STAPHANOFILARIAL DERMATITIS (HUMPSORE) TREATMENT TRIAL IN TASHICHOLING, SAMTSE DISTRICT

Abstract

Humpsore is a skin disease in cattle caused by a vector borne nematode belonging to the genus, Staphanofilaria. To select a treatment option with the highest sore recovery rate, a treatment trial was conducted in four villages under Tashicholing Drungkhag, Samtse involving 80 humpsore affected animals. These animals were randomly assigned to four groups namely: 1) group 1 (single ivermectin injection sub-cutaneously @ 1ml/50 kg body weight + topical application of Zinc Oxide (ZnO) ointment daily); 2) group 2 (single levamisole HCl injection sub-cutaneously @ 1ml/50 kg body weightt + topical application of Zinc Oxide (ZnO) ointment daily); 3) group 3 (Topical application of Zinc Oxide (ZnO) ointment daily); and group 4 (untreated control). ZnO ointment was applied daily for the entire trial period. Ivermectin and Levamisole injection was given on the second day of the trial. The sore size (in cm) was measured before application of any treatment and thereafter on weekly interval. The change in mean sore size for each group was computed using a one sample t-test while the comparison between group was made using one-way ANOVA and pair-wise t-test. In total 24 deep lesion scrapings were collected from the animals that were enrolled in the trial as well as from those which were not. Samples were processed using conventional sedimentation method and the Baermann’ technique for recovery of the parasite. By the end of the trial, complete healing of the lesion was observed in 14 (70%) animals under group 1, 12 (60%) under group 2 and 13 (62%) under group 3. Analysis showed that the reduction in the mean sore size for all the group was statistically significant (p <0.0001) except for the control group (p=0.06). There was no statistically significant difference in the mean sore size between the groups before the start of the trial (p=0.24). By the third week, the difference in the mean sore size for all the treatment groups, group 1 (p <0.0001), group 2 (p <0.001) and group three (p <0.0001) was statistically significant difference from the control group. Microfilaria was isolated in 9 of the 24 samples with a microfilaria recovery rate of 37.5%. This study has further validated that ivermectin injection @ 1 ml/50kg body weight with topical application of zinc oxide ointment for three weeks has the highest efficacy against humpsore. It also proposes a speculation, for further validation, that isolating active microfilaria is more likely in samples that are collected in the later part of the day.