Seroepidemiological Survey of Chronic Chagas Disease in a Rural Community in Southern Bahia, Brazil, Using Recombinant Chimeric Antigens

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is a neglected tropical disease with life-threatening implications. In this study, we conducted a seroepidemiological survey to determine the prevalence and clinical profiles of CD in 217 individuals from an impoverished rural community in Southern Bahia, Brazil. The overall prevalence of CD in the studied community was 0.92%, detected through latent class analysis (LCA). Two individuals tested positive for anti-T. cruzi IgG, both being male farmers. One case was a 22-year-old man born in Camamu, with no evidence of congenital transmission, suggesting other routes of transmission such as vector-borne transmission due to migratory activities. The other case was a 69-year-old man born in São Felipe, who had lived in an adobe/brick house and had a pacemaker due to cardiac involvement caused by CD. The prevalence in this community was lower than expected, given the socioeconomic conditions and environmental factors that contribute to T. cruzi transmission. This could be attributed to the implementation of preventive measures and vector control programs by the Brazilian Government. However, continuous monitoring and surveillance are essential to sustain control efforts and detect any potential re-emergence of the disease. While the overall prevalence was low, the detection of positive cases underscores the need for continued surveillance and control measures in vulnerable populations, such as rural communities. Active surveillance, early diagnosis, and timely treatment are crucial in preventing disease progression and complications, thereby enhancing the effectiveness of screening and treatment programs.

Seroepidemiology of Chagas disease in at-risk individuals in Caraíbas, a city with high endemicity in Bahia State, Brazil

Introduction

In Brazil, an estimated 1.1 million people are infected with Trypanosoma cruzi, the causative agent of Chagas disease (CD). Despite the high number of cases, the estimated prevalence of infection per 100 inhabitants is low (0.03). However, the actual number of chronically infected individuals is still unknown. Therefore, we sought to determine the prevalence of chronic CD in at-risk individuals in Caraíbas (Bahia, Brazil) through active case finding.

Methods

A total of 572 individuals living in rural or urban areas of Caraíbas were eligible for the study. A serum sample was collected from 226 individuals, and the diagnosis performed according to international guidelines.

Results

The overall prevalence of anti-T. cruzi IgG was 4.42%. The median age of anti-T. cruzi IgG-positive individuals was 54.5 years, and the female-to-male ratio was 1.5:1. The prevalence of anti-T. cruzi IgG was similar in rural (4.29%) and urban areas (4.65%).

Discussion

Compared with national estimates, we concluded that Caraíbas had a high prevalence for chronic CD and a high risk for persistent transmission. Through our study, it was possible to monitor individuals who were unaware of their clinical condition, thus improving their quality of life.

An RBD-Based Diagnostic Method Useful for the Surveillance of Protective Immunity against SARS-CoV-2 in the Population

After more than two years, the COVID-19 pandemic is still ongoing and evolving all over the world; human herd immunity against SARS-CoV-2 increases either by infection or by unprecedented mass vaccination. A substantial change in population immunity is expected to contribute to the control of transmission. It is essential to monitor the extension and duration of the population’s immunity to support the decisions of health authorities in each region and country, directed to chart the progressive return to normality. For this purpose, the availability of simple and cheap methods to monitor the levels of relevant antibodies in the population is a widespread necessity. Here, we describe the development of an RBD-based ELISA for the detection of specific antibodies in large numbers of samples. The recombinant expression of an RBD-poly-His fragment was carried out using either bacterial or eukaryotic cells in in vitro culture. After affinity chromatography purification, the performance of both recombinant products was compared by ELISA in similar trials. Our results showed that eukaryotic RBD increased the sensitivity of the assay. Interestingly, our results also support a correlation of the eukaryotic RBD-based ELISA with other assays aimed to test for neutralizing antibodies, which suggests that it provides an indication of protective immunity against SARS-CoV-2.

Dengue Fever in Burkina Faso, 2016

We report 1,327 probable cases of dengue in Burkina Faso in 2016. Of 35 serum samples tested by a trioplex test, 19 were confirmed dengue virus (DENV)‒positive: 11 DENV-2, 6 DENV-3, 2 nontypeable, and 1 DENV-2/DENV-3 co-infection. Molecular testing should be conducted to correctly identify causative agents in this complex infectious disease landscape.

Accuracy of GastroPanel for the diagnosis of atrophic gastritis

BACKGROUND

It has been suggested that GastroPanel might be a useful tool for the diagnosis of chronic atrophic gastritis (CAG) measuring four biomarkers in blood: basal gastrin-17 (G17), pepsinogen I and II (PGI and PGII), and Helicobacter pylori antibodies.

AIM

To determine the accuracy of GastroPanel for the diagnosis of CAG.

METHODS

This was a prospective, blinded, multicenter study that included dyspeptic patients. G17, PGI, and PGII were determined by enzyme immunoassays. Three antrum and two corpus biopsies were obtained for standard histological analysis and rapid urease test. Biopsies were analyzed by a single blinded expert pathologist.

