Gastrointestinal Parasite Burden Research Articles

Prevalence and Associated Risk Factors of Gastrointestinal Parasite Infections among Meat Goats in Khon Kaen Thailand.

This study investigated the epidemiology of gastrointestinal (GI) parasite infections among 42 meat goat herds in Khon Kaen, Northeast Thailand, based on 913 fecal samples. The predominant parasites identified in the herd were strongyle (100.0%, 42/42), Trichuris spp. (73.8%, 31/42), Eimeria spp. (66.7%, 28/42), Moniezia spp. (64.3%, 27/42), Strongyloides spp. (38.1%, 16/42), and Paramphistomum spp. (7.1%, 3/42). Coinfection with at least two GI parasites was observed in 90.4% of the herds. Molecular analysis confirmed Haemonchus contortus and Trichostrongylus spp. as the strongyle species. The study explored parasite prevalence among animals, finding significant correlations with season, sex, age, and breed. Notably, the wet season showed increased strongyle and Eimeria spp. infections. Female animals had higher odds of strongyle infection, while younger animals (less than 1 year) were more susceptible. Conversely, animals aged over 1 year were more likely to be positive for Trichuris spp., Moniezia spp., and Eimeria spp. infections. Female animals exhibited poor body condition scores (BCS) and anemia, as indicated by the FAMACHA score and packed cell volume (PCV) levels. Correlations between age, clinical signs, hematological parameters, biochemistry, and GI parasite burdens were investigated, revealing significant associations. These findings emphasize the need for tailored intervention strategies considering seasonal variations, age, and sex differences for effective GI parasite control in meat goats. Prioritizing animals exhibiting poor BCS and elevated FAMACHA score is imperative to mitigate the deleterious impacts of GI parasitic infections on health and productivity.

219 Identification of Functional Single Nucleotide Polymorphisms Responsible for Alternative Splicing Affecting Gastrointestinal Nematodes Resistance in Grazing Sheep

Abstract Sheep infected with gastrointestinal nematodes (GIN) can show weight loss, anemia, diarrhea, decrease appetite, and hypoproteinemia, which can sometimes lead to death. These signs of infection decrease productivity and cause economic losses. Economic losses can also be associated with treatment without efficacy due to GIN resistance to most anthelmintic classes. Combined approaches need to be used to reduce the reliance on anthelmintic as the only control method to GIN. The aim of this study is the identification of potential functional single nucleotide polymorphisms (SNPs) responsible for alternate splicing in Rideau X Dorset crossbred sheep with different immune profiles using RNA-Sequencing (RNA-Seq). Animals were exposed to GIN while grazing, after that those with the greatest and least gastrointestinal tract parasite burdens were selected for liver RNA extracting. These animals can be separated into groups of high (H; n = 5) and medium (M; n = 6) innate immune responses. In addition, liver RNA was extracted for GIN-unexposed control lambs (U; n = 4). RNA-Seq analysis was performed using the CLC genomics workbench software, version 20.0.4 (CLC Bio, Aarhus, Denmark). Quality control analyses, including guanine-cytosine (GC) content, ambiguous base content, Phred score, base coverage, nucleotide contributions, and over-represented sequences parameters, were performed on fastq files. Sequence reads were aligned to the annotated Oar_rambouillet_v.1 (release 109) ovine reference genome. After filtering steps, mRNA isoforms with multiple (³ 2) expressed mRNA isoforms with at least one mRNA isoform differently expressed (DE) between H- and M-innate immune response and GIN-unexposed control groups (FDR < 0.05 and |FC| > 2) were keep. A total of 1, 75, and 58 DE mRNA isoforms were identified for M versus H, U versus M, and U versus H comparisons, respectively. Gene ontology (GO) analysis including the biological process, molecular function, and cellular component GO categories and metabolic pathways analysis were performed using STRING-db software. Enriched biological processes and metabolic pathways related to the immune system, as well as cholesterol and other sterol metabolism (e.g., sterol biosynthesis, steroid metabolism, cholesterol biosynthesis, cholesterol metabolism, ascorbate and aldarate metabolism, drug metabolism, and terpenoid biosynthesis) were identified (FDR < 0.05). Next, the list of DE mRNA isoforms identified will be deeply studied by performing SNP discovery analysis to validate if specific functional SNPs are responsible for the alternative splicing affecting GIN resistance in grazing sheep. The complete results will help to better understand the biological mechanisms that may be regulating the immune response to GIN. Candidate functional SNPs have the potential to be included in a commercial SNP panel for selection of more resistant animals to improve GIN resistance in sheep flocks.

