A novel neurotropic microsporidium from the swamp guppy Micropoecilia picta from Grenada, West Indies.

A novel microsporidium was observed in wild swamp guppies Micropoecilia picta from Levera Pond within Levera National Park Grenada, West Indies. Initial observations indicated similarity with Pseudoloma neurophilia, an important pathogen in zebrafish Danio rerio. P. neurophilia exhibit broad host specifity, including members of the family Poecillidae, and both parasites infect the central nervous system. However, spore morphology and molecular phylogeny based on rDNA showed that the swamp guppy microsporidium (SGM) is distinct from P. neurophilia and related microsporidia (Microsporidium cerebralis and M. luceopercae). Spores of the SGM were smaller than others in the clade (3.6 µm long). Differences were also noted in histology; the SGM formed large aggregates of spores within neural tissues along with a high incidence of numerous smaller aggregates and single spores within the surface tissue along the ventricular spaces that extended submeninx, whereas P. neurophilia and M. cerebralis infect deep into the neuropile and cause associated lesions. Analysis of small subunit ribosomal DNA sequences showed that the SGM was <93% similar to these related microsporidia. Nevertheless, one of 2 commonly used PCR tests for P. neurophilia cross reacted with tissues infected with SGM. These data suggest that there could be other related microsporidia capable of infecting zebrafish and other laboratory fishes that are not being detected by these highly specific assays. Consequently, exclusive use of these PCR tests may not accurately diagnose other related microsporidia infecting animals in laboratory and ornamental fish facilities.

Physician deaths from COVID-19 have been lower than expected.

BACKGROUND: More than 100 US physicians have died from COVID-19. I considered the number of US physician deaths in comparison to the expected COVID death rate in the general population. AIMS: To estimate the whether US physicians are at increased risk of death from COVID-19 due to occupational exposures. METHODS: COVID-related physician deaths were identified through searches using Medscape In Memoriam, and multiple internet searches using Google and Facebook. An obituary or death notice was obtained in all but one case. Death rates among physicians were compared to the expected rate based on COVID deaths in the US population. RESULTS: Up to 7 October 2020, there were 108 deaths among US physicians. Physicians make up about 0.33% of the US population. By 1 October 2020, there were 210 000 COVID deaths in the US population with 693 expected physician deaths. Observed deaths were 16% of expected. Seventy-five per cent of the deaths occurred among physicians older than age 60 and about half appeared to be among those retired from clinical practice. CONCLUSIONS: Observed physician deaths were significantly below expected based on deaths the general population. Prudent use of personal protective equipment may explain the lower-than-expected death rates.

Importation of macrocyclic lactone resistant cyathostomins on a US thoroughbred farm.

Anthelmintic resistance in equine cyathostomins is both widespread and highly prevalent in the benzimidazole and tetrahydropyrimidine classes; however, reports of resistance to macrocyclic lactone (ML) drugs are sparse and sporadic. This study reports a case of clear ML resistance in a group of Thoroughbred yearlings imported from Ireland to the US in 2019. Fecal egg count reduction (FECR) following ivermectin administered in February 2020 demonstrated 100% reduction in the US bred yearlings, but 93.5%, 70.5%, and 74.5% reduction in three groups of the imported yearlings. The two former groups were then retreated with ivermectin, yielding FECRs of 33.8% and 23.5%, respectively. Horses from these two groups were then assigned randomly to two possible treatments; moxidectin or a triple combination of moxidectin, oxibendazole, and pyrantel pamoate. The groups treated with moxidectin had FECRs of 90.2%, 57.3%, and 50.0%, while the triple combination had a 100% FECR in all treated groups. Subsequently, the efficacy of ivermectin was reassessed in June 2020 yielding FECRs of 99.8%, 87.7%, and 62.0% in the three imported groups. The FECRs of the US bred yearlings all remained in the 99-100% range. This is the first study to clearly demonstrate ML resistance in cyathostomins and to confirm the suspicion through reassessment. These data demonstrate that ML-resistant cyathostomins were imported from Ireland and serve to illustrate that the global movement of horses has the potential to quickly spread ML-resistant parasite isolates around the world. The equine industry is strongly encouraged to routinely monitor anthelmintic efficacy, so occurrence of ML resistant cyathostomins can be detected and appropriate interventions implemented as early as possible.

