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PubMed1999

Accuracy of four commercially available serologic tests, including two office-based tests and a commercially available 13C urea breath test, for diagnosis of Helicobacter pylori.

BACKGROUND: Diagnosis of H. pylori infection may be made by endoscopic (invasive) tests, or by nonendoscopic (noninvasive) tests. Our aim was to evaluate recently available nonendoscopic tests, including two office-based serologic tests and a commercially available 13C urea breath test. METHODS: Gastric biopsy specimens (for culture and stain) from 178 patients (mean age 46 +/- 13.3 years, 79 men and 99 women), none of whom had received anti-H. pylori therapy, were tested for H. pylori infection. These tests were compared against two commercial serum IgG antibody immunoassays (Biowhittaker's Pyloristat, and Quidel), 2 office-based serum qualitative IgG antibody tests (FlexSure HP, and QuickVue One-Step), the Meretek 13C urea breath test, and the CLOtest (a biopsy urease test). RESULTS: The breath test (n = 147) had the best accuracy (96%) of the noninvasive tests studied. The serologic tests had similar accuracy to one another (84%-90%). The major drawback of the serologic tests was suboptimal specificity (75%-87%). Diagnosis of H. pylori based on the two office-based tests were not significantly different compared to the quantitative IgG antibody tests. The CLOtest had an accuracy of 97%. CONCLUSIONS: The Meretek 13C urea breath test is an excellent test, but is considerably more expensive than serologic tests. The FlexSure HP and the QuickVue One-Step office-based qualitative IgG serologic antibody tests gave similar results to laboratory based quantitative antibody tests, and are acceptable for initial diagnosis of H. pylori infection. The advantages of the office-based tests are low cost, simplicity, and immediacy of results.

Adult↗
PubMed2006

Schistosomiasis in Swedish travellers to sub-Saharan Africa: Can we rely on serology?

In the absence of egg excretion, laboratory diagnosis of recently acquired schistosomiasis is dependent on serology. 42 of 83 Swedish adventure tourists to sub-Saharan Africa had serum anti-schistosome antibodies indicating recent infection. There is little doubt regarding the specificity and sensitivity of serology for the demonstration of infection, but there is a need for alternative serological methods which could be more widely used than the standard immunofluorescence assay (IFA) for antibodies against gut-derived antigens (anti-GAA). We present results suggesting that 40/42 anti-GAA positive cases also react with keyhole limpet haemocyanin (KLH), a readily available commercial antigen. High anti-GAA titres were seen for more than 2 y despite treatment with praziquantel. Thus we are faced with several questions. How likely is it that positive serology means treatment failure? What is the risk involved in chronic infection? What is the prospect for monitoring treatment outcome by serology? We conclude that there is a need for better information on the risk of becoming infected, for improved methods for testing and for monitoring the therapeutic effects in adventure tourists.

Adolescent↗
PubMed2004

Recommendations for the selective use of herpes simplex virus type 2 serological tests.

BACKGROUND: Herpes simplex virus (HSV) type-specific serological tests are now widely available, but indications for their use have not been well defined. The California Sexually Transmitted Diseases (STD) Controllers Association convened a committee of clinicians and researchers to make recommendations for the use of type-specific HSV type 2 (HSV-2) serological tests. METHODS: By means of a systematic review of the literature, evidence to support screening in selected high-risk groups was compiled. Screening recommendations were developed by applying standard screening criteria to each specific population. RESULTS: The committee concluded that, in addition to serological testing for the diagnostic evaluation of patients with symptoms, screening of asymptomatic patients is likely to be beneficial among the following groups: those at high risk for STDs and human immunodeficiency virus (HIV) infection who are motivated to reduce their sexual risk behavior, HIV-infected patients, and patients with sex partners with genital herpes. In contrast, universal screening for HSV-2 infection in pregnant women is unlikely to be beneficial. CONCLUSIONS: The targeted use of HSV-2 serological tests for specific diagnostic situations and selected populations should benefit patients, providers, and the community. Until more data become available, these recommendations provide justification for selective diagnostic and screening uses of HSV-2 serological tests.

