Nutrition-parasite interactions in goats: is immunoregulation involved in the control of gastrointestinal nematodes?

Mucosal Immunity of Major Gastrointestinal Nematode Infections in Small Ruminants Can Be Harnessed to Develop New Prevention Strategies

Gastrointestinal parasitic nematode (GIN) infections are the cause of severe losses to farmers in countries where small ruminants such as sheep and goat are the mainstay of livestock holdings. There is a need to develop effective and easy-to-administer anti-parasite vaccines in areas where anthelmintic resistance is rapidly rising due to the inefficient use of drugs currently available. In this review, we describe the most prevalent and economically significant group of GIN infections that infect small ruminants and the immune responses that occur in the host during infection with an emphasis on mucosal immunity. Furthermore, we outline the different prevention strategies that exist with a focus on whole and purified native parasite antigens as vaccine candidates and their possible oral-nasal administration as a part of an integrated parasite control toolbox in areas where drug resistance is on the rise.

Seasonal Prevalence and Status of Anthelmintic Resistance of Goats' Gastrointestinal Nematodes, Mirab Abaya, Southern Ethiopia

Goats are an important source of livelihood especially for smallholder communities. But gastrointestinal nematodosis is the greatest threats of goat production. A repeated cross-sectional and field experimental study design was conducted from December 2020 to August 2021 in Mirab Abaya district, with the aim of seasonal prevalence gastrointestinal nematode infection and assessment of anthelmintic resistance. A systematic random sampling strategy was used to select the study goats. The overall prevalence of gastrointestinal nematode infections of goats in the study area was 57.9% (95% CI: 54.4-61.4), of which 48.7% (95% CI: 43.7-53.7) and 67.2% (95% CI: 62.3-71.7) accounted to dry and wet seasons, respectively. The multivariable logistic regression analysis showed that season, age, sex, and flock size were significantly (p < 0.05) influenced the prevalence of gastrointestinal nematode infection of goats. The number of eggs per gram of faeces (EPG) was ranged from 100 to 2500. The overall mean egg per gram of faeces (EPG) was 461.1 ± 20.9. The mean EPG of wet season (532.7 ± 28.6) was higher than the dry season (362.3 ± 29.1). From faecal culture, 552 nematode larvae were recovered, and the most commonly identified nematode genera were Haemonchus (36.4%) that followed by Trichostrongylus (28.1%), Oesophagostomum (15.4%), Bunostomum (11.4), Teladorsagia (5.4%), and Strongyloides (3.0%) species. From the anthelmintic resistance test in the field, the percentage reduction and 95% confidence limit of albendazole were 96% (84.2-99.0) and 97.0% (84.6-99.4) in dry and wet seasons, respectively. Here, the lower limit of 95% CI was less than 90% both in dry and wet seasons; and hence, albendazole was suspected for resistance development by gastrointestinal nematode. From a pooled faecal culture that collected from albendazole-treated goats, Haemonchus species was recovered. Therefore, due attention shall be by animal health professionals in the area in the use of albendazole. Animal health extension work to create awareness of how anthelmintic is used is helpful in reducing the risk. Changing the type of anthelmintic drug after using for some period will minimize the risk of anthelmintic resistance development.

Early Transcriptome Differences Between Pre-Infected and Naïve Kid Goats Infected With Haemonchus contortus

In small ruminant production, gastrointestinal nematode (GIN) infection is one of the major causes of economic losses. The aim of this study was to compare the abomasal mucosa transcriptome of naïve and pre-infected goats at early time points after Haemonchus contortus infection, in order to identify different pathways and upstream regulators involved in the host immune response. Naïve and pre-infected Creole kids were orally infected with 10,000 H. contortus infective larvae (L3), and abomasal mucosa was sampled at 0, 4, and 6 days post-infection (dpi). At 6 dpi, all the animals were slaughtered to perform parasite burden counts. The mean number of L4 recovered in naïve kids was more than twice as high as that recovered in the pre-infected ones (5,860 and 2,474 respectively, p &lt; 0.001). RNA-seq analysis showed a number of differentially expressed genes (DEGs) very low for both naïve and pre-infected animals when comparing day 0 vs. day 4 post-infection. A total of 2,237 and 3,206 DEGs were identified comparing 0 vs. 6 dpi in naïve and pre-infected animals, respectively. Interestingly, only 18 DEGs were found for the comparison of pre-infected vs. naïve animals at 6 dpi. Ingenuity pathway analysis (IPA) showed that several immune responses were activated in pre-infected compared with naïve animals at 0 and 4 dpi such as Th2 and Th1 pathways, natural killer cell, B cell receptor, IL-2, and IL-15 signaling. On the other hand, both naïve and pre-infected animals showed activation for those pathways comparing 6 vs. 0 dpi, with no difference between them. A similar pattern was recorded for upstream regulator genes which were related to immunity like TNF, IL-1β, IL-2, IL-5, TGFβ1, IFNγ, TCR, IL-18, IL-6, and IL-4. Our results showed that at 0 and 4 dpi the immune response was activated toward Th1 and Th2 pathways in pre-infected kids compared to the naïve ones, however, the same immune response was developed in naïve kids as earlier as 6 dpi. We conclude that repeated H. contortus infection in kid goats induced a concomitant early activation of a Th1 and Th2 immune response resulting in the regulation of worm establishment.