Equine parasite control and the role of national legislation - A multinational questionnaire survey.

Experts recommend a change in the control of equine parasites across the world in order to adopt a surveillance-based approach utilizing parasite faecal egg counts (FEC). Several European countries have implemented prescription-only restrictions of anthelmintic usage by law, which is in stark contrast to US, where all anthelmintic products continue to be available over the counter. This study aimed to describe and compare equine parasite control strategies employed in Germany, Austria, the Netherlands, US, and Denmark. An invitation to participate in an online questionnaire survey was published on a large equine news website in each of the participating countries. The main focus of the study was on usage of FEC and anthelmintic treatment intensity in three different equine age groups; foals, 1-3 year-olds and >3 years old. A total of 3092 respondents participated in the study. Danish respondents used significantly more faecal analyses in their parasite control strategies than participants from the other four countries (p < 0.0001). Similarly, Danish participants administered significantly fewer anthelmintic treatments per horse per year (p < 0.0001) independent of the age of the horse, and had been using a selective treatment strategy for a significantly longer time period than their counterparts in other countries (p < 0.0001). Only minor differences were found between respondents from the other four countries. This is remarkable as both Austria and Germany have had prescription-only restrictions for 3-4 decades. Yet, their parasite control strategies were more similar to those employed by American respondents. The Netherlands had only recently introduced prescription-only restrictions by the time this survey was conducted which can explain why Dutch respondents were also similar to their American counterparts. Taken together, this study illustrates substantially different worm control strategies practiced in Denmark, and this difference cannot be explained by legislation alone.

Antiparasitic efficacy of a novel plant-based functional food using an Ascaris suum model in pigs.

Ascaris lumbricoides is the most prevalent soil-transmitted helminth (STH) infection of human beings worldwide. Chemotherapy with synthetic anthelmintics such as albendazole, mebendazole, and pyrantel pamoate is the current method of treatment; however, the emergence of anthelmintic resistance could substantially decrease the efficacy of such treatments and the sustainability of STH control programs. Additionally, benzimidazoles are not recommended for pregnant women or children under age one. A blinded, controlled study was conducted to evaluate the efficacy of two microencapsulated, plant-based essential oil blends, TTN1013 (α-pinene, linalyl acetate, p-cymene, and thymol octanoate) and TTN1014 (α-pinene, linalyl acetate, p-cymene, and thymol acetate) as functional foods against Ascaris suum infection in pigs, an important pathogen that closely resembles human infections with A. lumbricoides. Four groups of 16 female, 21-24 day old, Yorkshire-cross pigs were treated daily with 0.5 or 1.0mg/kg TTN1013, 1.0mg/kg TTN1014, or 1.0mg/kg equivalent of empty capsules, delivered inside a cream-filled sandwich cookie for 14 weeks. Three days after the initiation of daily treatments, pigs were inoculated daily with A. suum eggs for four weeks. Pigs were weighed weekly and fecal egg counts (FEC) were conducted weekly starting five weeks after initial inoculation with A. suum eggs. Fourteen weeks after first infection with eggs, pigs were necropsied and worms were recovered, counted and separated according to sex. TTN1013 administered daily at a dose of 1.0mg/kg yielded a statistically significant reduction in total worm counts (76.8%), female worm counts (75.5%), FEC (68.6%), and worm volume (62.9%) when compared to control group. Reduction of total and female worm numbers and FEC were not significant for TTN1014 or at the 0.5mg/kg dose of TTN1013. All treatments were well-tolerated by all pigs and did not cause any adverse reactions. All pigs remained clinically normal and showed no signs of reduced intestinal health for the duration of treatment. Based on these results, TTN1013 shows promise as a daily supplement to reduce infection burdens of soil transmitted helminths in both pigs and human beings.

Anthelmintic resistance in equine parasites--current evidence and knowledge gaps.

