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1.
Trop Anim Health Prod ; 53(1): 181, 2021 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-33625587

RESUMEN

Goats are critical in mixed smallholder agricultural systems in lower and middle-income countries, while fleas are important human and animal health concerns around the world. Convenience sampling was used to describe and consider risk factors for flea infestations of peri-urban goats, with the aim of informing the iterative development of animal husbandry and management based control strategies. Seven hundred and ninety-two goats were examined in 228 households across 10 peri-urban communities surrounding Blantyre in southern Malawi. The prevalence of Ctenocephalides felis fleas was 18.3, 37.1 and 100% at the levels of individual goats, households and communities, respectively, highlighting a neglected human and animal health concern. Constant introduction of new livestock coupled to a lack of biosecurity within communities, the ubiquitous presence of dog and cat hosts for C. felis, the frequency and thoroughness of cleaning overnight goat accommodation, and goat age less than 12 months old were identified as risk factors for flea infestation. This focal cross-sectional study highlights the significance of fleas in peri-urban communities and uncovers trends and commonalities that are needed to inform sustainable disease management. The majority of the peri-urban goat keepers were female, had resided in the same community throughout their whole life and had primary level education. Advice on the planned management of fleas in livestock needs to be tailored towards this demographic group. This approach affords an opportunity to promote public health measures to address household flea infestations and zoonotic disease spread.

2.
Acta Trop ; 216: 105828, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33465353

RESUMEN

Malaria is the world's deadliest parasitic disease. Great progress has been made in the fight against malaria over the past two decades, but this has recently begun to plateau, in part due to the global development of antimalarial drug resistance. The ability to track drug resistance is necessary to achieve progress in treatment, disease surveillance and epidemiology, which has prompted the development of advanced diagnostic methods. These new methods provide unprecedented access to information that can help to guide public health policies. Development of new technologies increases the potential for high throughput and reduced costs of diagnostic tests; improving the accessibility of tools to investigate the forces driving disease dynamics and, ultimately, clinical outcomes for malaria patients and public health. This literature review provides a summary of the methods currently available for the detection of antimalarial drug resistance from the examination of patients' blood samples. While no single method is perfect for every application, many of the newly developed methods give promise for more reliable and efficient characterisation of Plasmodium resistance in a range of settings. By exploiting the strengths of the tools available, we can develop a deeper understanding of the evolutionary and spatiotemporal dynamics of this disease. This will translate into more effective disease control, better-informed policy, and more timely and successful treatment for malaria patients.

3.
Acta Trop ; 215: 105821, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33406444

RESUMEN

Pyrimethamine was first introduced for the treatment of malaria in Asia and Africa during the early 1980s, replacing chloroquine, and has become the first line of drugs in many countries. In recent years, development of pyrimethamine resistance in Plasmodium vivax has become a barrier to effective malaria control strategies. Here, we describe the use of meta-barcoded deep amplicon sequencing technology to assess the evolutionary origin of pyrimethamine resistance by analysing the flanking region of dihydrofolate reductase (dhfr) locus. The genetic modelling suggests that 58R and 173L single mutants and 58R/117N double mutants are present on a single lineage; suggesting a single origin of these mutations. The triple mutants (57L/58R/117N, 58R/61M/117N and 58R/117N/173L) share the lineage of 58R/117N, suggesting a common origin. In contrast, the 117N mutant is present on two separate lineages suggesting that there are multiple origins of this mutation. We characterised the allele frequency of the P. vivax dhfr locus. Our results support the view that the single mutation of 117N and double mutations of 58R/117N arise commonly, whereas the single mutation of 173L and triple mutations of 57L/58R/117N, 58R/61M/117N and 58R/117N/173L are less common. Our work will help to inform mitigation strategies for pyrimethamine resistance in P. vivax.