Local immune response of Canarian Majorera goats infected with Teladorsagia circumcincta

BACKGROUND

Due to increased anthelmintic resistance, alternative methods to drugs are necessary to control gastrointestinal nematodes (GINs). Some of the most promising alternatives are based on the immune response of the host, such as the selection of genetically resistant breeds or the use of vaccines against these parasites. Given the limited information available on the immune response against GINs in goats, this study investigated the local immune response of goat kids of an indigenous Canary Islands breed (Majorera breed) experimentally infected with Teladorsagia circumcincta, one of the most pathogenic and prevalent GIN species.

METHODS

For this purpose, the relationship between different parasitological (number of mature and immature worms, worm length, and number of intrauterine eggs) and immunological parameters at the local level (related to both the humoral and cellular immune response) was analyzed at early (1 week post-infection [wpi]) and late (8 wpi) stages of infection.

RESULTS

Primary infection of goat kids with T. circumcincta infective larvae (L3) generated a complex immune response that could be defined as Th2 type, characterized by increased infiltration in abomasal tissues of several effector cells as well as a progressive presence of specific antibodies against parasitic antigens in the gastric mucus. Cellular responses were evidenced from 1 wpi onward, showing an increase in antigen-presenting cells and various lymphocyte subsets in the gastric mucosa.

CONCLUSIONS

The complexity of the host response was evidenced by statistically significant changes in the number of all these subpopulations (MHCII⁺, CD4⁺, CD8⁺, γδ⁺, CD45R⁺, IgA⁺, and IgG⁺), as well as in the evolution of the relative cytokine gene expression. From a functional point of view, negative associations were observed between the number of most of the immune cells (CD4, IgA, IgG, and CD45R cells) and parameters that could be related to the fecundity of worms, a phenomenon that was especially evident when the number of IgG and CD45R cells or the specific IgA levels of the gastric mucus were compared with parasitological parameters such as the female worm length or fecal egg counts at 8 wpi.

Changes in the Serum Protein Fractions in Goats after Treatment of Natural Gastrointestinal Parasite Infections

Gastrointestinal parasitic infections in small ruminants belong to major health problems. The regulation of gastrointestinal infections in goats and the responses developed against them appear to be different from those observed in sheep. In the literature, there is a lack of data on the effect of gastrointestinal parasitic infections on the serum protein profile in goats. Therefore, the aim of the study was to determine the electrophoretic pattern of serum proteins in goats naturally infected with gastrointestinal parasites and to compare the changes in the total serum proteins and serum protein fractions (albumin and α₁-, α₂-, β-, and γ-globulins) obtained after antihelminthic treatment. Eight adult female goats of the white shorthaired breed from a small dairy goat farm at the age ranging between 3 and 5 years with average body weight 35.4 ± 3.2 kg and body condition score (BCS) from 1.5 to 2.5 were used in the study. The serum proteins in goats were separated into five fractions: albumin, α₁- and α₂-globulins, and β- and γ-globulins. Significant changes after treatment were found in the relative concentrations of albumin (P < 0.01) and α₂- (P < 0.05), β- (P < 0.001), and γ-globulins (P < 0.01), as well as albumin/globulin ratio (P < 0.01). The mean concentration of total serum proteins was, after the antiparasitic treatment, significantly higher. Among the globulin fractions, the γ-globulin fraction contributed most significantly to these changes (P < 0.001). The results presented in the study suggest a significant effect of antiparasitic treatment in goats on the synthesis of blood serum proteins and on the changes of the proportion of serum protein fractions.