Anthelmintic resistance is becoming increasingly prevalent among equine nematode parasites. The first reports documenting resistance were published in the 1960s, just a short time after introduction of the first modern anthelmintics phenothiazine and thiabendazole. Several factors are known to influence development of resistance, but evidence specific to equine parasites is limited. Most current knowledge and applications have been extrapolated from research with trichostrongylid parasites of sheep. The number of cyathostomin species co-infecting horses adds to the complexity of investigating drug resistance but, given their apparent limited biological diversity, viewing these in a unispecific context remains a pragmatic approach. Factors affecting resistance development in cyathostomins include parasite seasonality, life span and fecundity, host immunity, and the existence of encysted stages. Further, parasite refugia have been shown to play a vital role in resistance development in other parasites, and likely is also important in equine parasites. Specific genetic factors for drug resistance and possible modes of inheritance have been identified for trichostrongylid nematodes, but it is widely accepted that several more remain undiscovered. Current evidence with equine and ruminant parasites suggests that fitness is not significantly compromised in drug resistant strains. Attempts to develop in vitro and molecular assays for diagnosing anthelmintic resistance in equine nematodes have had only limited success, standardized guidelines are sorely needed for performing the fecal egg count reduction test in horse populations. Taken together, this review illustrates the complexity of understanding anthelmintic resistance in equine nematodes, and emphasizes the need for further research.

Impact of integrated gastrointestinal nematode management training for U.S. goat and sheep producers.

The objective of this study was to determine the impact of integrated parasite management (IPM) training, including FAMACHA(©) eyelid color scoring, on the ability of U.S. sheep and goat producers to control gastrointestinal nematodes (GIN) on their farms. A survey was developed and provided to over 2000 producers trained from 2004 to 2008 in IPM with questions involving farm size (number of sheep/goats), location (U.S. state), impact of training on parasite control efforts and parasite problems on farm, and IPM practices used. Responses were divided into U.S. Census regions of the U.S. Descriptive statistics and logistic regression were used to describe results. Most of the 729 respondents were from the southern region of the U.S. (54.3%) and were small-scale producers (50 or less animals; 64.8%). Nearly all of the respondents (95.1%) agreed that IPM workshop attendance made a difference in their ability to control and monitor parasitism in their herd or flock and employed IPM practices to control GIN (96.3%). The most popular practices respondents used were rotational grazing (71.2%), genetic selection (choosing a parasite resistant breed and/or culling susceptible animals; 52.7%), grain supplementation on pasture to improve nutrition (44.0%), and increased height of plants being grazed (41.8%). Although reporting using a practice decreased (P<0.05) the likelihood of reporting fewer problems, for each 1-point increase in the number of practices which producers employed to control internal parasitism in their herd or flock, they were 16% more likely to report fewer GIN problems (P<0.05). Approximately 75% of respondents indicated an economic benefit of IPM on their farm (P<0.05), and those reporting savings of over $80 were more likely to report fewer problems (P<0.05) with parasites after the training while those reporting no economic benefit were less likely to report fewer problems with GIN (P<0.001). Overall, IPM training resulted in positive impacts for producers responding to the survey and should continue.

Equine parasite control under prescription-only conditions in Denmark--awareness, knowledge, perception, and strategies applied.

Due to widespread development of anthelmintic resistance in equine parasites, recommendations for their control are currently undergoing marked changes with a shift of emphasis toward more coprological surveillance and reduced treatment intensity. Denmark was the first nation to introduce prescription-only restrictions of anthelmintic drugs in 1999, but other European countries have implemented similar legislations over recent years. A questionnaire survey was performed in 2008 among Danish horse owners to provide a current status of practices and perceptions with relation to parasite control. Questions aimed at describing the current use of coprological surveillance and resulting anthelmintic treatment intensities, evaluating knowledge and perceptions about the importance of various attributes of parasite control, and assessing respondents' willingness to pay for advice and parasite surveillance services from their veterinarians. A total of 1060 respondents completed the questionnaire. A large majority of respondents (71.9%) were familiar with the concept of selective therapy. Results illustrated that the respondents' self-evaluation of their knowledge about parasites and their control associated significantly with their level of interest in the topic and their type of education (P<0.0001). The large majority of respondents either dewormed their horses twice a year and/or performed two fecal egg counts per horse per year. This approach was almost equally pronounced in foals, horses aged 1-3 years old, and adult horses. The respondents rated prevention of parasitic disease and prevention of drug resistance as the most important attributes, while cost and frequent fecal testing were rated least important. Respondents' actual spending on parasite control per horse in the previous year correlated significantly with the amount they declared themselves willing to spend (P<0.0001). However, 44.4% declared themselves willing to pay more than what they were spending. Altogether, results indicate that respondents were generally familiar with equine parasites and the concept of selective therapy, although there was some confusion over the terms small and large strongyles. They used a large degree of fecal surveillance in all age groups, with a majority of respondents sampling and/or treating around twice a year. Finally, respondents appeared willing to spend money on parasite control for their horses. It is of concern that the survey suggested that foals and young horses are treated in a manner very similar to adult horses, which is against current recommendations. Thus, the survey illustrates the importance of clear communication of guidelines for equine parasite control.