4.
Ticks Tick Borne Dis ; 12(1): 101595, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33113478

RESUMEN

A study was designed to improve understanding of the genetics of Theileria annulata populations in sympatric cattle and Asian buffalo (Bubalus bubalus). The study was undertaken in the Punjab province of Pakistan, where the prevalence of tropical theileriosis is high. Parasite materials were collected from infected animals in defined regions, where cattle and Asian buffalo are kept together. Six satellite DNA markers and a mitochondrial cytochrome b marker were used to explore the multiplicity of T. annulata infection and patterns of emergence and spread of different parasite genotypes. The results show differences in the numbers of unique satellite locus alleles, suggesting that T. annulata is genetically more diverse in cattle- than in buffalo-derived populations. Heterozygosity (He) indices based on satellite and cytochrome b loci data show high levels of genetic diversity among the cattle- and buffalo-derived T. annulata populations. When considered in the context of high parasite transmission rates and frequent animal movements between different regions, the predominance of multiple T. annulata genotypes and multiple introductions of infection may have practical implications for the spread of parasite genetic adaptations; such as those conferring vaccine cross-protection against different strains affecting cattle and Asian buffalo, or resistance to antiprotozoal drugs.

5.
Vet Parasitol ; 289: 109339, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33359968

RESUMEN

Our current understanding of differences in the epidemiology of gastrointestinal nematode (GIN) species in co-grazed sheep and goats is inadequate with reference to the development of sustainable control strategies. The next-generation metabarcoding sequencing method referred to as the 'nemabiome' allows some of these differences to be explored to describe the intensity of co-infecting GIN species. We applied this platform to study sheep and goats that were co-grazed on Guinea grass pasture in northeastern Brazil. Co-grazed goats and sheep were treated with a monepantel anthelmintic, then exposed to the same gastrointestinal nematode species. Overall, there were differences in the prevalence of GIN species identified in the sheep and goats; Trichostrongylus colubriformis and Teladorsagia circumcincta predominated in goat kids, while Haemonchus contortus predominated in adult does, ewes and lambs once burdens became re-established after anthelmintic treatment. Description of the pattern of re-infection following anthelmintic treatment was prevented by the unpredicted poor efficacy of 2.5 mg/kg and 5 mg/kg, respectively, of monepantel against O. columbianum and T. circumcincta in lambs, and T. circumcincta adult does. Differences in drug efficacy between host age and species groups may be important when considering sustainable GIN control strategies for co-grazed animals. The aggregated FECs of the adult does and goat kids representing re-established GIN burdens, were higher than those of the co-grazed adult ewes and lambs. This implies that there are inherent differences in GIN species adaptation to the two naïve small ruminant host species, and shows the need for better understanding of the factors giving rise to this situation associated with exposure to infective larvae and host responses. At the start of the study, the adult does were co-infected with several GIN species, with the highest intensity of T. circumcincta, contrasting with the situation in the adult ewes, in which H. contortus predominated. However, once burdens became re-established after treatment, H. contortus predominated in both adult does and ewes. This demonstrates the potential for host burdens of H. contortus to establish and predominate after anthelmintic treatment when burdens of co-infecting GIN species are low.

6.
Parasitol Int ; 81: 102276, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33370606

RESUMEN

Lancet liver flukes of the genus Dicrocoelium (Trematoda: Digenea) are recognised parasites of domestic and wild herbivores. The aim of the present study was to confirm the species identity of Dicrocoeliid flukes collected from the Chitral valley in the Himalayan ranges of Pakistan. The morphology of 48 flukes belonging to eight host populations was examined; but overlapping traits prevented accurate species designation. Phylogenetic comparison of published D. dendriticum ribosomal cistron DNA, and cytochrome oxidase-1 (COX-1) mitochondrial DNA sequences with those from D. chinensis was performed to assess within and between species variation and re-affirm the use of species-specific single nucleotide polymorphism markers. PCR and sequencing of 34 corresponding fragments of ribosomal DNA and 14 corresponding fragments of mitochondrial DNA from the Chitral valley flukes, revealed 10 and 4 unique haplotypes, respectively. These confirmed for the first time the molecular species identity of Pakistani lancet liver flukes as D. dendriticum. This work provides a preliminary illustration of a phylogenetic approach that could be developed to study the ecology, biological diversity, and epidemiology of Dicrocoeliid lancet flukes when they are identified in new settings.

