Introduction The World Health Organisation (WHO) estimates there are 7 13 600 to 1,575,000 cases of congenital syphilis worldwide annually. Congenital syphilis can lead to several health conditions at birth. Currently there is no rapid point of care test available for its diagnosis.Here we introduce a novel rapid point of care test for congenital syphilis. The objective of this test includes the ability to test whole blood or serum taken from the infant or cord blood while blocking the mother’s IgG antibodies.
Methods Thirty-four (34) syphilis positive and negative gestational serum samples and five (5) positive congenital syphilis samples, were obtained from University of Connecticut Health Centre. Twenty-two (22) samples were RPR reactive. Chembio DPP Syphilis IgG and IgM test devices were obtained from the manufacturer. The required number of IgG and IgM devices were modified at the CDC to include an IgG blocker in the device to produce four different assay devices used for this study. Each serum sample was tested in the four separate devices. Results were reported based on the patterns observed in the assay windows.
Results All (17/17) the RPR positive gestational samples were positive (100%),and 5 of 5 congenital positive samples were positive (100%) using the IgM device with IgG blocking agent. Only 5/17 of gestational samples (29.4%) and 1/5 congenital samples (20%) were positive using the IgM device without IgG blocking agent. For the IgG device with the IgG blocking agent all samples were negative. The IgG device without the blocking reagent resulted in the detection of 19/22 (86.4%) of the RPR positive samples. With the exception of one sample all negative samples were negative by all 4 test devices.
Conclusion Only a limited number of positive and negative gestational and congenital syphilis samples were evaluated in this study, due to the short supply of such rare samples. It is apparent from this limited data that by blocking the mother’s IgG an increase in sensitivity can be achieved. More in depth studies are necessary in order to prove the concept.
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