle in wild hosts is likely to be more important than the domestic cycle for the maintenance of Mesocestoides spp. globally. Currently available genetic data at the mitochondrial COI locus was also phylogenetically analyzed. The genetic data supports the taxonomic distinctiveness of only a few of the numerous morphologically described Mesocestoides spp.

Contracaeciasis in an American white pelican.

An American white pelican migrating through Iowa, USA exhibited regurgitation and anorexia. At the time of necropsy, numerous nematodes were observed in the crop and proventriculus with evidence of proventriculitis. Nematodes were identified as Contracaecum spp. based on morphological features of the adult worms and eggs. Species level identification of C. fagerholmi were made using nucleotide sequence analysis of the partial cox2 gene. Contracaecum infections are highly prevalent in piscivorous birds that acquire the infection by ingesting fish infected with larval stages of the parasite. Considering the possible zoonotic nature of Contracaecum, humans whose diets include uncooked fresh-water and/or marine fish should handle fresh fish with care, as these may harbor immature stages of Contracaecum spp.

Syngamus asphyxiation in a captive ring-necked pheasant.

A deceased ring-necked pheasant (Phasianus colchicus) presented for necropsy following a history of chronic wasting. Necropsy revealed nematodes consistent with the genus Syngamus partially obstructing the trachea. Phylogentic analysis failed to reveal conclusive results regarding the species. Syngamus spp. can cause obstruction of the trachea in several different hosts. Additional genetic data from this taxon would aid in the more precise identification of diagnostic specimens.

Afoxolaner as a Treatment for a Novel Sarcoptes scabiei Infestation in a Juvenile Potbelly Pig.

A 2 months old female Vietnamese potbellied pig presented to a veterinary teaching hospital with a referring complaint of pruritus. A human caretaker of the pig had recently been diagnosed with a Sarcoptes spp. dermatitis. Microscopic examination of the skin scrape samples and BLAST analysis confirmed the species of the mite as most closely related to Sarcoptes scabiei var. canis (AY493391). The pig was treated with afoxolaner as previous treatment with ivermectin was not efficacious. Recheck examinations and follow up revealed the pig to be non-pruritic and resolving. Afoxolaner may be a therapeutic option when treating Sarcoptes spp. infections in companion pigs.

Laboratory assays reveal diverse phenotypes among microfilariae of Dirofilaria immitis isolates with known macrocyclic lactone susceptibility status.

Prevention of canine heartworm disease caused by Dirofilaria immitis relies on chemoprophylaxis with macrocyclic lactone anthelmintics. Alarmingly, there are increased reports of D. immitis isolates with resistance to macrocyclic lactones and the ability to break through prophylaxis. Yet, there is not a well-established laboratory assay that can utilize biochemical phenotypes of microfilariae to predict drug resistance status. In this study we evaluated laboratory assays measuring cell permeability, metabolism, and P-glycoprotein-mediated efflux. Our assays revealed that trypan blue, propidium iodide staining, and resazurin metabolism could detect differences among D. immitis isolates but none of these approaches could accurately predict drug susceptibility status for all resistant isolates tested. P-glycoprotein assays suggested that the repertoire of P-gp expression is likely to vary among isolates, and investigation of pharmacological differences among different P-gp genes is warranted. Further research is needed to investigate and optimize laboratory assays for D. immitis microfilariae, and caution should be applied when adapting cell death assays to drug screening studies for nematode parasites.

Repurposing the open access malaria box reveals compounds with activity against Tritrichomonas foetus trophozoites.

The protozoan parasite Tritrichomonas foetus causes early embryonic death in cattle which results in severe economic loss. In the United States, there are no drugs are approved for treatment of this pathogen. In this study, we evaluated in vitro anti-protozoal effects of compounds from an open access chemical library against T. foetus trophozoites. An initial high-throughput screen identified 16 compounds of interest. Further investigation revealed 12 compounds that inhibited parasite growth and 4 compounds with lethal effects. For lethal compounds, dose-response curves were constructed and the LD50 was calculated for laboratory and field strains of T. foetus. Our experiments revealed chemical scaffolds that were parasiticidal in the micromolar range, and these scaffolds provide a starting point for drug discovery efforts. Further investigation is still needed to investigate suitability of these scaffolds and related compounds in food animals. Importantly, open access chemical libraries can be useful for identifying compounds with activity against protozoan pathogens of veterinary importance.

Room Decontamination Using Ionized Hydrogen Peroxide Fog and Mist Reduces Hatching Rates of Syphacia obvelata Ova.

This study evaluated the efficacy of ionized hydrogen peroxide (iHP) fog and mist for environmental and surface decontaminationof Syphacia obvelata ova in rodent rooms. Ova were collected by perianal tape impression from S. obvelata infectedmice. In experiment 1, ova were exposed to iHP using a whole-room fogging decontamination system with a 15 min initialfog application cycle in unoccupied rodent rooms. Ova were removed from the fogged environment after a 15 min, 30 min, 90min, or 240 min iHP exposure time. In experiment 2, a second cohort of ova were exposed to iHP using the whole-room foggingdecontamination system. Ova were removed after 3, 4 or 6 continuous fog application cycles with 45 min dwelling timebetween each cycle and 15 h dwelling time for the last time point. In experiment 3, a third set of ova was exposed to an iHPsurface misting unit with 1, 2, or 3 iHP mist applications. A 7 min contact time followed each application. After exposure, ovawere incubated in a hatching medium for 6 h. Control ova were maintained at room temperature without iHP exposure beforeincubation in the hatching medium. After incubation, the number of ova hatched was assessed by microscopic examination.For experiment 1, results ranged from 46% to 57% of exposed ova hatched. For experiment 2, results ranged from 43% to 49%of ova hatched. For experiment 3, 37% to 46% of exposed ova hatched. Conversely, for the control groups above 80% of ovahatched for all 3 experiments. These data suggest that exposure to iHP fog and mist has variable effectiveness in reducingviability of S. obvelata ova at the time points tracked. Further studies are needed to identify iHP exposures that will furtherreduce or eliminate the hatching of rodent pinworm ova.