Anthelmintic Drugs: Their Efficacy and Cost-Effectiveness in Different Parity Cattle.

Gastrointestinal nematodes are responsible for economic losses in bovines and are characterized by reduced milk production, decreased working efficiency, and even death. In our study, the effect of different anthelmintic treatments on nematode control in different parity cattle (Friesian crossbreds) at calving and their effect on milk yield were evaluated. The economics of anthelmintics and farm benefits in terms of increased milk production after deworming was also calculated. We screened cattle of first and second parity for nematodes. Animals were randomly selected in each group. In first parity animals, there were 23 positive cattle found, which were divided into 3 different groups, while in second parity animals there were 20 positive cattle which were also divided into 3 groups. For treatment of gastrointestinal nematodes, we used albendazole (velbazine) at 10 mg/kg body weight and levamisole (Nilverm®) at 7.5 mg/kg. In this study, both drugs were found effective in controlling nematode infections in cattle. Percentage reduction of eggs per gram (EPG) by albendazole was 48.20, 85.34, and 93.90% and 51.54, 81.43, 91.74% on day 7, 14, and 21 in first and second parity animals, respectively. Percentage reduction of EPG by levamisole was 44.45, 76.92, and 88.03% and 46.60, 73.78, 85.43% on day 7, 14, and 21 in first and second parity animals, respectively. The average increase in milk production in albendazole-treated groups was 0.39 and 0.92 L per day while increases in levamisole treated groups were 0.27 and 0.55 L per day in first and second parity cattle, respectively. After treatment, albendazole increased the milk fat by 0.07 and 0.1% while levamisole decreased by 0.02 and 0.05% in first and second parity cattle, respectively. It is concluded that anthelmintic treatments of recently calved cattle have a significant effect on milk production due to the nematode control. Milk production increased significantly in second parity cattle following anthelmintic treatment as compared to first parity animals. Levamisole had a negative effect on fat concentration in cattle while albendazole-treated cattle showed a positive effect. Albendazole has been found more efficient in reducing EPG of helminths in both parity animals as compared to levamisole-treated animals while the cost-benefit ratio of levamisole was greater than albendazole.

Prevalence of anthelmintic resistance in gastrointestinal nematodes of dairy goats under extensive management conditions in southwestern France.

The occurrence of benzimidazole (BZ) and levamisole resistance was investigated in 18 randomly selected dairy goat herds located in southwestern France and characterized by extensive management. On each of the 18 farms, 45 adult goats were randomly allocated into three groups of 15 animals each: an untreated control group, a group that was orally administered fenbendazole (10 mg kg(-1) body weight) and a group that received orally a levamisole drench (12 mg kg(-1) body weight). Individual faecal egg counts and pooled larval cultures were done 10 days after anthelmintic treatment. Naive lambs were infected with larvae obtained from control and fenbendazole treated groups and were necropsied 35 days after infection for worm recovery. Faecal egg count reductions (FERC) were calculated for fenbendazole and levamisole and, when less than 95 per 100, were considered as indicative of anthelmintic resistance. An in vitro egg hatch test (EHT) was conducted with thiabendazole on eggs isolated from pooled faeces of fenbendazole treated goats in nine farms. Faecal egg count reductions indicated the occurrence of benzimidazole resistance in 15 out of 18 farms. Among these farms, nine had EHT values above 0.1 microg thiabendazole ml(-1) confirming the benzimidazole resistance status. Levamisole resistance was detected in two farms through FECR. Based on necropsy results, the prevalence of benzimidazole resistance was higher in Trichostrongylus colubriformis, medium in Haemonchus contortus and lower in Teladorsagia circumcincta. In nine farms the benzimidazole resistance was monospecific whereas multispecific resistance was found in the six remaining farms. A negative relationship was found between FECR for fenbendazole and the average number of anthelmintic treatments given per year on the farm. Despite extensive management including a low number of treatments, the prevalence of benzimidazole resistance was very high suggesting that the repeated and sometimes exclusive use of benzimidazole drugs, even at low frequency, is probably the main cause in developing nematode resistance in dairy goat herds. The importance of other factors such as under-dosing or buying animals already carrying resistant nematodes are discussed.

Economic evaluation of three anthelmintic strategies for lamb flocks affected by benzimidazole-resistant nematodes.

OBJECTIVE: To compare the profitability of three anthelmintic strategies in growing lambs in flocks with nematodes resistant to benzimidazole anthelmintics. METHOD: A partial-budgeting analysis was carried out by means of a stochastic simulation model, which allows inputs to be described as distributions rather than as fixed values, and hence permits variation between farms to be considered in the analysis. RESULTS: The results show that control of nematode parasites by use of an effective anthelmintic provides the highest net returns, yielding a margin over ineffectively treated lambs of A$114 per 100 lambs on average. Suppressive treatment based on the administration of two controlled-release capsules and monthly with moxidectin resulted in an average loss of A$131 per 100 lambs in comparison with animals treated with an ineffective anthelmintic. Analysis of the results from capsule-treated lambs did not take into account the unmeasured benefits associated with less contamination of pastures. Sensitivity analysis using a stochastic model indicates that apart from the effect of treatment on weight gain variation in carcase price greatly influences the profitability of all the parasite control programs examined. CONCLUSION: The results suggest that it is economically important for farmers to adjust their strategy in the presence of anthelmintic resistance. But as a result of uncertainty in the factors influencing economic return, the expected economic benefit is likely to vary substantially.