Effects of supplementation on production and age anticipation at first mating of ewe lambs in tropical pastures

Studies on the rearing of ewe lambs in the Cerrado are scarce, so the objective was to evaluate the effects of protein-energy supplementation with 1.6 and 2.4% BW on the productive and reproductive performance of ewe lambs raised on pastures of Brachiaria brizantha cv. Marandu. Twenty-four Texel ewe lambs, with a mean age of 5 months, were distributed in two treatments with provision of energy protein supplementation at levels of 1.6 and 2.4% BW, formulated for average daily gains of 150 and 200 g/day for ewe lambs weighing 20 kg, respectively. The experimental delineation adopted was the completely randomized design, with fifteen repetitions per treatment. The performance of the ewe lambs was evaluated by weight at the beginning and end of the breeding season (BS), average daily gain (ADG), and total weight gain (TWG). The count of fecal eggs was performed monthly. The evaluation of the ewe lambs reproductive organs took place at 8 months of age. The fertility of the ewe lambs was detected by transrectal ultrasonography at the end of the BS. The supplementation level of 2.4% BW was higher for ADG and TWG; however, it did not influence the other performance characteristics. There was no effect of supplementation on the reproductive characteristics, parasite load, and nutrients of the pasture. Pasture nutrients were influenced by the month of use. Supplementation levels were not effective to ensure the reproductive success of 8-month-old ewe lambs.

The Goat as a Risk Factor for Parasitic Infections in Ovine Flocks

Simple Summary

Small ruminants in northwestern Spain are frequently managed in mixed flocks. Sheep-goat joint management has not been considered a risk factor for parasite infection, so the main objective of this study was to establish if mixed management with goats supposes a risk factor for parasitic infections in ovine flocks. Goat contact was a risk factor for sheep to be infected by protostrongylids, Dictyocaulus filaria, gastrointestinal nematodes and Eimeria spp. In relation to host-specific parasites, goats cannot be considered as a source for sheep, but competition for food and spaces between both small ungulates can suppose a reduced grazing area to sheep, provoking high environmental contamination and stress that facilitate their infection.

Abstract

Small ruminants in northwestern Spain are frequently managed in mixed flocks. Sheep–goat joint management has not been considered a risk factor for parasite infection, so the main objective of this study was to establish if mixed management with goats supposes a risk factor for parasitic infections in ovine flocks. Two thousand and ninety-three sheep were sampled from 74 commercial meat ovine flocks for diagnostic of the main parasites. Goat contact was a risk factor for sheep to be infected by protostrongylids, Dictyocaulus filaria, gastrointestinal nematodes and Eimeria spp. In contrast, Moniezia, Fasciola hepatica, Dicrocoelium dendriticum and Paramphistomidae prevalences were not influenced. Sheep–goat mixed management can be considered as a risk factor, since goats would act as a source of pasture contamination for interspecific parasites (protostrongylids, Dictyocaulus filaria and gastrointestinal nematodes). In relation to host-specific parasites, such as Eimeria spp., goats cannot be considered as a source for sheep, but competition for food and spaces between both small ungulates can suppose a reduced grazing area to sheep, provoking high environmental contamination and stress that facilitate their infection. Future epidemiological studies for parasitic infections in small ruminants should consider sheep–goat mixed management as a possible risk factor to be included in multivariate analyses.

Immunoglobulins as Biomarkers for Gastrointestinal Nematodes Resistance in Small Ruminants: A systematic review

The rise of anthelmintic resistance worldwide has led to the development of alternative control strategies for gastrointestinal nematodes (GIN) infections, which are one of the main constraints on the health of grazing small ruminants. Presently, breeding schemes rely mainly on fecal egg count (FEC) measurements on infected animals which are time-consuming and requires expertise in parasitology. Identifying and understanding the role of immunoglobulins in the mechanisms of resistance could provide a more efficient and sustainable method of identifying nematode-resistant animals for selection. In this study we review the findings on immunoglobulin response to GIN in the literature published to date (june 2019) and discuss the potential to use immunoglobulins as biomarkers. The literature review revealed 41 studies which measured at least one immunoglobulin: 35 focused on lamb immune response (18 used non-naïve lambs) and 7 on yearlings. In this review we propose a conceptual model summarizing the role of immunoglobulins in resistance to GIN. We highlight the need for more carefully designed and documented studies to allow comparisons across different populations on the immunoglobulin response to GIN infection.

Kinetics of IgA and eosinophils following a low-dose, predominantly Haemonchus contortus infection of Boer goats

AIMS

Most breeds of goat are more susceptible to nematode infection than sheep, and this appears to be a consequence of less effective immune responses. Several papers have considered the effectiveness of eosinophils and immunoglobulin A (IgA) in goats but differences in the induction of responses have not been studied in the same detail. The aim of this study was to look at the induction of eosinophil and IgA responses in Boer goats reared indoors under intensive conditions.

METHODS AND RESULTS

The goats were experimentally infected with a low dose of 2400 Haemonchus contortus, Trichostrongylus spp. and Oesophagostomum spp. at a 6:1:1 ratio. Faecal egg counts (FEC), packed cell volume (PCV), IgA activity against third-stage larvae and peripheral eosinophilia were measured twice a week for eight weeks. The infection generated an IgA response but did not significantly increase peripheral eosinophilia in the 25 infected kids compared with the 4 control animals. FEC was not associated with IgA activity or eosinophilia.

