Discrepancies and consequences of indirect hemagglutination, indirect immunofluorescence and Elisa tests for the diagnosis of Chagas disease

Using the indirect hemagglutination (IH), indirect immunofluorescence (IIF) and enzyme linked immunosorbent assay (ELISA) tests for the diagnosis of Chagas disease, 4000 serum samples were examined. This study was conducted with different purposes: clinical interest, research support and parasitological monitoring of those patients with Chagas disease who were treated with heart transplantations. The tests occurred without patient selection and in accordance with the medical requests. The results showed discrepancies and brought about several questions, considering the different results that all three methods showed when considered together. What was found brought about concerns and we suggest the adoption of different measures, aiming to avoid these mismatches in the context of this disease.

PREVALENCE OF PARACOCCIDIOIDOMYCOSIS INFECTION BY INTRADERMAL REACTION IN RURAL AREAS IN ALFENAS, MINAS GERAIS, BRAZIL

This study aimed to estimate the prevalence of paracoccidioidal infection by intradermal reaction (Delayed-Type Hypersensitivity, DTH) to Paracoccidioides brasiliensis in rural areas in Alfenas, Southern Minas Gerais (MG) State, Brazil, and to assess risk factors (gender, occupation, age, alcohol intake and smoking) associated with infection. We conducted a population-based cross-sectional study using intradermal tests with gp 43 paracoccidioidin in 542 participants, who were previously contacted by local health agents and so spontaneously attended the test. Participants underwent an interview by filling out a registration form with epidemiological data and were tested with an intradermal administration of 0.1 mL of paracoccidioidin in the left forearm. The test was read 48 hours after injection and was considered positive if induration was greater than or equal to 5 mm. Out of 542 participants, 46.67% were positive to the skin test. Prevalence increased in accordance with an increase of age. There was statistical significance only for males. Occupation, alcohol intake and smoking habits were not significantly associated with the risk of paracoccidioidomycosis infection. There is relevance of paracoccidioidomycosis infection in such rural areas, which suggests that further epidemiological and clinical studies on this mycosis should be done in the southern part of Minas Gerais State.

The avirulence of the cultivated PF strain of Trypanosoma cruzi: V - the evaluation of parasitologic tests after vaccination of different animal species

After vaccination with the live PF strain of Trypanosoma cruzi, 194 blood cultures were performed in 143 mice, 9 dogs, 5 Cebus monkeys and 7 human subjects. Some of these blood cultures were simultaneously done with xenodiagnosis, subinoculation in baby mice and/or culture of viscerae. The trypanosomes isolated from the few positive cases (6,1%) were incapable of infecting baby mice were considered as cases of immunotolerance. All the other tests were negative.

Longitudinal study of the indirect immunofluorescence and complement fixation tests for diagnosis of chagas' disease in immunosuppressed patients submitted to renal transplantation

Clinical and serological follow-up of 7 patients submitted to renal transplantation and presenting positive serological reactions to Chagas 'disease before immunossupression did not show significant changes in indirect immunofluorescence and complement fixation titres for Chagas ' disease, or signs and symptoms indicating exacerbation of the disease during follow- up. In addition, 18 of 66 recipients of renal transplants considered to be non-chagasic before immunosuppression showed at least one positive result to the indirect immunofluorescence test for Chagas ' disease during the study period. The results suggest that the immunosuppression State induced in chagasic patients submitted to renal transplant did notpromoted exacerbation of the chronic infection in these patients and not interfere with the serological response of chronic chagasics, thus permitting the use of these serologic reactions for diagnostic purposes in these cases. However, the positive results ofthe indirect immunofluorescence test in non- chagasic patients indicate the needforjudicious interpretation ofthe indirect immunofluorescence test for the diagnosis of Chagas' disease in renal transplanted patients.

