Cimino RO

Date: 
10/02/2015
Investigation Line: 

Abstract

BACKGROUND:

Traditional faecal-based methods have poor sensitivity for the detection of S. stercoralis, therefore are inadequate for post-treatment evaluation of infected patients who should be carefully monitored to exclude the persistence of the infection. In a previous study, we demonstrated high accuracy of five serology tests for the screening and diagnosis of strongyloidiasis. Aim of this study is to evaluate the performance of the same five tests for the follow up of patients infected with S. stercoralis.

METHODS:

Retrospective study on anonymized, cryo-preserved samples available at the Centre for Tropical Diseases (Negrar, Verona, Italy). Samples were collected before and from 3 to 12 months after treatment. The samples were tested with two commercially-available ELISA tests (IVD, Bordier), two techniques based on a recombinant antigen (NIE-ELISA and NIE-LIPS) and one in-house IFAT. The results of each test were evaluated both in relation to the results of fecal examination and to those of a composite reference standard (classifying as positive a sample with positive stools and/or at least three positive serology tests). The associations between the independent variables age and time and the dependent variable value of serological test (for all five tests), were analyzed by linear mixed-effects regression model.

RESULTS:

A high proportion of samples demonstrated for each test a seroreversion or a relevant decline (optical density/relative light units halved or decrease of at least two titers for IFAT) at follow up, results confirmed by the linear mixed effects model that showed a trend to seroreversion over time for all tests. In particular, IVD-ELISA (almost 90% samples demonstrated relevant decline) and IFAT (almost 87%) had the best performance. Considering only samples with a complete negativization, NIE-ELISA showed the best performance (72.5% seroreversion).

CONCLUSIONS:

Serology is useful for the follow up of patients infected with S. stercoralis and determining test of cure.

Date: 
09/01/2014
Investigation Line: 

Abstract

BACKGROUND:

The diagnosis of Strongyloides stercoralis (S. stercoralis) infection is hampered by the suboptimal sensitivity of fecal-based tests. Serological methods are believed to be more sensitive, although assessing their accuracy is difficult because of the lack of sensitivity of a fecal-based reference ("gold") standard.

METHODS:

The sensitivity and specificity of 5 serologic tests for S. stercoralis (in-house IFAT, NIE-ELISA and NIE-LIPS and the commercially available Bordier-ELISA and IVD-ELISA) were assessed on 399 cryopreserved serum samples. Accuracy was measured using fecal results as the primary reference standard, but also using a composite reference standard (based on a combination of tests).

RESULTS:

According to the latter standard, the most sensitive test was IFAT, with 94.6% sensitivity (91.2-96.9), followed by IVD-ELISA (92.3%, 87.7-96.9). The most specific test was NIE-LIPS, with specificity 99.6% (98.9-100), followed by IVD-ELISA (97.4%, 95.5-99.3). NIE-LIPS did not cross-react with any of the specimens from subjects with other parasitic infections. NIE-LIPS and the two commercial ELISAs approach 100% specificity at a cut off level that maintains ≥70% sensitivity.

CONCLUSIONS:

NIE-LIPS is the most accurate serologic test for the diagnosis of S. stercoralis infection. IFAT and each of the ELISA tests are sufficiently accurate, above a given cut off, for diagnosis, prevalence studies and inclusion in clinical trials.

Date: 
01/07/2012
Investigation Line: 

Abstract

We evaluated the recombinant antigen SAPA (Shed Acute Phase Antigen) for the detection of Trypanosoma cruzi antibodies in sera from naturally infected dogs. The technique used was ELISA and the antigens were a homogenate of parasite T. cruzi (ELISA-H) and the recombinant SAPA (ELISA-SAPA). We analyzed 93 sera from dogs by ELISA-H and ELISA-SAPA, which were grouped as follows: G1: 11 negative control sera from the city of Salta, G2: 11 positive control sera from dogs naturally infected with T. cruzi and G3: 71 samples of dogs belonging to a Chagas disease-endemic area. The sensitivity and specificity of ELISA-SAPA were 100 %. The kappa index between ELISA-H and ELISA-SAPA was 0,85. These results confirm the use of SAPA antigen in the diagnosis of infection with T. cruzi in dogs.

Date: 
01/09/2012
Investigation Line: 

Abstract

The biological behavior of the different Trypanosoma cruzi strains is still unclear and the importance of exploring the relevance of these differences in natural isolates is of great significance. Herein we describe the biological behavior of four T. cruzi isolates circulating sympatrically in a restricted geographic area in Argentina endemic for Chagas Disease. These isolates were characterized as belonging to the Discrete Typing Units (DTUs) TcI, TcIII, TcV and TcVI as shown by Multilocus Enzyme Electrophoresis and Multilocus Sequence Typing. In order to study the natural behavior of the different isolates and to preserve their natural properties, we developed a vector transmission model that allows their maintenance in the laboratory. The model consisted of serial passages of these parasites between insect vectors and mice. Vector-derived parasite forms were then inoculated in C57BL/6J mice and number of parasite in peripheral blood, serological response and histological damage in acute and chronic phases of the infection were measured. Parasites from DTUs TcI, TcIII and TcVI were detected by direct fresh blood examination, while TcV parasites could only be detected by Polimerase Chain Reaction. No significant difference in the anti-T. cruzi antibody response was found during the chronic phase of infection, except for mice infected with TcV parasites where no antibodies could be detected. Histological sections showed that TcI isolate produced more damage in skeletal muscle while TcVI induced more inflammation in the heart. This work shows differential biological behavior among different parasite isolates obtained from the same cycle of transmission, permitting the opportunity to formulate future hypotheses of clinical and epidemiological importance.

Date: 
01/11/2004
Investigation Line: 

Abstract

We studied the seroprevalence of antibodies against Trypanosoma cruzi in the human population along with domiciliary infestation by triatomine bugs in an area endemic for Chagas disease in the Chaco Province of Argentina. In addition, we carried out parasitologic surveys in patients, dogs, wild mammals, and vectors. The mean seroprevalence in humans was 27.81% (109 of 392) and 24.14% (63 of 261) in 1-15-year-old children. The minimum domiciliary infestation rate was 13.33%, with certain areas reaching 53.85%. The prevalence was 15.09% (16 of 106) in dogs and 35.71% (10 of 28) in opossums. Infection with T. cruzi was detected in 30.10% (59 of 196) of the Triatoma infestans tested. Compared with nationwide studies, our data suggest that 1) there are zones requiring immediate sanitary action, and 2) nationwide estimates are based on very heterogeneous epidemiologic situations. This heterogeneity emphasizes the importance of in-depth studies of restricted areas to provide additional information for a better understanding of the present status of Chagas disease in Argentina.

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