Effectiveness Evaluation of Levamisole, Albendazole, Ivermectin, and Vernonia amygdalina in West African Dwarf Goats

First evaluation and detection of ivermectin resistance in gastrointestinal nematodes of sheep and goats in South Darfur, Sudan

In Sudan, resistance to benzimidazoles has been reported recently in cattle and goats from South Darfur. Herein, ivermectin efficacy against gastrointestinal nematodes (GINs) was evaluated in sheep and goats in three study areas in South Darfur. The faecal egg count reduction test (FECRT) was used to evaluate the efficacy of ivermectin in sheep and goats naturally infected with GINs in the region of Bulbul (goats: n = 106), Kass (goats: n = 40) and Nyala (Domaia (sheep: n = 47, goats: n = 77) and the University farm (goats: n = 52)), using different treatment plans, and the efficacy was evaluated 12 days after treatment. Ivermectin efficacy was also evaluated in goats experimentally infected using local Haemonchus contortus isolates from Kass and Nyala. Nematodes surviving ivermectin treatment in goats in Bulbul and Nyala were harvested and larvae used to infect worm-free male sheep (n = 6, ≤6 months old). Infected sheep were dosed subcutaneously with ivermectin every eight days with increasing doses from 0.2 mg/kg to 1.6 mg/kg bodyweight (bw). Reduced ivermectin efficacy was identified in sheep and goats in the four study locations. Using a paired statistic, the efficacy of a therapeutic dose in sheep was 75.6% (90% upper credible limit (UCrL): 77.5%), while twice the recommended dose led to a reduction of 92.6% (90% UCrL: 93.3%). In goats, the FECRs of a therapeutic dose were 72.9-95.3% (90% UCrL range: 73.6-95.7%) in Bulbul, Nyala Domaia, Nyala University farm and Kass. Twice the dose recommended for goats in Bulbul revealed a 90% UCrL of 87.6%. All post-treatment faecal cultures contained only Haemonchus spp. larvae. The experimental infection trials in sheep and goats supported our findings from field trials and calculated upper 90% CrL of below 98.9%. For the first time highly ivermectin resistant H. contortus populations have been identified in sheep and goats in Sudan, and resistance was experimentally confirmed.

In Vitro Antischistosomal Activity of Bridelia ferruginea, Clausena anisata, Khaya senegalensis, and Vernonia amygdalina

Background

Schistosomiasis is caused by parasitic flatworms and the disease is endemic to most countries in sub-Saharan Africa including Ghana. The current therapeutic agent for managing this disease solely relies on praziquantel. The continual dependence on this single available drug could lead to possible drug resistance. This study seeks to evaluate the antischistosomal activity of the following Ghanaian medicinal plants: Khaya senegalensis, Vernonia amygdalina, Clausena anisata, and Bridelia ferruginea. Methodology. Two concentrations (100 μg/mL and 50 μg/mL) of each extract were tested in a 96-well plate containing 30 newly transformed schistosomula (NTS). Moreover, six worms of both sexes of adult Schistosoma mansoni were exposed to the extracts diluted in the RPMI medium. The assay was performed in a 24-well plate. The parasitic worms were examined using an inverted optical microscope.

Results

At 100 μg/mL and 50 μg/mL, all extracts performed better and showed strong activity (p < 0.001) against NTS; thus, 98.08%, 100%, 80.77%, and 100% for Clausena, Vernonia, Bridelia, and Khaya, respectively, when compared to praziquantel. Strong activity was recorded when the extracts underwent testing against Schistosoma mansoni adults at 100 μg/mL; 96.35%, 100%, and 94.55% for Vernonia, Bridelia, and Khaya, respectively, except for Clausena which exhibited weak activity, i.e., 56.02%. There was no significant difference between Vernonia, Bridelia, and Khaya when compared to praziquantel.

Conclusion

At 100 μg/mL, Khaya senegalensis, Vernonia amygdalina, and Bridelia ferruginea extracts demonstrated strong activity against both schistosomula and adult Schistosoma mansoni. These data can serve as baseline information in the quest to find alternative therapeutic agents to treat schistosomiasis.

Research on the Removal of Levamisole Residues in Bovine, Ovine, Caprine, Porcine and Poultry Tissues

In this paper, we set the waiting time for the elimination of levamisole residues at a safe level from tissues (muscles and organs) from animals treated with levamisole 10%—oral solution. We studied the depletion of levamisole residues by high performance liquid chromatography with a mass spectrometer (limit of quantification 2 μg/kg) in the tissues of bovine, ovine, caprine, porcine and poultry (chickens and pigeons) after administration of levamisole (10 mg levamisole/kg body weight for cattle, sheep, goats, pigs and 20 mg levamisole/kg body weight for birds). We found that in cattle, sheep and goats at 7 days after treatment, the residues of levamisole in the liver and at 14 days and in the other tissues were below the established limit value. In pigs at 7 days, residues from all tissues were below the set limit value. Residue depletion in chickens treated with levamisole was rapid, such that 3 days after treatment, the residues in all tissues were below the set limit. Residue depletion was slower in turkeys than in chickens.