Evaluation of trace elements in forages and their effect on gastrointestinal parasite burden in grazing sheep

This study was designed to evaluate the trace elements (minerals) in forages fed to sheep and their effect on gastrointestinal parasite burdens. The ultimate objective was to determine the correlation between the burden of gastrointestinal (GI) parasites and the level of trace minerals in sheep serum as a result of the forages they grazed on.A total of 384 faecal samples were collected from sheep in each of the districts (Sialkot and Multan) and examined quantitatively using the McMaster technique. Serum collected from them and plants were pre-treated, and spectrophotometry was used to determine the concentration of trace minerals (Mn, Co, Cu, and Zn). The level of these trace elements differed significantly (P < 0.05) in forages from both districts. In the district of Sialkot, the highest concentrations (mg/Kg) of Zn (38.53 ± 0.16) were found in Cichorium intybus, Cu (41.57 ± 0.07) in Cynodon dactylon, Mn (39.61 ± 0.05) in Parthenium hysterophorus, and Co (1.42 ± 0.03) in Coronopus didymus. In the district of Multan, the highest concentrations (mg/Kg) of Zn (39.43 ± 0.46) were found in Cichorium intybus, Cu (25.76 ± 0.36) in Cynodon dactylon, Mn (34.29 ± 0.53) in Launaea nudicaulis, and Co (1.74 ± 0.08) in Brachiaria raptens. The prevalence of GI parasites in sheep populations in district Sialkot was 34%, while in district Multan, it was 32%. In tehsil Sialkot of district Sialkot, Zn and Cu were significantly (P < 0.05) correlated with eggs per gram (EPG) of faeces, while in tehsil Multan City of district Multan, only Cu was significantly (P < 0.05) correlated with EPG. The potential mechanism behind the role of trace mineralsin lowering the burdens of GI parasites requires more investigation. It is recommended that plants with high content of trace minerals should be utilized as part of comprehensive preventive and control strategies against GI parasitism in ruminant animals like sheep.

Age-specific impacts of vegetation functional traits on gastrointestinal nematode parasite burdens in a large herbivore.

Gastrointestinal nematode (GIN) parasites play an important role in the ecological dynamics of many animal populations. Recent studies suggest that fine-scale spatial variation in GIN infection dynamics is important in wildlife systems, but the environmental drivers underlying this variation remain poorly understood. We used data from over two decades of GIN parasite egg counts, host space use, and spatial vegetation data from a long-term study of Soay sheep on St Kilda to test how spatial autocorrelation and vegetation in an individual's home range predict parasite burden across three age groups. We developed a novel approach to quantify the plant functional traits present in a home range to describe the quality of vegetation present. Effects of vegetation and space varied between age classes. In immature lambs, strongyle parasite faecal egg counts (FEC) were spatially structured, being highest in the north and south of our study area. Independent of host body weight and spatial autocorrelation, plant functional traits predicted parasite egg counts. Higher egg counts were associated with more digestible and preferred plant functional traits, suggesting the association could be driven by host density and habitat preference. In contrast, we found no evidence that parasite FEC were related to plant functional traits in the host home range in yearlings or adult sheep. Adult FEC were spatially structured, with highest burdens in the north-east of our study area, while yearling FEC showed no evidence of spatial structuring. Parasite burdens in immature individuals appear more readily influenced by fine-scale spatial variation in the environment, highlighting the importance of such heterogeneity for our understanding of wildlife epidemiology and health. Our findings support the importance of fine-scale environmental variation for wildlife disease ecology and provides new evidence that such effects may vary across demographic groups within a population.

Ovine gastrointestinal parasite burden and the impact of strategic anthelmintic treatment in community-based breeding sites in Ethiopia.