Intrahepatic lymphocyte analyses and assessment of the effects of levamisole in murine hepatic metastasis model.

We used hepatic metastasis models to determine the mechanism and effect of levamisole. BALB/c mice and Colon 26 cells were used. Group I was injected with tumor cells through the portal vein. Group II was primed with tumor cells before tumor cells injecting. Group III was same as Group II, but treated with levamisole. Surface antigens of intrahepatic lymphocytes and spleen cells were determined by FACScan with Anti-CD3, anti-CD4, anti-CD8, anti-CD45, anti-NK1.1 and anti-F4/80. Nodules on the liver were greatest in Group I and fewest in Group III. Concerning intrahepatic lymphocytes, Group II, when compared with Group I, had increases of CD3+, CD4+ and CD8+ cells, and decreases of CD45+ and NK1.1+ cells. Group III when compared with Group II, showed increased CD8+ cells and decreased of NK1.1+ cells. Levamisole is considered to be effective in the prevention of liver metastasis and is suggeste to enhanced CD8+ cells.

Avaliaçäo do levamizole como imuno-estimulador na hanseníase / Levamizole assessment as immuno-stimulator in leprosy

Pacientes hansenianos classificados como portadores da forma clínica virchoviana foram inicialmente submetidos a avaliaçäo imulógica específica (Mitsudina) e inespecífica (PPD, tricofitina, DNCB e determinaçäo do percentual de linfócitos T no sangue periférico). A seguir, foram estimulados com levamizole (150 mg/dia, 2 vezes por semana, durante 2 meses) e novamente submetidos a avaliaçäo imunológica, visando determinar o efeito deste modulador sobre o defeito imunológico descrito nestes pacientes

In vitro model for the assessment of luminal factors on rectal mucosa.

An organ culture method for the maintenance of rectal biopsies over a period of 24 hours is described. Good preservation of histological architecture and continued crypt cell proliferation were shown over the culture period. The colonic enzyme alkaline phosphatase was found to rise over the period of culture. This rise was dependent upon continued protein synthesis by the cell. Changes in alkaline phosphatase activity during culture in biopsies from patients with ulcerative colitis and Crohn's disease are reported. This organ culture system and the measurement of alkaline phosphatase activity during culture provides a new approach to the assessment of luminal antigens as possible effectors of colonic epithelial cell damage.

An in vitro assessment of cellular and humoral immune function in pulmonary tuberculosis: correction of defective neutrophil motility by ascorbate, levamisole, metoprolol and propranolol.

Fifty-six tuberculosis patients and twenty-eight control subjects were evaluated in a comprehensive investigation of cellular and humoral immune function in pulmonary TB. The patient group showed significantly higher levels of secretory IgA and serum IgG, IgA and IgM than did the control group but 7% of patients displayed a selective secretory IgA deficiency. Levels of alpha-1-antitrypsin were also significantly higher in the patient group. There were no significant differences in levels of total haemolytic complement, C'3 and C'4. In moderate to moderately advanced TB patients there were no significant differences in T and B cell numbers nor in mitogen-induced lymphocyte transformation and lymphokine production, when compared with the control group. The range of PPD-induced lymphocyte transformation and lymphokine production levels encountered was similar in both groups although certain patients did not respond to the PPD antigen. Neutrophils from TB patients showed increased random motility in vitro but eight out of ten patients showed impaired directed motility (chemotaxis). Phagocytic and anti-microbial functions were normal in the patient group. The neutrophil chemotactic defect was reversible and could be corrected in vitro when the patients' cells were treated with sodium and calcium ascorbate, levamisole, metoprolol and propranolol.

The in vitro evaluation of certain neutrophil and lymphocyte functions following the ingestion of 150 mg oral dose of levamisole: assessment of the extent and duration of stimulation of neutrophil chemotaxis, protein iodination and lymphocyte transformation.

Certain functions of human blood neutrophils and lymphocytes were investigated at varying time intervals after the ingestion of a single 150 mg dose of levamisole. The functions tested were neutrophil chemotaxis and post-phagocytic metabolic activity and mitogen-induced DNA and protein synthesis of lymphocytes. It was found that levamisole causes a stimulation of neutrophils motility (cell- and serum-associated) and post-phagocytic hexose monophosphate shunt activity and protein iodination. Increased lymphocyte DNA synthesis, but not protein synthesis, to the mitogen phytohaemagglutinin was observed. The stimulation which was detected almost immediately of these neutrophil and lymphocyte functions was still evident 24 hr later but not at 48 hr, indicating that a single oral dose of levamisole can cause the alteration (stimulation) of leucocyte functions which persists until 24--48 hr after intake of the drug.