Female↗
PubMed1996

Serological and molecular biology screening techniques for HVC infection.

This is a review of the main biological tests that can be requested by nephrologists to diagnose hepatitis C virus infection, together with a tentative specification of their indications and interpretation methods. This diagnosis is mainly based on serological tests (ELISA). The second and third generation tests contain, in addition to the NS4, proteins of the core and NS3 region. The latter two proteins provided great specificity and are antigenically well preserved in most virus types. They constitute the backbone of serological screening systems. In parallel with ELISA, analytical tests have been developed. In the form of immunoblots, they use proteins similar to those of ELISA and permit separate reading of antibody response to each protein. To achieve serological results, biologists must use at least two different techniques. Several strategies for using the various tests are thus available. However, serological diagnosis has its limitations: acute hepatitis most often precedes seroconversion; the results do not date the disease nor do they specify infectivity, evolution or recovery; seronegativity does not exclude a positive diagnosis with any certainty, especially in such populations as haemodialysis patients. To make up for the shortcomings of serological tests, direct viral detection can be achieved by genic amplification, most often by polymerase chain reaction in the best preserved part of the genome (5' non-coding end). PCR is currently becoming the real reference test for hepatitis C diagnosis. It is also possible to quantify viraemia and to determine the viral genotype. The relevancy of these two factors to therapy is controversial. Immunohistochemical study of liver biopsy specimens is still little used.

Antibodies, Viral↗
PubMedDate not supplied

Serologic testing for gonorrhea.

A simple, adequately evaluated serologic test is not now available for use in gonorrhea screening programs. Some of the factors responsible for the relatively low sensitivity and specificity of serologic tests for gonorrhea as compared to cultural techniques are discussed. These include the time required for development of an immunologic response after infection, cross-reactivity with other antigens, and the persistence of antibody after therapy. At present, gonococcal serologic tests may be useful to the clinician in establishing the diagnosis of disseminated gonococcal infection, especially if paired sera demonstrate a change in antibody titer. Current research on the antigenic structure of the gonococcus may lead to the development of improved serologic tests for use in screening programs. However, the performance of any test may vary according to sex of the patient, presence of symptoms, history of prior gonococcal infection, and duration of the current infection. The physician must understand these factors when considering the use of any serologic test for gonorrhea.

False Positive Reactions↗
PubMed2006

An office-based serological test for detection of current Helicobacter pylori infection: is it useful?

OBJECTIVE: To compare the accuracy of a new office-based serological test for the detection of current Helicobacter pylori infection with gastric histopathology. METHODS: An office-based serological test for detection of current H. pylori infection was performed in 92 consecutive patients with dyspeptic symptoms. The result of this test was compared blindly with the rapid urease test and histopathology for H. pylori on gastric biopsies. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of this test were calculated against the histopathology. RESULTS: Among 92 patients, H. pylori was detected by histopathology and rapid urease test in 61 (66%) and 56 (60%) patients, respectively. Meanwhile the serological test diagnosed current H. pylori infection in 55 patients (59%). On comparison against the histology, the sensitivity and specificity of this new serological test was 85 and 90%, respectively. The positive predictive value and negative predictive value of this test were 94 and 76%, and the accuracy was 87% in this study. CONCLUSION: The specificity and sensitivity of the serological test was found comparable with histopathology in the diagnosis of current H. pylori infection. This test is a useful tool for rapid diagnosis of H. pylori in out patients' setting.

Adult↗
PubMed2005

Evaluation of a point-of-care immunodot assay for predicting results of allergen-specific intradermal and immunoglobulin E serological tests.