In vitro effect of three tropical plants on adult Haemonchus placei, an haematophagous nematode from cattle

Background

Vernonia amygdalina (leaf), Garcinia kola (seed), and Leucaena leucocephala (seed) are three well-known tropical plants used in African ethnomedicine to reduce parasitic worm burdens and are potential sources of alternative solution for controlling parasitic helminths infection in grazing livestock. This study investigated extracts from these plants for anthelmintic activity against adult Haemonchus placei, an haematophagous nematode from cattle abomasa. Powdered plant materials were macerated in acetone and the crude acetone extracts evaluated for anthelmintic activity using H. placei adult worm motility assay. Afterwards, fresh sample of V. amygdalina was macerated successively in chloroform and acetone and the extracts evaluated for anthelmintic activity. The chloroform extract was subjected to phytochemical and FT-IR analyses and fractionated by vacuum liquid chromatography. Anthelmintic data were fitted to a nonlinear regression equation (Log [extract or fraction] vs. lethality; variable slope) to produce best-fit sigmoidal curves and LC50 values computed with associated uncertainty.

Results

Of the three tropical plants, only V. amygdalina was active against adult H. placei with best-fit LC50 of 6.51 mg/mL (95% CI: 5.32–7.75). Evaluation of the two extracts obtained by successive maceration showed that chloroform extract (LC50, 2.46 mg/mL, 95% CI: 1.87–3.28) was 11 times as potent as acetone extract (LC50, 27.01 mg/mL, 95% CI: 21.32–48.57) (α < 0.0001). Chromatographic fractionation of the chloroform extract yielded four fractions (FA-FD) with FB (LC50, 2.38 mg/mL, 95% CI: 1.76–3.28) 2.19 times as potent as FC (LC50, 5.21 mg/mL, 95% CI: 4.40–5.79) against H. placei, while FA and FD were inactive. Phytochemical evaluation of the chloroform extract revealed the presence of saponins, steroids, terpenoids, cardiac glycosides, and the absence of tannins, flavonoids, alkaloids, and anthraquinones. FT-IR structural analysis of chloroform extract indicated the presence of key functional groups which are chemical fragments/ structural motifs known to be present in the two major classes of bioactive compounds (sesquiterpene lactones and steroid glucosides) reportedly to be found in V. amygdalina.

Conclusions

The findings showed that chloroform extract of V. amygdalina leaf possessed relatively good anthelmintic activity against adult H. placei. This could be indicative of its potential usefulness as an anthelmintic phytomedicine to control gastrointestinal nematodes infection in cattle.

Key highlights

Graphical abstract

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.

Haemonchus contortus Susceptibility and Resistance to Anthelmintics in Naturally Infected Egyptian Sheep

PURPOSE

Susceptibility and resistance of Haemonchus contortus to anthelmintic drugs, including ivermectin, levamisole, and albendazole in naturally infected sheep were investigated.

METHODS

Three sets of assays were conducted to detect drug efficacy. Firstly, in vivo estimation of drug resistance to H. contortus was explored in 80 sheep naturally infected with H. contortus. Sheep were divided into four equal groups (20 sheep for each group): the first group was treated with albendazole (5.00 mg/kg BW), the second with levamisole (7.50 mg/kg BW), the third with ivermectin (0.20 mg/kg BW), and the fourth group served as the untreated control. Fecal egg reduction test (FERT) was done at days 7 and 14 after treatment. Secondly, for in vitro egg hatching assay (EHA), H. contortus eggs from naturally infected sheep were collected and treated with 0.0002, 0.002, 0.02, 0.2, and 2.0 µg/mL albendazole. Thirdly, molecular detection of the albendazole resistance gene in adult male H. contortus worms and larvae from infected sheep was carried out using allele-specific PCR.

RESULTS

The FECRT results showed that the drug efficacy was 86.84% for albendazole and 100% for both levamisole and ivermectin. The result of EHA showed that eggs did not hatch at 2.0 µg/mL albendazole concentration. Molecular findings showed two forms, including H. contortus homozygous susceptible (SS) and heterozygous (RS) of "β-tubulin" gene at 200 sites, which were recorded in both single male worms and larvae.