CONCLUSION

A detailed analysis of IgA and eosinophil responses to deliberate nematode infection in Boer goats showed that there was an increase in nematode-specific IgA activity but no detectable eosinophil response. In addition, there was no association between increased IgA activity or eosinophilia with egg counts and worm burdens. These suggest that IgA and eosinophils do not act to control nematode infection in goats.

Prevalence of gastrointestinal parasites in communal goats from different agro-ecological zones of South Africa

Aim:

A longitudinal study was conducted to assess the epidemiology of common gastrointestinal parasite (GIP) infections affecting goats in South Africa as influenced by agro-ecological zone (AEZ), sampling season, and the age and sex of animals.

Materials and Methods:

A total of 288 goats (101 male and 187 female) were randomly sampled during winter and summer in areas representing four AEZs (arid: 80; semi-arid: 76; humid: 62; and dry sub-humid: 70) of South Africa. Fecal samples from each animal were collected from the rectum, and the presence of GIP eggs was determined using a modified McMaster technique. A sample was considered positive when a minimum of one GIP egg was detected under the microscope. Fecal cultures were prepared, and infective larvae were collected and identified. The data were analyzed by MiniTab17 (2017) using the FREQ procedure, and the association between the independent factors and the prevalence of various GIPs were evaluated using the Pearson Chi-square test (p<0.05).

Results:

The overall prevalence of GIP in the present study was 37.1%, with a mean prevalence of 30.0, 26.4, 31.1, 36.6, and 59.6% for Eimeria spp., Trichuris, Strongyloides papillosus, Moniezia spp., and strongyles, respectively. There was a significant (p<0.05) association between the prevalence of strongyles, Trichuris, Moniezia spp., and AEZs, whereas an insignificant (p>0.05) association was observed for the prevalence of Eimeria spp. and S. papillosus. A significant (p<0.05) association between goat age and prevalence of all GIPs was observed, where the prevalence was higher in young goats, followed by adults, and then by suckling goats. The prevalence of various GIPs was similar between male and female goats. The percentage of infection with Eimeria spp., Trichuris, S. papillosus, and strongyle parasitic infections was marginally higher in males than in females, whereas that of the Moniezia spp. was higher in females. A significant (p<0.05) association between the prevalence of Eimeria spp. and sampling season was observed, and there was an insignificant (p>0.05) association between the other GIPs and sampling season. The prevalence of Eimeria spp. infection was higher in winter (34.0%) than in summer (26.0%).

Conclusion:

AEZs and goat age are the most important risk factors influencing GIP infections in South African communal goats. These epidemiological parameters are important for outlining effective parasite control management systems against these GIPs in goats.

Signatures of selection for resistance to Haemonchus contortus in sheep and goats

Background

Gastrointestinal nematode infection (GNI) is the most important disease affecting the small ruminant industry in U.S. The environmental conditions in the southern United States are ideal for the survival of the most pathogenic gastrointestinal nematode, Haemonchus contortus. Host genetic variation for resistance to H. contortus allows selective breeding for increased resistance of animals. This selection process increases the prevalence of particular alleles in sheep and goats and creates unique genetic patterns in the genome of these species. The aim of this study was to identify loci with divergent allelic frequencies in a candidate gene panel of 100 genes using two different approaches (frequentist and Bayesian) to estimate Fst outliers in three different breeds of sheep and goats exposed to H. contortus.

Results

Our results for sheep populations showed SNPs under selection in C3AR1, CSF3, SOCS2, NOS2, STAT5B, TGFB2 and IL2RA genes using frequentist and Bayesian approaches. For goats, SNPs in CD1D, ITGA9, IL12A, IL13RA1, CD86 and TGFB2 genes were under selection. Common signatures of selection in both species were observed in NOS2, TGFB2 and TLR4 genes. Directional selection was present in all SNPs evaluated in the present study.

Conclusions

A total of 13 SNPs within 7 genes of our candidate gene panel related to H. contortus exposure were identified under selection in sheep populations. For goats, 11 SNPs within 7 genes were identified under selection. Results from this study support the hypothesis that resistance to H. contortus is likely to be controlled by many loci. Shared signatures of selection related to mechanisms of immune protection against H. contortus infection in sheep and goats could be useful targets in breeding programs aimed to produce resistant animals with low FEC.

