Pray Ian W, Ayvar Viterbo, Gamboa Ricardo, Muro Claudio, Moyano Luz M, Benavides Victor, Flecker Robert H, 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.
Center for Global Health Tumbes, Universidad Peruana Cayetano Heredia, Tumbes, Peru.
PLoS Negl Trop Dis. 2017 Apr 13;11(4):e0005536. doi: 10.1371/journal.pntd.0005536. eCollection 2017 Apr.
Taenia solium, a parasite that affects humans and pigs, is the leading cause of preventable epilepsy in the developing world. Geographic hotspots of pigs testing positive for serologic markers of T. solium exposure have been observed surrounding the locations of human tapeworm carriers. This clustered pattern of seropositivity in endemic areas formed the basis for geographically targeted control interventions, which have been effective at reducing transmission. In this study, we further explore the spatial relationship between human tapeworm carriers and infected pigs using necroscopic examination as a quantitative gold-standard diagnostic to detect viable T. solium cyst infection in pigs.
METHODOLOGY/PRINCIPAL FINDINGS: We performed necroscopic examinations on pigs from 7 villages in northern Peru to determine the number of viable T. solium cysts in each pig. Participating humans in the study villages were tested for T. solium tapeworm infection (i.e., taeniasis) with an ELISA coproantigen assay, and the distances from each pig to its nearest human tapeworm carrier were calculated. We assessed the relationship between proximity to a tapeworm carrier and the prevalence of light, moderate, and heavy cyst burden in pigs. The prevalence of pig infection was greatest within 50 meters of a tapeworm carrier and decreased monotonically as distance increased. Pigs living less than 50 meters from a human tapeworm carrier were 4.6 times more likely to be infected with at least one cyst than more distant pigs. Heavier cyst burdens, however, were not more strongly associated with proximity to tapeworm carriers than light cyst burdens.
CONCLUSION/SIGNIFICANCE: Our study shows that human tapeworm carriers and pigs with viable T. solium cyst infection are geographically correlated in endemic areas. This finding supports control strategies that treat humans and pigs based on their proximity to other infected individuals. We did not, however, find sufficient evidence that heavier cyst burdens in pigs would serve as improved targets for geographically focused control interventions.
猪带绦虫是一种可感染人类和猪的寄生虫，是发展中世界可预防癫痫的主要病因。在人类绦虫携带者所在地点周围，已观察到猪的猪带绦虫暴露血清学标志物检测呈阳性的地理热点区域。流行地区这种血清阳性的聚集模式构成了地理靶向控制干预措施的基础，这些措施在减少传播方面已见成效。在本研究中，我们使用尸检作为定量金标准诊断方法，进一步探索人类绦虫携带者与感染猪之间的空间关系，以检测猪体内存活的猪带绦虫囊肿感染情况。
方法/主要发现：我们对秘鲁北部7个村庄的猪进行了尸检，以确定每头猪体内存活的猪带绦虫囊肿数量。对参与研究的村庄中的人类进行猪带绦虫感染（即绦虫病）的ELISA粪抗原检测，并计算每头猪到其最近的人类绦虫携带者的距离。我们评估了靠近绦虫携带者与猪的轻度、中度和重度囊肿负担患病率之间的关系。猪感染率在绦虫携带者50米范围内最高，且随着距离增加而单调下降。生活在距人类绦虫携带者不到50米处的猪感染至少一个囊肿的可能性是距离更远的猪的4.6倍。然而，较重的囊肿负担与靠近绦虫携带者的关联并不比轻度囊肿负担更强。
结论/意义：我们的研究表明，在流行地区，人类绦虫携带者与感染有存活猪带绦虫囊肿的猪在地理上存在相关性。这一发现支持基于人与其他感染个体的接近程度对人和猪进行治疗的控制策略。然而，我们没有找到充分的证据表明猪身上较重的囊肿负担会成为地理聚焦控制干预措施的更好目标。
