A Schistosoma haematobium-Specific Real-Time PCR for Diagnosis of Urogenital Schistosomiasis in Serum Samples of International Travelers and Migrants

BackgroundDiagnosis of urogenital schistosomiasis by microscopy and serological tests may be elusive in travelers due to low egg load and the absence of seroconversion upon arrival. There is need for a more sensitive diagnostic test. Therefore, we developed a real-time PCR targeting the Schistosoma haematobium-specific Dra1 sequence.Methodology/Principal FindingsThe PCR was evaluated on urine (n = 111), stool (n = 84) and serum samples (n = 135), and one biopsy from travelers and migrants with confirmed or suspected schistosomiasis. PCR revealed a positive result in 7/7 urine samples, 11/11 stool samples and 1/1 biopsy containing S. haematobium eggs as demonstrated by microscopy and in 22/23 serum samples from patients with a parasitological confirmed S. haematobium infection. S. haematobium DNA was additionally detected by PCR in 7 urine, 3 stool and 5 serum samples of patients suspected of having schistosomiasis without egg excretion in urine and feces. None of these suspected patients demonstrated other parasitic infections except one with Blastocystis hominis and Entamoeba cyst in a fecal sample. The PCR was negative in all stool samples containing S. mansoni eggs (n = 21) and in all serum samples of patients with a microscopically confirmed S. mansoni (n = 22), Ascaris lumbricoides (n = 1), Ancylostomidae (n = 1), Strongyloides stercoralis (n = 1) or Trichuris trichuria infection (n = 1). The PCR demonstrated a high specificity, reproducibility and analytical sensitivity (0.5 eggs per gram of feces).Conclusion/SignificanceThe real-time PCR targeting the Dra1 sequence for S. haematobium-specific detection in urine, feces, and particularly serum, is a promising tool to confirm the diagnosis, also during the acute phase of urogenital schistosomiasis.背景：旅行者感染泌尿生殖道血吸虫病（urogenital schistosomiasis）后，由于虫卵负荷较低，且抵达时尚未发生血清转换，通过显微镜检查与血清学检测往往难以确诊。因此亟需灵敏度更高的诊断方法。为此，我们开发了针对埃及血吸虫（Schistosoma haematobium）特异性Dra1序列的实时荧光定量PCR（real-time PCR）。 方法学/主要研究结果：本研究对111份尿液样本、84份粪便样本、135份血清样本，以及1份来自确诊或疑似血吸虫病的旅行者与移民的活检组织样本开展了PCR评估。结果显示，经显微镜证实含埃及血吸虫虫卵的7份尿液样本、11份粪便样本及1份活检组织样本均呈PCR阳性；经寄生虫学证实感染埃及血吸虫的患者血清样本中，22/23份呈PCR阳性。此外，对于尿液与粪便中无虫卵排出的疑似血吸虫病患者，本PCR还在其7份尿液、3份粪便及5份血清样本中检测到了埃及血吸虫DNA。除1例患者粪便样本中检出人芽囊原虫（Blastocystis hominis）与内阿米巴包囊（Entamoeba cyst）外，其余疑似患者均未检出其他寄生虫感染。针对含曼氏血吸虫（Schistosoma mansoni）虫卵的21份粪便样本，以及经显微镜证实感染曼氏血吸虫（22例）、蛔虫（Ascaris lumbricoides，1例）、钩虫科（Ancylostomidae，1例）、粪类圆线虫（Strongyloides stercoralis，1例）或毛首鞭形线虫（Trichuris trichuria，1例）的患者血清样本，本PCR检测结果均为阴性。本PCR展现出了优异的特异性、重复性与分析灵敏度（每克粪便0.5个虫卵）。 结论与意义：针对埃及血吸虫特异性Dra1序列的实时荧光定量PCR可应用于尿液、粪便，尤其是血清样本中的埃及血吸虫特异性检测，是一款极具应用前景的确诊工具，甚至可用于泌尿生殖道血吸虫病的急性期诊断。