7.
Commun Biol ; 3(1): 656, 2020 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-33168940

RESUMEN

Haemonchus contortus is a globally distributed and economically important gastrointestinal pathogen of small ruminants and has become a key nematode model for studying anthelmintic resistance and other parasite-specific traits among a wider group of parasites including major human pathogens. Here, we report using PacBio long-read and OpGen and 10X Genomics long-molecule methods to generate a highly contiguous 283.4 Mbp chromosome-scale genome assembly including a resolved sex chromosome for the MHco3(ISE).N1 isolate. We show a remarkable pattern of conservation of chromosome content with Caenorhabditis elegans, but almost no conservation of gene order. Short and long-read transcriptome sequencing allowed us to define coordinated transcriptional regulation throughout the parasite's life cycle and refine our understanding of cis- and trans-splicing. Finally, we provide a comprehensive picture of chromosome-wide genetic diversity both within a single isolate and globally. These data provide a high-quality comparison for understanding the evolution and genomics of Caenorhabditis and other nematodes and extend the experimental tractability of this model parasitic nematode in understanding helminth biology, drug discovery and vaccine development, as well as important adaptive traits such as drug resistance.

8.
Front Vet Sci ; 7: 584323, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33195608

RESUMEN

Iranian studies have shown a high prevalence of broad spectrum anthelmintic resistance (AR) in gastrointestinal helminths of ruminants. However, there is a lack of information about levels of knowledge, attitudes and practices among livestock farmers in Iran regarding the concept of parasite control and AR. This study aimed to evaluate the knowledge, attitudes and practices of livestock farmers of Hamedan, Iran, regarding parasitic diseases and AR by interviewing 150 farmers using a structured questionnaire. Most of farmers had some knowledge of the clinical signs associated with helminth parasitism, but more than half were unaware of the existence of zoonotic parasites. More than half of the participants had never heard about AR, but were interested to learn about it through their veterinarians. Those who were aware of the problem considered non-prescribed anthelmintic drugs to play a role in its emergence, while several of the participants believed that "more expensive" and "foreign-branded" drugs worked best. Almost all of the farmers reported that they frequently consulted with a veterinarian about anthelmintic treatments, but very few adhered to recognized principles of responsible and sustainable drug use. About half of the participating farmers treated their sheepdogs for helminth parasites, despite the common practice of regularly feeding likely infected livestock offal. Education had a significantly positive association with farmers' knowledge, attitudes, and best practice scores, while knowledge was significantly associated with both attitudes and practices. Based on these results, we recommend that regular country-wide classes should be held to educate farmers on the evidence-based principles of sustainable helminth control and prevention of zoonotic helminth diseases.

9.
PLoS One ; 15(11): e0242526, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33196660

RESUMEN

Chlamydia abortus is one of the most commonly diagnosed causes of infectious abortion in small ruminants worldwide. Control of the disease (Enzootic Abortion of Ewes or EAE) is achieved using the commercial live, attenuated C. abortus 1B vaccine strain, which can be distinguished from virulent wild-type (wt) strains by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Published studies applying this typing method and whole-genome sequence analyses to cases of EAE in vaccinated and non-vaccinated animals have provided strong evidence that the 1B strain is not attenuated and can infect the placenta causing disease in some ewes. Therefore, the objective of this study was to characterise the lesions found in the placentas of ewes vaccinated with the 1B strain and to compare these to those resulting from a wt infection. A C. abortus-free flock of multiparous adult ewes was vaccinated twice, over three breeding seasons, each before mating, with the commercial C. abortus 1B vaccine strain (Cevac® Chlamydia, Ceva Animal Health Ltd.). In the second lambing season following vaccination, placentas (n = 117) were collected at parturition and analysed by C. abortus-specific real-time quantitative PCR (qPCR). Two placentas, from a single ewe, which gave birth to live twin lambs, were found to be positive by qPCR and viable organisms were recovered and identified as vaccine type (vt) by PCR-RFLP, with no evidence of any wt strain being present. All cotyledons from the vt-infected placentas were analysed by histopathology and immunohistochemistry and compared to those from wt-infected placentas. Both vt-infected placentas showed lesions typical of those found in a wt infection in terms of their severity, distribution, and associated intensity of antigen labelling. These results conclusively demonstrate that the 1B strain can infect the placenta, producing typical EAE placental lesions that are indistinguishable from those found in wt infected animals.

