Epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep in a semi-arid region of eastern Ethiopia

Prevalence and Risk Factors of Lungworm Infection in Small Ruminants in Selected Districts of Wolaita Zone, Southern Ethiopia

Among small ruminants, lungworms are important parasitic nematodes that infect the lower respiratory tract and are implicated in a high mortality and morbidity rate. However, the magnitude and its determinants of lungworm infection in the study districts are not known. The objective of this study was to estimate the prevalence of lungworm infection and assess associated risk factors in selected districts, Wolaita Zone, southern Ethiopia. A total of 742 fecal samples collected from 443 sheep and 299 goats were examined, using modified Baermann techniques, to recover first-stage larvae from fecal samples. Lungworms were detected in 271 (36.52%) samples infecting 192 (43.34%) sheep and 79 (26.42%) goats, respectively. Lungworm species Dictyocaulus filaria, Protostrongylus rufescens, and Muellerius capillaris were recovered in 114 (15.36%), 68 (9.16%), and 57 (7.68%) fecal samples, respectively. Mixed infection by two or more above species was noted in 32 (4.31%) of the samples. Among the determinants examined, agroecological environment, management system, and season showed statistically significant differences (p < 0.05) with the prevalence of infection in small ruminants. On the other hand, lungworm infection among sexes, age groups, and body condition scores showed no statistically significant difference (p > 0.05). The present study indicated that lungworm infection was a problem for sheep and goats in this study area. Thus, measures like deworming, early treatment, and improving animal husbandry should be practiced.

Factors associated with strongylida infections in sheep on farms in peri-urban Nairobi, Kenya

Gastrointestinal parasite infections are among the major limitations to production in sheep in many parts of the world. It is important to continually assess their levels of infection in order to institute control measures and reduce the impact. This study determined the factors associated with the strongylida egg counts in sheep on selected farms in peri-urban Nairobi, Kenya. This was a cross-sectional study in which farm and animal-level data, including faecal samples, were collected from 1640 sheep from 30 purposively selected farms in Ruai, and Kamulu wards in Kasarani sub-county and Utawala and Mihango wards in Embakasi East Sub-County, in Nairobi County Kenya. The faecal samples were subjected to coprological examination using a modified McMaster technique to determine counts of strongylida eggs and coccidia oocysts with a detection level of 100 egg or oocyst per gram (EPG or OPG) of faeces. The positive faecal samples for strongylida eggs were pooled per farm and cultured for morphological identification of larval stage three. Descriptive statistics and multilevel mixed-effect logistic regression analyses were used to determine factors associated with strongylida egg count ≥600 EPG (p < 0.05). The receiver operating characteristics curve was used to assess the overall diagnostic performance in the final model. Strongylida eggs were detected in 45.5% (746/1640) of the sheep, and the mean EPG was 486.0± 858.9 with a median of 200 and a range of 0-16,700. The coccidia oocysts were detected in 49.4% (810/1640) of the sheep with a mean OPG was 341.7± 1782.4, a median of 0 and a range of 0-60,000. In the coprocultures, the nematode genera identified (% differential count of L3) were Haemonchus (90%), Trichostrongylus (5%) and Oesophagostomum (5%). In the final multivariable regression model, the odds of detecting EPG ≥ 600 was 1.44 times higher for sheep shedding coccidia oocysts than those that did not. The odds for detecting EPG ≥ 600 was 4.01 times for sheep in Ruai ward compared with those in the combined Kamulu, Utawala and Mihango wards. The receiver operating characteristic curve area was 73.1%, suggestive of good model performance. The results suggest that gastrointestinal strongylida and coccidia infections are common in sheep and farmers should be educated on the importance of appropriate control measures.

Finisher lamb growth and rumen fermentation responses to the plane of nutrition and naturally occurring coccidiosis

The objective of the present study was to investigate the interaction of plane of nutrition and naturally occurring coccidiosis on finisher lamb growth performance, FAMACHA score, and rumen volatile fatty acid profile. The study included 30 Suffolk, Dorset or Suffolk x Dorset lambs and were divided into 2 groups based on their initial body weight and assigned to 2 feeding groups differing in dietary energy intake to create lambs representing divergent growth curves due to differing nutritional management. Lambs with naturally occurring coccidiosis and healthy lambs were present in both feeding groups making a 2 × 2 factorial arrangement of treatments, (a) high plane of nutrition (HPN) lambs with no clinical coccidiosis diagnosis (HPNH), (b) HPN lambs with clinical coccidiosis (HPNC), (c) low plane of nutrition (LPN) lambs with no clinical coccidiosis diagnosis (LPNH), (d) LPN lambs with clinical coccidiosis (LPNC). Body weight and FAMACHA scores were recorded once every 2 weeks. On d 65 of feeding, lambs were slaughtered, and rumen fluid samples were collected and analyzed for volatile fatty acid concentrations. All response variables were analyzed statistically using a linear mixed effects model with fixed effects for plane of nutrition, health status, and a random effect for initial body weight nested within the pen. The total and average weight gain were not associated with planes of nutrition, health status, or the interaction. Health status had an impact on FAMACHA© score (P = 0.047) and concentration of isobutyrate (P = 0.037) and tended to affect total VFA (P = 0.085) and acetate (P = 0.071) concentrations. The interaction between the plane of nutrition and the health status tended to affect butyrate concentration (P = 0.058). These data support the conclusion that coccidiosis infection impacted on rumen fermentation in a manner independent of the plane of nutrition; however, the translation of these rumen level impacts did not translate to the production responses.

