Reliability of an ELISA test for diagnosing oestrosis in Iberian ibex

Prophylactic Effects of Ivermectin and Closantel Treatment in the Control of Oestrus ovis Infestation in Sheep

The sheep nasal bots Oestrus ovis is parasite of the nasal cavities and sinuses of small ruminants causing oestrosis, one of the most frequent parasitic diseases in sheep and goats. The widely use of ivermectin and closantel by the sheep breeders in the treatment and prophylaxis of gastrointestinal nematodes resulted in widespread cases of anthelmintic resistance. However, there is no report about cases of O. ovis with drug-resistance. In this study, we evaluated the prophylactics and therapeutic effects of both antiparasitics in sheep with O. ovis natural infestation. The trial was carried out from early December 2019 to March 2020, with 30 crossbred males lambs allocated into three groups of 10 animals each: control (without treatment), treated with ivermectin (0.2 mg/kg subcutaneously) and treated with closantel (10 mg/kg orally). The animals were kept together grazing the same pasture area. The treatment groups were drenched in two occasions 70 days apart: on 5th December 2019 and on 13th February 2020. On 19th March 2020, all lambs were slaughtered. The lamb heads were removed and sectioned along their longitudinal and sagittal axis to search for larvae. Recovered O. ovis larvae were counted and identified according to their developmental stage (L1, L2, and L3). Seven of the control lambs were infested with O. ovis larvae ranging from six to 17 larvae (11.6 mean infestation intensity). All recovered larvae from control group were intact and active. Three animals treated with ivermectin had O. ovis larvae (1-3 larvae), however they were dead and in degeneration. The animals treated with closantel did not have any larvae. The clinical suggestive signs of oestrosis were scarce over the experimental period. The averages of daily weight gain were similar (p > 0.05) among groups. Closantel and ivermectin had high efficacy against oestrosis and O. ovis parasitism did not hinder the performance of lambs.

Immune humoral response of young lambs naturally infested by Oestrus ovis (Diptera: Oestridae)

Twenty-six newborn lambs were evaluated for 21 weeks, from birth to slaughter, to assess their plasma anti-Oestrus ovis immunoglobulin (IgG) using the ELISA technique. On the last day of sampling, all the lambs were slaughtered and O. ovis larvae were recovered, quantified and identified according to the larval stage. High levels of IgG were observed over the first three weeks of life, thus indicating that antibodies are transferred via colostrum from ewes to lambs. Afterwards, the antibody levels declined progressively until the lambs were 11 weeks of age and subsequently started to increase again when they were around 13 weeks of age, reaching the apex on the last week of sampling. All the lambs were parasitized with different larval stages of O. ovis, with an average of 39 larvae per lamb, and the intensity of the infestation ranged from 10 to 97 larvae. However, there was non-significant correlation coefficients between IgG levels and O. ovis larval burden (P > 0.05). In conclusion, although the lambs became infested with O. ovis at an early age, the larval burden was not associated with specific IgG levels.

Cephenemyiosis, an emergent myiasis in roe deer (Capreolus capreolus) from northwestern Spain

Cephenemyia stimulator larvae cause a specific myiasis in roe deer, which is widely distributed in Europe. In Spain, this parasite was detected by the first time in 2005, coinciding with a high mortality of this ruminant especially in northwest of the country. The aim of this study was to analyse the results obtained by necropsy and ELISA to elucidate when the first infestation by C. stimulator in roe deer from northwestern Spain occurred, as well as to determine the influence of some intrinsic factors on the prevalence and intensity of infestation. During 1994-2000, none seropositive roe deer was observed by ELISA. However, from 2007 to 2014, 38 % of animals were seropositive. The results of the necropsy pointed that prevalence and intensity of infestation had increased over the years. There was a positive and significant correlation between the number of animals harbouring C. stimulator larvae and seroprevalence values. This significant correlation was also observed between the seroprevalence and mean intensity of infestation. Adult roe deer showed higher prevalence and intensity of infestation than younger reaching statistical significance. It is also detected that the prevalence of infestation was significantly higher in males than in females although the mean number of larvae found in females were higher than in males. The combined use of direct and indirect techniques demonstrated a high prevalence of C. stimulator infestation in roe deer in the northwest of Spain, which certainly highlights the importance of this myiasis during the last years.