Hierarchical model for evaluating pyrantel efficacy against strongyle parasites in horses.

Anthelmintic resistance is an increasing challenge for the control of equine parasites. The fecal egg count reduction test (FECRT) is the practical gold standard method for evaluating reduction in anthelmintic efficacy, but the interpretation is complicated due to high levels of variability. A hierarchical statistical model was described for analysis of FECRT data from multiple farms to evaluate the role of biological factors in determining the strongyle efficacy of pyrantel pamoate in a study performed in Denmark. The model was then used to describe two notions of farm efficacy, namely conditional and marginal efficacy. The median of the lower prediction limits was used to describe a robust classification rule. The performance of the methodology was evaluated using Monte Carlo simulations. The field study was performed on 64 Danish horse farms of different breeds. Of 1644 horses, 614 had egg counts ≥ 200 eggs per gram (EPG) and were treated. Individual coprocultures were performed for identification of Strongylus vulgaris from all horses pre-treatment. Thirty-one farms (48.4%) were positive for S. vulgaris, but pyrantel efficacy was unaffected by the presence of this parasite in the statistical model. Further, there were no significant effects of age, gender, or interactions between these, while the pre-treatment egg count was negatively associated with the egg count reduction. The statistical model classified 81.3%, 10.9%, and 7.8% of farms as no signs of resistance (NR), suspect resistance (SR), and resistance (RE), respectively. In comparison, arithmetic calculations classified 68.8%, 17.2%, and 14.1% in the same categories. Using 10,000 simulated data sets, the methodology provided a classification of farms into different efficacy categories with a false discovery of reduced farm efficacy rate equaling 8.74%. In addition, model-classification was unaffected by presence of single outlier horses in a separate simulation study.

Novel approaches for the control of helminth parasites of livestock VI: summary of discussions and conclusions.

Gastrointestinal helminth parasites impact on livestock production systems throughout the world, and the use of anthelmintics to control this problem has lead to the inevitable development of populations of helminths resistant to these treatments. This, coupled with consumer desires for minimal chemical inputs into food and fibre production, has prompted research into non-chemical approaches to helminth control. Scientists of the "Novel Approaches to the Control of Helminth Parasites of Livestock" group met for the 6th time in August 2010 and this paper summarises that meeting. Six scientific sessions addressed current approaches and topics of interest through formal presentations and discussion of issues raised by the contributing authors. Close interaction between researchers and extension specialists during the meeting has contributed to enhanced prospects for field application of research outcomes in the future.

Statistical and biological considerations in evaluating drug efficacy in equine strongyle parasites using fecal egg count data.

Anthelmintic resistance (AR) is a serious problem for the control of equine gastrointestinal nematodes, particularly in the cyathostomins. The fecal egg count reduction test (FECRT) is the most common method for diagnosing AR and serves as the practical gold standard. However, accurate quantification of resistance and especially accurate diagnosis of emerging resistance to avermectin/milbemycin (A/M) drugs, is hampered by a lack of accepted standards for study design, data analysis, and data interpretation. In order to develop rational evidence-based standards for diagnosis of resistance, one must first take into account the numerous sources of variability, both biological and technical, that affect the measurement of fecal egg counts (FECs). Though usually ignored, these issues can greatly impact the observed efficacy. Thus, to accurately diagnose resistance on the basis of FECRT data, it is important to reduce levels of variability through improved study design, and then deal with inherent variability that cannot be removed, by performing thorough and proper statistical analysis. In this paper we discuss these issues in detail, and provide an explanation of the statistical models and methods that are most appropriate for analyzing these types of data. We also provide several examples using data from laboratory, field, and simulation experiments illustrating the benefits of these approaches.