Diagnostic tests for amoebic liver abscess: comparison of enzyme - linked immunosorbent assay (Elisa) and counterimmunoelectrophoresis (CIE)

The liver abscess is the most frequent extraintestinal complication of intestinal amoebiasis: its diagnosis is suggested by the clinical picture but it must be confirmed by paraclinic tests. Themost stringent diagnosis requires identification of E. histolytica. But this is possible only in a few cases. Serological tests greatly improve the diagnosis of this severe complication of amoebiasis. We compared the Enzyme Linfed Immunosorbent Assay and the Counterimmunoeletrophoresis techniques. Both techniques were used to detect amoebic antibodies in 50 control patients, 30 patients with liver abscess and 30 patients with intestinal amoebiasis. All the sera from control patients gave negative results iin both techniques. When analysing the sera from patients with intestinal amoebiasis, 10% of them were positive by ELISA but non by CIE. The sera of patients with liver abscess, we found that 90% were positive by the ELISA method and 66.6% by the CIE technique. In patients with amoebic liver abscess, the results showed that the ELISA was more sensitive than the CIE, as it presented a higher sensitivity (100%) than that of the CIE technique (66%).

Parotid enlargement due to adenovirus infection in patient with human immunodeficiency virus infection

The authors report a case of adenovirus- induced enlargement of the parotid gland involving a patient infected with human immunodeficiency virus (HIV). Physical examination revealed good general condition, no fever and bilateral enlargement of the parotid region, which was of increased consistency and slightly tender to palpation. Histological examination of the parotid gland demonstrated a slight periductal lymphomononuclear inflammatory infiltrate with the presence of focal points of necrosis. Tests to determine the presence of fungi and alcohol-acid resistent bacilli were negative. Immunohistochemistry for cytomegalovirus, heipes simplex, HIV p24 antigen and adenovirus showed positivity only for adenovirus in the epithelial nuclei of numerous gland ducts. Tins is the third case of this type reported in the literature, indicating the importance of including adenovirus in the differential diagnosis of this condition.

Assessment of chemiluminescence and PCR effectiveness in relation to conventional serological tests for the diagnosis of Chagas' disease

While testing 414 sera for the diagnosis of Chagas' disease, the conventional reactions of indirect hemagglutination, indirect immunofluorescence and the immunosorbent assay showed a sensitivity of 95.7%, 100% and 98.2% and a specificity of 98%, 98% and 96.4%, respectively, and an excellent association using Fisher's exact test. Chemiluminescence presented 100% sensitivity and 89.6% specificity, while PCR showed 100% specificity and 1.2% sensitivity. It is believed that the three conventional serological reactions are still adequate for diagnosing Chagas' disease.

International meeting: new diagnostic tests are urgently needed to treat patients with Chagas disease

Trypanosoma cruzi infection is often not detected early on or actively diagnosed, partly because most infected individuals are either asymptomatic or oligosymptomatic. Moreover, in most places, neither blood banks nor healthcare units offer diagnostic confirmation or treatment access. By the time patients present clinical manifestations of advanced chronic Chagas disease, specific treatment with current drugs usually has limited effectiveness. Better-quality serological assays are urgently needed, especially rapid diagnostic tests for diagnosis patients in both acute and chronic phases, as well as for confirming that a parasitological cure has been achieved. Some new antigen combinations look promising and it is important to assess which ones are potentially the best, together with their requirements in terms of investigation and development. In August 2007, a group of specialized researchers and healthcare professionals met to discuss the state of Chagas infection diagnosis and to build a consensus for a plan of action to develop efficient, affordable, accessible and easy-to-use diagnostic tests for Chagas disease. This technical report presents the conclusions from that meeting.

Contributions of culture and antimicrobial susceptibility tests to the retreatment of patients with pulmonary tuberculosis

Introduction This study evaluated the efficacy of retreatment of pulmonary tuberculosis (TB) with regard to treatment outcomes and antimicrobial susceptibility testing (ST) profiles. Methods This retrospective cohort study analyzed 144 patients treated at a referral hospital in Brazil. All of them had undergone prior treatment, were smear-positive for TB and received a standardized retreatment regimen. Fisher's 2-tailed exact test and the χ2 test were used; RRs and 95% CIs were calculated using univariate and multivariate binary logistic regression. Results The patients were cured in 84 (58.3%) cases. Failure was associated with relapsed treatment and abandonment (n=34). Culture tests were obtained for 103 (71.5%) cases; 70 (48.6%) had positive results. ST results were available for 67 (46.5%) cases; the prevalence of acquired resistance was 53.7%. There were no significant differences between those who achieved or not therapeutic success (p=0.988), despite being sensitive or resistant to 1 or more drugs. Rifampicin resistance was independently associated with therapeutic failure (OR: 4.4, 95% CI:1.12-17.37, p=0.034). For those cases in which cultures were unavailable, a 2nd model without this information was built. In this, return after abandonment was significantly associated with retreatment failure (OR: 3.59, 95% CI:1.17-11.06, p=0.026). Conclusions In this cohort, the general resistance profile appeared to have no influence on treatment outcome, except in cases of rifampicin resistance. The form of reentry was another independent predictor of failure. The use of bacterial culture identification and ST in TB management must be re-evaluated. The recommendations for different susceptibility profiles must also be improved.

