University of Khartoum

Parasitological and immuonological evaluation of filaricidal effects of Chloroquine, Ivermectin and Artemether on Onchocerca gutturosa in zebu calves (Bus indicus

Parasitological and immuonological evaluation of filaricidal effects of Chloroquine, Ivermectin and Artemether on Onchocerca gutturosa in zebu calves (Bus indicus

Show full item record

Title: Parasitological and immuonological evaluation of filaricidal effects of Chloroquine, Ivermectin and Artemether on Onchocerca gutturosa in zebu calves (Bus indicus
Author: ElBasheir, Husna Mohammed
Abstract: This study was conducted to evaluate the filaricidal activity of two anti-malarial compounds, Chloroquine and Artemether against Onchocerca gutturosa in naturally infected zebu calves (Bos indicus), and to compare the results with the known microfilaricidal effects of Ivermectin. Four groups of zebu calves (naturally infected with Onchocerca gutturosa ) of both sexes, 2-4 years old and weighing 150-200 kg, were used in this study. Each group consisted of 5-6 animals. Group one received a daily intramuscular injection of Chloroquine 200 mg for one week and then a weekly injection for 14 successive weeks. Group two received weekly subcutaneous injections of Ivermectin at 150 =549;g/kg body weight for 14 weeks. Group three received intramuscular injections of standard dose of Artemether 160 mg for three consecutive days. The fourth group remained untreated and acts as a control. Artemether showed high efficacy (100%) against dermal microfilariae (mf) within 24 hours post treatment. This result was comparable with that of Ivermectin where 100% clearance was observed one-week post treatment. As for Chloroquine gradual but consistent decrease occurred with repeated weekly injections for 14 weeks whereby, 100% clearance of skin mf was obtained two month after treatment. Pre treatment sections of skin revealed active cellular reactions to the presence of mf. However these reactions became more intense after mf death following treatment, this may indicate that the body started to combat and get rid off the dead parasite through the enhancement of the cellular immune response. In animals sacrificed 4-month post last dose of treatment by each drug, the effects on adult worm viability, morphology and reproductive status (gravid and non- gravid) was examined and compared to that of the control. The study revealed that male worms were more sensitive to Chloroquine and Artemether than female worms; this was noticed in terms of post treatment scarcity of the male worms in tissues. The recovered female worms showed a significant difference (P< 0.05) in terms of mortality rate (range 27%- 32%) among treated calves compared to that of the control ones where all the worms were recovered alive. However, the effect of these drugs on the reproductive status of female worms did not show a significant difference (P >0.05) compared to the controls and the potentially gravid females in treated animals ranged between 75 – 90.5% compared to 100% in the control group. Embryogram analysis of the collected uterine stages from treated females showed obvious adverse effects of the drugs used. High proportion of the developing embryonic stages were morphologically affected and showed signs of degeneration resulting in partial or complete inhibition of development. The most affected stage was the oocyst, which was presented in Chloroquine, Ivermectin and Artemether treated group as 56.40%, 40.55% and 40.36% respectively. The morula stage was highly affected by Ivermectin (72%) followed by Chloroquine (48.85%) whereas in Artemether- treated group this stage was almost completely absent. In Chloroquine and Artemether treated calves the number of affected stretched mf retained within female uteri was significantly higher (P< 0.021) than in Ivermectin treated group. Sera collected from calves were screened before and after treatment using the Enzyme Linked Immuno Sorbent Assay (ELISA) to monitor the changes in the stage specific antibody response to whole worm crude antigens, to skin mf and uterine mf crude antigens. In all calves the pretreatment level of IgG to whole worms crude antigens and skin mf antigens was found to be significantly higher (P<0.001) than the level of the IgG to uterine mf crude antigens. Mean values of optical densities (O.D.) were 0.443, 0.402 and 0.324, respectively. After treatment with Chloroquine the level of IgG to whole worm crude antigens started to decrease significantly (P<0.05) after week5 whereas it remained essentially unchanged in all