In Ethiopia, small ruminants contribute significantly to livelihoods and food security but productivity is low with high disease burden and essential endoparasite control not widely practiced. The current study assessed worm burden and its control in three districts in Ethiopia. All sheep older than 3 months in nine villages were treated en-masse with albendazole and triclabendazole twice a year from 2018 to 2021. Treatments were administered under field conditions by animal health workers. Pre- and post-treatment data were assessed looking at fecal egg presence/absence and fecal egg per gram (EPG) count. A total of 1,928 and 735 sheep were examined before and after deworming, respectively. Before treatment worms were detected in 54.4% (95% CI: 52.2-56.6) of sheep. Strongylid (30.4%) and Fasciola (18.2%) were the most frequently identified parasites. Animals living in wet mid-highland environments were more than 23 times more likely to have strongylid eggs in their feces and 5 times more likely to have eggs from any gastrointestinal tract (GIT) parasites detected, as compared to animals living in moist highland agro-ecology. Over the course of the 2018-2021 community intervention there was total elimination of animals with a high worm burden (EPG > 1,500), and elimination of a third of those with moderate infections. Mild infections remained, largely accounted for by strongylid, which remains at low levels in healthy sheep. However, there were signs of emerging drug resistance. Generally, sheep in smallholder systems in Ethiopia experience a needlessly large economic burden from GIT worms. Routine therapy reduces this burden but smart strategies are needed to limit the onset of drug resistance.

Evaluation of the Gastrointestinal Parasite Burden of Goats in Traditional Breeding in Benin

Evaluation of the Gastrointestinal Parasite Burden of Goats in Traditional Breeding in Benin

Association of gastrointestinal parasite burden, serum cytokines and hormones concentrations, and pregnancy in Angus-cross beef cows

The objective was to elucidate the relationships among gastrointestinal (GI) parasite load, serum cytokines (Th 1 – Interleukin (IL) 2, Interferon (IFN) γ and Tumor necrosis factor (TNF) α; Th 2- IL4, IL6, and IL10) levels, hormones (progesterone, cortisol, 8-epi-prostaglandin F2 alpha (isoprostane), prolactin, substance-p, and prostaglandin F metabolites) concentrations, and pregnancy in beef cattle. Angus-cross beef cows (n = 700; age, 3–8 y) were blocked by age and body condition score (BCS, 1–9), and were randomly assigned to treatment (n = 350, TRT, 50 mg of eprinomectin/50 kg BW, im) or control (n = 350, CON, no treatment) on Day -30. Cows were synchronized using Controlled Internal Drug Release insert (CIDR) + CO-Synch protocol and artificially inseminated at a fixed time on Day 0 (66 h after CIDR removal). Fecal samples were collected to determine fecal egg count per gram (FEG, McMaster method) on Days -30, -23, -16, -7, 7, 0, 16 and 23, and blood samples were collected on Days -7, 0, 7, 16 and 23. Serum cytokines were determined on Days -7, 0, 7, 16 and 23, and circulating hormones were measured on Day 16. BCS were recorded on Day 16 following artificial insemination (AI), and pregnancy status was diagnosed on Day 30 and 60. Pregnancy/AI varied among treatment groups on Day 30 [TRT, 62.0% (217/350); CON, 54.9% (192/350) (P = 0.05)] and Day 60 [TRT, 60.9% (213/350); CON, 51.7% (181/350) (P < 0.05)]. Pregnancy loss between 30 and 60 days for TRT and CON groups were 1.8% (4/217) and 5.7% (11/192), respectively (P < 0.05). The BCS on Day 16 did not differ among treatment groups (P> 0.1). Four groups of 40 cows were selected based on their pregnancy status and treatment: pregnant, TRT; non-pregnant, TRT; pregnant, CON; and non-pregnant, CON to compare the mean FEG, cytokines, and hormones levels. The FEG and cytokine concentrations were significantly (P < 0.05) influenced by treatment, pregnancy status, day, treatment by pregnancy status, and treatment by day. Day 16 hormone concentrations were considerably influenced by treatment, pregnancy status, and treatment by pregnancy. Although FEG on Day -30 did not differ among the groups (P> 0.1), it was lower in treated, pregnant cows compared with cows in other three groups from Day -23 onwards (P < 0.05). Overall and pairwise comparisons showed that serum concentrations of Type 1 cytokines, IL2, IFNγ, and TNFα were lower (P < 0.05) from gestational Day 7 onwards in treated, pregnant cows compared with cows in other three groups. In contrast, serum concentrations of Type 2 cytokines, IL4, IL6 and IL10 were greater (P < 0.05) from gestational Day 7 onwards in treated, pregnant cows compared with cows in other groups. Serum concentrations of progesterone was greater and other hormones were lower for pregnant cows in TRT group compared to cows in other groups on gestational Day 16. In conclusion, GI parasite load was reduced; Th 1 cytokines levels were decreased; Th 2 cytokines concentrations were increased; progesterone level was increased; and cortisol, substance-P, prolactin, isoprostane, and PGFM were decreased in pregnant, TRT cows. These changes also resulted in an increase in P/AI. It is plausible that direct and bidirectional host-parasite interactions mediated by cytokines and hormones may have promoted maternal tolerance of an immunologically diverse conceptus and the establishment of pregnancy.