RESULTS

Ninety-one patients were included (77% women, mean age 44 years, 51% H. pylori positive, 17% with CAG). G17 was reduced in patients with antrum CAG (5.4 vs. 13.4 pmol/l; P<0.01) and increased in patients with corpus CAG (11 vs. 24 pmol/l; P<0.05), but its accuracy was only acceptable in the case of corpus localization [area under the receiver operating characteristic curve (AUC), 74%]; PGII difference was almost statistically significant only when testing for corpus atrophy (33 vs. 21 μg/l; P=0.05; AUC=72%). The PGI and PGI/PGII ratio showed no significant differences (AUCs were all unacceptably low). Helicobacter pylori antibody levels were higher in H. pylori-infected patients (251 vs. 109 EIU, P=0.01; AUC=70). The accuracy of GastroPanel for the diagnosis of CAG was as follows: sensitivity 50%; specificity 80%; positive 25% and negative 92% predictive values; and positive 2.4 and negative 0.6 likelihood ratios.

CONCLUSION

GastroPanel is not accurate enough for the diagnosis of CAG; thus, its systematic use in clinical practice cannot be recommended.

A case of mucocutaneous leishmaniasis diagnosed by serology

A 43-year-old Japanese Bolivian male had been suffering from a right leg ulcer after an insect bite during his residence in Bolivia. The ulcer healed after herbal medicine treatment. Ten years later, the patient had symptoms of nasal obstruction, nasal bleeding, and pharyngodynia, which were accompanied by a destructive ulcer with surrounding erythema involving the right nostril apex and columella. Papillary, irregular mucosal lesions were seen on the soft palate. Giemsa staining and polymerase chain reaction (PCR) using biopsy specimens of the papillary mucosal lesions on the soft palate failed to identify Leishmania parasites. However, the IgG antibody test was positive for Leishmania (Leishmania) donovani, and the dot enzyme-linked immunosorbent assay (dot-ELISA) using five Leishmania antigens L. (L.) mexicana, L. (L.) amazonensis, Leishmania (Viannia) guyanensis, L. (V.) braziliensis, and L. (V.) panamensis was positive. Combined, the findings suggested mucocutaneous leishmaniasis. Treatment with liposomal amphotericin B was started but was soon terminated because of palpitation, epigastralgia and facial flushing. It is sometimes difficult to identify the parasites in lesions of mucocutaneous leishmaniasis and serological tests are useful for such occasions.

Alloimmune neonatal neutropenia in Croatia during the 1998-2008 period

PROBLEM

The aim of this study was to estimate the incidence of the disease and to analyze laboratory data of 23 newborns undergoing serologic testing for alloimmune neonatal neutropenia (ANN) during the 1998-2008 period in Croatia.

METHOD OF STUDY

Laboratory data on 23 newborns undergoing serologic testing for ANN during the 1998-2008 period and epidemiologic data on the number of live births in Croatia were analyzed. Laboratory testing for ANN included serologic screening of maternal and neonatal sera and granulocytes (neutrophils) by immunofluorescence (IF) method. The monoclonal antibody immobilization of neutrophil antigens (MAINA) was employed to determine anti-HNA antibody specificity.

RESULTS

Anti-HNA antibodies were detected in seven (54%) of 13 cases of serologically positive ANN. Only anti-HLA class I antibodies were demonstrated in four (31%) of 13 cases In the 2007-2008 period of prospective data collection, the number of serologically verified ANN cases was one case per 17,323 live births. Results of the prospective study conducted at Maternity Ward, Department of Gynecology and Obstetrics, Sestre milosrdnice University Hospital Center yielded the ANN incidence of one case per 2843 live births.

CONCLUSION

Monitoring of neutrophil count in neonatal blood and serologic testing for ANN in case of isolated neutropenia in the newborn contributed considerably to timely detection of ANN.

DESCRIPTORS

Neonatal alloimmune neutropenia-incidence, serologic diagnosis, antineutrophil antibodies, anti-HNA, anti-HLA class I, Croatia.

A comparison of immuncapture agglutination and ELISA methods in serological diagnosis of brucellosis

BACKGROUND

Different serological tests are used in serologic diagnosis of brucellosis. The most widely used of these are Standard Tube Agglutination and Coombs anti-brucella tests. Whereas ELISA Ig M and Ig G tests have been in use for a long time, immuncapture agglutination test has been recently introduced and used in serological diagnosis. The aim of this study was to compare diagnostic values of ELISA Ig M and Ig G and immuncapture agglutination tests with Coombs anti-brucella test.

METHODS

Sera from 200 patients with presumptive diagnosis of brucellosis were included into the study. Coombs anti-brucella test, ELISA Ig M and Ig G tests and Immuncapture test were investigated in these sera. Then, sensitivity, specificity, negative predictive and positive predictive values were calculated.

RESULTS

Sensitivity, specificity, negative predictive and positive predictive values were found to be 90.6%, 76.3%, 94.2%, and 65.9% respectively for the Immuncapture test, whereas they were found to be 73.7%, 58.9%, 84.2%, and 42.8% for Ig G and 72.2%, 67.8%, 85.2%, and 48.7% for Ig M. The Immuncapture test was found to be compatible with ELISA Ig M and Ig G tests but it was statistically incompatible with Coombs anti-brucella test.

CONCLUSIONS

Immuncapture agglutination test yields similar results to those of Coombs anti-brucella test. This test is a useful test by virtue of the fact that it determines blocking antibodies in the diagnosis and follow-up of brucellosis.