Immunotherapy to prevent recurrence of clinical signs of atopic dermatitis (AD) is based on intradermal or serological tests that assist in identifying allergen-specific immunoglobulin E hypersensitivities. Unfortunately, the results of such tests can be negatively influenced by several factors, which include the age of the patients, the season of testing and the administration of anti-allergic drugs. Screening to predict when these expensive tests will be useful would benefit owners of dogs with AD. The objectives of this study were to determine whether a point-of-care allergen-specific immunodot assay (Allercept E-Screen, Heska Corp., Ft Collins, CO, USA) could predict results of either intradermal or Allercept full panel serological tests in atopic dogs. Thirty dogs living in the south-eastern USA were diagnosed with AD in accordance with current standards. Allergen-specific intradermal, serological and E-Screen tests were performed in all subjects. For flea, house dust mite and pollen allergens altogether, results of the E-Screen assay agreed with those of intradermal and serological tests in 26/30 dogs (87%) and 25/30 dogs (83%), respectively. In this group of dogs, the probabilities of obtaining intradermal or serological tests positive for these allergens were 70 and 67%, respectively. If either skin or serum tests were performed only in dogs with positive E-Screen tests, the probability of obtaining positive results would be increased from 70 to 95% and from 67 to 90%, respectively. In this population of dogs with AD, results of the E-Screen point-of-care immunodot assay was found to often agree with those of allergen-specific intradermal or Allercept tests for selected allergen groups.

Allergens↗
PubMed2005

Comparison of cytomegalovirus polymerase chain reaction and serology for screening umbilical cord blood components.

BACKGROUND: Recipients of umbilical cord blood (UCB) transplants are susceptible to opportunistic infections, including cytomegalovirus (CMV). To prevent CMV transmission from UCB donors, most laboratories perform serology on corresponding maternal samples and quarantine units when the mother has immunoglobulin M (IgM) anti-CMV. STUDY DESIGN AND METHODS: UCB units and associated samples (UCB plasma and red cell pellet; maternal whole blood and serum) from two cord blood banks were tested with two validated CMV polymerase chain reaction assays (UL54 and UL93 targets). Results were compared with maternal CMV serology (IgG and IgM). RESULTS: Only 4 of 48 (8.3%) quarantined CMV IgM-positive units were also CMV nucleic acid testing (NAT)-positive (651-68,600 copies/mL). In contrast, 1 of 200 "CMV-safe" UCB units (CMV IgM-equivocal or -negative) had CMV DNA (0.5%). The corresponding maternal samples were CMV NAT-negative. Positive maternal IgM serology demonstrates only modest sensitivity (80%) and specificity (82%) and poor positive predictive value (8%), when correlated with the presence of CMV DNA in UCB units. CONCLUSION: CMV NAT may be a useful adjunct to serologic screening, potentially reducing wastage of IgM-positive and NAT-negative units while also detecting potentially infectious units that would pass serologic screening. A prospective clinical trial to further evaluate the role of CMV NAT in UCB transplantation appears warranted.

Cells, Cultured↗
PubMed1990

Diagnosis of Mycoplasma pneumoniae pneumonia: sensitivities and specificities of serology with lipid antigen and isolation of the organism on soy peptone medium for identification of infections.

The sensitivities and specificities of isolation and serology for detection of Mycoplasma pneumoniae infections were determined for 3,546 pneumonia patients for whom both isolation and serological data were available. Soy peptone, fresh yeast extract, horse serum-supplemented agar, and diphasic medium were employed for isolation, and the lipid antigen of M. pneumoniae was used for serodiagnosis by complement fixation. The number of M. pneumoniae colonies most frequently detected was 200 to 600 per throat swab, with a range of less than or equal to 60 to greater than or equal to 2,000. The use of diphasic medium increased the number of isolates by 26% compared with direct isolation on agar plates. The organism was isolated from 360 of 525 patients who showed fourfold or greater antibody increases in their paired sera, resulting in a sensitivity of culture of 68%. When persons with titers of greater than or equal to 32 but no fourfold increase were used as the reference, the sensitivity of culture was 58%. The combined sensitivity of the culture method for persons with serological evidence of infection (fourfold increase and titer of greater than or equal to 32) was 64%. The specificity of the culture method was 97% for the 2,527 serologically negative persons. Fourfold antibody increases were found in 360 of 674 persons with isolates of the organism, resulting in a sensitivity of 53%. An additional 247 persons showed titers of greater than or equal to 32 (without a fourfold increase), resulting in a combined sensitivity of 90% for serology with the lipid antigen for the detection of antibodies in culture-positive persons. Fourfold antibody increases were found in 6% of culture-negative persons, resulting in a specificity of 94%. The quantitative culture results provide important base-line data for the development of rapid diagnostic tests for M. pneumoniae infection.