Transcriptome variation in response to gastrointestinal nematode infection in goats

Gastrointestinal nematodes (GIN) are a major constraint for small ruminant production. Due to the rise of anthelmintic resistance throughout the world, alternative control strategies are needed. The development of GIN resistance breeding programs is a promising strategy. However, a better understanding of the mechanisms underlying genetic resistance might lead to more effective breeding programmes. In this study, we compare transcriptome profiling of abomasal mucosa and lymph node tissues from non-infected, resistant and susceptible infected Creole goats using RNA-sequencing. A total of 24 kids, 12 susceptible and 12 GIN resistant based on the estimated breeding value, were infected twice with 10,000 L3 Haemonchus contortus. Physiological and parasitological parameters were monitored during infection. Seven weeks after the second infection, extreme kids (n = 6 resistant and 6 susceptible), chosen on the basis of the fecal egg counts (FEC), and 3 uninfected control animals were slaughtered. Susceptible kids had significantly higher FEC compared with resistant kids during the second infection with no differences in worm burden, male and female worm count or establishment rate. A higher number of differentially expressed genes (DEG) were identified in infected compared with non-infected animals in both abomasal mucosa (792 DEG) and lymph nodes (1726 DEG). There were fewer DEG in resistant versus susceptible groups (342 and 450 DEG, in abomasal mucosa and lymph nodes respectively). ‘Cell cycle’ and ‘cell death and survival’ were the main identified networks in mucosal tissue when comparing infected versus non-infected kids. Antigen processing and presentation of peptide antigen via major histocompatibility complex class I were in the top biological functions for the DEG identified in lymph nodes. The TGFβ1 gene was one of the top 5 upstream DEG in mucosal tissue. Our results are one of the fist investigating differences in the expression profile induced by GIN infection in goats.

Effect of Ovar-DRA and Ovar-DRB1 genotype in small ruminants with haemonchosis

The effect of Ovar-DRA and Ovar-DRB1 genotypes on faecal egg count (FEC) was determined in sheep and goats infected with Haemonchus contortus. One hundred and forty-three sheep from 3 different breeds (St. Croix, Katahdin and Dorper) and 150 goats from three different breeds (Spanish, Boer and Kiko) were used. Parasitological (FEC), haematological (packed cell volume) and immunological (IgA, IgG and IgM) parameters were measured. Sheep populations showed a higher FEC and humoural response than goat breeds. Genotypes were determined by high-resolution melting assays and by conventional PCR. For Ovar-DRA, sheep and goats carrying the AA genotype showed significant lower FEC than AG and GG genotypes. The additive effect was found to be 115.35 less eggs per gram of faeces for the A allele for goats. For Ovar-DRB1, only in sheep, the GC genotype was associated with low FEC. The additive effect was 316.48 less eggs per gram of faeces for the G allele, and the dominance effect was 538.70 less eggs per gram of faeces. The results indicate that single nucleotide polymorphisms within Ovar-DRA and Ovar-DRB1 could be potential markers to be used in selection programmes for improving resistance to Haemonchus contortus infection.

Microbial community and ovine host response varies with early and late stages of Haemonchus contortus infection

The interactions between gastric microbiota, ovine host, and Haemonchus contortus portray the ovine gastric environment as a complex ecosystem, where all factors play a pertinent role in fine-tuning each other and in haemeostasis. We delineated the impact of early and late Haemonchus infection on abomasal and ruminal microbial community, as well as the ovine host. Twelve, parasite-naive lambs were divided into four groups, 7 days post-infection (dpi) and time-matched uninfected-control groups; 50 dpi and time-matched uninfected control groups were used for the experiment. Six sheep were inoculated with 5000 H. contortus infective larvae and followed for 7 or 50 days with their corresponding uninfected-control ones. Ovine abomasal tissues were collected for histological analysis and gastric fluids were collected for PH value measurements, microbial community isolation and Illumina MiSeq platform and bioinformatic analysis. Our results showed that Haemonchus infection increased the abomasal gastric pH (P = 0.05) and resulted in necrotizing and inflammatory changes that were more severe during acute infection. Furthermore, infection increased the abomasal bacterial load and decreased the ruminal microbiome. A 7-day infection of sheep with H. contortus significantly altered approximately 98% and 94% of genera in the abomasal and ruminal bacterial profile, respectively (P = 0.04-0.05). However, the approximate altered genera 50 days after infection in the ovine abomasal and ruminal microbiome were about 62% and 69%, correspondingly (P = 0.04-0.05) with increase in some bacteria and decrease in others. Overall, these results indicate that Haemonchus infection plays a crucial role in shaping stomach microbial community composition, and diversity.