10.
PLoS One ; 15(9): e0237902, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32970707

RESUMEN

Improvements to smallholder farming are essential to improvements in rural prosperity. Small farmers in the Kaziranga region of Assam operate mixed farming enterprises in a resource limited environment, which is subject to seasonal flooding. Participatory techniques, were used to elucidate the animal health challenges experienced in this landscape in order to inform and guide future animal health education and interventions. The flooding is essential for agricultural activities, but is a source of major losses and disruption. Farmers experience significant losses to their crops due to raiding by wild species such as elephants; predation of livestock by wild carnivores is also of concern. Access to veterinary services and medicines is limited by both financial and geographic constraints. Interviewees discussed nutritional and management issues such as poor availability of fodder and grazing land, while meeting attendees preferred to concentrate discussions on animal health issues. Livestock keepers were adept and consistent at describing disease syndromes. The key challenges identified by farmers were: foot-and-mouth disease; Newcastle disease; haemorrhagic septicaemia; chronic fasciolosis; diarrhoea; bloating diseases; goat pox; and sarcoptic mange. Improvements in the efficiency of farming in this region is a prerequisite for the local achievement of United Nations Sustainable development goals. There exist clear opportunities to increase productivity and prosperity among farmers in this region through a combination of vaccination programmes and planned animal management schemes, driven by a programme of participatory farmer education.


Asunto(s)
Crianza de Animales Domésticos , Métodos Epidemiológicos , Agricultores , Adolescente , Adulto , Agricultura , Animales , Animales Salvajes , Ambiente , Femenino , Inundaciones , Geografía , Educación en Salud , Humanos , India , Masculino , Persona de Mediana Edad , Parques Recreativos , Estaciones del Año
11.
Vet Parasitol ; 286: 109240, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32950742

RESUMEN

The benzimidazoles are one of the most important broad-spectrum anthelmintic drug classes for parasitic nematode control in domestic animals and humans. They have been widely used in livestock, particularly in small ruminants for over 40 years. This has resulted in widespread resistance in small ruminant gastrointestinal nematode parasite species, especially Haemonchus contortus. Benzimidazole resistance mutations have also been reported in Haemonchus placei, but only at low frequencies, suggesting resistance is at a much earlier stage of emergence than is the case for H. contortus. Here, we investigate the haplotype diversity of isotype-1 ß-tubulin benzimidazole resistance mutations and the population genetic structure of H. contortus and H. placei populations from sheep and cattle from the southern USA. Microsatellite genotyping revealed a low level of genetic differentiation in six H.placei and seven H. contortus populations examined. This is consistent with several previous studies from other regions, mainly in H. contortus, supporting a model of high gene flow between parasite populations. There was a single F200Y(TAC) haplotype present in all six H. placei populations across Georgia, Florida and Arkansas. In contrast, there were at least two different F200Y(TAC) haplotypes (up to four) and two different F167Y(TAC) haplotypes across the seven H. contortus populations studied. These results provide further evidence to support a model for benzimidazole resistance in Haemonchus spp, in which resistance mutations arise from a single, or the small number of locations, in a region during the early phases of emergence, and subsequently spread due to animal movement.