Monitoring environmental conditions on the speed of development and larval migration of gastrointestinal nematodes in Urochloa decumbens in northeastern Brazil

The study aimed to evaluate the speed of development of gastrointestinal nematodes (GIN) eggs to infective larvae (L3) and its migration under effect of meteorological variables: temperature, rainfall, relative humidity, solar radiation to Urochloa (=Brachiaria) decumbens grass pasture during rainy season, from June to September 2019, and dry season, October to March 2020, in Recôncavo baiano region of Bahia state, Brazil. Monthly, fecal samples obtained from goats with recurrent GIN infection were deposited in six plots of one square meter. In +7, +14 and + 21-days post-deposition, lower and upper strata grass (0-15 and > 15 cm, respectively) and remaining feces were collected and submitted to Baermann's technique modified to perform larval count and identification. Meteorological data were obtained from a local weather station database. The log-transformed larval count results were analyzed regarding the collection day effect, stratum effect, comparing the means by Tukey's test (p < 0.05). Multivariate regression analysis and correlation of meteorological variables with larval counts was performed. In the rainy season, the largest proportion of recovered L3 was concentrated in +7-days post-deposition in the months of June and July, both in the remaining feces and herbage samples, while in August development took place more slowly, after +14-days post-deposition. During the dry season, L3 development only occurred after the first collection in January and February. Lower strata had higher proportion of recovery than in upper strata. Negative correlation was found for solar radiation. Greater rainfall in the rainy season compared to dry season was a favorable condition for high contamination of grass samples. However, reduced vertical migration to upper strata may have been influenced by low temperatures during the rainy season. Regarding the genera present in the fecal samples used in the experiment were found Haemonchus sp., Trichostrongylus sp. and Oesophagostomum sp. Thus, it is possible to conclude that in the region of the study, during the rainy season, there is a rapid larval development and the L3 are able to migrate more effectively to the grass. On the other hand, in the dry season, larval development tends to be slower, with less migration to the grass. Solar radiation can be useful for predicting months with the highest risk of infection. Therefore, prophylactic measures should be employed in goat herds during the rainy season whilst natural reduced pasture contamination in the dry season may favor animal maintenance for a longer time.

Seasonal prevalence of gastrointestinal parasites in desert bighorn sheep (Ovis canadensis) in northern Mexico

This study aimed to describe the shedding pattern of gastrointestinal parasite eggs by a wild population of desert bighorn sheep (DBS; Ovis canadensis) in northern Mexico. Seventy-five fresh faecal samples were collected from the ground in each season within an hour after being expelled by these animals. The generalized linear mixed model showed that eggs per gram of faeces were highest in winter (577 ± 399) and lowest in summer (260 ± 198). Generalized linear models revealed that Strongyloides spp. predominated during most seasons with a peak in summer (85% of faecal samples analysed) and the absence of this helminth in winter. Nematodirus spp. was another helminth present in three seasons, with the presence of this nematode in 35% of the faecal samples in spring and 0% in summer. Other parasites in DBS faeces included Bunostomun spp., Trichostrongylus spp., Cooperia spp., Mecistocirrus digitatus, Haemonchus contortus, Chabertia ovina and Eimeria ovinoidalis. There were differences among seasons in the percentage of these helminths and coccidia in faecal samples for all these parasites. It was concluded that helminths egg output in DBS in a semi-arid rangeland is lowest in summer and spring and highest in autumn and winter. Furthermore, it was shown that DBS in the study site do not suffer from severe parasite burden. Therefore, this nematode parasite burden is compatible with the conservation and well-being of this particular population.

Anthelmintic Drug Resistance of Gastrointestinal Nematodes of Naturally Infected Goats in Haramaya, Ethiopia

Gastrointestinal parasites and their anthelmintic resistance are major constraints to goat production in Ethiopia. Experimental investigation by faecal egg count reduction test (FECRT) and larval cultures were used to assess the occurrence of anthelmintic resistance in naturally infected goats with gastrointestinal nematodes (GIN) in Haramaya, Ethiopia. One hundred goats with a minimum of 150 eggs per gram (EPG) count were selected and randomly divided into five groups, 20 goats in each group, four treated and one untreated group. The result of the faecal egg count reduction test percentage (FECRT%) and the lower 95% confidence limit showed the presence of anthelmintic resistance for all tested drugs except tetramisole. FECRT% and lower 95% confidence limit were 69.9% and 36.9 for albendazole, 84.3% and 66.1 for tetraclozan, 95.7% and 87.4 for tetramisole, and 71.1% and 38.2 for ivermectin, respectively. Trichostrongylus, Teladorsagia, and Haemonchus showed anthelmintic resistance for tested drugs. Coproculture from different treatment groups revealed Trichostrongylus (69.2% in ivermectin and 59.6% in albendazole) were the predominant nematode followed by Teladorsagia (21.9% in albendazole and 14.7% in ivermectin). In tetraclozan treatment group, Trichostrongylus (42%) and Teladorsagia (41.3%) were comparable, followed by Haemonchus (13%). In group treated with tetramisole, Teladorsagia (54.3%) were the most frequently detected nematode followed by Trichostrongylus (25.7%) and Haemonchus (11.4%). Therefore, this study demonstrated the presence of multidrug resistant nematodes that may limit the productivity of goats. Moreover, further studies covering wider areas of Ethiopia and mechanisms of nematode resistance need to be studied in the future.