CONCLUSION

H. contortus, which was susceptible to levamisole and ivermectin, had developed resistance to albendazole.

Environmental risk assessment of the anthelmintic albendazole in Eastern Africa, based on a systematic review

This study performs an environmental risk assessment (ERA) of the anthelmintic medicine albendazole (ABZ) in the eastern African region. A systematic literature search strategy was applied to obtain quantitative information on the physicochemical characteristics, the metabolization-fate, the ecotoxicity and the environmental occurrence in different countries worldwide serving as model regions. In addition, insilico tools were employed to obtain data on physicochemical characteristics and toxic hazards of ABZ and its metabolites. Moreover, ERA models were used to predict environmental concentrations in different compartments and compare them with the measured environmental concentrations. Finally, the environmental risk of ABZ in the eastern Africa was estimated by calculating the risk quotient (RQ), and its uncertainty estimated by Monte Carlo simulation. The predicted environmental concentrations of ABZ in surface water in the model region based on consumption (1.6-267 ng/L) were within the range of values obtained from the measured environmental concentrations of the same region (0.05-101,000 ng/L). Using these models with adapted input variables for eastern Africa, the predicted surface water concentration in that region was 19,600 ± 150 ng/L (95% CI). The calculated soil concentrations of ABZ in the model regions and the eastern Africa were found to be 0.057 ± 0.0 μg/kg and 0.022 ± 0.0 μg/kg, respectively. The environmental risk expressed as risk quotient of ABZ in eastern Africa estimated for the aquatic compartment (146 ± 1) indicated a significant environmental risk calling on appropriate actions from the competent authorities to reduce this risk in this region.

Ethnopharmacological evaluation of schistosomicidal and cercaricidal activities of some selected medicinal plants from Ghana

Background

The adulticidal and cercaricidal activities of five Ghanaian medicinal plants, namely, Phyllanthus amarus, Vernonia amygdalina, Azadirachta indica, Morinda lucida and Nauclea latifolia against S. mansoni were evaluated in this study. Six weeks old ICR mice (n = 25) were percutaneously infected with S. mansoni cercariae. Nine weeks later, infected mice (n = 5) were anaesthetised and perfused for adult S. mansoni. Cercariae were treated with different concentrations (1000, 500, 250, 125, 62.5, 31.25 μg/mL) of methanolic extracts of the experimenting plants in triplicates. Adult S. mansoni incopula were also treated with same concentrations of each extract or 20 μg/mL praziquantel. The cercariae and adult worms were observed at time intervals for 180 min and 120 h to assess mortality and viability respectively. Additionally, 9-week cercariae-infected mice (4 groups of 5 mice) were treated with either 500 mg/kg po A. indica or V. amygdalina, 400 mg/kg po praziquantel or distilled water for 14 days. The mice were euthanized after adult worms were recovered from them. The liver was processed and histologically examined for granuloma formations.

Results

All the plants exhibited varying cercaricidal and adulticidal activities against S. mansoni in a time and concentration-dependent manner. A. indica (3 h IC₅₀ = 27.62 μg/mL) and V. amygdalina (3 h IC₅₀ = 35.84 μg/mL) exerted the highest cercaricidal activity. Worm recovery after treatment with V. amygdalina, A. indica and praziquantel in vivo was 48.8%, 85.1 % and 59.9 % respectively (p < 0.05). A. indica and V. amydalina-treated mice recorded lesser mean liver and spleen weights compared to untreated groups (p < 0.05).

Conclusion

A. indica demonstrated the highest cercaricidal and alduticidal activities in vitro, whereas V. amygdalina exhibited the most potent aldulticidal activity in vivo. This study could provide baseline information which can be used to develop plant-based alternative commercial drugs against S. mansoni.

Quality of albendazole tablets legally circulating in the pharmaceutical market of Addis Ababa, Ethiopia: physicochemical evaluation

BACKGROUND

Parasitic diseases are the main challenge of livestock production in the world. They are mainly controlled by the use of anthelmintic drugs. To be effective, the drugs should contain the appropriate amount of active pharmaceutical ingredient (API) and have the required physical characteristics. In this study, qualitative and quantitative assessments were performed to evaluate the quality of different brands of albendazole tablets legally circulating in pharmaceutical markets of Addis Ababa, Ethiopia.

METHODS

Ultraviolet-Visible Spectroscopy (UVS), Fourier Transform Infrared Spectroscopy (FTIR) and High-Performance Liquid Chromatography (HPLC) were used for identification. Quantitative analysis was performed by HPLC. United States Pharmacopeia standard was used as a control to evaluate the identity and content of the API in the samples. A total of 10 batches of albendazole tablets from six different brands were collected and evaluated.