Gastrointestinal parasite burden in 4th-5th c. CE Florence highlighted by microscopy and paleogenetics.

The study of ancient parasites, named paleoparasitology, traditionally focused on microscopic eggs disseminated in past environments and archaeological structures by humans and other animals infested by gastrointestinal parasites. Since the development of paleogenetics in the early 1980s, few paleoparasitological studies have been based on the ancient DNA (aDNA) of parasites, although such studies have clearly proven their utility and reliability. In this paper, we describe our integrative approach for the paleoparasitological study of an ancient population from Florence in Italy, dated to the 4th-5th c. CE. The first stage consisted in the study of sediment samples from the pelvic area of 18 individuals under light microscopy. This allowed us to detect Ascarid-type eggs belonging very probably to the human-infesting roundworm Ascaris lumbricoides. Ten subsamples were selected corresponding to five individuals, and we extracted their whole DNA following sediment aDNA protocols. A targeted approach allowed us to detect two nematodes and one trematode aDNA fragments, namely Ascaris sp., Trichuris trichiura, and Dicrocoelium dendriticum. Among the five individuals tested for microscopic eggs and aDNA, three of them showed the remains of eggs (only Ascarid-type), but all of them tested positive to the presence of at least one parasite aDNA. Microscopic diagnosis first guided our research for the selection of promising samples while the targeted aDNA approach significantly improved our knowledge in terms of parasitic diversity and frequency in this population subgroup. These results enabled us to discuss the possible impact of latent parasitism in this past population at the time of an epidemic, as suggested in Florence. In particular, the singular case of D. dendriticum detection is discussed in light of the present-day scarcity of genuine human infections. Nevertheless, actual infections are known in the paleoparasitological record, and food habits may have led to false parasitism in this historical context. aDNA leaching from overlying strata may also explain this detection. This study strongly pleads for a systematic integrative approach combining microscopy and aDNA in paleoparasitology.

The effect of plant bioactive compounds on lamb performance, intake, gastrointestinal parasite burdens, and lipid peroxidation in muscle.

Plant extracts have been widely used in animal production systems due to the benefits promoted by their bioactive components, mainly through their antioxidant effects and positive effects on animal growth, health, and meat quality. We determined whether bioactive compounds (BC) from grape (Vitis vinifera), olive (Olea europaea), and pomegranate (Punica granatum) have beneficial effects on lamb growth while controlling gastrointestinal parasitism and reducing skeletal lipid peroxidation in muscle. Fourteen lambs (4 to 5 mo of age) were housed in individual pens and assigned to two treatment groups (seven animals/group), where they received: 1) a basal diet of beet pulp:soybean meal (90:10) (CONTROL) and 2) the same diet, but containing 0.3% of BC extracted from grape, olive, and pomegranate (BNP). After 21 d of consuming their respective rations (period 1), all lambs were dosed with 10,000 L3 stage larvae of Haemonchus contortus. Intake, production, and physiological parameters were determined before infection (period 1), after oral dosage with L3 (period 2), and during early (period 3) and later (period 4) developmental stages of infection. Groups of animals did not differ in their ration intake or average daily gain, either before or after the infection, or in their parasitic burdens estimated through fecal egg counts (P > 0.05). Lambs under BNP showed greater feed efficiency before infection (P < 0.001), but the pattern reversed after infection. In addition, the inclusion of plant bioactives to the diet did not have an effect (P > 0.05) on blood or lipid peroxidation in muscle or on hemogram, serum concentration of haptoglobin, and immunoglobulin E. These results could be explained by low dietary doses and constrained absorption or ruminal inactivation of these compounds. Changes in feed efficiencies suggest a negative interaction between BC in the diet and parasitism, which warrants further research.

Noninvasive measurement of mucosal immunity in a free-ranging baboon population.