Gastrointestinal helminth infections of dairy goats in Slovakia

The aim of this study was to identify the most common gastrointestinal (GI) parasites in flocks of dairy goats on 30 farms in Slovakia. A total of 944 adult goats were examined during the pasturing seasons for 2014 – 2016. Eggs from one or more species of gastrointestinal parasites were identified in 906 of the samples (95.90 %). Strongyle eggs were present in most of the samples (92.00 %), followed by Strongyloides papillosus (14.05 %), Trichuris spp. (7.84 %), Nematodirus spp. (3.98 %), and Moniezia spp. (2.65 %). The counts of strongyle eggs per gram of faeces ranged from 0 to 11 000. Subsamples from each farm were used to prepare faecal coprocultures to identify the genera of the nematodes. Third-stage larvae of Trichostrongylus spp. (100 %) and Teladorsagia/Ostertagia spp. (96.60 %) were present on most of the farms, followed by Oesophagostomum spp./Chabertia ovina (86.60 %) and Haemonchus contortus (76.60 %). Teladorsagia/Ostertagia spp. were the dominant genera on 60 % of the farms.

Field evaluation of the efficacy of common anthelmintics used in the control of gastrointestinal nematodes of sheep in Dabat district, Northwest Ethiopia

Background

Gastrointestinal nematode (GIN) infections are the main impediments that restrict the welfare and productivity of small ruminant in the world. Effective management of GINs in grazing sheep relies heavily on the use of highly efficacious anthelmintic drugs. However, anthelmintic resistance is becoming a significant concern in the world, and this phenomenon severely threatens the potential utilisation of this control strategy. Therefore, this study was conducted 1) to evaluate the efficacy of commonly used anthelmintic on GINs in naturally infected sheep and 2) to assess the farmers’ perception on anthelmintics utilisation practices in Dabat district, Northwest Ethiopia.

Methods

One hundred twenty nematode infected sheep were used in this study. Sheep were selected based on the egg count (≥150 eggs per gram of faeces). The animals were allocated randomly into four groups (30 animals per group). Group-I, II and III were treated with Albendazole, Tetramisole, and Ivermectin, respectively. The 4th group was left untreated (as control). Faecal samples were collected on day 0 (before treatment), on day 3, 7, 10 and 14 (post-treatment). The modified McMaster technique was used for quantifying the eggs. Faecal egg count reduction test (FECRT) was applied to determine the efficacy of anthelmintic at day 14 (post-treatment). In addition, a questionnaire survey was conducted on 100 randomly selected sheep owners.

Results

All anthelmintics tested revealed significant (P < 0.05) reduction in nematode egg excretion in the sheep post-treatment. Faecal egg count reduction (FECR) levels for Albendazole, Tetramisole, and Ivermectin were 97.2, 98.9 and 97.7%, respectively. Post-treatment egg counts and percentage reduction of egg counts were not significantly different (P > 0.05) among the treatment groups. The nematode genera identified before treatment were Haemonchus, Trichostrongylus, Cooperia, Trichuris, Teladorsagia, Bunostomum, and Strongyloides. Haemonchus and Trichostrongylus were detected after treatment with Albendazole and Ivermectin. The questionnaire survey revealed that Albendazole was the most commonly (90%) used anthelmintic to treat nematodes in sheep, followed by Tetramisole (36%) and Tetraclozan (Tetramisole-Oxyclozanide combination) (20%). Respondents expressed that anthelmintic selection was made based on veterinarian prescription (84%), colour (27%), efficacy (4%), price affordability (1%) and availability (1%).

Conclusion

This study demonstrated that the tested anthelmintics had an acceptable level of efficacy against GINs of sheep.

The use of <i>Lespedeza cuneata</i> for natural control of gastrointestinal nematodes in Merino sheep

Lespedeza cuneata (poorman’s lucerne; sericea lespedeza), a tannin-rich perennial legume, was offered as hay to dry Merino ewes in a confined feeding experiment to evaluate the effect on the level of gastrointestinal parasite infection in sheep. Medicago sativa (a low tannin containing perennial legume) was used as the control treatment. Parameters faecal egg count (FEC), FAMACHA^© scores and rectal temperatures were used. FECs were substantially lower (p = 0.05) in the Lespedeza group after 35 days, together with a trend of higher rectal temperatures, compared with the Medicago group. Although non-significant (p > 0.05), the higher rectal temperatures suggested a lower level of anaemia in the sheep on the Lespedeza ration and, therefore, a lower parasite-worm burden. However, FAMACHA^© scores showed no significant (p > 0.05) differences between treatments despite the differences in FEC that were recorded, indicating that host homeostasis was possibly mediated by improved nutrition as a result of the high protein content of both experimental diets.