Effects of fecal collection and storage factors on strongylid egg counts in horses.

Fecal analyses are becoming increasingly important for equine establishments as a means of parasite surveillance and detection of anthelmintic resistance. Although several studies have evaluated various egg counting techniques, little is known about the quantitative effects of pre-analytic factors such as collection and storage of fecal samples. This study evaluated the effects of storage temperature, storage time and airtight versus open-air storage on fecal egg counts. The experimental protocols were replicated in two study locations: Copenhagen, Denmark and Athens, Georgia, USA. In both locations, the experiment was repeated three times, and five repeated egg counts were performed at each time point of analysis. In experiment A, feces were collected rectally and stored airtight at freezer (-10 to -18 degrees C), refrigerator (4 degrees C), room (18-24 degrees C), or incubator (37-38 degrees C) temperatures. Egg counts were performed after 0, 6, 12, 24, 48, and 120h of storage. In experiment B, feces were collected rectally and stored airtight or in the open air in the horse barn for up to 24h. Egg counts were performed after 0, 3, 6, 12, and 24h of storage. In experiment A at both locations, samples kept in the refrigerator showed no decline in egg counts, whereas storage in the freezer and incubator led to significantly declining egg numbers during the study. In contrast, storage at room temperature yielded marked differences between the two study locations: egg counts remained stable in the U.S. study, whereas the Danish study revealed a significant decline after 24h. In experiment B, the Danish study showed no differences between airtight and open-air storage and no changes over time, while the U.S. study found a significant decline for open-air storage after 12h. This difference was attributed to the different barn temperatures in the two studies. To our knowledge, this is the first study to evaluate the pre-analytic factors affecting egg counts in horses using an experimental protocol replicated in two contrasting geographic and climatic locations. Our results demonstrate that refrigeration is the best method for storage of fecal samples intended for egg count analysis, but that accurate results can be derived from fecal samples collected from the ground within 12h of passage.

Herbal dewormer fails to control gastrointestinal nematodes in goats.

Gastrointestinal nematode (GIN) parasitism is the most important disease of small ruminants. Control is usually based on the use of chemical anthelmintics (dewormers); but these are prohibited from use in organic livestock, and the effectiveness of chemical anthelmintics in conventional operations is limited by high levels of anthelmintic resistance. Consequently, herbal dewormers are increasing in popularity as an alternative to chemical dewormers for GIN control. However, the effectiveness of herbal dewormers remains unproven. The objective of this study was to examine the effectiveness of a commercially available herbal dewormer to control GIN in goats. Lactating (n=16) and young (n=8) dairy goats grazed poor quality mixed grass pastures between March and July 2006 at the Heifer International Ranch in Perryville, AR. Goats were supplemented with grass hay and concentrate. Goats were untreated or administered herbal dewormer (n=12/treatment) according to manufacturer recommendations. FAMACHA scores (1=red or healthy; 5=severely anemic) were determined and fecal samples collected for fecal egg count (FEC) determination every 14 days between Days 0 (day of first herbal treatment) and 112. FAMACHA scores in the herbal treated group were greater than in the untreated control group (P<0.005), indicating a higher level of anemia. FEC were greater for herbal treated goats on Pasture A compared with B by Day 42, but similar among groups thereafter. FEC (P<0.03) and FAMACHA scores (P<0.001) were greater in lactating than in non-lactating goats. Herbal dewormer treatment yielded no measurable health benefits indicating that the herbal dewormer failed to control GIN in these goats.

The role of polymorphisms at beta tubulin isotype 1 codons 167 and 200 in benzimidazole resistance in cyathostomins.