Ecoimmunological patterns and processes remain understudied in wild primates, in part because of the lack of noninvasive methods to measure immunity. Secretory immunoglobulin A (sIgA) is the most abundant antibody present at mammalian mucosal surfaces and provides an important first line of defense against pathogens. Recent studies show that sIgA can be measured noninvasively in feces and is a good marker of mucosal immunity. Here we validated a commercial ELISA kit to measure fecal IgA in baboons, tested the robustness of its results to variation in collection and storage conditions, and developed a cost-effective in-house ELISA for baboon fecal IgA. Using data from the custom ELISA, we assessed the relationship between fecal IgA concentrations and gastrointestinal parasite burden, and tested how sex, age, and reproductive effort predict fecal IgA in wild baboons. We find that IgA concentrations can be measured in baboon feces using an in-house ELISA and are highly correlated to the values obtained with a commercial kit. Fecal IgA concentrations are stable when extracts are stored for up to 22 months at -20°C. Fecal IgA concentrations were negatively correlated with parasite egg counts (Trichuris trichiura), but not parasite richness. Fecal IgA did not vary between the sexes, but for males, concentrations were higher in adults versus adolescents. Lactating females had significantly lower fecal IgA than pregnant females, but neither pregnant nor lactating female concentrations differed significantly from cycling females. Males who engaged in more mate-guarding exhibited similar IgA concentrations to those who engaged in little mate-guarding. These patterns may reflect the low energetic costs of mucosal immunity, or the complex dependence of IgA excretion on individual condition. Adding a noninvasive measure of mucosal immunity will promote a better understanding of how ecology modulates possible tradeoffs between the immune system and other energetically costly processes in the wild.

Androgens predict parasitism in female meerkats: a new perspective on a classic trade-off

The immunocompetence handicap hypothesis posits that androgens in males can be a 'double-edged sword', actively promoting reproductive success, while also negatively impacting health. Because there can be both substantial androgen concentrations in females and significant androgenic variation among them, particularly in species portraying female social dominance over males or intense female-female competition, androgens might also play a role in mediating female health and fitness. We examined this hypothesis in the meerkat (Suricata suricatta), a cooperatively breeding, social carnivoran characterized by aggressively mediated female social dominance and extreme rank-related reproductive skew. Dominant females also have greater androgen concentrations and harbour greater parasite loads than their subordinate counterparts, but the relationship between concurrent androgen concentrations and parasite burdens is unknown. We found that a female's faecal androgen concentrations reliably predicted her concurrent state of endoparasitism irrespective of her social status: parasite species richness and infection by Spirurida nematodes, Oxynema suricattae, Pseudandrya suricattae and coccidia were greater with greater androgen concentrations. Based on gastrointestinal parasite burdens, females appear to experience the same trade-off in the costs and benefits of raised androgens as do the males of many species. This trade-off presumably represents a health cost of sexual selection operating in females.

Feeding Ecology of Dolphinfish in the Western Gulf of Mexico

AbstractDolphinfish Coryphaena hippurus support important commercial and recreational fisheries in the Gulf of Mexico. Understanding the feeding ecology of this economically important pelagic fish is key to its sustainable management; however, dietary data from this region are sparse. We conducted a comprehensive diet study to develop new trophic baselines and investigate potential ontogenetic and sex‐related shifts in Dolphinfish feeding ecology. The stomach contents of 357 Dolphinfish (27.6–148.5 cm TL) were visually examined from fishery‐dependent sources off Port Aransas, Texas. Our analyses revealed a highly piscivorous diet with Actinopterygii comprising 70.44% of the stomach contents by number. The most commonly observed taxa were carangid (12.45%N) and tetraodontiform (12.08%N; families Balistidae, Monacanthidae, and Tetraodontidae) fishes. Malacostracans were also common (24.83%N), mostly in the form of pelagic megalopae. Other prey categories included squid and the critically endangered Kemp's Ridley sea turtles Lepidochelys kempii. Although increasingly commom in larger fish, Sargassum spp. was found across a range of sizes in Dolphinfish, indicating that these fish feed from this drifting macroalgae throughout ontogeny. An ontogenetic shift from primary consumption of carangids and brachyurans in smaller size‐classes to tetraodontids, monocanthids, and squid in larger size‐classes was also observed. No sex‐related difference in diet was observed. The overall infection rate for gastric parasites was 54%, an order of magnitude increase from that previously reported in the region, but consistent with recent studies from other areas. Trematode parasites in the genus Dinurus were found in 55% of stomachs and nematode parasites of the family Raphidascarididae in 16% of stomachs. Overall, Dolphinfish in the western Gulf of Mexico are highly opportunistic carnivores with a gastrointestinal parasite burden consistent with that reported in other ocean basins. These data will be important for sustainable management of this economically important species.Received November 20, 2015; accepted February 17, 2016 Published online June 24, 2016

