Interpretation Of Serological Tests Research Articles

Sero-prevalence and risk factors associated with occurrence of anti-Brucella antibodies among slaughterhouse workers in Uganda.

Brucellosis is a febrile zoonosis occurring among high-risk groups such as livestock keepers and abattoir workers and is a public health priority in Uganda. The technical complexities of bacteriological and molecular methods make serological approaches the cornerstone of diagnosis of human brucellosis in resource limited settings. Therefore, proper application and interpretation of serological tests is central to achieve a correct diagnosis. We conducted a cross-sectional study to estimate the seroprevalence and factors associated with anti-Brucella antibodies among slaughterhouse workers processing ruminants and pigs in three regions of the country with serial testing using a combination of the Rose Bengal Test (RBT) and the BrucellaCapt test. An authorized clinician collected 543 blood samples from consenting abattoir workers as well as attribute medical and social demographic data. Univariable and multivariable logistic regression were used to determine factors associated with anti-Brucella sero-positivity. The sero-prevalence among ruminant slaughterhouse workers ranged from 7.3% (95% CI: 4.8-10.7) using BrucellaCapt to 9.0% (95% CI: 6.3-12.7) using RBT. Slaughterhouse workers from the Eastern regions (AOR = 9.84, 95%CI 2.27-69.2, p = 0.006) and those who graze animals for alternative income (AOR = 2.36, 95% CI: 1.91-6.63, p = 0.040) were at a higher risk of exposure to Brucella. Similarly, those who wore Personal Protective Equipment (AOR = 4.83, 95%CI:1.63-18.0, p = 0.009) and those who slaughter cattle (AOR = 2.12, 95%CI: 1.25-6.0, p = 0.006) were at a higher risk of exposure to Brucella. Those who slaughter small ruminants (AOR = 1.54, 95%CI: 1.32-4.01, p = 0.048) were also at a higher risk of exposure to Brucella. Our study demonstrates the combined practical application of the RBT and BrucellaCapt in the diagnosis of human brucellosis in endemic settings. Both pharmaceutical (e.g., routine testing and timely therapeutic intervention), and non-pharmaceutical (e.g., higher index of suspicion of brucellosis when investigating fevers of unknown origin and observation of strict abattoir hygiene) countermeasures should be considered for control of the disease in high-risk groups.

MODERN APPROACH AND CLINICAL EXPERIENCE OF DIAGNOSIS OF CONGENITAL TOXOPLASMOSIS

Diagnosis of congenital toxoplasmosis is one of the most pressing and complex problems of perinatology. Difficulties in the interpretation of serological tests, the lack of clearly defined steps in the detection of seroconversion in women leads to late diagnosis and the development of irreversible changes and severe complications from the newborn. When infected during pregnancy, the disease is extremely unfavorable for the fetus and can lead to miscarriage, stillbirth, intrauterine growth retardation or the formation of birth defects. This article presents a review of the literature on the modern diagnosis of congenital toxoplasmosis and presents his own clinical case of diagnostic search for this infectious disease in the newborn. Practitioners should keep in mind prenatal ultrasound markers, the main manifestations of the disease and methods of diagnosis, because timely recognized and confirmed congenital toxoplasmosis will have the best long-term treatment results and prognosis in the newborn.

Follow-up Brucellacapt and Rose Bengal Tests in 110 Children with Brucellosis

Abstract Objective The interpretation of serologic tests in brucellosis can be difficult because of nonspecific symptoms and vague signs of disease, and limitations of serological tests to distinguish persistent and cleared infection. Here, we evaluated the role of Brucellacapt test in conjunction with Rose Bengal test (RBT) in the follow-up of children treated for brucellosis. Methods A total of 174 children diagnosed with brucellosis were included in the study. Data about demographic characteristics of patients, clinical and laboratory findings including Brucellacapt and RBT results, therapeutic approach, and response to treatment were collected from medical records. Results Of the 174 cases, 109 (62.6%) were boys and 65 (37.4%) were girls. The mean age of children at the diagnosis was 122 ± 54 months. Sixty-four cases were excluded from the study for loss to follow-up. The follow-up period for the remained 110 cases was 4.3 ± 2.9 months. Eleven cases (10%) had persistent illness, 7 (6.4%) had recurrence/relapse, and 92 had favorable outcome. During the follow-up, Brucellacapt titers did not drop under 1/320 in cases with persistent illness, and it increased again to 1/320 in cases with relapses at average 6.1 months after treatment. In 48 of cases with favorable outcome, Brucellacapt titers decreased to 1/160 in average 3.3 ± 1.8 months; in 35 cases, RBT became negative in average 3.8 ± 2.5 months, and there was no statistically significant difference between them (p = 0.241). In cases with higher Brucellacapt titers on admission, decrement of titers took longer time. Conclusion Persistent serological titers without clinical findings of brucellosis should not lead physician to prolong or repeat treatment because the decline in Brucellacapt titers and RBT negativity may be delayed in contrast to clinical recovery.