Whole-Genome Sequence Data Suggest Environmental Adaptation of Ethiopian Sheep Populations

Great progress has been made over recent years in the identification of selection signatures in the genomes of livestock species. This work has primarily been carried out in commercial breeds for which the dominant selection pressures are associated with artificial selection. As agriculture and food security are likely to be strongly affected by climate change, a better understanding of environment-imposed selection on agricultural species is warranted. Ethiopia is an ideal setting to investigate environmental adaptation in livestock due to its wide variation in geo-climatic characteristics and the extensive genetic and phenotypic variation of its livestock. Here, we identified over three million single nucleotide variants across 12 Ethiopian sheep populations and applied landscape genomics approaches to investigate the association between these variants and environmental variables. Our results suggest that environmental adaptation for precipitation-related variables is stronger than that related to altitude or temperature, consistent with large-scale meta-analyses of selection pressure across species. The set of genes showing association with environmental variables was enriched for genes highly expressed in human blood and nerve tissues. There was also evidence of enrichment for genes associated with high-altitude adaptation although no strong association was identified with hypoxia-inducible-factor (HIF) genes. One of the strongest altitude-related signals was for a collagen gene, consistent with previous studies of high-altitude adaptation. Several altitude-associated genes also showed evidence of adaptation with temperature, suggesting a relationship between responses to these environmental factors. These results provide a foundation to investigate further the effects of climatic variables on small ruminant populations.

Haemonchosis: A Challenging Parasitic Infection of Sheep and Goats

The paper reviews the challenges about haemonchosis-a significant and common parasitic infection of small ruminants. Haemonchus contortus is a highly pathogenic parasite that localises in the abomasum of affected animals and exerts its pathogenicity by blood-sucking activity, adversely affecting the health and productivity of animals. The first challenge is the uneven distribution of the infection globally, this being more prevalent in tropical and subtropical and warm temperate and summer rainfall regions than in cool and cold temperate and arid regions; hence, this leads in differences in the approaches required for its control. Another challenge is the widespread presence of Haemonchus strains resistant to the various anthelmintics available: Benzimidazoles, imidazothiazoles, macrocyclic lactones, closantel and monepantel, which makes the control of the infection difficult. The third challenge refers to the difficulty of diagnosing the disease, given that field evidence can provide suspicion about the infection, which needs to be subsequently confirmed by laboratory tests through parasitological or molecular techniques. The final challenge relates to the difficulties in the control of the infection and the necessity to use pharmaceutical products cautiously and with a planned approach, to avoid further development of anthelmintic resistance, also given that use of a recently licenced vaccine is not widespread. In conclusion, at the moment, we should be concerned, but not worried, about this infection, and apply correctly the appropriate health management plans.

Gastrointestinal parasite infection intensity and hematological parameters in South African communal indigenous goats in relation to anemia

Aim:

The study was conducted to determine the intensity of gastrointestinal parasite (GIP) infections and hematological parameters in South African communal indigenous goats in relation to anemia.

Materials and Methods:

A total of 288 goats were randomly sampled in areas representing four agro-ecological zones. Fecal and blood samples were collected from the rectum and jugular vein, respectively, of each animal. The number of eggs per gram (EPG) and oocysts per gram (OPG) of feces and the hematological parameters were determined using the modified McMaster technique and a BC-2800Vet® automatic hematology analyzer, respectively. Data were analyzed using the repeated measures techniques of Minitab 17, modeling the covariance structure of the observed data.

Results:

Based on EPG and OPG, goats in humid zone were significantly infected (p<0.05) with strongyles, Eimeria, Moniezia, and Trichuris spp. Hematological parameters of goats in arid and humid zone were lower (p<0.05) than those in semi-arid and dry sub-humid zone. GIP infection intensities were higher (p<0.05) in young animals than in adult and suckling goats. GIP infection intensity was similar between goat sexes, while hematological parameters were higher (p<0.05) in females. Higher (p<0.05) infection intensities for strongyles (302.90 EPG) and Eimeria (216.09 EPG) were observed in winter compared to summer (strongyles: 302.90, Eimeria: 216.09 EPG). Higher (p<0.05) values for the hematological parameters were observed during summer compared to that in winter.

Conclusion:

GIP infection intensity in the winter could be associated with hypochromic and normocytic anemia which likely to affects suckling goats while in the summer could be associated with normochromic and normocytic anemia which likely to affect young goats.

Molecular identification of different Trichostrongylus species infecting sheep and goats from Dakahlia governorate, Egypt

Nematodes of genus Trichostrongylus can cause remarkable economic losses in the small ruminant`s industry and some species have a zoonotic potential. Since the most common source for human infection is the infected animals, accurate identification of different Trichostrongylus species in animals would reflect the species that can infect humans from the same area. The objective of the present study is to identify common Trichostrongylus species infecting small ruminants in Dakahlia governorate, Egypt using molecular-based techniques. Fecal samples from 340 sheep and 115 goats from rural areas in 3 cities of Dakahlia governorate and 2 cities at its borders were collected, and the strongyle-type eggs were detected in 33.2% and 14.7% of sheep and goats, respectively. PCR amplification of the internal transcribed spacer of the ribosomal DNA (ITS2 rDNA) for 3 Trichostrongylus spp.; T. axei, T. colubriformis and T. vitrinus was conducted for eggs harvested from 25 sheep and 16 goat samples. Two species were detected; T. axei (in 16 sheep and 14 goats) and T. colubriformis (in 2 sheep but no goats). This is the first report of T. colubriformis in sheep from Dakahlia governorate, where this species was reported earlier from humans. No T. vitrinus was detected in any tested sample of sheep or goats. Purified PCR products of T. axei isolates were successfully sequenced and revealed 3 haplotypes; 2 from sheep and 1 from goats, and the isolates are related genetically to T. axei isolates from camels in Egypt. Phylogenetic analysis of the Genbank-retrieved ITS2-amplified T. axei isolates worldwide suggested the existence of genetic variants. Earlier reports on the identified Trichostrongylus spp. in different animals from Egypt as well as African and Arabian countries are tabulated.

