Flecker Robert H, Pray Ian W, Santivaňez Saul J, Ayvar Viterbo, Gamboa Ricardo, Muro Claudio, Moyano Luz Maria, Benavides Victor, Garcia Hector H, O'Neal Seth E
School of Public Health, Oregon Health & Science University and Portland State University, Portland, Oregon, United States of America.
School of Sciences, Department of Microbiology, Universidad Peruana Cayetano Heredia, Lima, Peru.
PLoS Negl Trop Dis. 2017 Jan 5;11(1):e0005282. doi: 10.1371/journal.pntd.0005282. eCollection 2017 Jan.
Taenia solium inflicts substantial neurologic disease and economic losses on rural communities in many developing nations. "Ring-strategy" is a control intervention that targets treatment of humans and pigs among clusters of households (rings) that surround pigs heavily infected with cysticerci. These pigs are typically identified by examining the animal's tongue for cysts. However, as prevalence decreases in intervened communities, more sensitive methods may be needed to identify these animals and to maintain control pressure. The purpose of this study was to evaluate ultrasonography as an alternative method to detect pigs heavily infected with T. solium cysts.
METHODOLOGY/PRINCIPAL FINDINGS: We purchased 152 pigs representing all seropositive animals villagers were willing to sell from eight communities (pop. 2085) in Piura, Peru, where T. solium is endemic. Tongue and ultrasound examinations of the fore and hind-limbs were performed in these animals, followed by necropsy with fine dissection as gold standard to determine cyst burden. We compared the sensitivity and specificity of ultrasonography with tongue examination for their ability to detect heavy infection (≥ 100 viable cysts) in pigs. Compared to tongue examination, ultrasonography was more sensitive (100% vs. 91%) but less specific (90% vs. 98%), although these differences were not statistically significant. The greater sensitivity of ultrasound resulted in detection of one additional heavily infected pig compared to tongue examination (11/11 vs. 10/11), but resulted in more false positives (14/141 vs. 3/141) due to poor specificity.
CONCLUSIONS/SIGNIFICANCE: Ultrasonography was highly sensitive in detecting heavily infected pigs and may identify more rings for screening or treatment compared to tongue examination. However, the high false positive rate using ultrasound would result in substantial unnecessary treatment. If specificity can be improved with greater operator experience, ultrasonography may benefit ring interventions where control efforts have stalled due to inadequate sensitivity of tongue examination.
猪带绦虫给许多发展中国家的农村社区带来了严重的神经疾病和经济损失。“环形策略”是一种控制干预措施，针对围绕着感染囊尾蚴的猪的家庭集群（环）中的人和猪进行治疗。这些猪通常通过检查动物舌头是否有囊肿来识别。然而，随着干预社区中患病率的降低，可能需要更敏感的方法来识别这些动物并维持控制压力。本研究的目的是评估超声检查作为检测重度感染猪带绦虫囊肿的猪的替代方法。
方法/主要发现：我们从秘鲁皮斯科的八个社区（人口2085）购买了152头猪，这些猪代表了村民愿意出售的所有血清阳性动物，猪带绦虫在这些地方为地方病。对这些动物进行了舌头检查以及前肢和后肢的超声检查，随后进行尸检并精细解剖作为金标准来确定囊肿负担。我们比较了超声检查和舌头检查检测猪重度感染（≥100个活囊肿）的敏感性和特异性。与舌头检查相比，超声检查更敏感（100%对91%）但特异性较低（90%对98%），尽管这些差异无统计学意义。超声检查更高的敏感性导致与舌头检查相比多检测出一头重度感染的猪（11/11对10/11），但由于特异性差导致更多假阳性（14/141对3/141）。
结论/意义：超声检查在检测重度感染的猪方面高度敏感，与舌头检查相比可能识别出更多用于筛查或治疗的环。然而，超声检查的高假阳性率会导致大量不必要的治疗。如果随着操作人员经验的增加可以提高特异性，超声检查可能会使由于舌头检查敏感性不足而控制工作停滞的环形干预受益。