Antibodies, Bacterial↗
PubMed2005

Contribution of systematic serological testing in diagnosis of infective endocarditis.

Despite progress with diagnostic criteria, the type and timing of laboratory tests used to diagnose infective endocarditis (IE) have not been standardized. This is especially true with serological testing. Patients with suspected IE were evaluated by a standard diagnostic protocol. This protocol mandated an evaluation of the patients according to the modified Duke criteria and used a battery of laboratory investigations, including three sets of blood cultures and systematic serological testing for Coxiella burnetii, Bartonella spp., Aspergillus spp., Legionella pneumophila, and rheumatoid factor. In addition, cardiac valvular materials obtained at surgery were subjected to a comprehensive diagnostic evaluation, including PCR aimed at documenting the presence of fastidious organisms. The study included 1,998 suspected cases of IE seen over a 9-year period from April 1994 to December 2004 in Marseilles, France. They were evaluated prospectively. A total of 427 (21.4%) patients were diagnosed as having definite endocarditis. Possible endocarditis was diagnosed in 261 (13%) cases. The etiologic diagnosis was established in 397 (93%) cases by blood cultures, serological tests, and examination of the materials obtained from cardiac valves, respectively, in 348 (81.5%), 34 (8%), and 15 (3.5%) definite cases of IE. Concomitant infection with streptococci and C. burnetii was seen in two cases. The results of serological and rheumatoid factor evaluation reclassified 38 (8.9%) possible cases of IE as definite cases. Systematic serological testing improved the performance of the modified Duke criteria and was instrumental in establishing the etiologic diagnosis in 8% (34/427) cases of IE.

Antibodies, Bacterial↗
PubMed1999

A clinical and serological comparison of group A versus non-group A streptococcal reactive arthritis and throat culture negative cases of post-streptococcal reactive arthritis.

OBJECTIVE: To identify clinical and serological differences of patients with reactive arthritis after infection with Lancefield group A beta-haemolytic streptococci (GAS), compared with non-group A-that is, group C or G streptococci (NGAS:GCS/GGS), and a group of culture negative or unidentified streptococci (GUS). METHODS: A prospective study of consecutive patients with reactive arthritis after serologically or culture confirmed infection with beta-haemolytic streptococci, presenting to the outpatient department of rheumatology from January 1992 until January 1998. Alternative causes for reactive arthritis were excluded. Main outcome measures were clinical and serological characteristics including antistreptolysine-O (ASO) and antideoxyribonuclease-B (antiDNase-B) antibody titres. RESULTS: 41 patients (female/male ratio 22/19; mean (SD) age 38 (13) years) with reactive arthritis were included. Culture of throat swab was positive in 13 cases (32%): 6 (15%) GAS, 7 NGAS (17%), that is, 5 (12%) GCS, 2 (5%) GGS. In 28 cases throat culture remained negative resulting in a group of unidentified streptococci; antibiotic pre-treatment had been given by the general practitioner in 18 cases (64%). Arthritis was non-migratory, the number of arthritic joints in GAS and NGAS was similar, whereas in NGAS patients fewer joints were involved than in GUS: mean (SEM) 36 swollen joint index: 3.3 (1.0) in NGAS v 5.6 (1.0) in GUS (p<0.005); 28 swollen joint index: 2.9 (1.0) in NGAS v 4.3 (0.8) in GUS (p<0.05). Extra-articular manifestations-that is, erythema nodosum/ multiforme, AV conduction block or hepatitis-were observed after GAS or GUS infection, but not after NGAS infection. ASO and/or antiDNase-B rose significantly in all patients. The maximal titres for ASO and antiDNase-B in 41 PSRA patients were: mean (SEM) 1242 (232) U/l and 890 (100) U/l respectively; the maximal ASO titres were similar in the three groups: mean (SEM) 1125 (185) in GAS, 625 (160) in NGAS (GAS v NGAS: p=0.17), and 1430 (320) U/l in GUS (NGAS v GUS: p=0.10). AntiDNase-B titres were: mean (SEM) 1075 (180) in GAS, 375 (105) in NGAS (GAS v NGAS: p<0.01), and 995 (125) U/l in GUS (NGAS v GUS: p<0.005). ASO: antiDNase-B ratios were: mean (SEM) 0.89 (0.21) in GAS, 2.60 (0.76) in NGAS (GAS v NGAS: p<0.05), and 1.43 (0.28) in GUS (NGAS v GUS: p=0.12). CONCLUSION: Post-streptococcal reactive arthritis occurs not infrequently. Differentiation of PSRA based on the causative streptococcal strain is frequently thwarted by negative throat cultures. Sometimes extra-articular manifestations are present that exclude NGAS as the causative organism. Serologically, lower antiDNase-B titres may be indicative for primary NGAS infection; the ASO/antiDNase-B ratio may be of additive value for differentiation in cases of a negative throat culture: the higher ASO/antiDNase-B ratios suggesting primary NGAS infection. In reactive arthritis, serological monitoring consisting of a simultaneous titration of antiDNase-B and ASO, seems to be of clinical importance to trace GAS induced cases, especially when throat cultures remain negative.