12.
Infect Genet Evol ; 82: 104305, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32247865

RESUMEN

Various PCR based methods have been described for the diagnosis of malaria, but most depend on the use of Plasmodium species-specific probes and primers; hence only the tested species are identified and there is limited available data on the true circulating species diversity. Sensitive diagnostic tools and platforms for their use are needed to detect Plasmodium species in both clinical cases and asymptomatic infections that contribute to disease transmission. We have recently developed for the first time a novel high throughput 'haemoprotobiome' metabarcoded DNA sequencing method and applied it for the quantification of haemoprotozoan parasites (Theleria and Babesia) of livestock. Here, we describe a novel, high throughput method using an Illumina MiSeq platform to demonstrate the proportions of Plasmodium species in metabarcoded DNA samples derived from human malaria patients. Plasmodium falciparum and Plasmodium vivax positive control gDNA was used to prepare mock DNA pools of parasites to evaluate the detection threshold of the assay for each of the two species. The different mock pools demonstrate the accurate detection ability and to show the proportions of each of the species being present. We then applied the assay to malaria-positive human samples to show the species composition of Plasmodium communities in the Punjab province of Pakistan and in the Afghanistan-Pakistan tribal areas. The diagnostic performance of the deep amplicon sequencing method was compared to an immunochromatographic assay that is widely used in the region. The deep amplicon sequencing showed that P. vivax was present in 69.8%, P. falciparum in 29.5% and mixed infection in 0.7% patients examined. The immunochromatographic assay showed that P. vivax was present in 65.6%, P. falciparum in 27.4%, mixed infection 0.7% patients and 6.32% malaria-positive cases were negative in immunochromatographic assay, but positive in the deep amplicon sequencing. Overall, metabarcoded DNA sequencing demonstrates better diagnostic performance, greatly increasing the estimated prevalence of Plasmodium infection. The next-generation sequencing method using metabarcoded DNA has potential applications in the diagnosis, surveillance, treatment, and control of Plasmodium infections, as well as to study the parasite biology.

13.
PLoS One ; 15(3): e0228819, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32160186

RESUMEN

Smallholder cattle farming in Assamese villages is sub-optimal in terms of calf survivability, growth, age at first service, and milk yield. Proper understanding of the local situation is essential to formulate appropriate, locally driven, livestock keeper education to sustainably improve animal health, welfare and productivity. In-depth interviewing and direct observation were used to understand the farming strategies, husbandry practices and challenges to health and productivity in a cluster of typical villages in the Kaziranga region of Assam, India, where resource use is balanced between the needs of humans and livestock, with competition from wild species. Knowledge of the importance of colostrum consumption by calves is poor. Timely consumption of sufficient colostrum (locally called "phehu") by calves was clearly sub-optimal in the majority of households. The reasons behind this are nuanced, but the practice of collecting colostrum from newly calved cows to make confectionery for human consumption is an important contributory factor. Care of the umbilicus of the newborn is not routine practice in the locality. Local women are the key group assisting with young and sick animals, including cases of simple dystocia and retained foetal membranes. Cows are usually milked once daily, to attempt to balance the needs for milk of household with those of the calf, which can result in suboptimal nutrition for calves. There are clear opportunities to improve animal health and productivity through locally provided farmer education, particularly with reference to colostrum provision, and the engagement of women farmers in any such programme is key to success.


Asunto(s)
Crianza de Animales Domésticos/métodos , Calostro , Industria Lechera/métodos , Agricultores/educación , Animales , Bovinos , Granjas , Femenino , Humanos , India , Leche , Estado Nutricional , Embarazo
14.
Parasitol Int ; 76: 102071, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32045674

RESUMEN

Fasciola spp. are responsible for over 3 billion US dollars of production loss annually in livestock and cause widespread zoonotic disease. Nevertheless, understating of the emergence and spread of the trematode species is poor. The multiplicity of F. gigantica infection and its spread is potentially influenced by multiple factors, including the abundance of suitable intermediate hosts, climatic conditions favouring the completion of the parasite's lifecycle, and translocation of infected animals, or free-living parasite stages between regions. Here we describe the development of a 'tremabiome' metabarcoding sequencing method to explore the numbers of F. gigantica genotypes per infection and patterns of parasite spread, based on genetic characteristics of the mitochondrial NADH dehydrogenase 1 (mt-ND-1) locus. We collected F. gigantica from three abattoirs in the Punjab and Balochistan provinces of Pakistan, and our results show a high level of genetic diversity in 20 F. gigantica populations derived from small and large ruminants consigned to slaughter in both provinces. This implies that F. gigantica can reproduce in its definitive hosts through meiosis involving cross- and self-breeding, as described in the closely related species, Fasciola hepatica. The genetic diversity between the 20 populations derived from different locations also illustrates the impact of animal movements on gene flow. Our results demonstrate the predominance of single haplotypes, consistent with a single introduction of F. gigantica infection in 85% of the hosts from which the parasite populations were derived. This is consistent with clonal reproduction in the intermediate snail hosts.