Study of gastrointestinal parasites in water buffalo (Bubalus bubalis) reared under Mexican humid tropical conditions

The objective was to determine the frequency of gastrointestinal parasites (GP) genera affecting water buffalo (Bubalus bubalis) reared under humid tropical conditions of Mexico. Three hundred eighty-three Munrah breed water buffalo were included, 251 adult females and 132 calves. Feces were directly collected form the rectum of the animals and processed by the McMaster technique. Coprocultures were made to identify the genera of the nematodes. The frequency of GP in B. bubalis was 42%, independently of their age, 60% of calves resulted parasitized. Age had a strong association with the presence of GP (Xi² = 77.4014, d.f. = 1, p = 0.001). The family Trichostrongylidae was found in both age groups. The genera identified were Strongyloides sp. (47.2%), Cooperia sp. (33.9%), and Haemonchus sp. (10.4%), as well as Eimeria sp., Moniezia sp., Trichuris sp., and Strongyloides sp. The highest parasite burden corresponded to the genus Strongyloides sp. with 1108.9 EPG. There is a need to carry out further studies in order to know the prevalence and incidence of nematode affecting to B. bubalis as an introduced animal species to Mexican tropics.

Effectiveness of Albendazole for Hookworm Varies Widely by Community and Correlates with Nutritional Factors: A Cross-Sectional Study of School-Age Children in Ghana

Mass drug administration (MDA) targeting school-age children is recommended by the World Health Organization for the global control of soil-transmitted helminth (STH) infections. Although considered safe and cost-effective to deliver, benzimidazole anthelminthics are variably effective against the three most common STHs, and widespread use has raised concern about the potential for emerging resistance. To identify factors mediating response to albendazole, we conducted a cross-sectional study of hookworm infection in the Kintampo North Municipality of Ghana in 2011. Among 140 school-age children residing in five contiguous communities, the hookworm prevalence was 59% (82/140). The overall cure rate following administration of single-dose albendazole (400 mg) was 35% (27/76), with a community-wide fecal egg reduction rate (ERR) of 61% (95% confidence interval: 51.8-71.1). Significant disparities were observed in albendazole effectiveness by community, with a cure rate as low as 0% (N = 24) in Jato Akuraa and ERRs ranging from 53% to 95% across the five study sites. Individual host factors associated with response to deworming treatment included time since last meal, pretreatment blood hemoglobin level, and mid-upper arm circumference. These data demonstrate significant community-level variation in the effectiveness of albendazole, even among populations living in close proximity. Identification of host factors that influence response to albendazole, most notably the timing of drug administration and nutritional factors, creates an opportunity to enhance the effectiveness of deworming through targeted interventions. These findings also demonstrate the importance of measuring anthelminthic response as part of the monitoring and evaluation of community-based deworming programs.

Effect of experimental infection with Haemonchus contortus on parasitological and local cellular responses in resistant and susceptible young Creole goats

This study was carried out to evaluate the relationships of cellular changes in the abomasal mucosa and parasitological parameters, by comparing resistant and susceptible young Creole goats (kids) after experimental infection with Haemonchus contortus. The kids were infected over 2 periods (challenges 1 and 2) of 7 and 6 weeks, respectively. Fecal egg count (FEC), blood eosinophilia, packed cell volume (PCV), and body weight were weekly monitored. At the end of both challenges a subgroup of kids was slaughtered for nematode burden measurements and analysis of inflammatory cell infiltration in the abomasal mucosa. The average daily gain was higher in resistant kids after both challenges. Blood eosinophilia and FEC were higher in susceptible kids after both challenges. The number of immature worms and the means of female length were lower after challenge 2 whatever the genetic status. No differences were observed in the eosinophil and mononuclear cell infiltration between challenges 1 and 2 and resistant and susceptible kids. Globule leukocyte infiltration was found higher after the challenge 1 in resistant kids. This effect of the genetic status on globule leukocytes counts but not on the other inflammatory cell highlights the need for further study on the functional activity of these cell populations.

Comparison of Boer, Kiko, and Spanish meat goat does for stayability and cumulative reproductive output in the humid subtropical southeastern United States

Background

Longevity is the amount of time breeding females stay active in a herd by avoiding death or culling because of illness or reproductive failure. This is a trait of economic relevance in commercial small ruminant breeding herds as it affects lifetime reproductive output. The purpose of this study was to determine if breed of meat goat influences breeding doe survival rates and cumulative reproductive performance under semi-intensive management.

