Gee Emily, Young James R, Khounsy Syseng, Phommachanh Phouvong, Christensen Peter, Theppangna Watthana, Hughes Tom, Brownlie Tom, Temmerath Adisone, Inthavong Alex, Inthapanya Phoummavanh, Punyasith Sivone, Blacksell Stuart D, Ward Michael P
Sydney School of Veterinary Science, The University of Sydney, Camden, NSW, Australia.
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Front Vet Sci. 2024 Jul 29;11:1392885. doi: 10.3389/fvets.2024.1392885. eCollection 2024.
Foot-and-mouth disease (FMD) is a highly infectious and endemic disease in Lao PDR. However, surveillance is weak, and outbreaks are not routinely reported. To address this, serum samples were routinely collected from cattle and buffalo from provincial abattoirs between November 2021 and December 2022. A total of 2,663 serum samples were collected from large ruminants ( = 1,625 cattle; = 1,038 buffalo) from 17 provinces. Samples were tested for specific antibodies directed against FMD non-structural protein (NSP) to determine the proportion of animals exposed to FMD virus. In addition to sampling from abattoirs, further independent data was collected to report clinical signs and outcomes from 94 districts in 12 northern provinces. These incident reports were recorded by district staff using a Google Form and summarised monthly in the National Animal Disease Reporting System. Information was collected on species, incident date, herd size, location and which clinical signs the animals presented. Overall, 46% of the tested animals returned a positive result using ID Screen® FMD NSP Competition ELISA. Results from serological testing were then compared with reported clinical signs from the same district. In districts reporting 'mouth problems' (regardless of other clinical signs) the median FMD seroprevalence was 49.7%, compared to 31.6% in districts not reporting mouth problems ( = 0.021). This finding suggests that reporting clinical cases of 'mouth problems' could be a potential predictor of FMD infection at a district level in cattle and buffalo in Lao PDR. Furthermore, in districts reporting 'fever', 'mouth problems', and 'nose/mouth secretions' together, the median FMD seroprevalence was 46.2%, compared to 24.4% in districts not reporting these signs ( = 0.033). In districts reporting 'mouth problems' and 'nose/mouth secretions' the median FMD seroprevalence was 49.4%, compared to 25.5% in districts not reporting these signs ( = 0.037). In districts reporting both 'fever' and 'mouth problems,' the median FMD seroprevalence was 46.4% compared to 25% in districts not reporting these signs ( = 0.017). Based on serological data generated by abattoir surveillance, this study identified clinical signs most predictive of FMD seroprevalence. These novel findings can be used to guide passive surveillance efforts in the future specifically in northern Laos and help support improved FMD surveillance more broadly in FMD endemic countries in Southeast Asia.
口蹄疫（FMD）是老挝人民民主共和国一种高度传染性的地方病。然而，监测工作薄弱，疫情爆发情况未得到常规报告。为解决这一问题，2021年11月至2022年12月期间，从省级屠宰场的牛和水牛中定期采集血清样本。共从17个省的大型反刍动物（1625头牛；1038头水牛）中采集了2663份血清样本。对样本进行检测，以确定针对口蹄疫非结构蛋白（NSP）的特异性抗体，从而确定接触口蹄疫病毒的动物比例。除了从屠宰场采样外，还收集了更多独立数据，以报告12个北部省份94个地区的临床症状和结果。这些事件报告由地区工作人员使用谷歌表单记录，并每月在国家动物疾病报告系统中汇总。收集了有关物种、事件日期、畜群规模、地点以及动物出现的临床症状等信息。总体而言，使用ID Screen® FMD NSP竞争ELISA检测，46%的受试动物呈阳性结果。然后将血清学检测结果与同一地区报告的临床症状进行比较。在报告有“口腔问题”（无论有无其他临床症状）的地区，口蹄疫血清阳性率中位数为49.7%，而在未报告口腔问题的地区为31.6%（P = 0.021）。这一发现表明，报告“口腔问题”的临床病例可能是老挝人民民主共和国牛和水牛地区口蹄疫感染的一个潜在预测指标。此外，在同时报告有“发热”、“口腔问题”和“鼻/口腔分泌物”的地区，口蹄疫血清阳性率中位数为46.2%，而在未报告这些症状的地区为24.4%（P = 0.033）。在报告有“口腔问题”和“鼻/口腔分泌物”的地区，口蹄疫血清阳性率中位数为49.4%，而在未报告这些症状的地区为25.5%（P = 0.037）。在同时报告有“发热”和“口腔问题”的地区，口蹄疫血清阳性率中位数为46.4%，而在未报告这些症状的地区为25%（P = 0.017）。基于屠宰场监测产生的血清学数据，本研究确定了最能预测口蹄疫血清阳性率的临床症状。这些新发现可用于指导未来老挝北部地区的被动监测工作，并更广泛地帮助支持东南亚口蹄疫流行国家改善口蹄疫监测。