Interpretation of serological tests in the diagnosis of celiac disease: Anti-deamidated gliadin peptide antibodies revisited

Algorithms for celiac disease diagnosis provided by guidelines are based primarily on anti-tissue transglutaminase 2 (TG2) antibodies and/or anti-endomysium antibodies. The place of anti-deamidated gliadin peptide (DGP) antibodies is less well established. This study was designed to assess the clinical relevance of anti-DGP antibodies. Two thousand and twenty-six consecutive unselected patients systematically tested for anti-TG2, endomysium, gliadin, DGP antibodies and IgA dosage were investigated. The serological interpretation was assessed by analyzing the medical records of patients. From the 1984 newly investigated patients suspected of celiac disease, 10% had at least one celiac marker. Anti-TG2, anti-endomysium, anti-gliadin and anti-DGP antibodies were found in 1.1%, 0.6%, 6.8% and 4.1% of cases respectively, with different combinations. The diagnosis of celiac disease was retained in 0.45% of patients. When using the duodenal biopsies as a gold standard, analysis of the anti-DGP diagnosis performance showed that the specificity and the predictive positive value (PPV) were lower than that of the anti-TG2 assay. The combined detection of anti-TG2 and anti-DGP antibodies had a lower PPV than that of anti-TG2 and anti-endomysium antibodies (p = 0.04). When analyzing the contribution of anti-DGP antibodies as an additional marker to both anti-TG2 and anti-endomysium antibodies, the PPV of the three associated antibodies was shown to be significantly lower than the PPV of the both anti-TG2 and anti-endomysium antibodies (p = 0.04). As a conclusion, anti-DGP antibodies may not have the diagnosis value required as an additional screening test to anti-TG2 antibodies for identifying celiac disease patients in medical centers where anti-endomysium detection is available.

Introduction to Antigen and Antibody Assays

Serological tests are used widely in veterinary practice; most often in the diagnosis of infectious disease. Such tests may be used to detect antigen from an infectious agent within a biological sample or to detect the presence of serum antibody specific for the pathogen as evidence of immunological exposure. These tests are all based on the fundamental principles of interaction between antigenic epitopes and antibodies of either the immunoglobulin (Ig) G, IgM, IgA, or IgE classes. The relative concentration of specific antibody within a sample is traditionally determined by calculation of the titer of antibody. With few exceptions, the primary interaction between an antigen and antibody in vitro cannot be visualized and so serological tests generally employ a secondary indicator system based on the use of a polyclonal antiserum or monoclonal antibody. A range of such tests has been developed, but many in veterinary medicine are based on the principle of the enzyme-linked immunosorbent assay, which is described in detail in this article. The interpretation of serological tests must be made carefully, taking into consideration the sensitivity and specificity of the test and the possible reasons for false-positive and false-negative outcomes.

Current standards for diagnosis of syphilis: comparing the russian and foreign guidelines (part I)

Despite the abundance of existing laboratory methods the diagnosis of syphilis still faces many challenges. Though direct detection of T. pallidum plays an important role in early manifest forms of the disease, serological tests remain the mainstay of diagnosis. Traditional syphilis screening algorithm based on nontreponemal tests with subsequent confirmation using treponemal tests is a standard worldwide. Recently, the ability to automate the treponemal tests promotes the increasingly widespread implementation of reverse algorithm when these tests are used for syphilis screening. None of the current serological algorithms are able to reliably differentiate between active and previously treated syphilis, which causes uncertainty in the management of patients. There is no «gold standard» for the diagnosis of neurosyphilis, ocular, auricular and visceral syphilis. The interpretation of serological tests in children born to seropositive mothers is also complicated. Diagnosis of congenital syphilis in newborns and, consequently, the prescription of antibiotic therapy often depends on assessment of the adequacy of maternal treatment during pregnancy, which leads to subjective decisions. This article provides a comparative analysis of the «Federal guidelines for the management of patients with syphilis» and their foreign analogues, discusses significant peculiarities of these guidelines and reviews current concerns and controversies in syphilis diagnosis.