Factors influencing regional epidemiology of strongyle nematodes at organized sheep farms in Rajasthan

A study was conducted to observe the influence of year, season, month, breed, age and sex on epidemiology of strongyle nematodes in different sheep breeds managed at organised farms in arid and semi-arid Rajasthan by evaluating 14,030 fresh faecal samples (from April 2016 to March 2019). The overall incidence of strongyle worms was significantly higher (74.1%) in semi-arid as compared to 27.4% in arid region. Among breeds, it varied from 25.6% in Magra to 74.8% in Malpura sheep. The effect of year was significant on regional as well breed-wise incidence. Season had significant effect on regional incidence with maximum incidence during monsoon. A significant breed variation in overall and seasonal incidence was found only in arid region. Irrespective of sheep breed, significantly higher incidence of strongyle worms was observed in adult sheep in both the regions. Male had significantly higher incidence of strongyle worms in both the regions. The effect of agro-climatic region was significant on overall intensity of strongyle worms with mean FECs of 117.8±3.7 epg in arid and 1098.9±45.2 epg in semi-arid region. Breed-wise, the effect of year on intensity of strongyle nematodes was significant in arid region only. Seasonal intensity was significantly higher during monsoon season in both the agro-climatic regions and in all the breeds. Effect of age on overall intensity of infection was also significant in both the regions with higher mean FECs in adult animals as compared to young ones. In both the regions, males possessed higher FECs as compared to females. On coproculture, Haemonchus contortus, Trichostrongylus sp and Oesophagostomum sp were recovered with maximum (71.1±2.1%) mean annual proportion of H. contortus. Availability of infective larvae of GI nematodes on herbage was observed during monsoon and extended up to post-monsoon season in semi-arid region. Comparatively higher herbage infectivity was not noticed in semi-arid farm with a peak of 2,100.0±97.9 L3/kg dry matter of herbage in September. The study suggest a marked influence of agro-climatic region on epidemiology and dynamics of strongyle nematodes in sheep flocks and on pasture. The breed variation was evident only in arid conditions. Further, the magnitude of monthly intensity of strongyle infection in arid region suggested anthelmintics intervention through targeted selective approach instead of strategic en-mass drench.

Seasonal Dynamics of Gastrointestinal Nematode Infections of Goats and Emergence of Ivermectin Resistance in Haemonchus contortus in Hubei Province, China

INTRODUCTION

Gastrointestinal nematodes (GINs) are a major constraint to the survival and productivity of animals. In southern China, goats are the most important small domestic ruminants.

METHODS

From May 2013 to May 2017, we conducted a longitudinal study of hircine GIN infections in Huangshantou Town, Gongan County, Hubei Province, China, using fecal egg counts.

RESULTS

Our investigation revealed that the GINs of goats in Hubei Province have changed significantly. Over 90% of eggs detected in the first month of investigation, May 2013, belonged to the species Haemonchus contortus and Chabertia sp. There was no seasonal variation in positive rates (PRs) of GINs, but the mean eggs per gram (EPG) of GINs were higher between April and July than between September and November (P < 0.05). The gradual increase in the percentage of H. contortus eggs among all detected eggs during our research and the low cure rate of IVM mass treatment revealed the emergence of IVM resistance in H. contortus. After the implementation of an integrated GIN control strategy, which included two mass treatments (one in April/May with ABZ and another in September/October with IVM + ABZ), in 2016 and 2017, both the PRs and EPG of GINs were significantly reduced.

CONCLUSION

The results presented here reveal that controlling GINs of small ruminants in small farms in southern China requires an integrated control strategy that should include monitoring of infection and anthelmintic resistance, and increased farmer education on the importance of using the appropriate drugs at the correct dose.

Infection dynamics of gastrointestinal helminths in sympatric non-human primates, livestock and wild ruminants in Kenya

BACKGROUND

Gastrointestinal parasites are neglected infections, yet they cause significant burden to animal and human health globally. To date, most studies of gastrointestinal parasites focus on host-parasite systems that involve either a single parasite or a host species. However, when hosts share habitat and resources, they may also cross-transmit generalist gastrointestinal parasites. Here we explore multi-host-parasite interactions in a single ecosystem to understand the infection patterns, especially those linked to livestock-wildlife interfaces and zoonotic risk.

METHODS

We used both coprological methods (flotation and sedimentation; N = 1,138 fecal samples) and molecular identification techniques (rDNA and mtDNA; N = 18 larvae) to identify gastrointestinal parasites in nine sympatric host species (cattle, sheep, goats, wildebeest, Grant's gazelles, Thomson's gazelles, impala, vervet monkeys and baboons) in the Amboseli ecosystem, Kenya.

RESULTS

We found that the host community harbored a diverse community of gastrointestinal helminths, including 22 species and/or morphotypes that were heterogeneously distributed across the hosts. Six zoonotic gastrointestinal helminths were identified: Trichuris spp., Trichostrongylus colubriformis, Enterobius spp. Oesophagostomum bifurcum, Strongyloides stercoralis and Strongyloides fuelleborni. The dominant parasite was Trichuris spp, whose ova occurred in two morphological types. Baboons were co-infected with Strongyloides fuelleborni and S. stercoralis.