Results

Boer (n = 132), Kiko (n = 92) and Spanish (n = 79) does were evaluated for longevity trends and cumulative kid production. The herd was managed on humid subtropical pasture. Does had the chance to complete 2 to 6 production years. Survival curves were analyzed for 2 culling methods. The actual culling practice removed does after two failures to wean a kid. An alternative culling protocol removed doe records after the first failure to wean a kid. Kid production traits analyzed across herd life were the total number of kids weaned and cumulative kid weight weaned to the 2-, 3-, and 5-year stayability endpoints. Most (82%) doe exits were illness-related under the actual culling method. Reproductive failure represented 51% of doe exits under the alternative culling protocol. Boer does had greater survival declines (P < 0.01) from 2 to 6 years of herd life compared with Kiko and Spanish under both culling protocols. Boer does had lower stayability rates (P < 0.01) at each year endpoint for both culling protocols. Under the alternative protocol, over 50% of Boer does failed to complete 2 years, whereas over 50% of Kiko and Spanish does successfully completed 4 years. Boer does had lower (P < 0.01) total number of kids weaned and cumulative weight weaned through each stayability endpoint compared with Kiko and Spanish.

Conclusion

Boer does had low stayability and cumulative kid production rates compared with Kiko and Spanish does. Poor health was the primary driver of does exiting the herd. Kiko and Spanish does did not differ for longevity and lifetime performance indicators.

Epidemiology of hookworm infection in Kintampo North Municipality, Ghana: patterns of malaria coinfection, anemia, and albendazole treatment failure

A cross-sectional pilot study of hookworm infection was carried out among 292 subjects from 62 households in Kintampo North, Ghana. The overall prevalence of hookworm infection was 45%, peaking in those 11-20 years old (58.5%). In children, risk factors for hookworm infection included coinfection with malaria and increased serum immunoglobulin G reactivity to hookworm secretory antigens. Risk factors for infection in adults included poor nutritional status, not using a latrine, not wearing shoes, and occupation (farming). Although albendazole therapy was associated with an overall egg reduction rate of 82%, 37 subjects (39%) remained infected. Among those who failed therapy, treatment was not associated with a significant reduction in egg excretion, and nearly one-third had higher counts on repeat examination. These data confirm a high prevalence of low-intensity hookworm infection in central Ghana and its association with poor nutritional status. The high rate of albendazole failure raises concern about emerging resistance.

The unique resistance and resilience of the Nigerian West African Dwarf goat to gastrointestinal nematode infections

Background

West African Dwarf (WAD) goats serve an important role in the rural village economy of West Africa, especially among small-holder livestock owners. They have been shown to be trypanotolerant and to resist infections with Haemonchus contortus more effectively than any other known breed of goat.

Methods

In this paper we review what is known about the origins of this goat breed, explain its economic importance in rural West Africa and review the current status of our knowledge about its ability to resist parasitic infections.

Conclusions

We suggest that its unique capacity to show both trypanotolerance and resistance to gastrointestinal (GI) nematode infections is immunologically based and genetically endowed, and that knowledge of the underlying genes could be exploited to improve the capacity of more productive wool and milk producing, but GI nematode susceptible, breeds of goats to resist infection, without recourse to anthelmintics. Either conventional breeding allowing introgression of resistance alleles into susceptible breeds, or transgenesis could be exploited for this purpose. Appropriate legal protection of the resistance alleles of WAD goats might provide a much needed source of revenue for the countries in West Africa where the WAD goats exist and where currently living standards among rural populations are among the lowest in the world.

Gastrointestinal nematode infections in small ruminants under the traditional husbandry system during the dry season in southern Ethiopia

A cross-sectional study was conducted from November 2008 to February 2009 to investigate the prevalence and intensity of infection and risk factors of gastrointestinal (GI) nematodes in small ruminants kept under the traditional husbandry system in two districts in southern Ethiopia. Faecal samples collected from a total of 510 small ruminants (284 sheep and 226 goats) and analysed by a modified McMaster technique revealed that 222 animals (43.5%) were found to be infected with one or more GI nematodes. Five identical genera of nematodes were found in both sheep and goats, which in order of predominance were Haemonchus (56.3%), Trichostrongylus (39.6%), Oesophagostomum (22.9%), Trichuris (21.6%) and Bunostomum (10.4%). No significant (p > 0.05) differences were observed between sheep and goats proportions except for Trichuris (p < 0.05). In both sheep and goats, most of the animals were heavily infected showing faecal egg counts (FECs) above 1,200 epg. Sheep had a significantly (p < 0.05) higher mean FEC than goats. In sheep and goats, both the prevalence of GI nematodes and mean FEC were significantly (p < 0.001) associated with body condition score and faecal consistency but not with district, sex and age (p > 0.05 for each factor). In conclusion, the observation of a strong association of GI nematodes with poor body condition coupled with heavy intensity of infection in the majority of infected animals and an abundance of nematode genera of widespread economic and pathological significance warrants the institution of appropriate control measures that should necessarily include improvement of the nutritional status of the animals.