Adult↗
PubMed1994

Possible role of Helicobacter pylori serology in reducing endoscopy workload.

We validated a commercial enzyme-linked immunosorbent assay (ELISA), Helico-G, in diagnosing H. pylori in 129 patients (mean age 50 years, range 15-86). We analysed the results of endoscopy against serology to see whether there was a possibility of adopting the strategy of not endoscoping dyspeptic subjects under the age of 45. H. pylori infection was considered present if either histology and/or culture were positive. The ELISA had a sensitivity of 88%, specificity of 72%, positive predictive value of 85%, negative predictive value of 77% and accuracy of 82% in detecting H. pylori. In a subgroup of 52 subjects aged 45 or less (mean age 35 years, range 15-45), 17 out of 25 patients with positive endoscopic findings were H. pylori seropositive while 16 out of 27 patients had normal endoscopic findings. Eighteen out of the 52 patients (35%) were H. pylori seronegative and normal endoscopically except for five patients (10%) who had mild to moderate oesophagitis and two who had non-erosive gastritis (4%). All patients with duodenal ulcer disease (7) were seropositive giving predictive values of positive and negative serology for a diagnosis of duodenal ulcer disease as 28% and 100%, respectively. Therefore adopting a strategy of endoscoping subjects under the age of 45 only if they were H. pylori seropositive would have saved 35% of endoscopies in this age group but missed oesophagitis in 10%. Negative serology would tend to exclude duodenal ulcer disease while positive serology discriminates poorly for it. Serology may be a useful adjunct in screening to reduce endoscopy workload provided that patients with gastro-oesophageal reflux symptoms are excluded.

Aged↗
PubMed2004

HSV type specific serology in sexual health clinics: use, benefits, and who gets tested.

OBJECTIVES: To determine which sexual health clinic clients were tested for herpes simplex virus (HSV) type specific antibodies and whether this test was useful for patient management. METHODS: Demographic, sexual and reproductive history, reasons for performing type specific serology, results, and benefits were derived from patient records from Parramatta Sexual Health Clinic for all patients who were tested between 13 September1993 and 31 December 2001. The value of serology was defined under five categories-diagnostic, counselling, initiating suppressive antiviral therapy, pregnancy counselling, and not useful. To establish whether patients tested for HSV were representative of clinic attendees, a sex matched "control" group was randomly selected. RESULTS: 382/886 (43.1%) were HSV-2 antibody positive and 774/884 (80.8%) were HSV-1 positive. The commonest reasons for requesting serology were having a partner with genital herpes (30%), undiagnosed recurrent genital ulceration (26%), and first episode of genital ulceration (22%). The test was of value in confirming the diagnosis in 57% of men and 60% of women with recurrent genital ulceration and in 28% of men and 40% of women with first episode genital herpes. In patients with a partner with genital herpes the test was of value in making a diagnosis in 27% men and 50% of women and in counselling 50% of women and 73% of men. Patients offered serology were older and more likely to have had genital herpes in the past than controls. CONCLUSION: Type specific serology should be recommended for the management of couples where one has genital herpes and the other apparently does not and in individuals with genital complaints suggestive of herpes.