Cyathostomins are recognised as the primary parasitic pathogens of horses. Despite the use of benzimidazole (BZ) anthelmintics in horses for more than 40 years and widespread drug resistance in the field, the mechanisms of resistance to this drug class in cyathostomins are not fully understood. The results presented here constitute a detailed comparison of beta tubulin gene mutations and mRNA transcript levels in populations of BZ-susceptible (BZ-S) and -resistant (BZ-R) cyathostomins. Full-length cDNA sequences were generated from individual parasites of four (n=24) and two (n=19) cyathostomin species for isotypes 1 and 2, respectively. Levels of intra- and inter-specific nucleotide sequence variation were comparable with previous findings and single amino acid substitutions were observed at several locations. On comparison of BZ-S and BZ-R parasites, differences were consistently observed at only two sites, codons 167 and 200 of the beta tubulin isotype 1 gene. Four populations of parasites were genotyped at these two loci by pyrosequencing; one that was fenbendazole (FBZ)-sensitive (FBZ-rS), two that were FBZ-resistant (FBZ-R1 and -R2) and one that was oxibendazole-resistant (OBZ-R), as previously assessed by faecal egg count reduction tests. This analysis revealed statistically significant differences between FBZ-rS and FBZ-R populations at both loci and this was highly significant for codon 167. For the OBZ-R population, the only significant difference compared with the FBZ-rS population was observed at codon 200. These observations suggest that mutations at codons 167 and 200 are important in BZ resistance and raise the possibility that selection at different loci may occur in FBZ- and OBZ-resistant parasites. Multiple parasites (n=158) were genotyped for both codons 167 and 200, the majority of which showed homozygous 'resistant' mutations at one locus only and none showed homozygous 'resistant' genotypes at both loci. No significant differences in mRNA levels of beta tubulin isotypes 1 and 2 were observed between the FBZ-rS and FBZ-R1 populations.

Evaluation of the validity of the Quality of Well-being Scale in Trinidad and Tobago.

Both developing countries in the Caribbean and developed countries face resource allocation challenges. However, cost-effectiveness analysis instruments that may assist in allocation of resources have not been tested in Caribbean countries. Trinidad and Tobago is an advantageous location to test an instrument for potential use in the Caribbean. It has a single payer healthcare system and a literate population. Due to historical and current migration from other Caribbean countries, the population might be a fair representation of English-speaking Caribbean nations. We tested the validity of the Quality of Well-being Scale (QWB) on a sample of the non-institutionalized general population in Trinidad. The survey included reports of chronic conditions and items from the Trinidad and Tobago National Health Interview Survey. Data were analyzed using a multivariable regression model. One adult from each of 235 households consented to the interview. The results are consistent with results obtained in the United States of America. Being older female, more chronic conditions and more symptoms/problems were significantly associated with lower mean QWB scores. These results suggest that the QWB with US-derived weights show evidence of validity in Trinidad and Tobago. Thus, health decision makers can use the QWB to compare the effects of different health conditions and health interventions. In addition, investigators can make cross-cultural comparisons of QWB scores for diseases or health conditions.

Statistical approach to measure the efficacy of anthelmintic treatment on horse farms.

Resistance to anthelmintics in gastrointestinal nematodes of livestock is a serious problem and appropriate methods are required to identify and quantify resistance. However, quantification and assessment of resistance depend on an accurate measure of treatment efficacy, and current methodologies fail to properly address the issue. The fecal egg count reduction test (FECRT) is the practical gold standard for measuring anthelmintic efficacy on farms, but these types of data are fraught with high variability that greatly impacts the accuracy of inference on efficacy. This paper develops a statistical model to measure, assess, and evaluate the efficacy of the anthelmintic treatment on horse farms as determined by FECRT. Novel robust bootstrap methods are developed to analyse the data and are compared to other suggested methods in the literature in terms of Type I error and power. The results demonstrate that the bootstrap methods have an optimal Type I error rate and high power to detect differences between the presumed and true efficacy without the need to know the true distribution of pre-treatment egg counts. Finally, data from multiple farms are studied and statistical models developed that take into account between-farm variability. Our analysis establishes that if inter-farm variability is not taken into account, misleading conclusions about resistance can be made.

Accuracy of the FAMACHA system for on-farm use by sheep and goat producers in the southeastern United States.

