School of Veterinary Medicine and Animal Science, UNESP - São Paulo State University, Botucatu, Brazil; Institute of Biociences, UNESP - São Paulo State University, Botucatu, Brazil.
School of Veterinary Medicine and Animal Science, UNESP - São Paulo State University, Botucatu, Brazil; Institute of Biociences, UNESP - São Paulo State University, Botucatu, Brazil.
Vet Parasitol. 2022 Oct;310:109789. doi: 10.1016/j.vetpar.2022.109789. Epub 2022 Aug 27.
The aim of this study was to assess the suitability of PCR and ELISA as diagnostic method in young sheep naturally infested by Oestrus ovis larvae. The experiment was carried out from December 2020 to April 2021 with 39 lambs divided into two groups: infested (n = 26) and control treated group (n = 13). The infested group did not receive treatment against oestrosis, and the control group was treated with closantel (10 mg/kg orally) every 28 days in order to keep the animals as free as possible of O. ovis infestation. The clinical signs varied among animals regardless of the number of recovered larvae of each lamb, however, the thick mucus and mucopurulent nasal discharge scores were less frequent in lambs from treated group. There was no correlation between the nasal discharge score and the number of O. ovis recovered larvae (R² = 0.012, P = 0.165). Three control treated animals only presented first instar larvae (L1) (1 - 4 larvae/animal) which were smaller than L1 found in the lambs of the infested group. Ninety-two percent of the lambs from infested group (24/26) were parasitized by O. ovis with number ranging from 1 to 54 larvae per animal. A gradual increase in plasma IgG (anti-antigen of O. ovis larvae) levels of animals from infested group after the third week of the trial was observed, whereas the control lambs had low levels of IgG until the end of the experiment. The PCR had low sensitivity (26 %) and high specificity (100 %), and it presented poor agreement (k = 0.177) with the larvae detection after the lamb slaughter. The oestrosis clinical signs were not related to larvae infestation intensity and ELISA showed a greater advantage over the PCR technique in identifying animals that are carrying O. ovis.
本研究旨在评估 PCR 和 ELISA 作为自然感染 Oestrus ovis 幼虫的幼羊诊断方法的适用性。该实验于 2020 年 12 月至 2021 年 4 月进行，共有 39 只羔羊分为两组：感染组（n=26）和对照组（n=13）。感染组未接受针对痒螨病的治疗，而对照组每 28 天用氯氰碘柳胺（10mg/kg 口服）治疗，以使动物尽可能免受 O.ovis 感染。尽管每只羔羊回收的幼虫数量不同，但动物的临床症状各不相同，但治疗组的羔羊鼻腔分泌物评分较少出现浓稠的黏液和脓性分泌物。鼻腔分泌物评分与回收的 O.ovis 幼虫数量之间无相关性（R²=0.012，P=0.165）。仅 3 只经治疗的对照动物仅出现第一龄幼虫（L1）（每只动物 1-4 条幼虫），比感染组羔羊中发现的 L1 小。感染组 92%（24/26）的羔羊被 O.ovis 寄生，每只动物的幼虫数量从 1 到 54 条不等。感染组动物在试验的第三周后，其血浆 IgG（O.ovis 幼虫抗原）水平逐渐升高，而对照组羔羊在实验结束时 IgG 水平较低。PCR 的灵敏度（26%）较低，特异性（100%）较高，与羔羊屠宰后幼虫检测的一致性较差（k=0.177）。痒螨病的临床症状与幼虫感染强度无关，ELISA 比 PCR 技术更有利于识别携带 O.ovis 的动物。