Adolescent↗
PubMed2004

Basic problems of serological laboratory diagnosis.

Serological laboratory diagnosis of infectious diseases is inflicted with several kinds of basic problems. One difficulty relates to the fact that the serological diagnosis of infectious diseases is double indirect: The first indirect aim in diagnosing an infectious disease is to identify the microbial agent that caused the disease. The second indirect aim is to identify this infectious agent by measuring the patient's immune response to the potential agent. Thus, the serological test is neither measuring directly disease nor the cause of the disease, but the patient's immune system. The latter poses another type of problem, because each person's immune system is unique. The immune response to an infectious agent is usually of polyclonal nature, and the exact physicochemical properties of antibodies are unique for each clone of antibody. The clonal makeup and composition and, therefore, the way an individual's immune system sees an infectious agent, depends not only on the genetic background of the person but also on the individual experience from former encounters with various infectious agents. In consequence, the reaction of a patient's serum in an analytical system is not precisely predictable. Also, the antigenic makeup of an infectious agent is not always foreseeable. Antigenic variations leading to different serotypes is a quite common phenomenon. Altogether, these biological problems lead to complexities in selecting the appropriate tests and strategies for testing, in interpreting the results, and in standardizing serological test systems. For that reason, a close collaboration of the laboratory with the clinic is mandatory to avoid erroneous conclusions from serological test results, which might lead to wrong decisions in patient care.

Antibody Affinity↗
PubMed1999

Basic problems of serological laboratory diagnosis.

Serological laboratory diagnosis is inflicted with at least two kinds of basic problems. One type relates to the fact that the serological diagnosis of infectious diseases is double indirect: First, to diagnose an infectious disease, the identification of the microbial agent is sought that caused the disease. Second, to identify this infectious agent, the patient's immune response to potential agents is measured. So, the serological test is neither measuring directly disease nor the cause of the disease, but the patient's immune system. Another type of problem is based on the fact that each person's immune system is very individual. The exact physicochemical properties of antibodies are unique for each clone of antibodies. The way an individual's immune system sees an infectious agent depends not only on the genetic makeup of the person but also on the personal experience from former encounters with infectious agents. Both types of problems lead to complexities in selecting the appropriate test, in interpreting the results, and in standardizing serological tests. Therefore, a close collaboration of the laboratory with the clinic is mandatory to avoid erroneous conclusions from serological test results, which might lead to wrong decisions in patient care.

Clinical Laboratory Techniques↗
PubMedDate not supplied

Comparison of serology, antigenemia assay and the polymerase chain reaction for monitoring active cytomegalovirus infections in hematopoietic stem cell transplantation patients.

Forty-six allogeneic hematopoietic stem cell transplantation (HSCT) patients were monitored for the presence of CMV antibodies, CMV-DNA and CMV antigens after transplantation. Immunoenzymatic serological tests were used to detect IgM and the increase in CMV IgG antibodies (increase IgG), a nested polymerase chain reaction (N-PCR) was used to detect CMV-DNA, and an antigenemia assay (AGM) was used to detect CMV antigens. The presence of CMV-IgM and/or CMV-increase IgG antibodies was detected in 12/46 (26.1%) patients, with a median time between HSCT and the detection of positive serology of 81.5 days. A positive AGM was detected in 24/46 (52.2%) patients, with a median time between HSCT and antigen detection of 62 days. Two or more consecutive positive N-PCR results were detected in 32/46 (69.5%) patients, with a median time between HSCT and the first positive PCR of 50.5 days. These results confirmed that AGM and mainly PCR are superior to serology for the early diagnosis of CMV infection. Six patients had CMV-IgM and/or CMV-increase IgG with a negative AGM (five cases) or N-PCR assay (one case). In five of these cases the serological markers were detected during the first 100 days after HSCT, the period of highest risk. These findings support the idea that serology may be useful for monitoring CMV infections in HSCT patients, especially when PCR is unavailable.

