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Additional Evaluation of the Point-of-Contact Circulating Cathodic Antigen Assay for Schistosoma mansoni Infection.

Mwinzi, PN; Kittur, N; Ochola, E; Cooper, PJ; Campbell, CH; King, CH; Colley, DG (2015) Additional Evaluation of the Point-of-Contact Circulating Cathodic Antigen Assay for Schistosoma mansoni Infection. Front Public Health, 3. ISSN 2296-2565
SGUL Authors: Cooper, Philip John

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Studies of the urine-based point-of-contact cathodic circulating antigen test (POC-CCA) in Schistosoma mansoni-endemic settings in Africa indicate it has good sensitivity in detecting infections, but in areas of low prevalence, the POC-CCA can be positive for persons who are egg-negative by Kato-Katz stool assays. We examined the POC-CCA assay for: (a) batch-to-batch stability; (b) intra-reader and inter-reader variability; (c) day-to-day variability compared to Kato-Katz stool assays, and (d) to see if praziquantel (PZQ) treatment converted Kato-Katz-negative/POC-CCA positive individuals to POC-CCA negativity. We found essentially no batch-to-batch variation, negligible intra-reader variability (2%), and substantial agreement for inter-reader reliability. Some day-to-day variation was observed over 5 days of urine collection, but less than the variation in Kato-Katz stool assays over 3 days. To evaluate the effect of treatment on Kato-Katz(-)/POC-CCA(+) children, 149 children in an area of 10-15% prevalence who were Kato-Katz(-) based on 3 stool samples but POC-CCA(+) were enrolled. Seven days after treatment (PZQ 40 mg/kg) samples were again collected and tested. Almost half (47%) POC-CCA positive children turned negative. Those still POC-CCA positive received a second treatment, and 34% of them turned POC-CCA negative upon this second treatment. Most who remained POC-CCA positive shifted each time to a "lesser" POC-CCA "level of positivity." The data suggest that most Kato-Katz-negative/POC-CCA positive individuals harbor low-intensity infections, and each treatment kills all or some of their adult worms. The data also suggest that when evaluated by a more sensitive assay, the effective cure rates for PZQ are significantly less than those inferred from fecal testing. These findings have public health significance for the mapping and monitoring of Schistosoma infections and in planning the transition from schistosomiasis morbidity control to elimination of transmission.

Item Type: Article
Additional Information: Copyright: © 2015 Mwinzi, Kittur, Ochola, Cooper, Campbell, King and Colley. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Keywords: Kato-Katz, POC-CCA, Schistosoma mansoni, diagnosis, praziquantel, schistosomiasis
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: Front Public Health
Article Number: 48
ISSN: 2296-2565
Language: eng
19 March 2015Published
Publisher License: Creative Commons: Attribution 4.0
PubMed ID: 25853117
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