CONCLUSIONS

We found that the interface zone shared by wild ungulates, livestock and non-human primates is rich in diversity of gastrointestinal helminths, of which some are extensively shared across the host species. Closely related host species were most likely to be infected by the same parasite species. Several parasites showed genetic sub-structuring according to either geography or host species. Of significance and contrary to expectation, we found that livestock had a higher parasite richness than wild bovids, which is a health risk for both conservation and livestock production. The zoonotic parasites are of public health risk, especially to pastoralist communities living in areas contiguous to wildlife areas. These results expand information on the epidemiology of these parasites and highlights potential zoonotic risk in East African savanna habitats.

Morbidity Parameters Associated with Gastrointestinal Tract Nematodes in Sheep in Dabat District, Northwest Ethiopia

Gastrointestinal nematode (GIN) infections of sheep and their interaction with selected morbidity parameters were studied in smallholder farms. 120 faecal samples were collected and examined using faecal flotation to determine nematode infection in sheep. Thus, the study demonstrated overall prevalence of 57.5% GIN infections, while the mean faecal egg count (FEC) was 517.5 EPG. The severity of GIN infection was determined based on EPG as a mild infection (EPG <500), 55.1%, moderate infection (EPG = 500–1500), 30.4%, and heavy infection (EPG >1500), 14.6%. Five genera of nematodes were identified using coproculture: Haemonchus (33.3%), Trichostrongylus (26.7%), Bunostomum (20%), Oesophagostomum (13.3%), and Cooperia (6.7%). A significant difference was observed in the mean FEC among the FC (P < 0.001), FAMACHA© score (P < 0.01), and the BCS of the animals (P < 0.001). FEC was positively correlated with the FAMACHA© score (FS), while FC and BCS were negatively correlated. Thus, FAMACHA© chart can suggest well the severity of nematode infections and can serve as a suitable on-farm tool to identify nematode-infected sheep and gives a guide to identify sheep that need to be treated with an anthelmintic.

Seasonally timed treatment programs for Ascaris lumbricoides to increase impact-An investigation using mathematical models

There is clear empirical evidence that environmental conditions can influence Ascaris spp. free-living stage development and host reinfection, but the impact of these differences on human infections, and interventions to control them, is variable. A new model framework reflecting four key stages of the A. lumbricoides life cycle, incorporating the effects of rainfall and temperature, is used to describe the level of infection in the human population alongside the environmental egg dynamics. Using data from South Korea and Nigeria, we conclude that settings with extreme fluctuations in rainfall or temperature could exhibit strong seasonal transmission patterns that may be partially masked by the longevity of A. lumbricoides infections in hosts; we go on to demonstrate how seasonally timed mass drug administration (MDA) could impact the outcomes of control strategies. For the South Korean setting the results predict a comparative decrease of 74.5% in mean worm days (the number of days the average individual spend infected with worms across a 12 month period) between the best and worst MDA timings after four years of annual treatment. The model found no significant seasonal effect on MDA in the Nigerian setting due to a narrower annual temperature range and no rainfall dependence. Our results suggest that seasonal variation in egg survival and maturation could be exploited to maximise the impact of MDA in certain settings.

Investigations into nematode parasites of goats in pastoral and crop livestock systems of Ethiopia

We generated epidemiological information on the prevalence of nematode parasites and possible resistance/resilience of goats in three areas, Bati, Shinille, and Borana, of Ethiopia. A total of 350 breeding does were randomly selected and monitored for one year. Fecal egg counts (FEC), packed cell volume (PCV), body weight (BW), body condition score (BC), and fecal larvae identification were done. In Borana, the long rainy season had higher FEC, lower PCV, lower BC, and smaller BW compared to dry and short rainy seasons (p < 0.01). For Bati and Shinille, the differences between the seasons were significant (p < 0.01) but not clear-cut. Breed differences were also evident (p < 0.01) on FEC, PCV, and BW. The mean FEC for Borana goat was 158.5 ± 1.12, whereas for Bati it was 38.9 ± 1.12. Age differences did not have effect on FECs, PCV, and BC. No differences in parasite load, as reflected by FEC, was verified between male and female goats. In the wet season, large numbers of larvae were recovered from the study sites except for Bati. In the three sites, Haemonchus contortus followed by Trichostrongylus colubriformis were the dominant species. In the dry season, however, very little number of larvae was recovered, only of H. contortus in Bati and of H. contortus and T. colubriformis in Borana. Generally, the level of nematode infection was low. Therefore, nematode parasites are not a major problem and strategic control program using broad spectrum anthelmintic is not advisable. Rather, monitoring parasite load and selective de-worming should be sufficient to reduce productivity loses and pasture contamination.

