Parasitic diseases are a major impediment to livestock production worldwide. However, knowledge about the epidemiology of gastrointestinal parasites in many low-income countries is still limited. An epidemiological survey on these parasites in traditionally reared cattle was performed in central Ethiopia (West Shewa Zone), from September 2019 to November 2021. Overall, 691 samples were analyzed qualitatively (flotation technique) and quantitatively (McMaster technique) to detect helminth eggs and Eimeria oocysts. Furthermore, coprocultures were conducted on pooled samples to identify the genera of gastrointestinal strongyles (GIS). The difference in prevalence according to agroecology, season, age, sex and body condition score (BCS) was investigated using univariable tests and through a multivariable logistic regression analysis, whereas abundance values were interpreted using a descriptive approach. The highest prevalence values were observed for GIS (50.2%) and Eimeria spp. (36.0%), whereas Moniezia spp. (16.3%), Strongyloides spp. (5.1%) and Schistosoma spp. (4.2%) showed lower values. Trichuris spp. and Toxocara vitulorum were sporadically found. A coproculture revealed that Haemonchus spp. (34.6%), Trichostrongylus spp. (25.9%) and Bunostomum spp. (19.1%) were the most frequent genera of GIS. A poor BCS was strongly associated with the occurrence of GIS, while seasonal variations were detected for Eimeria spp., GIS, Moniezia spp. and Schistosoma spp., with a higher prevalence and burden during the rainy season, and agroecology also strongly influenced different parasitic taxa. This present study increases the knowledge about the epidemiological features of gastrointestinal parasites in the context of a low-income country, suggesting a more tailored approach for their control. The use of a BCS as an indicator for the selective treatment of highly infested animals is supported by our findings, introducing a possible way to prevent anthelmintic resistance in areas where basic diagnostic services are rarely used by farmers.
Parasites have had a significant impact on domestic ruminant health and production for a long time, but the emerging threat of drug resistance urgently requires an improved approach to parasite monitoring and control activities. The study reviewed the international literature to analyze the different proposals for the sampling approach and the quantitative estimation of parasite burdens in groups of animals. Moreover, the use of thresholds to decide when and which animal to treat was also investigated. The findings of the study highlighted the presence of a wide-ranging literature on quantitative monitoring for gastrointestinal nematodes (GIN), while more limited data were found for coccidia, and no specific indications were reported for tapeworms. Concerning liver flukes, bronchopulmonary nematodes (BPN) and permanent ectoparasites (lice and mange mites), the diagnostic process is usually aimed at the detection of the parasite rather than at the burden estimation. The main research gaps that need further investigation were also highlighted. For some groups of parasites (e.g., GIN and coccidia) the quantitative approach requires an improved standardization, while its usefulness needs to be confirmed for others (e.g., BPN and lice). The development of practical guidelines for monitoring is also encouraged.
With the spread of anthelmintic resistance (AR), endoparasite monitoring consolidates its role for a more sustainable targeting of treatments. A survey on endoparasites in dairy goat farms of north-eastern Italy was conducted to test a monitoring approach based on a farm-tailored sample size. Farm management and parasites control practices were investigated in 20 farms through a questionnaire survey. Further, fecal samples were collected (November 2018–September 2019) from 264 animals from 13 farms and were analyzed individually with a modified McMaster method and subsequently pooled to perform a coproculture. Coccidia (78.4%), gastrointestinal strongyles (37.9%), Strongyloides (28.4%), Skrjabinema (18.9%), Trichuris (8.0%) and Nematodirus/Marshallagia (0.4%) were identified. Abundances were higher for coccidia and gastrointestinal strongyles. Haemonchus (71%) was the dominant gastrointestinal nematode. Pasture and age class resulted in the main risk factors at the multivariable analysis through a negative binomial regression model. Results from farm monitoring indicate that our approach can be a cost-effective decision tool to target treatments more effectively, but farmers need to be educated about the importance of parasitological testing, which is currently scarcely implemented, against the risk of AR.
Monitoring endoparasite burden (FEC) and treatment efficacy (FECR) is a key element of sustainable parasite control. However, the costs of the analysis often discourage their implementation by farmers and veterinary practitioners. Pooling samples is considered to be a good alternative to reduce time and monetary costs, but limited data are available on the use of pooled samples in small ruminants, especially for goats. In this study, data collected over the years in sheep and goat farms were analyzed, and results obtained from individual and pooled analysis were compared for the purposes of FEC and FECR assessment. A total of 801 individual and 134 pooled samples (composed of 3-12 individual samples) were included. For FECR testing, 2 pools of 5 samples each were created per trial and the same animals were sampled at day 0 (D0 - treatment day) and 14 days after (D14). Samples were analyzed by McMaster technique (limit of detection 20 EPG). Results from pooled and individual FEC were not significantly different (Wilcoxon signed-rank test) and correlation (Spearman's rank test) was high for all sub-categories, although agreement (Lin's concordance correlation) was often classified as poor. Results were not influenced by the pool size (<6 or ≥6). Interpretation of treatment efficacy between the two methods was comparable for all sheep trials, while it differed for goats in 4 out of 10 trials. Wilcoxon signed-rank test indicated a non significant difference between pooled and individual FECR. However, correlation and agreement between FECR were considerably better for sheep compared to goats, for which they were very limited, despite the correlation between FEC at D0 and D14 was always high. According to our results, pooled FECR can be a good option but the absence of 95 %CI represents a major drawbacks in the interpretation of results. Further studies on the topic for goats are needed.
20 November 2024 in Tropical Animal Health and Production