Interpretation of serologic tests in an HIV-infected patient with kidney disease

A 32-year-old African American man with HIV infection presented with hemoptysis, shortness of breath and renal insufficiency. Serologic testing revealed the presence of anti-glomerular basement membrane antibodies and equivocal levels of anti-myeloperoxidase antibodies. Physical examination, urine and blood analysis, kidney ultrasound, chest radiograph, sputum cultures, bronchoscopy and renal biopsy. Reactivation of tuberculosis infection, immune complex glomerulonephritis, and 'false-positive' anti-glomerular basement membrane and anti-myeloperoxidase antibodies. Directly observed therapy with four-drug anti-tuberculosis therapy and conservative management of chronic kidney disease.

Neospora caninum seroprevalence in dairy cattle in central Thailand

The seroprevalence, in dairy cattle, of antibodies to Neospora caninum, the relationship between seropositivity and age (heifer versus cow), the relationship of herd infection with herd size and the relationship of herd infection with the presence of dogs on the farm were studied. The study involved 549 cows and 82 dogs in 59 dairy herds in Nakhon Pathom, Thailand. A competitive enzyme-linked immunosorbent assay (cELISA) with NC-specific monoclonal antibody was used to detect the NC antibodies in the sera. Individual and herd seroprevalence of NC were 5.5% (30/549) and 34% (20/59), respectively. No significant relationships between NC seropositivity with the age of the cows (heifer versus cow; P>0.05) and between herd infection and the presence of dogs on the farm ( P>0.05) were found. Herd size significantly affected herd infection ( P<0.05) with higher infection in large than small herds (≥21 versus ≤20 cows). Of 12 cows with a history of abortion, one was seropositive to NC. The seroprevalence of NC antibodies in dogs was 1.2% (1/82). This is the first NC seroprevalence study in dogs in Thailand. It was concluded that Neospora infection was more common at the herd level rather than the individual level in Thailand and the presence of dogs on the farm was not related to the level of herd infection. Caution should be taken in the interpretation of serological tests from the farm dogs.

Vertical transmission of Treponema pallidum to various litters and generations of guinea pigs.

The transmission of congenital syphilis was studied in a 4-generation guinea pig family with 10 litters and 38 offspring. By use of one or all of the following tests (ELISA-IgM, polymerase chain reaction, and rabbit infectivity), transplacental infection was demonstrated through 5 litters and up to 4 generations. Twenty-eight (93%) of 30 animals were positive by >/=1 test, and 2 (7%) were negative by 1 or 3 tests. While transmission of the pathogen appeared to be unaffected by the maternal acquisition of immunity, signs of smoldering infection in the young was suggested by the decline in humoral responses in successive progeny and by unusual rabbit infectivity test results. With each pregnancy there was a remarkable booster in the maternal humoral response, which dropped significantly prior to term. These findings shed new light on the understanding and interpretation of serologic testing during pregnancy and the perinatal period.

Syphilis in Pregnancy

Syphilis is a chronic infectious process caused by the spirochete Treponema pallidum. In the pregnant woman, syphilis is generally quite easily treated. Long term effects for the mother are rare. Infection during pregnancy may result in spontaneous abortion, stillbirth or premature delivery. The most devastating manifestations are seen in infants born with congenital syphilis. In the HIV-infected pregnant woman who also is infected with syphilis, treatment with the standard regimes may be inadequate. The recent increase in syphilis among women in their childbearing years requires physicians to reacquaint themselves with this disease. The risk factors, manifestations of syphilis, interpretation of serological tests, and management guidelines for the exposed mother are presented.

Hepatitis-B: a review.