Gastrointestinal strongyles burden monitoring in a flock of Zerasca sheep treated with homeopathy

IntroductionThe widespread use of conventional drugs in farm animals has resulted in anthelmintic resistance as well as the contamination of deleterious molecules in animal products and in the environment. Researchers are thus focusing on production systems that rely less on chemicals. The aim of this study was to monitor the gastrointestinal strongyle burden, blood count, body condition scores (BCS), and FAffa MAlan CHArt (FAMACHA) in a local Italian breed of sheep reared in natural conditions. MethodsThe study was carried out in a farm where homeopathy was utilised. Over a one-year period, faeces were sampled six times from ten Zerasca ewes to evaluate the fecal eggs count using a modified McMaster technique. At the same time, blood samples were collected to evaluate white blood cells, red blood cells, hemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and red cell distribution width. BCS and FAMACHA were also recorded. ResultsResults showed low parasite levels in most of the samples with the highest value in the spring. Blood parameters were within the normal range, with significant fluctuations during the sampling period. BCS values corresponded to an adequate nutritional condition of the animals and FAMACHA scores did not suggest a worrying state of anemia. ConclusionsIn this farm, a thorough monitoring of the gastrointestinal parasite burden together with a BCS and FAMACHA evaluation allowed the amount of chemical treatments to be limited, normally administered twice a year without laboratory tests.

Hemotropic Mycoplasma ovis infection in goats with concurrent gastrointestinal parasitism in Malaysia

Hemotropic Mycoplasmosis is common in sheep and goats worldwide, which leads to huge economic losses. In this study, ten goats each were sampled from five herds belonging to the Ladang Angkat, Faculty of Veterinary Medicine (FVM) for the assessment of Mycoplasma ovis infection and concomitant intestinal parasites burden. Giemsa stain and Modified McMaster techniques were used to study the hemotropic mycoplasmosis and gastrointestinal parasite burden, respectively. Questionnaires were equally administered to each farmer and a fly trap was used to trap biting flies around the goat herds. Out of 50 samples analyzed, 94.0% (n=47/50) were positive for M. ovis infection. Among the positive samples, 93.6% (n=44/47) were mild infection while 6.4% (n=3/47) were moderate infection, with highest infection rate of 38.5% parasitemia. There was a significant association (P

Landscape characteristics influence helminth infestations in a peri-domestic rodent--implications for possible zoonotic disease.

BackgroundAnthropogenic habitat change often results in altered landscapes that can provide new environments where hosts, parasites and pathogens can interact. The latter can have implications for human and animal health when in close proximity to developed areas. We recorded the helminth species richness and level of infestation in the peri-domestic rodent, Rhabdomys pumilio, in three different human linked landscapes. The aim was, to investigate the potential of R. pumilio to act as a reservoir host for zoonotic helminths and to compare the effect of anthropogenic habitat change on its parasite infestation patterns.MethodsRodents (n = 518) were trapped in natural areas (nature reserves) and in three human linked landscapes (crop, livestock and urban fragments). Gastrointestinal parasite burdens were recovered and helminths identified from each animal. Generalized linear models were applied to investigate the effect of different landscape types on helminth infestation.ResultsRhabdomys pumilio was the most abundant rodent species within each landscape type. Eight helminths species were recovered and overall helminth prevalence was 86.68%. Mean helminth species richness, prevalence and abundance were significantly higher in crop fragments compared to natural landscapes and overall lower for nematodes in livestock and urban areas. Cestode prevalence showed a tendency to be elevated at anthropogenic linked landscape types.ConclusionsHost parameters and parasite infestations were strongly influenced by landscape characteristics. Resource-rich landscapes (crop fragments) provide favorable conditions for helminth infestations, while landscapes that are more closely associated with humans (livestock and urban landscapes) pose a larger risk by zoonotic species.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-3305-7-393) contains supplementary material, which is available to authorized users.