Serological cross-reactivity of Trypanosoma cruzi, Ehrlichia canis, Toxoplasma gondii, Neospora caninum and Babesia canis to Leishmania infantum chagasi tests in dogs

Introduction: The aim of this study was to evaluate the serological cross-reactivity between Leishmania sp. and other canine pathogens. Methods: Positive serum samples for Ehrlichia canis, Babesia canis, Toxoplasma gondii, Neospora caninum and Trypanosoma cruzi were tested using three serological methods enzyme linked immunosorbent assay (ELISA), indirect immunofluorescent antibody test (IFAT) and Kalazar Detect™, for canine visceral leishmaniasis. Results: Of the 57 dog samples tested, 24 (42.1%) tested positive using one of the three serological methods: 10/57 (17.5%) for ELISA, 11/57 (19.3%) for IFAT and 3/57 (5.3%) for Kalazar Detect™. Conclusions: Our results demonstrated that the presence of other infectious agents may lead to cross-reactivity on leishmaniasis serological tests.

Depressive symptoms and harmful alcohol use in hepatitis C patients: prevalence and correlates

Introduction It is important to understand the characteristics and vulnerabilities of people who have hepatitis C because this disease is currently an important public health problem. The objective of this study was to estimate the prevalence of depressive symptoms and harmful alcohol use in patients with hepatitis C and to study the association between these outcomes and demographic, psychosocial and clinical variables. Methods This cross-sectional, descriptive and analytical study involved 82 hepatitis C patients who were being treated with pegylated interferon and ribavirin at a public university hospital. The primary assessments used in the study were the Alcohol Use Disorders Identification Test and the Beck Depression Inventory. Bivariate analyses were followed by logistic regression. Results The prevalence of depressive symptoms was 30.5% (n=25), and that of harmful alcohol use was 34.2% (n=28). Logistic regression analysis showed that individuals who were dissatisfied with their social support (OR=4.41; CI=1.00-19.33) and were unemployed (OR=6.31; CI=1.44-27.70) were at a higher risk for depressive symptoms, whereas harmful alcohol use was associated with the male sex (OR=6.78; CI=1.38-33.19) and the use of illicit substances (OR=7.42; CI=1.12-49.00). Conclusions High prevalence rates of depressive symptoms and harmful alcohol use were verified, indicating vulnerabilities that must be properly monitored and treated to reduce emotional suffering in this population.

Hybrid capture II and PapilloCheck® tests for detection of anal high-risk human papillomavirus

Introduction This study evaluated the level of concordance between hybrid capture II (HCII) and PapilloCheck® for the detection of high-risk human papillomavirus (HPV) in anal samples. Methods Anal cell samples collected from 42 human immunodeficiency virus (HIV)+ patients were analyzed. Results Considering only the 13 high-risk HPV types that are detectable by both tests, HCII was positive for 52.3% of the samples, and PapilloCheck® was positive for 52.3%. The level of concordance was 80.9% (Kappa = 0.61). Conclusions Good concordance was observed between the tests for the detection of high-risk HPV.