The recent literature on various aspects of hepatitis-B is reviewed with emphasis on the interrelationships of viral structure, antigenic components, and host immune response in acute, chronic, and asymptomatic carrier states of the infection. The mode of replication and mechanisms of transmission are discussed. Special attention is paid to potential non-parenteral routes of spread. The role of hepatitis-B in associated immune complex diseases and in hepatoma is outlined. A guide to the interpretation of serologic tests for hepatitis-B associated antigen and antibody patterns is presented in relation to the clinical stage and prognosis of the infection. Therapy, except in conceptual terms, is not covered but a summary of the current status of active and passive immunization is given. The unresolved question of the infectivity of carrier medical staff for their patient contacts, and the reverse, is discussed.

Effects of a single histoplasmin skin test on the serological diagnosis of histoplasmosis.

Numerous reports have indicated that a single histoplasmin skin test may stimulate humoral antibodies to Histoplasma capsulatum antigens in histoplasmin-hypersensitive individuals. Although these investigations concur that antibody elevations are evoked, they vary in the reported degree of incidence and response induced, and they cast doubt on the interpretation of serological tests in the diagnosis of histoplasmosis. Histoplasmin-hypersensitive subjects (114) were bled prior to administration of the skin test, 2 days later, at the time this test was read, and 15 and 30 days after testing. No significant antibody titers were observed at 2 days. At 15- and 30-day intervals, only 17 (15%) of the subjects demonstrated circulating antibodies. All 17 showed agar gel bands; 5 demonstrated no complement-fixation (CF) titers, 10 produced CF antibodies ranging from 1:8 to 1:16, and 2 demonstrated titers of 1:32. The data suggest that skin testing does not interfere significantly with antibody levels in sera drawn approximately 2 days after administration of antigen. However, since titers as high as 1:32 were obtained at later intervals, such reactions should be evaluated cautiously and only after consideration of clinical findings.

Current Serodiagnosis and Treatment of Syphilis

In recent years there has been a resurgence of syphilis in the United States. 1 Reported cases of primary and secondary syphilis rose from a low of 6,399 in 1956 to 22,969 in 1964, with nearly half of the recent cases occurring in teen-agers and young adults. Reported cases of infectious syphilis among teen-agers have increased by more than 213% since 1956. Apparently there are many additional cases which, for various reasons, are not reported, and a consideration of these raises the probable number of cases in 1964 to more than 120,000. 2 Thus it seems timely to consider both the interpretation of serologic tests for syphilis and the treatment of this infection. Consideration of Serologic Tests Although there have been a number of changes in the serologic testing and therapy of syphilis since a publication in 1961 by one of us, 3 much of that basic information is still

Vaccination against Parasitic Disease: Reactions in Vaccinated and Immune Hosts in Dictyocaulus viviparus Infection

A comparison has been made between the course of infections of normal and irradiated larvae of D. viviparus in calves; this was done to investigate the mode of action of, and the host's reaction to, the vaccine against bovine parasitic bronchitis which is now being widely used in the field. Approximately one-quarter of the irradiated larvae were present in the lungs 11 days after infection, but this level fell steeply until only a few stunted sterile worms with a male/female ratio of approximately 1:10 were found. By the time that full patency had been reached in normal infections no worms could be found in those infected with irradiated larvae. The pathological basis of the mild and transient clinical signs sometimes seen after vaccination is described; the stages in the development of peribronchial lympho-reticular nodules are outlined, and the relationship of these to the clinical signs seen after heavy challenge in an immune animal is pointed out. The possible functions of these sites in antibody production and their influence on interpretation of serological tests are discussed. Vaccines have been developed against certain parasitic diseases by attenuating larvae with ionizing radiation so that they retain their immunizing potential but fail to mature to produce disease (Jarrett et al., 1960c; Jarrett et al., 1959a, b). One of these vaccines, against parasitic bronchitis, has been widely and successfully used in the field (Poynter et al., 1960). In an earlier paper (Jarrett et al., 1957b) we described the course of events caused by infection of calves with normal Dictyocaulus viviparus larvae; this information on the pathogenesis of the disease was obtained by killing experimentally infected calves at fairly close intervals. During the development of the vaccine, due to the nature of the experiments, a similar technique could not be applied and the changes produced could only be studied at a fairly late stage; therefore, only tentative hypotheses could be advanced as to the mode of action of, and the tissue reactions to, the vaccine. The experiments reported below were designed to obtain more details of these and of the reaction of the immune host