Table 1.
Sheep and goats used to assess the efficacy of ivermectin in three different study areas in South Darfur, Sudan.
Table 2.
Study design of experimental infections of sheep and goats.
Fig 1.
Comparisons between the faecal egg count reductions (FECRs) with both 90% and 95% credible intervals (CrIs) in sheep and goats naturally infected with gastrointestinal nematodes (strongyles (A) and Strongyloides papillosus (B)) after subcutaneous administration of ivermectin (IVM) at different doses to the treated groups in three different study areas in South Darfur, Sudan, using different statistical analyses methods. ECr: paired faecal egg count reductions (FECRs) and 90% credible intervals (CrIs) were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. BCr: the 90% CrIs of the FECR for paired data were calculated using the Bayesian-Frequentist Hybrid Inference method through an open-source webpage using the R package bayescount version 1.1.0 (https://www.fecrt.com). The average reduction in FECs after treatment was calculated separately. ECo; the paired FECRs and 95% CrIs were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. Results for ECr and BCr were assigned to the status resistance (red colour), low resistance (orange), susceptible (green) or inconclusive (black) as recommended in the revised guideline [27]. Results of the ECo were assigned resistance (red colour), susceptible (green) or inconclusive (black) as in the original guideline [36]. Calculation of CrI using the BCr was not possible for S. papillosus data since the CrIs are not calculable if all post-treatment data are zero. The grey zone indicates the range between the lower efficacy target of 95% and the expected efficacy of 99%. #Retreated goats were initially treated with 0.4 mg/kg ivermectin (day 0) and received a twice the recommended dose of ivermectin (0.8 mg/kg body weight) on day 12.
Table 3.
Results of the faecal egg count reduction (FECR) (and 90% credible interval (CrI)) with sheep and goats naturally infected with gastrointestinal nematodes before and after subcutaneous administration of ivermectin at different doses to the treated groups at three different study areas in South Darfur, Sudan.
Table 4.
Coprocultures of gastrointestinal helminths in the faeces of naturally infected sheep and goats before treatment (day 0) at three different study areas in South Darfur, Sudan.
Fig 2.
Paired values for the width of the 90% credible interval (CrI) for the eggCounts (EC) and the bayescount delta method (BC).
According to the Wilcoxon matched-pairs signed rank test, the width of the 90% CrI was significantly smaller when calculated according to eggCounts in comparison to the bayescount delta method.
Table 5.
Final logistic regression model to identify variables with significant effect on the odds (95% confidence interval (CI)) of goats naturally infected with gastrointestinal nematodes in three different study areas in South Darfur, Sudan, to treatment with ivermectin.
Fig 3.
Faecal egg count reductions (FECRs) with both 90% or 95% credible intervals (CrIs) of male goats experimentally infected with Haemonchus contortus isolates collected from local abattoirs at Kass and Nyala, South Darfur, Sudan, post either subcutaneous or oral administration of 0.4 mg/kg body weight ivermectin on day 25 of infection, using different statistical analyses methods.
Data were analysed separately for different days post treatment. ECr: paired FECRs and 90% credible intervals (CrIs) were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. BCr: the 90% CrIs of the FECR for paired data were calculated using the Bayesian-Frequentist Hybrid Inference method through an open-source webpage using the R package bayescount version 1.1.0 (https://www.fecrt.com). The average reduction in FECs after treatment was calculated separately. ECo; the paired FECRs and 95% CrIs were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. Results for ECr and BCr were assigned to the status resistance (red colour), low resistance (orange), susceptible (green) or inconclusive (black) as recommended in the revised guideline [27]. Results of the ECo were assigned resistance (red colour), susceptible (green) or inconclusive (black) as in the original guideline [36]. The grey zone indicates the range between the lower efficacy target of 95% and the expected efficacy of 99%.
Table 6.
Faecal egg count reduction (FECR) (and 90% credible interval (CrI)) with male goats experimentally infected with Haemonchus contortus isolates collected from local abattoirs of Kass and Nyala, South Darfur, Sudan, before and after either subcutaneous or oral administration of 0.4 mg/kg body weight ivermectin on day 25 of infection to the treated groups.
Fig 4.
Comparisons between the faecal egg count reductions (FECRs) with both 90% and 95% credible intervals (CrIs) with male sheep (n = 6) experimentally infected with nematodes surviving ivermectin treatment in goats from Bulbul and Nyala, South Darfur, Sudan, pre and post-subcutaneous administration of ivermectin with increasing doses, using different statistical analyses methods.
Treatments with ivermectin were repeated every eight days with increasing doses, starting with the recommended sheep dose (0.2 mg/kg body weight) and ending at an eight-time higher dosage (1.6 mg/kg bw). Strongyle eggs were the only nematode eggs differentiated in faecal samples pre and post-treatment. ECr: paired faecal egg count reductions (FECRs) and 90% credible intervals (CrIs) were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. BCr: the 90% CrIs of the FECR for paired data were calculated using the Bayesian-Frequentist Hybrid Inference method through an open-source webpage using the R package bayescount version 1.1.0 (https://www.fecrt.com). The average reduction in FECs after treatment was calculated separately. ECo; the paired FECRs and 95% CrIs were calculated in R 4.1.1 using the eggCounts Bayesian hierarchical model version 2.3–2 without zero-inflation option and without individual efficacy. Results for ECr and BCr were assigned to the status resistance (red colour), low resistance (orange), susceptible (green) or inconclusive (black) as recommended in the revised guideline [27]. Results of the ECo were assigned resistance (red colour), susceptible (green) or inconclusive (black) as in the original guideline [36]. The grey zone indicates the range between the lower efficacy target of 95% and the expected efficacy of 99%.
Table 7.
Faecal egg count reduction (FECR) (and 90% credible interval (CrI)) with male sheep (n = 6) experimentally infected with nematode surviving ivermectin treatment in goats from Bulbul and Nyala, South Darfur, Sudan, before and after subcutaneous administration of ivermectin with increasing doses.