Asunto(s)
Búfalos , Enfermedades de los Bovinos/epidemiología , Fasciola/aislamiento & purificación , Fascioliasis/veterinaria , Variación Genética , Enfermedades de las Cabras/epidemiología , Enfermedades de las Ovejas/epidemiología , Animales , Bovinos , Enfermedades de los Bovinos/parasitología , Fasciola/clasificación , Fascioliasis/epidemiología , Fascioliasis/parasitología , Genotipo , Enfermedades de las Cabras/parasitología , Cabras , Pakistán/epidemiología , Ovinos , Enfermedades de las Ovejas/parasitología
15.
Int J Parasitol ; 49(11): 847-858, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31525371

RESUMEN

Differential expression analysis between parasitic nematode strains is commonly used to implicate candidate genes in anthelmintic resistance or other biological functions. We have tested the hypothesis that the high genetic diversity of an organism such as Haemonchus contortus could complicate such analyses. First, we investigated the extent to which sequence polymorphism affects the reliability of differential expression analysis between the genetically divergent H. contortus strains MHco3(ISE), MHco4(WRS) and MHco10(CAVR). Using triplicates of 20 adult female worms from each population isolated under parallel experimental conditions, we found that high rates of sequence polymorphism in RNAseq reads were associated with lower efficiency read mapping to gene models under default TopHat2 parameters, leading to biased estimates of inter-strain differential expression. We then showed it is possible to largely compensate for this bias by optimising the read mapping single nucleotide polymorphism (SNP) allowance and filtering out genes with particularly high single nucleotide polymorphism rates. Once the sequence polymorphism biases were removed, we then assessed the genuine transcriptional diversity between the strains, finding ≥824 differentially expressed genes across all three pairwise strain comparisons. This high level of inter-strain transcriptional diversity not only suggests substantive inter-strain phenotypic variation but also highlights the difficulty in reliably associating differential expression of specific genes with phenotypic differences. To provide a practical example, we analysed two gene families of potential relevance to ivermectin drug resistance; the ABC transporters and the ligand-gated ion channels (LGICs). Over half of genes identified as differentially expressed using default TopHat2 parameters were shown to be an artifact of sequence polymorphism differences. This work illustrates the need to account for sequence polymorphism in differential expression analysis. It also demonstrates that a large number of genuine transcriptional differences can occur between H. contortus strains and these must be considered before associating the differential expression of specific genes with phenotypic differences between strains.


Asunto(s)
Perfilación de la Expresión Génica/métodos , Perfilación de la Expresión Génica/normas , Variación Genética , Haemonchus/genética , Animales , Antihelmínticos/farmacología , Mapeo Cromosómico/métodos , Mapeo Cromosómico/normas , Biología Computacional/métodos , Biología Computacional/normas , Resistencia a Medicamentos , Haemonchus/efectos de los fármacos , Ivermectina/farmacología , Análisis de Secuencia de ARN/métodos , Análisis de Secuencia de ARN/normas
16.
Ticks Tick Borne Dis ; 10(6): 101276, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31473098