Antibodies, Viral↗
PubMedDate not supplied

[External serology quality control programs developed in Latin America with the support of PAHO from 1997 through 2000].

OBJECTIVE: To evaluate the quality of serological screening of blood donors in five groups of blood banks in Latin America that participated over the 1997-2000 period in an external serology control project developed with support from the Pan American Health Organization (PAHO). METHODS: With assistance from PAHO, the Serology Authority of the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo), of São Paulo, Brazil, carried out the external quality control project and served as its "organizing center" (OC). The OC developed five external serology quality control "programs" (ESQCPs), or external evaluation activities, for the respective groups of participating blood banks. There was one ESQCP each in 1997, 1999, and 2000, and there were two in 1998. In these five programs, the number of participating blood banks ranged from 13 to 21, and the number of countries ranged from 11 to 16. In each program, the OC used a set of 24 blinded sera samples with different reactivities for the various infectious agents for which screening is obligatory in Brazil. Each participating institution in each program received a sera set, to be processed using that institution's standard screening procedures. After returning its results to the OC, each participant received an answer key for the sera set, to be used in evaluating its own performance. All the individual results were kept strictly confidential. At the end of each program, the OC prepared and sent to all the participants a final report that contained information on the overall results from that program. RESULTS: An analysis of the five programs showed that there was a lack of homogeneity among the countries with respect to the strategies and the parameters used in screening blood donors. Few laboratories screened for human T-cell-lymphotropic virus (beginning with the 1997 program, the respective rates were 17%, 27%, 35%, 39%, and 45%). Rates of screening were also low for antibodies to the hepatitis B core antigen (again, beginning with the 1997 program, the rates were 42%, 27%, 39%, 50%, and 60%). There were also important differences with respect to which tests and which combinations of tests were used, making it hard to compare the types of screening done. In the five programs, with the various tests used, the overall rate of false positive results fluctuated around 2%. The highest false positive rate for any of the tests, 4.6%, was for antibodies against the hepatitis C virus. The lowest false positive rate, 0.4%, was for antibodies against Trypanosoma cruzi. CONCLUSIONS: These results show the need for PAHO to continue using these external quality control programs as well as other activities in order to strengthen the procedures for serological screening blood banks in Latin America, until there is more uniformity in the procedures that the countries use.

Blood Banks↗
PubMed2004

Chagas cardiomyopathy and serologic testing in a small rural hospital in Chiapas, Mexico.

OBJECTIVES: To conduct a study in a small rural hospital located in the state of Chiapas, Mexico, to: (1) examine the prevalence of chagasic cardiomyopathy among patients with the diagnosis of congestive heart failure and (2) assess the prevalence of positive serologic results in blood donors in the hospital, in an attempt to ascertain whether Chagas' disease remains an important cause of heart failure at least in some areas of Mexico. METHODS: The study of patients with cardiomyopathy was conducted by retrospective chart review of patients with the diagnosis of congestive heart failure treated at the hospital during the years 2000-2002. With the blood donors, the results of their serologic screening were reviewed for a six-month period beginning in April 2002. Serologic testing was done in both groups with either indirect hemagglutination (IHA) or enzyme-linked immunosorbent assay (ELISA), or with both. RESULTS: Of 67 patients with heart failure and no risk factors for other causes of heart failure, 40 of them had serologic tests performed. Thirty-three of these 40 (82.5%) were positive by ELISA, IHA, or both. With 97 blood donors, one or both serologic tests were positive in 17 of them (17.5%). CONCLUSIONS: This research adds to the evidence that Chagas' disease continues to be a major cause of heart failure in some areas of Mexico and that there continues to be a risk of transmission by blood transfusion if donated blood is not consistently screened.

Adult↗