Sensitivity and specificity of the circulating cathodic antigen rapid urine test in the diagnosis of Schistosomiasis mansoni infection and evaluation of morbidity in a low- endemic area in Brazil

• Main Authors: Fernanda Teixeira Ferreira, Thiago André Fidelis, Thiago Almeida Pereira, Alba Otoni, Leonardo Campos Queiroz, Frederico Figueiredo Amâncio, Carlos Maurício Antunes, José Roberto Lambertucci
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Medicina Tropical (SBMT)
• Series: Revista da Sociedade Brasileira de Medicina Tropical
• Subjects: Schistosomiasis; Diagnosis; Stool examination; Rapid urine test (POC-CCA); Hepatosplenic schistosomiasis
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0037-86822017002300358&lng=en&tlng=en

Abstract INTRODUCTION: The Kato-Katz technique is the standard diagnostic test for Schistosoma mansoni infection in rural areas. However, the utility of this method is severely limited by the day-to-day variability in host egg excretion in the stool. In high-transmission areas, the point-of-care circulating cathodic antigen (POC-CCA) urine assay has proven to be a reliable test. However, investigations of the reliability of the POC-CCA assay in low-transmission regions are under way. This study aimed to evaluate the sensitivity and specificity of the POC-CCA assay and the morbidity of schistosomiasis in a low-endemic area in Brazil. METHODS: Pains City is a low-transmission zone for schistosomiasis. A total of 300 subjects aged 7-76 years were randomly selected for the POC-CCA cassette test. For S. mansoni diagnosis, three stool samples on six slides were compared with one urine sample for each subject. The sensitivity and specificity in the absence of a gold standard were calculated using latent class analysis. Clinical examinations and abdominal ultrasounds were performed in 181 volunteers to evaluate morbidity associated with schistosomiasis. RESULTS: The sensitivity and specificity of the Kato-Katz technique were 25.6% and 94.6%, respectively. By contrast, the sensitivity and specificity of the POC-CCA assay were 68.1% and 72.8%, respectively. Hepatosplenic schistosomiasis was diagnosed in two patients (1.1%). CONCLUSIONS: Overall, the POC-CCA urine assay proved to be a useful test for diagnosing S. mansoni in a low-endemic area in Brazil. Severe clinical forms of schistosomiasis can be present even in such low-endemic areas.