RESUMEN

Piroplasmosis is caused by tick-borne haemoprotozoa of the genera Theileria and Babesia. These parasitic infections can seriously impact on the health of livestock and production. Piroplasms of multiple species can be present in a single host, but reliable molecular diagnostic tools are needed in order to understand the composition of these complex parasite communities. Theileria and Babesia vary in their epidemiology, drug sensitivity, pathogenicity and interaction with co-infecting species, but are similar in that infected animals become persistent carriers after recovery from primary infection, acting as reservoir hosts. Here, we describe for the first time the use of a deep amplicon sequencing platform to identify proportions of piroplasm species in co-infecting communities and develop the concept of a "haemoprotobiome". First, four phenotypically-verified species of Theileria and Babesia were used to prepare mock DNA pools with random numbers of the parasites amplified by four different numbers of PCR cycles to assess sequence representation for each species. Second, we evaluated the detection threshold of the deep amplicon sequencing assay for each of the four species and to assess the accuracy of proportional quantification of all four species. Finally, we applied the assay to the field samples to afford insight of the species composition of piroplasm communities in small and large ruminants in the Punjab province of Pakistan. The "haemoprotobiome" concept has several potential applications in veterinary and human research, including understanding of responses to drug treatment; parasite epidemiology and ecology; species interactions during mixed infections; and parasite control strategies.


Asunto(s)
Babesia/clasificación , Babesiosis/epidemiología , Secuenciación de Nucleótidos de Alto Rendimiento/veterinaria , Microbiota , Theileria/clasificación , Theileriosis/epidemiología , Animales , Babesia/aislamiento & purificación , Búfalos , Bovinos , Enfermedades de los Bovinos/epidemiología , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Pakistán/epidemiología , Ovinos , Enfermedades de las Ovejas/epidemiología , Theileria/aislamiento & purificación
17.
Prev Vet Med ; 171: 104752, 2019 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-31479849

RESUMEN

Gastrointestinal nematodes (GIN) are a serious concern for sheep producers worldwide. However, there is a paucity of evidence describing the epidemiology of GIN on modern UK sheep farms. The aim of this paper was to understand whether expected seasonal variations of infection are still found in ewes and lambs under varying management strategies in temperate climates. Faecal egg counts (FEC) were conducted on freshly voided samples collected from groups of ewes and lambs every third week for twelve months on three farms in southeast Scotland. The patterns of egg output have been described here in relation to management practices undertaken on the farms. Despite changes in farming practice and climatic conditions, the findings complement historical studies detailing the epidemiology of GIN. Findings include a periparturient rise in ewe FEC on two of the farms, while lambing time treatment appeared to suppress this on the third farm. On the same two farms lamb FEC increased during the summer, reaching a peak in the autumn. The work also highlights how the ad hoc use of anthelmintics does little to impact these patterns.


Asunto(s)
Animales Lactantes/parasitología , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/epidemiología , Enfermedades de las Ovejas/parasitología , Crianza de Animales Domésticos/métodos , Animales , Antihelmínticos/uso terapéutico , Estudios de Cohortes , Granjas , Heces/parasitología , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/epidemiología , Recuento de Huevos de Parásitos/veterinaria , Escocia/epidemiología , Estaciones del Año , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológico
18.
Artículo en Inglés | MEDLINE | ID: mdl-31425900

RESUMEN

Anthelmintic resistant gastrointestinal helminths have become a major cause of poor health in sheep and goats. Sensitive and specific molecular markers are needed to monitor the genotypic frequency of resistance in field parasite populations. Gastrointestinal nematode resistance to benzimidazole is caused by a mutation in one of three positions within the isotype 1 ß-tubulin gene. In the absence of markers for resistance to the other broad spectrum anthelmintic classes, these provide a relevant study example. Determination of the prevalence of these single nucleotide polymorphisms in field nematode populations can be impractical using conventional molecular methods to examine individual parasites; which can be laborious and lack sensitivity in determining low levels of resistance in parasite populations. Here, we report the development of a novel method based on an Illumina MiSeq deep amplicon sequencing platform to sequence the isotype 1 ß-tubulin locus of the small ruminant gastrointestinal nematode, Teladorsagia circumcincta, and determine the frequency of the benzimidazole resistance mutations. We validated the method by assessing sequence representation bias, comparing the results of Illumina MiSeq and pyrosequencing, and applying the method to populations containing known proportions of resistant and susceptible larvae. We applied the method to field samples collected from ewes and lambs on over a period of one year on three farms, each highlighting different aspects of sheep management and approaches to parasite control. The results show opportunities to build hypotheses with reference to selection pressures leading to differences in resistance allele frequencies between sampling dates, farms and ewes or lambs, and to consider the impact of their genetic fixation or otherwise. This study provides proof of concept of a practical, accurate, sensitive and scalable method to determine frequency of anthelmintic resistance mutations in gastrointestinal nematodes in field studies and as a management tool for livestock farmers.