Developing a conceptual model of possible benefits of condensed tannins for ruminant production

Enteric methane (CH4) emissions from ruminants have compelled a wide range of research initiatives to identify environmental abatement opportunities. However, although such mitigations can theoretically be attained with feed additives and feeding strategies, the limited empirical evidence on plant extracts used as feed additives does not support extensive or long-term reductions. Nevertheless, their strategic use (i.e. alone or combined in a simultaneous or consecutive use) may provide not only acceptable CH4 abatement levels, but also relevant effects on animal physiology and productivity. Condensed tannins (CT) represent a range of polyphenolic compounds of flavan-3-ol units present in some forage species that can also be added to prepared diets. Methods to determine CT, or their conjugated metabolites, are not simple. Although there are limitations and uncertainties about the methods to be applied, CT are thought to reduce CH4 production (1) indirectly by binding to the dietary fibre and/or reducing the rumen digestion and digestibility of the fibre and (2) directly by inhibiting the growth of rumen methanogens. On the basis of their role in livestock nutrition, CT influence the digestion of protein in the rumen because of their affinity for proteins (e.g. oxidative coupling and H bonding at neutral pH) that causes the CT-protein complex to be insoluble in the rumen; and dissociate in the abomasum at pH 2.5 to 3.0 for proteolysis and absorption in the small intestine. CT may also reduce gastro-intestinal parasite burdens and improve reproductive performance, foetal development, immune system response, hormone serum concentrations, wool production and lactation. The objectives of this paper are to discuss some of the beneficial and detrimental effects of CT on ruminant production systems and to develop a conceptual model to illustrate these metabolic relationships in terms of systemic physiology using earlier investigations with the CT-containing legume Lotus corniculatus. Our conceptual model indicated four complex and long-lasting relationships (digestive, toxicological, physiological and morphological) that can alter the normal biology of the animal. These relationships are interdependent, integrative, and sometimes, complementary to each other. This conceptual model can be used to develop mechanistic models to improve the understanding of the interaction between CT and the ruminants as well as to guide research initiatives of the impact of polyphenol-rich foods on human health.

Monitoring the health status of free-ranging tammar wallabies using hematology, serum biochemistry, and parasite loads

Population differences in body condition, parasitic burden, hematology, and serum biochemistry of free-living tammar wallabies (Macropus eugenii) are presented and compared to studies reporting values in captive tammar wallabies. The nutritional distinction in the composition and quality of the available vegetation on Garden Island produces 3 sub-populations that differ in their human disturbance, body condition, rates of reproduction, and survival, providing unique opportunities to examine condition-related health parameters in free-living wallabies. Our results show several hematology analytes (in particular, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration), all the measured serum biochemistry analytes (urea, creatinine, triglycerides, and albumin), and total gastrointestinal parasite burden are significantly associated with body condition (body mass index), providing reliable indices of wallaby condition and habitat quality. The means and standard errors for hematology analytes (in particular, hemoglobin, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration) and all serum biochemistry values for free-ranging wallabies lie below and outside of reference ranges for captive wallabies, despite the naval base sub-population benefiting from human modified habitats with a consistent availability of food. This indicates that free-ranging tammar wallabies may be suffering from some challenges that captive wallabies do not face. The hematology and serum biochemistry values coupled with body condition indices suggest wallabies in the south bush sub-population are under greater nutritional stress and suffering from prolonged malnutrition. Examining all parameters in a single year and across years would be beneficial to further investigate habitat differences driving this change to help distinguish if vegetative structure and associated nutritional deficiencies and/or disease are limiting this population. Health monitoring is an integral part of the management of both captive and free-living populations and the data presented here will serve as an effective management tool in assessing the health status of free-living tammar wallabies. © 2013 The Wildlife Society.