FAMACHA is a practical on-farm system designed to provide small ruminant producers a tool for improving their management of Haemonchus contortus infections. Although this system has become very popular and widely accepted by small ruminant producers in many regions of the southern United States, there is very limited data reported on the effectiveness of the FAMACHA system when performed by farmers. The objective of this study was to evaluate the accuracy of the FAMACHA system for on-farm use by small ruminant producers during the summer season. Small ruminant producers from Georgia, Louisiana, Florida, and Puerto Rico were trained to use the FAMACHA system by veterinarians and scientists experienced with this method. FAMACHA scores were assigned at least every 2 weeks by producers to weaned and mature sheep (n=552) and goats (n=676) of various breeds and ages between April and September 2004. At intervals that varied among farms from 2 to 8 weeks, researchers determined body condition scores (BCS; 1=thin and 5=fat) and collected blood and feces from a group of animals selected randomly to determine packed cell volume (PCV) and fecal egg counts (FEC). Two separate anemia thresholds were evaluated; these were defined by either FAMACHA score (>or=3 versus >or=4) or PCV (or=3 were considered anemic and PCV cutoff was or=3 were considered anemic and PCV cutoff was

A novel approach for combining the use of in vitro and in vivo data to measure and detect emerging moxidectin resistance in gastrointestinal nematodes of goats.

Ivermectin and moxidectin are closely related avermectin/milbemycin anthelmintics and available data suggest that side resistance occurs with these two drugs. However, moxidectin remains effective against many species of ivermectin-resistant worms due to its higher potency. The larval development assay (LDA) is routinely used to diagnose ivermectin resistance in Haemonchus contortus but laboratory diagnosis of moxidectin resistance is hampered by the lack of any validated in vitro tests. The objective of this study was to measure the relative susceptibility/resistance of H. contortus to moxidectin on goat farms in Georgia, and to validate the DrenchRite LDA for detecting resistance to moxidectin. Fecal egg count reduction tests (FECRT) were performed at five different moxidectin dose levels and DrenchRite LDAs were performed in duplicate on nine meat goat farms in Georgia, USA. To improve our ability to make inferences on the relative levels of resistance between farms, FECRT data were first analysed using a linear mixed model, and then Tukey's sequential trend test was used to evaluate the trend in response across dose levels. LDA data were analysed using log-dose logit-response and probit models. Using these statistical results, we were able to rank the nine farms from the least to the most resistant, and to develop a set of criteria for interpreting DrenchRite LDA results so that this assay can be used to diagnose both clinically apparent moxidectin resistance, as well as sub-clinical emerging resistance. These results suggest that our novel approach for examining these types of data provides a method for obtaining an increased amount of information, thus permitting a more sensitive detection of resistance. Based on results of the LDA, moxidectin-resistant farms had resistance ratios, compared with an ivermectin-sensitive farm, ranging from 32 to 128, and had resistance ratios of 6-24 compared with an ivermectin-resistant/moxidectin naive farm. Moxidectin resistance was diagnosed both in Haemonchus and Trichostrongylus on almost half of the farms tested, despite this drug only being used on these farms for 2-3 years.

Development and characterization of microsatellite markers for the canine hookworm, Ancylostoma caninum.

Microsatellites are repetitive genomic elements that show high levels of variation and therefore provide excellent tools to study the genetics of eukaryotic organisms. Hookworms are extremely common and important nematode parasites of humans and animals, causing potentially serious disease morbidity. Control of hookworms in dogs is achieved by frequent treatment with anthelmintics, and in humans, anthelmintics are frequently administered in a mass-treatment community-wide approach. Understanding the population genetics of hookworms has important implications for studies on the development and spread of drug resistance. We investigated the genome of Ancylostoma caninum for microsatellites by developing and then screening an enriched genomic library as well as by data mining published sequences of a whole genome shotgun library. Investigations revealed a high abundance of trinucleotide repeats. Dinucleotide repeats were characterized by a high number of AT, GA, and GT repeats. After testing and optimization of 68 markers, a panel of 34 polymorphic microsatellite markers were selected. Microsatellite analysis of hookworm isolates revealed a high degree of polymorphism, which was not influenced by the length of the repeats. This panel of microsatellite markers makes it possible to pursue investigations on the population genetics of A. caninum. Furthermore, a number of the markers demonstrated suitability for analysis of the human hookworm species Necator americanus and A. duodenale.