RESULTS

All brands of albendazole tablets, except one, had acceptable physical characteristics. There was gross contamination in one batch, weight variation in 4 (40%) batches, and absence of package insert in 2 (20%) batches. All three methods of evaluation (UVS, FTIR and HPLC) confirmed that all batches passed the identity test. Quantitative analysis showed that no batch had API above the acceptable limit. However, 30% of batches from three different brands contained lower amount of API per tablet than the acceptable limit.

CONCLUSIONS

All batches of albendazole circulating in the market in Addis Ababa did not fulfil either physical or chemical quality standards. The most important finding of this research was the presence of drugs with lower level of API than the acceptable limit. This can lead to treatment failure and favour the emergence of parasites that are resistant to drugs. Therefore, there should be a thorough evaluation of drugs before approval. The study also revealed the importance of occasional assessment of drugs circulating even in the legal market.

Pharmacokinetics of levamisole in the red-eared slider turtles (Trachemys scripta elegans)

The pharmacokinetics and bioavailability of levamisole were determined in red-eared slider turtles after single intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration. Nine turtles received levamisole (10 mg/kg) by each route in a three-way crossover design with a washout period of 30 days. Blood samples were collected at time 0 (pretreatment), and at 0.25, 0.5, 1, 1.5, 3, 6, 9, 12, 18, 24, 36, and 48 hr after drug administration. Plasma levamisole concentrations were determined by a high-performance liquid chromatography assay. Data were analyzed by noncompartmental methods. The mean elimination half-life was 5.00, 7.88, and 9.43 hr for IV, IM, and SC routes, respectively. The total clearance and volume of distribution at steady state for the IV route were 0.14 L hr^-1  kg^-1 and 0.81 L/kg, respectively. For the IM and SC routes, the peak plasma concentration was 9.63 and 10.51 μg/ml, respectively, with 0.5 hr of T_max . The bioavailability was 93.03 and 115.25% for the IM and SC routes, respectively. The IM and SC route of levamisole, which showed the high bioavailability and long t_1/2ʎz , can be recommended as an effective way for treating nematodes in turtles.

Molecular detection of benzimidazole resistance levels associated with F167Y and F200Y polymorphisms in Haemonchus contortus of goats from Mozambique

Benzimidazole (BZ) resistance of Haemonchus contortus has been associated with single nucleotide polymorphisms (SNPs) in codons 200 (F200Y) and 167 (F167Y) and, to a lesser extent, in codon E198A, of the β-tubulin isotype 1 gene. The present study was undertaken to survey the status of BZ resistance in naturally infected goats in smallholder farms in southern Mozambique by real-time PCR (qPCR) using TaqMan® assays. H. contortus-infective larvae (L3; n = 432) from 12 populations were individually genotyped for F200Y and F167Y SNPs to detect BZ resistance. For the F200Y SNP, the results revealed an overall mean percentages of 18.8% homozygous resistant (RR), 47.8% homozygous susceptible (SS) and 33.4% heterozygous (RS) H. contortus. For the F167Y SNP, the overall mean percentages were 1.6% RR, 94.9% SS and 3.5% RS. The percentage of resistant alleles (%R) for the F200Y and F167Y SNPs was 35.7 and 3.4%, respectively. Genotype combinations of the two mutations indicate resistant percentages ranging from 0.0 to 52.9%. From the four herds with high RR individuals, three farms dewormed the animals monthly, while the fourth farm dewormed the animals every 3 months. In farms where animals were dewormed every 6 months, low percentages of RR individuals were found, whereas no RR individuals were discovered in herds where animals were dewormed annually. These results suggest that the F200Y SNP is more significant in BZ resistance development of the surveyed population compared with the F167Y SNP.

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.

A review of bovine fasciolosis and other trematode infections in Nigeria

Trematode infections cause serious economic losses to livestock worldwide. Global production losses due to fasciolosis alone exceed US$3 billion annually. Many trematode infections are also zoonotic and thus a public health concern. The World Health Organization has estimated that about 56 million people worldwide are infected by at least one zoonotic trematode species, and up to 750 million people are at risk of infection. Fasciolosis caused by the fluke Fasciola gigantica is endemic in Nigeria and is one of the most common causes of liver condemnation in abattoirs. Total cattle losses from Fasciola infection in Nigeria have been estimated to cost £32.5 million. Other trematode infections of cattle, including paramphistomosis, dicrocoeliasis and schistosomiasis, have all been reported in various parts of Nigeria, with varying prevalence. Most publications on trematode infections are limited to Nigerian local and national journals, with very few international reports. This paper therefore summarized the current data on distribution, control and zoonotic trematode infections in Nigeria and other African countries. We also identified research gaps and made recommendations for future research and areas for funding for policy/planning.