calves in both Ivermectin- and Artemether- treated groups. The level of IgG to skin and uterine mf crude antigens showed a consistent, although non-significant decrease, (p>0.05) in all treated calves. These results indicate that the decrease in the level IgG was associated with a decrease in skin mf antigens. The plasma nitrate /nitrite (stable end product of Nitric Oxide) levels before treatment showed mean values of 0.139, 0.255 and 0.233 ug/mL in Chloroquine, Ivermectin and Artemether treated groups, respectively. In Chloroquine treated calves the nitrate values increased slightly above the pretreatment level and peaked at 24 hours and week 2-post treatment coinciding with peaks in skin mf count in this group. In Ivermectin- and Artemether- treated groups the pretreatment levels of nitrate/nitrite were maintained except for short peaks at 6 hours and week 3- in case of Ivermectin and 48 hours and week 1 in case of Artemether. The obtained results may indicate the involvement of nitric oxide in the mechanism of mf clearance. The different groups of calves showed no changes in their haematological parameters examined before and after treatment. However, eosinophils count dropped immediately after treatment and then followed by short peaks. The detected increase in circulating eosinophils and their subsequent migration into dermal tissue was enhanced upon mf death due to treatment. The highest mean eosinophils count post treatment was observed in Chloroquine- treated calves (3.66%) followed by Ivermectin (2.83%) then Artemether- treated calves (1.56%). There was no significant difference in metabolic profile between the treated and control groups. However, an increase in total protein was noticed (8.43 mg/dL) at week 3 post treatment with Chloroquine, whereas an increase to 8.419 and 7.360 ug/mL in Ivermectin and Artemether treated groups were observed respectively at 24 hours post treatment. In Chloroquine treated group the decrease in albumin was associated with a significant increase in globulins level (p<0.002) from week 9 and thereafter. This may be due to increase in specific immunoglobulins directed against dead mf. In all treated groups the post treatment values of urea tended to increase significantly (P<0.05) within the first two weeks nevertheless, the values were within the normal level. Peak concentrations of urea 38.2 and 32.2 mmol/L were observed one-week post treatment with Ivermectin and Artemether, respectively. Whereas a peak of 30.36 mmol/L urea was noticed 48 hours post treatment with Chloroquine. The irregular changes in the values of uric acid were statistically significant (P< 0.05) within each group, whereas the values of creatinine showed no significant changes after treatment. It may be concluded that any of the drugs used did not adversely affect the normal liver and kidney functions, as the increase in above metabolites were not clinically significant. Peripheral blood mononuclear cells (PBMC) from O. gutturosa -infected calves as well as from the control calves were subjected to cytoadherence assay and lymphocyte proliferation assay. The cytoadherence to mf was greater in cultures of immune sera from naturally infected calves whereby the adherent cells ranged between 17 – 20.9%, compared to a weak adherence to mf in cultures of sera from mf negative calves (3.4%). Treatment with Ivermectin resulted in a significant increase in cytoadherence rate to mf (35%) followed by Artemether (27.5%) and then Chloroquine (22.5%). The proliferation of PBMC in responses to OV-ASP2 cloned antigen or O. gutturosa whole worm crude antigens were rather weak in all treated groups with a stimulation index (SI) ranging between 1.8- 2.5, which is almost similar to that of uninfected calves. Therefore treatment did not significantly affect the proliferation responses. This observation indicates general suppression of T cell responses. This study may provide baseline data on the filaricidal effects of Artemether and support previous suggestions made on possible macrofilaricdal activity of Chloroquine on human onchocerciasis. The study also shows that repeated 14 weekly doses of Chloroquine had more adverse effects on adult worms of O. gutturosa compared to Ivermectin similarly administered for 14 weeks, in terms of adult worms mortality, female reproductivity and embryogenesis
URI: http://khartoumspace.uofk.edu/handle/123456789/13564
Date: 2015-06-17


Files in this item

Files Size Format View

This item appears in the following Collection(s)

Show full item record

Share

Search DSpace


Browse

My Account