Comparative Study of the Accuracy of Different Techniques for the Laboratory Diagnosis of Schistosomiasis Mansoni in Areas of Low Endemicity in Barra Mansa City, Rio de Janeiro State, Brazil

Abstract

Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82–95.5%), differed significantly from COPT in positivity (P < 0.05), and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs.

Assessment of a Brazilian public policy intervention to address schistosomiasis in Pernambuco state: the SANAR program, 2011–2014

“…Second, the use of the Kato-Katz method to diagnose schistosomiasis in areas of low endemicity has been questioned. Some authors suggest that more sensitive techniques, such as ELISA, should be used [26]. However, the prolonged presence of reactive IgM after treatment and the death of the worms is a critical problem in evaluating the effectiveness of an intervention.…”

“…The Kato-Katz method was used [25]. This predominant method for detecting S. mansoni eggs is relatively straightforward, inexpensive and highly specific [26–29]. Valid stool samples were those for which the stool quantity was sufficient to allow the sample to be processed via the Kato-Katz method.…”

Serological proteomic screening and evaluation of a recombinant egg antigen for the diagnosis of low-intensity infections in endemic area in Brazil Antigen target in schistosomiasis diagnosis

“…It has been suggested that a diagnostic test with high specificity and sensitivity will be needed for prevention, control and elimination of this disease [7, 12]. Some diagnostic methods have already shown their ability to detect positive individuals missed by parasitological techniques, due to low or absence of egg excretion [13, 14, 19]. Immunoassays based on antigen or antibody detection have been the most studied, due to high sensitivity and ease-of-translation to a format applicable to field settings [60].…”

“…Serum immunoreactivity to schistosome antigens allows detection of infections with loads as low as 1 epg. Even though the antibody-detection methods are currently not the first choice for endemic areas, due to their inability to discriminate current infection from previous exposure, as well as the inability to monitor treatment effectiveness, they have been accepted as a complementary tool during epidemiological survey [13, 19, 34, 62]. One of the difficulties in developing antibody-detection methods is the choice of antigen.…”

“…Methods that can accurately diagnosis the majority of individuals will contribute to the goal of elimination of low-burden transmitters and consequently, in the interruption of the disease transmission. In this regard, molecular and immunological techniques have proven to be more sensitive and promising for identifying infection in infected individuals that are negative by K-K coproscopy results [10, 13, 14, 18-20].…”