Prevalence and risk factors of gastrointestinal parasitic infections in goats in low-input low-output farming systems in Zimbabwe

A longitudinal study was conducted in low-input low-output farming systems to determine the prevalence of gastrointestinal parasitic infections in different age groups, sex and associated risk factors in goats. A total of 580 indigenous goats were randomly selected in areas representing the five agro-ecological regions of Zimbabwe in the dry and wet seasons. Blood and faecal samples were collected from each animal and egg/oocyst per gram of faeces (epg/opg), larval culture, and packed cell volumes (PCV) were determined. Factors affecting parasitic infections were evaluated. Highest prevalence was determined for Eimeria oocysts (43%), strongyles (31%) and lower levels in trematodes and cestodes. Parasites identified were Haemonchus, Strongyloides and Oesophagostomum. Area, season, sex and age significantly influenced patterns of gastrointestinal infections (P < 0.05). Cannonical correlations indicated that parasite species composition varied by area and impacts of risk factors also differed. Risk of infection was very high for goats sampled in Natural regions (NR) I, II, III (OR = 6.6-8.2; P < 0.05) as compared to those in NR IV and V. Highest helminths and Eimeria infections were observed in the wet vs. dry season (P < 0.05). Young animals were more susceptible to parasitic infections (P < 0.05). Prevalence was higher in males than females, with odds of infection for males being almost three times to that for females (P < 0.0001). Knowledge concerning gastrointestinal helminth biology and epidemiological infection patterns caused by these parasites is essential in the development of appropriate control strategies and this has a potential to reduce production losses.

Arrested development of abomasal trichostrongylid nematodes in lambs in a steppe environment (North-Eastern Algeria)

Arrested development of abomasal trichostrongylid nematodes was studied in 30 permanent grazing lambs on a large farm in the North-East of Algeria. The steppe climate has cold winters and hot and dry summers. The lambs were monitored monthly for gastrointestinal nematodes using nematode faecal egg counts, from February 2008 to February 2009. Every 2 months, two of the original 30 permanent lambs were necropsied after being held in pens for three weeks so that recently ingested infective larvae could develop into adults. The highest percentage of fourth stage larvae (L4), reaching 48% of the total worm burden, was recorded in abomasal contents in June. Teladorsagia and other Ostertagiinae constituted the highest percentage of L4 larvae (71%), whereas the percentage of Trichostrongylus (17.4%) or Haemonchus (11.6%) remained low. The dynamics of infection observed here (highest faecal egg count in August) and the stage composition of worm burden (highest percentage of L4 in June) provide strong evidence that arrested development had occurred.

Gastrointestinal nematode infection in small ruminants in Ethiopia: A systematic review and meta-analysis

Gastrointestinal (GI) nematode infections are a major health challenge affecting productive and reproductive performance of sheep and goats in Ethiopia. However, there is no comprehensive summary on the occurrence and distribution of the infection at national level. This systematic review provides pooled prevalence estimates and assesses potential predictors of the nematode infections in small ruminants, i.e. helpful in planning interventions or control strategies. The review used 50 animal level datasets retrieved from 24 manuscripts. The studies used data collected from 9407 sheep and 3478 goats. A meta-analytical approach was employed to analyze Effect size (ES). The reported GI nematodes represented eleven genera affecting sheep and goats including: Haemonchus, Trichostrongylus, Teladorsagia/Ostertagia, Strongyloides, Bunostomum, Nematodirus, Chabertia, Trichuris, Cooperia, Skrjabinema and Oesophagostomum. The GI nematodes pooled prevalence estimate in the random effect model was 75.8% (95% CI: 69.6, 80.8). The subgroup analysis revealed significant (p<0.05) differences in the prevalence between different regions and type of diagnostic methods used. 'Postmortem technique' and 'eastern part of the country' were associated with higher GI nematode prevalence and accounted for 68.1% of the between studies heterogeneity. In light of the high parasitic prevalence in all agro-ecologies, the need for strategic intervention is recommended. Meanwhile, data need to be generated for some of the regions where dependable survey reports are lacking.

The Pathophysiology, Ecology and Epidemiology of Haemonchus contortus Infection in Small Ruminants

The parasitic nematode Haemonchus contortus occurs commonly in small ruminants, and it is an especially significant threat to the health and production of sheep and goats in tropical and warm temperate zones. The main signs of disease (haemonchosis) relate to its blood-feeding activity, leading to anaemia, weakness and frequently to deaths, unless treatment is provided. Due to the high biotic potential, large burdens of H. contortus may develop rapidly when environmental conditions favour the free-living stages, and deaths may occur with little prior warning. More chronic forms of haemonchosis, resulting in reduced animal production and eventually deaths, occur with smaller persistent infections, especially in situations of prolonged, poor nutrition. The global distribution of the main haemonchosis-endemic zones is consistent with the critical requirements of the egg and larval stages of H. contortus for moisture and moderate to relatively warm temperatures, but the seasonal propensity for hypobiosis (inhibition of the fourth-stage larvae within the host) largely explains the common, though sporadic, outbreaks of haemonchosis in arid and colder environments. The wide climatic distribution may also reflect the adaptation of local isolates to less favourable ecological conditions, while an apparent increase in the prevalence of outbreaks in environments not previously considered endemic for haemonchosis - especially cold, temperate zones - may be attributable to climatic changes. Although the risk of haemonchosis varies considerably on a local level, even where H. contortus is endemic, the extensive range of ecological investigations provides a sound basis for predictions of the relative geographical and seasonal risk in relation to climatic conditions.

Significance of serum potassium level monitoring during the course of post-operative rehabilitation in patients with hypokalemia

OBJECTIVE

Our objective was to evaluate the significance of pre-hospital and post-operative serum potassium level monitoring and hypokalemia intervention in laparotomy patients with hypokalemia.

METHOD

A total of 118 laparotomy patients with hypokalemia were randomly divided into an intervention group (N = 60) and a control group (N = 58). Blood samples were collected for measurement of potassium levels at various time points (pre-admission, admission, 24 h and 48 h post-operation) for both groups. Hypokalemia interventions were administered to patients in the intervention group in the pre-admission period and the post-operative period. Visceral dynamics were assessed after laparotomy in both groups.

