PDF(Pubmed)
Abstract：
BACKGROUND: African swine fever (ASF) is a highly contagious and severe haemorrhagic disease of Suidae, with mortalities that approach 100 percent. Several studies suggested the potential implication of non-biting dipterans in the spread of ASFV in pig farms due to the identification of the ASFV DNA. However, to our knowledge, no study has evaluated the viral DNA load in non-biting dipterans collected in outbreak farms and no risk factors have been analysed. In this context, our study aimed to analyse the risk factors associated with the presence of non-biting dipterans collected from ASF outbreaks in relation to the presence and load of viral DNA.
METHODS: Backyard farms (BF), type A farms (TAF), and commercial farms (CF), were targeted for sampling in 2020. In 2021, no BF were sampled. Each farm was sampled only once. The identification of the collected flies to family, genus, or species level was performed based on morphological characteristics using specific keys and descriptions. Pools were made prior to DNA extraction. All extracted DNA was tested for the presence of the ASFV using a real-time PCR protocol. For this study, we considered every sample with a CT value of 40 as positive. The statistical analysis was performed using Epi Info 7 software (CDC, USA).
RESULTS: All collected non-biting flies belonged to five families: Calliphoridae, Sarcophagidae, Fanniidae, Drosophilidae, and Muscidae. Of the 361 pools, 201 were positive for the presence of ASFV DNA. The obtained CT values of the positive samples ranged from 21.54 to 39.63, with a median value of 33.59 and a mean value of 33.56. Significantly lower CT values (corresponding to higher viral DNA load) were obtained in Sarcophagidae, with a mean value of 32.56; a significantly higher number of positive pools were noticed in August, mean value = 33.12.
CONCLUSIONS: Our study brings compelling evidence of the presence of the most common synanthropic flies near domestic pig farms carrying ASFV DNA, highlighting the importance of strengthening the biosecurity measures and protocols for prevention of the insect life cycle and distribution.
METHODS: Backyard farms (BF), type A farms (TAF), and commercial farms (CF), were targeted for sampling in 2020. In 2021, no BF were sampled. Each farm was sampled only once. The identification of the collected flies to family, genus, or species level was performed based on morphological characteristics using specific keys and descriptions. Pools were made prior to DNA extraction. All extracted DNA was tested for the presence of the ASFV using a real-time PCR protocol. For this study, we considered every sample with a CT value of 40 as positive. The statistical analysis was performed using Epi Info 7 software (CDC, USA).
RESULTS: All collected non-biting flies belonged to five families: Calliphoridae, Sarcophagidae, Fanniidae, Drosophilidae, and Muscidae. Of the 361 pools, 201 were positive for the presence of ASFV DNA. The obtained CT values of the positive samples ranged from 21.54 to 39.63, with a median value of 33.59 and a mean value of 33.56. Significantly lower CT values (corresponding to higher viral DNA load) were obtained in Sarcophagidae, with a mean value of 32.56; a significantly higher number of positive pools were noticed in August, mean value = 33.12.
CONCLUSIONS: Our study brings compelling evidence of the presence of the most common synanthropic flies near domestic pig farms carrying ASFV DNA, highlighting the importance of strengthening the biosecurity measures and protocols for prevention of the insect life cycle and distribution.
摘要：
背景：非洲猪瘟（ASF）是一种高度传染性和严重出血性疾病，死亡率接近100%。几项研究表明，由于ASFVDNA的鉴定，非叮咬性双翅目动物在猪场ASFV传播中的潜在意义。然而,根据我们的知识，尚无研究评估在爆发场收集的非叮咬双翅目动物的病毒DNA载量,也未分析任何危险因素.在这种情况下，我们的研究旨在分析与病毒DNA的存在和载量相关的与ASF暴发收集的非叮咬性双翅目动物存在相关的危险因素.
方法：后院农场（BF），A型农场（TAF），和商业农场(CF)，目标是在2020年进行抽样。2021年，没有对BF进行采样。每个农场只取样一次。收集到的苍蝇给家人的鉴定，属,或物种水平是根据形态特征使用特定的键和描述进行的。在DNA提取之前制备池。使用实时PCR方案测试所有提取的DNA中ASFV的存在。对于这项研究，我们认为CT值为40的样本为阳性.使用EpiInfo7软件(CDC，美国）。
结果：所有收集到的非叮咬蝇属于五个家族：Calliphoridae，Sarcophagidae，Fanniidae,果蝇科，和Muscidae。在361个池中，201对ASFVDNA的存在呈阳性。所获得的阳性样品的CT值范围为21.54至39.63,中值为33.59,平均值为33.56。显著较低的CT值（对应于较高的病毒DNA载量）在食肉科中获得，平均值为32.56；8月份注意到阳性池的数量明显更高，平均值=33.12。
结论：我们的研究带来了令人信服的证据，证明在携带ASFVDNA的家养猪场附近存在最常见的同人蝇，强调加强预防昆虫生命周期和分布的生物安全措施和协议的重要性。
方法：后院农场（BF），A型农场（TAF），和商业农场(CF)，目标是在2020年进行抽样。2021年，没有对BF进行采样。每个农场只取样一次。收集到的苍蝇给家人的鉴定，属,或物种水平是根据形态特征使用特定的键和描述进行的。在DNA提取之前制备池。使用实时PCR方案测试所有提取的DNA中ASFV的存在。对于这项研究，我们认为CT值为40的样本为阳性.使用EpiInfo7软件(CDC，美国）。
结果：所有收集到的非叮咬蝇属于五个家族：Calliphoridae，Sarcophagidae，Fanniidae,果蝇科，和Muscidae。在361个池中，201对ASFVDNA的存在呈阳性。所获得的阳性样品的CT值范围为21.54至39.63,中值为33.59,平均值为33.56。显著较低的CT值（对应于较高的病毒DNA载量）在食肉科中获得，平均值为32.56；8月份注意到阳性池的数量明显更高，平均值=33.12。
结论：我们的研究带来了令人信服的证据，证明在携带ASFVDNA的家养猪场附近存在最常见的同人蝇，强调加强预防昆虫生命周期和分布的生物安全措施和协议的重要性。
