Evaluation of a novel kit (TF‐Test) for the diagnosis of intestinal parasitic infections

Abstract

Intestinal parasitic infections are currently a source of concern for Public Health agencies in developing and developed countries. Since three ovum-and-parasite stool examinations have been demonstrated to provide sensitive results, we designed a practical and economical kit (TF-Test) that is now commercially available (Immunoassay Com. Ind. Ltda., São Paulo, Brazil). This kit allows the separate collection of three fecal specimens into a preservative solution. The specimens are then pooled, double-filtered, and concentrated by a single rapid centrifugation process. The TF-Test was evaluated in four different laboratories in a study using 1,102 outpatients and individuals living in an endemic area for enteroparasitosis. The overall sensitivity found using the TF-Test (86.2-97.8%) was significantly higher (P<0.01) than the sensitivity of conventional techniques such as the Coprotest (NL Comércio Exterior Ltda, São Paulo, Brazil) and the combination of Lutz/Hoffman, Faust, and Rugai techniques (De Carli, Diagnóstico Laboratorial das Parasitoses Humanas. Métodos e Técnicas, 1994), which ranged from 48.3% to 75.9%. When the above combined three specimen technique was repeated with three specimens collected on different days, its sensitivity became similar (P>0.01) to that of the TF-Test. The kappa index values of agreement for the TF-Test were consistent (P<0.01), being higher and ranking in a better position than conventional techniques. The high sensitivity, cost/benefit ratio, and practical aspects demonstrate that the TF-Test is suitable for individual diagnosis, epidemiological inquiries, or evaluation of chemotherapy in treated communities.

Evaluation of two coproscopic techniques for the diagnosis of schistosomiasis in a low-transmission area in the state of Minas Gerais, Brazil

“…According to Gomes et al (2004), the TF-Test ® technique presents comparable results to the Kato-Katz method in cases of high worm burden. These authors further described that in cases of low worm burden, the positivity was higher using the TF-Test ® than the KatoKatz method.…”

“…In the first experiment, the three tubes containing the samples collected from consecutive days were connected to the centrifuge tube and centrifuged at 500 g for 2 min. The supernatant was discarded and the total sediment was re-suspended in 0.85% saline solution and analysed using optical microscopy (Gomes et al 2004) (Fig. 2).…”

Predicting frequency distribution and influence of sociodemographic and behavioral risk factors of Schistosoma mansoni infection and analysis of co-infection with intestinal parasites

“…The total number of study subjects included 570 individuals proportionally distributed between the four localities that compose the municipality of Ilha das Flores. Stool samples were collected from each member of the household and microscopic examination was performed using two methods: i) two slides from a single stool sample were quantitatively examined according to Kato-Katz et al (1972); and ii) in order to increase the sensitivity and to see protozoa, the three-fecal-test qualitative method (Gomes et al, 2004) was used. This test is based on microscopic examination of three pooled fecal samples collected on three different days and preserved in formalin.…”

Diagnosing schistosomiasis: where are we?

“…The development of other coproscopical techniques based on sedimentation [14][15][16][17] , centrifugation 18,19 , fluctuation 20 and miracidium hatching 21,22 , may constitute alternatives to the Kato Katz technique. In general, these methods provide better sensitivity but are more laborious, being more useful for research, schistosomiasis diagnosis in travelers and as additional diagnostic tools for in the depth analysis of infection rates before and after treatment.…”