RESULT

Average serum potassium levels at admission, time period of drinking, and time of first bowel sound after laparotomy differed significantly (p < 0.001) between the two groups. Average serum potassium levels, first time of defecation, urination, and ambulation at 24 h and 48 h post-operation differed significantly (p < 0.05) between the two groups.

CONCLUSION

An optimal pathway of serum potassium monitoring not only saves limited ward space but also allows for early correction of hypokalemia in patients undergoing laparotomy.

The influence of water on the migration of infective trichostrongyloid larvae onto grass

Detailed knowledge of the effects of water on the migration of infective larvae of economically important trichostrongyloid species is urgently needed to feed into prediction models of future epidemiology. The influence of water on the migration of the parasitic nematodes Nematodirus battus, Haemonchus contortus and Teladorsagia circumcincta from sheep dung onto grass was examined in a series of laboratory experiments. Turf plots were seeded with larvae, which were recovered from grass clippings by serial sampling. Free water was necessary for larvae to escape from dung, but not for vertical migration onto grass. When temperature and relative humidity were held constant, the proportion of a population of live larvae present on herbage reached a plateau of around 2 (1-10)% after 24 h, and then changed little over time. Larvae in soil and dung formed a reservoir, such that a similar proportion of the larval population was maintained on grass after clipping. These findings suggest continuing random movement of free larvae. Implications for the epidemiology of trichostrongyloid species are discussed in the context of trade-offs faced by the parasites.

Relevance of improved epidemiological knowledge to sustainable control of Haemonchus contortus in Nigeria

Nigeria experiences losses in small ruminant production as a result of a high prevalence of infection with Haemonchus contortus, but there have been very few investigative studies into the epidemiology of H. contortus in Nigeria, particularly in the south and western parts of the country. For successful planning and execution of control of hemonchosis in Nigeria, there is a need for insight into the epidemiology of free-living stages under the prevailing local conditions and models for climatic and environmental factors that control the risk of hemonchosis and distribution of H. contortus. In this review, we assess previous studies on the epidemiology of H. contortus in Nigeria, evaluate the present climatic and epidemiological situation, and highlight areas that require further investigative studies. The goal is to identify factors that underpin better control strategies and holistic integrated farm-management practice. Previous studies on H. contortus provided important information for formulation of control strategies and development toward integrated parasite management. However, this review has revealed the need for holistic evaluation of the current epidemiology and prevalence of H. contortus in Nigeria, particularly in relation to climate change. Accurate information is needed to build useful predictive models of the population dynamics of all free-living stages, particularly the L3.

Dynamics of infestation of tracers lambs by gastrointestinal helminths under a traditional management system in the North of Tunisia

The authors present a survey of gastrointestinal helminths of sheep on permanent pastures in the extreme north region of Tunisia (Mediterranean climate). Dynamic infestation of animals has been monitored by using batches of three tracer lambs introduced each two months during 2004 and 2005. These lambs were kept in the pens of veterinary school of Sidi Thabet (Tunisia) during three months and then necropsied. Faecal and blood samples were took from tracer lambs each two months during the whole period, and from animal flock only during 2004. The main helminth genera encountered were Trichostrongylus spp., Teladorsagia spp., Strongyloides papillosus and Anoplocephalidea; occasionaly were found Nematodirus, Oesophagostomum, Chabertia, Cooperia, Trichuris and Paramphistomum. The egg count of the ewes and lambs in the flock showed two peaks. For both ewes and lambs there is a gradual increase from January with a peak in May-June. This first peak is considered to be due to acquisition of infective larvae during the rainy and cold season, as evident from the worm burdens of tracer lambs. The second peak was exclusively observed in ewes during late autumn-early winter (November-December); it has two origins: infestation by third larvae stage and the periparturient rise. The worm burdens of tracer lambs showed that there was a gradual accumulation of nematodes from September-October, reaching a peak in March-April; a very low or naught infection is reported during the dry period (July-August). Infection by Anoplocephalidea was higher during the dry season. This study is primordial for a comprehensive control programme implementation against gastrointestinal helminths.

Susceptibility assay of Haemonchus contortus to commonly used anthelmintics in Jimma, southwest Ethiopia

An experimental study to investigate the susceptibility pattern of Haemonchus contortus to commonly used anthelmintics (albendazole, tetramisole, ivermectin, and triclobendazole) was conducted between June and September 2009. Adult H. contortus parasites were collected from a total of 30 sheep slaughtered at Jimma municipal abattoir. The anthelmintics were assessed for egg hatch inhibition ability against H. contortus eggs. The eggs (500 eggs/ml) were incubated with different concentrations (0.25, 0.125, 0.0625, 0.03125, and 0.015625 μg/ml) at 26°C for 48 h. Egg hatching inhibition of different anthelmintics at different concentrations was recorded. The overall mean percent inhibition showed that there was a significant difference (p < 0.05) among the different concentrations. Mean egg hatch inhibition of ivermectin showed the highest result (84.90 %) at 0.25 μg/ml, followed by albendazole (78.77 %), triclobendazole (76.66 %), and tetramisole (78.98 %), respectively. The overall mean percent inhibition showed a significant difference (p < 0.05) among the different anthelmintics. Further evaluation of these anthelmintics was recommended.

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.