Evaluation of diagnostic tests for Wuchereria bancrofti infection in Brazilian schoolchildren

Introduction Since the launch of the Global Programme to Eliminate Lymphatic Filariasis, more than 70% of the endemic countries have implemented mass drug administration (MDA) to interrupt disease transmission. The monitoring of filarial infection in sentinel populations, particularly schoolchildren, is recommended to assess the impact of MDA. A key issue is choosing the appropriate tools for these initial assessments (to define the best intervention) and for monitoring transmission. Methods This study compared the pre-MDA performance of five diagnostic methods, namely, thick film test, Knott's technique, filtration, Og4C3-ELISA, and the AD12-ICT card test, in schoolchildren from Brazil. Venous and capillary blood samples were collected between 11 pm and 1 am. The microfilarial loads were analyzed with a negative binomial regression, and the prevalence and associated 95% confidence intervals were estimated for all methods. The accuracies of the AD12-ICT card and Og4C3-ELISA tests were assessed against the combination of parasitological test results. Results A total of 805 schoolchildren were examined. The overall and stratified prevalence by age group and gender detected by Og4C3-ELISA and AD12-ICT were markedly higher than the prevalence estimated by the parasitological methods. The sensitivity of the AD12-ICT card and Og4C3-ELISA tests was approximately 100%, and the positive likelihood ratios were above 6. The specificity of the Og4C3-ELISA was higher than that of the AD12-ICT at different prevalence levels. Conclusions The ICT card test should be the recommended tool for monitoring school-age populations living in areas with ongoing or completed MDA.

Histological and endoscopic features of the stomachs of patients with Chagas disease in the era of Helicobacter pylori

Introduction Most studies that have evaluated the stomachs of patients with Chagas disease were performed before the discovery of Helicobacter pylori and used no control groups. This study compared the gastric features of chagasic and non-chagasic patients and assessed whether gastritis could be associated with Chagas disease. Methods Gastric biopsy samples were taken from patients who underwent endoscopy for histological analysis according to the Updated Sydney System. H. pylori infection was assessed by histology, 16S ribosomal ribonucleic acid (rRNA) polymerase chain reaction (PCR), serology and the 13C-urea breath test. Patients were considered H. pylori-negative when all of these diagnostic tests were negative. Clinical and socio-demographic data were obtained by reviewing medical records and using a questionnaire. Results The prevalence of H. pylori infection (70.3% versus 71.7%) and chronic gastritis (92.2% versus 85%) was similar in the chagasic and non-chagasic groups, respectively; such as peptic ulcer, atrophy and intestinal metaplasia. Gastritis was associated with H. pylori infection independent of Chagas disease in a log-binomial regression model. However, the chagasic H. pylori-negative patients showed a significantly higher grade of mononuclear (in the corpus) and polymorphonuclear (PMN) (in the antrum) cell infiltration. Additionally, the patients with the digestive form of Chagas disease showed a significantly lower prevalence of corpus atrophy than those with other clinical forms. Conclusions The prevalence of H. pylori infection and of gastric histological and endoscopic features was similar among the chagasic and non-chagasic patients. Additionally, this is the first controlled study to demonstrate that H. pylori is the major cause of gastritis in patients with Chagas disease.

Comparison of recombinant A2-ELISA with rKE16 dipstick and direct agglutination tests for diagnosis of visceral leishmaniasis in dogs in Northwestern Iran

INTRODUCTION: Various methods are used for the diagnosis of visceral leishmaniasis (VL), such as microscopic examination, culture and inoculation of laboratory animals; however, serological assays are commonly used for the detection of antibodies in serum samples with a wide range of specificity and sensitivity. METHODS: The purpose of this study was to compare three serological methods, including rA2-ELISA, the recombinant KE16 (rKE16) dipstick test and the direct agglutination test (DAT), for the detection of antibodies against VL antigens. The assays utilized 350 statistically based random serum samples from domestic dogs with clinical symptoms as well as samples from asymptomatic and healthy dogs from rural and urban areas of the Meshkinshahr district, northwestern Iran. RESULTS: Samples were assessed, and the following positive rates were obtained: 11.5% by rKE16, 26.9% by DAT and 49.8% by ELISA. The sensitivity among symptomatic dogs was 32.4% with rKE16, 100% with DAT and 52.9% with ELISA. Conversely, rA2-ELISA was less specific for asymptomatic dogs, at 46.5%, compared with DAT, at 88.9%. CONCLUSIONS : This study recommends rA2-ELISA as a parallel assay combined with DAT to detect VL infection among dogs. Further evaluations should be performed to develop an inexpensive and reliable serologic test for the detection of Leishmania infantum among infected dogs.