Asunto(s)
Antihelmínticos/farmacología , Bencimidazoles/farmacología , Resistencia a Medicamentos , Tracto Gastrointestinal/parasitología , Análisis de Secuencia de ADN/métodos , Enfermedades de las Ovejas/parasitología , Infecciones por Strongylida/veterinaria , Estrongílidos/efectos de los fármacos , Estrongílidos/genética , Animales , Frecuencia de los Genes/efectos de los fármacos , Proteínas del Helminto/genética , Filogenia , Ovinos , Estrongílidos/clasificación , Estrongílidos/aislamiento & purificación , Infecciones por Strongylida/parasitología , Tubulina (Proteína)/genética
19.
Artículo en Inglés | MEDLINE | ID: mdl-31125837

RESUMEN

Anthelmintic resistance is a threat to global food security. In order to alleviate the selection pressure for resistance and maintain drug efficacy, management strategies increasingly aim to preserve a proportion of the parasite population in 'refugia', unexposed to treatment. While persuasive in its logic, and widely advocated as best practice, evidence for the ability of refugia-based approaches to slow the development of drug resistance in parasitic helminths is currently limited. Moreover, the conditions needed for refugia to work, or how transferable those are between parasite-host systems, are not known. This review, born of an international workshop, seeks to deconstruct the concept of refugia and examine its assumptions and applicability in different situations. We conclude that factors potentially important to refugia, such as the fitness cost of drug resistance, the degree of mixing between parasite sub-populations selected through treatment or not, and the impact of parasite life-history, genetics and environment on the population dynamics of resistance, vary widely between systems. The success of attempts to generate refugia to limit anthelmintic drug resistance are therefore likely to be highly dependent on the system in hand. Additional research is needed on the concept of refugia and the underlying principles for its application across systems, as well as empirical studies within systems that prove and optimise its usefulness.


Asunto(s)
Antihelmínticos/farmacología , Resistencia a Medicamentos , Helmintos/efectos de los fármacos , Animales , Helmintiasis/parasitología , Helmintos/genética , Helmintos/crecimiento & desarrollo , Humanos , Refugio de Fauna
20.
Vet Rec ; 185(4): 107, 2019 07 27.
Artículo en Inglés | MEDLINE | ID: mdl-31127028

RESUMEN

Psoroptes ovis mites, the causative agent of sheep scab, can severely compromise sheep welfare and production. However, in subclinical infections, mite detection is difficult increasing the risk of spread. A recent serodiagnostic test, based on detecting host antibodies to the P ovis allergen, Pso o 2, has made the detection of subclinical infection possible. The use of this test was demonstrated in subclinical situations, through an opportunistic observational study on an extensive hill farm and a lowland flock with recently introduced, quarantined livestock. Twelve animals were tested from each group. Breeding ewes and lambs on the hill farm had seroprevalences of 16 per cent (12.5-17.8 per cent) and 8.3 per cent (4.8-10.1 per cent), respectively. Quarantined store lambs had a seroprevalence of 16.7 per cent (13.2-18.5 per cent); no evidence of P ovis was found in quarantined replacement ewes. By detecting subclinical infection, this serological test could be a powerful tool in sheep scab control, for quarantine procedures, accreditation programmes, and possibly regional or national eradication protocols.


Asunto(s)
Infestaciones por Ácaros/veterinaria , Psoroptidae , Enfermedades de las Ovejas/diagnóstico , Animales , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Masculino , Infestaciones por Ácaros/diagnóstico , Infestaciones por Ácaros/epidemiología , Prevalencia , Escocia/epidemiología , Estudios Seroepidemiológicos , Ovinos , Enfermedades de las Ovejas/epidemiología
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