Epidemiology of nematode parasites of sheep around Jimma, southwestern Ethiopia

An investigation was made into the epidemiology of nematode infections of sheep in two districts of Jimma zone, southwestern Ethiopia. We used two approaches--long-term monitoring of identified sheep for nematode infection and abattoir or market survey for analysis. In the first monitoring regime, we used 80 lambs [40 sheep (20 per sex) from each district (Dedo and Yebu)] averaging 4-5 months of age. Faecal egg counts (FEC), packed cell volume (PCV) and body weight changes were monitored over a period of 1 year. Additionally, faecal samples were collected (on a weekly basis) from sheep brought to abattoir/market for 1 year to monitor faecal egg counts. The nematode parasite burden, as judged by FEC and PCV, was generally low indicating that the climatic conditions are not conducive to the development and survival of nematode eggs and the free-living stages; hence, little transmission occurred. In the experimental flocks, the highest FEC and lower PCV were recorded during the long rainy season (June to September) with peak in August and September. Faecal samples collected from abattoir/market also followed the same trend. Results from experimental sheep indicated that location had a significant (P < 0.01) effect on FEC, PCV and average daily body weight gain. The FEC and PCV for sheep in Yebu (mid-altitude) district were 126 +/- 3.33 and 30.6 +/- 0.26, whereas the values for Dedo (highland) were 93 +/- 4.35 and 32.0 +/- 0.21, respectively. The results indicate that the highland areas are comparatively less favourable to the survival and development of nematodes. Female lambs had lower FEC and higher PCV compared to male lambs (P < 0.05). The overall nematode parasite challenge in the area, however, is low. We, therefore, recommend rotational grazing management combined with monitoring parasite load and selective treatment to reduce productivity loses and pasture contamination.

Evaluation of the efficacy of anthelmintics sold on Ethiopian markets against Haemonchus contortus in experimentally infected Sheep

A total of 54 lambs, aged between 6-8 months were experimentally infected with Haemonchus contortus to evaluate the efficacy of different anthelmintic brands sold on Ethiopian markets using the faecal egg count reduction test (FECRT) and controlled anthelmintic efficacy trial. Accordingly four different albendazole (Alzole, Analgon-300, Albenjung_s and Ahshialben-300), two tetramisole (Tetsole and Ashitetra 600) and two tetramisole-oxyclozanide (Tetraclozan sheep and Tetraclozash 900) brands were evaluated at the dosage rates recommended by the manufacturers. Animals were allocated into nine groups of six animals each, and balanced for faecal egg counts (FEC), based on their pre-treatment FEC and treatments were randomized among the groups. One group was kept untreated as a control. Faecal egg count was conducted on day 30 post-infection (day of treatment) and on the 10th day post-treatment. Evaluation of anthelmintics based on FECRT revealed high efficacy (99.55-100% reduction in FEC) for all anthelmintic brands tested against H. contortus. The worm count reduction test using controlled anthelmintic efficacy trial also supported the above finding with 99-100% efficacy of the tested anthelmintics. Therefore, the suspicion on the anthelmintic products as being substandard in quality is not credible, at least, for the brands investigated in this study and it might rather be attributed to under dosing. The need for a good extension system for livestock producers with regard to good anthelmintic usage practices, in light of the inevitable development of anthelminitic resistance, is emphasized. Regular surveillance and laboratory quality evaluation of the anthelmintic products in Ethiopia is indicated.

Evaluation of the FAMACHA system for detecting the severity of anaemia in sheep from southern Italy

Since it was first developed in South Africa, the FAMACHA system has been successfully tested in different geographic area where Haemonchus contortus is the major gastrointestinal (GI) strongyle species of sheep. The present study, the first on the use of the FAMACHA system in Italy, was aimed at obtaining a complete haematological profile in sheep with GI strongyle infection, in order to evaluate the validity of the FAMACHA system for detecting the severity of anaemia in sheep from southern Italy. Between April and September 2006, 793 blood and faecal samples were collected from 137 adult sheep of different local breeds of the Campania region (southern Italy). Each study animal was monthly subjected to blood collection, GI strongyle fecal egg counts (FEC) and a complete clinical examination, with particular attention to the colour of ocular mucous membranes. The FAMACHA score values (from 1 to 5) were compared to Hematocrit (Hct) and Haemoglobin (Hb) values. Considering the FAMACHA score number "3" as borderline value for anaemia, the eye score values for anaemic animals were considered in the categories of 4 and 5 (Group 4-5) or of 3, 4 and 5 (Group 3-4-5), respectively. Anaemia due to GI strongyle infection was considered when the Hct and/or Hb values were under 27% and 9g/dl, respectively. The correlation between FAMACHA score and both Hb and Hct was significant (P<0.001) and negative; however, the low correlation coefficients indicated a weak negative association between FAMACHA and either Hb and Hct parameters. The sensitivity, specificity, predictive negative value (NPV) and predictive positive value (PPV) of the FAMACHA system were calculated. The highest values of sensitivity were 66% and 60% in the Group 3-4-5 for Hct and Hb, respectively. The highest values of specificity were 98% in the Group 4-5, for Hb and Hct, respectively. In the Group 3-4-5, the specificity was 60% and 62% for Hb and Hct, respectively. The NPV was 92% (Hct) and 84% (Hb) in the Group 3-4-5, while it was 87% (Hct) and 78% (Hb) in the Group 4-5. The PPV, for the others categories considered (Hb, Hct, Group 4-5 and 3-4-5), was always below 54%. In conclusion, in the present study, the FAMACHA system showed a low sensitivity in detecting anemic sheep; these findings indicate that in southern Italy, under our experimental conditions, FAMACHA may represent an additional element that can integrate clinical examinations. It is important that such evaluations are performed in each region before the system is implemented, as there could be local issues that affect the accuracy of the system.

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger Oesopha-gostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.