Detecting genes for variation in parasite burden and immunological traits in a wild population: testing the candidate gene approach

Identifying the genes underlying phenotypic variation in natural populations can provide novel insight into the evolutionary process. The candidate gene approach has been applied to studies of a number of traits in various species, in an attempt to elucidate their genetic basis. Here, we test the application of the candidate gene approach to identify the loci involved in variation in gastrointestinal parasite burden, a complex trait likely to be controlled by many loci, in a wild population of Soay sheep. A comprehensive literature review, Gene Ontology databases, and comparative genomics resources between cattle and sheep were used to generate a list of candidate genes. In a pilot study, these candidates, along with 50 random genes, were then sequenced in two pools of Soay sheep; one with low gastrointestinal nematode burden and the other high, using a NimbleGen sequence capture experiment. Further candidates were identified from single nucleotide polymorphisms (SNPs) that were highly differentiated between high- and low-resistance sheep breeds. A panel of 192 candidate and control SNPs were then typed in 960 individual Soay sheep to examine whether they individually explained variation in parasite burden, as measured as faecal egg count, as well as two immune measures (Teladorsagia circumcincta-specific antibodies and antinuclear antibodies). The cumulative effect of the candidate and control SNPs were estimated by fitting genetic relationship matrices (GRMs) as random effects in animal models of the three traits. No more significant SNPs were identified in the pilot sequencing experiment and association study than expected by chance. Furthermore, no significant difference was found between the proportions of candidate or control SNPs that were found to be significantly associated with parasite burden/immune measures. No significant effect of the candidate or control gene GRMs was found. There is thus little support for the candidate gene approach to the identification of loci explaining variation in parasitological and immunological traits in this population. However, a number of SNPs explained significant variation in multiple traits and significant correlations were found between the proportions of variance explained by individual SNPs across multiple traits. The significant SNPs identified in this study may still, therefore, merit further investigation.

Gastrointestinal nematode burden in working equids from humid tropical areas of central Veracruz, Mexico, and its relationship with body condition and haematological values

The east coast of Veracruz, Mexico, has an important equine population used for working in rural production systems. The objectives of this study were (1) to calculate the prevalence of tropical working equids (donkeys, mules and horses) infected with gastrointestinal nematodes (GINs) and the GINs involved, and (2) to measure the body condition score (BCS) and haematological values for each working equid and its relationship with faecal worm egg count (EPG). One hundred and forty working equids were randomly selected from five different villages along the central coast of the state of Veracruz and faecal and blood samples were obtained from each animal. Gastrointestinal parasite burdens were determined using the McMaster technique. Packed cell volume, total plasma proteins, red blood cell count and white blood cell count were measured from each blood sample. Prevalence of infected equids was higher than 90 %. Mules had the highest median faecal worm egg counts (875 EPG), followed by horses and donkeys with 400 EPG. There was no correlation between EPG and BCS or haematological values (p > 0.05). Results suggest that despite the high prevalence and parasite burdens, equids involved in this trial are not being seriously affected. This study provides information which might help in designing future strategies to control nematode infections in working equids in the Mexican tropics; more emphasis should be placed on other inputs (nutrition perhaps), with individual anthelminthic treatment to those animals with the highest EPG or when signs present themselves.

Variety matters: adaptive genetic diversity and parasite load in two mouse opossums from the Brazilian Atlantic forest

The adaptive potential of a species to a changing environment and in disease defence is primarily based on genetic variation. Immune genes, such as genes of the major histocompatibility complex (MHC), may thereby be of particular importance. In marsupials, however, there is very little knowledge about natural levels and functional importance of MHC polymorphism, despite their key role in the mammalian evolution. In a previous study, we discovered remarkable differences in the MHC class II diversity between two species of mouse opossums (Gracilinanus microtarsus, Marmosops incanus) from the Brazilian Atlantic forest, which is one of the most endangered hotspots for biodiversity conservation. Since the main forces in generating MHC diversity are assumed to be pathogens, we investigated in this study gastrointestinal parasite burden and functional associations between the individual MHC constitution and parasite load. We tested two contrasting scenarios, which might explain differences in MHC diversity between species. We predicted that a species with low MHC diversity would either be under relaxed selection pressure by low parasite diversity (‘Evolutionary equilibrium’ scenario), or there was a recent loss in MHC diversity leading to a lack of resistance alleles and increased parasite burden (‘Unbalanced situation’ scenario). In both species it became apparent that the MHC class II is functionally important in defence against gastrointestinal helminths, which was shown here for the first time in marsupials. On the population level, parasite diversity did not markedly differ between the two host species. However, we did observe considerable differences in the individual parasite load (parasite prevalence and infection intensity): while M. incanus revealed low MHC DAB diversity and high parasite load, G. microtarsus showed a tenfold higher population wide MHC DAB diversity and lower parasite burden. These results support the second scenario of an unbalanced situation.