SEARCH · PubMed Health

Results for “seroconversion”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources

PubMed2005

Hepatitis E antibody seroconversion without disease in highly endemic rural Egyptian communities.

Hepatitis E virus (HEV) is enterically transmitted and causes self-limiting acute viral hepatitis (AVH) primarily in less developed countries. A prospective cohort study to assess incidence of, and risk factors for, seroconversion to HEV (anti-HEV) was conducted in two Egyptian villages with a 67.7% anti-HEV prevalence. Nine hundred and nineteen villagers who were initially anti-HEV-negative were followed for 10.7 months. Thirty-four (3.7%) had strong anti-HEV serologic responses at follow-up giving an estimated anti-HEV incidence of 41.6/1,000 person-years. No significant associations were found between anti-HEV seroincidence and demographic and socioeconomic factors, source of water, household plumbing or sanitation, hand and vegetable washing, ownership of animals, jaundice and many other variables. None of the seroconverting subjects gave a history compatible with AVH during the interval. We hypothesize that both zoonotic and anthroponotic transmission of avirulent (possibly genotype-3) HEV is occurring extensively in these rural villages. An alternative explanation for the lack of morbidity among anti-HEV incident cases could be initial asymptomatic infections occur during early childhood with subsequent antibody titer boosting without illness upon re-exposure to the virus.

Adolescent↗

PubMed2006

Canine neosporosis in Hungary: screening for seroconversion of household, herding and stray dogs.

In order to assess the seroprevalence of canine neosporosis 651 blood samples were collected from 586 household, 41 herding and 24 stray dogs, at small animal clinics in four large cities and other places of Hungary. Nineteen (2.9%) showed positivity in the IFAT with titres between 1:80 and 1:10240. Two dogs with high titres of antibodies to Neospora caninum had neuromuscular signs (imbalance, tremor) and a further one developed papulomatous, ulcerative and necrotizing dermatitis. There was no correlation between titers and age, sex, breed or keeping place. Although more male dogs had antibodies to N. caninum than females in case of both household and herding dogs, this association was not significant. No breed predisposition was observed. However, dogs with seroconversion were significantly more prevalent among rural (6%) than among urban dogs (1%), indicating that dogs in the countryside may have contact with or access to potentially infected offal from cattle and other intermediate hosts more frequently than those in large cities. Furthermore, significantly more herding dogs (29.3%) had antibodies to N. caninum than household dogs (1.2%), confirming the association between the occurrence of neosporosis and dog keeping on farms. The 12 dogs found seropositive among herding ones lived on 6 farms, on 5 of which seropositive cattle were also identified. This is the first report on the prevalence of N. caninum infection in dogs in Hungary.

Animals↗

PubMed2003

[Seroconversion and seroreversion rate of Helicobacter pylori infection in women attended at hospital for delivery].

BACKGROUND AND OBJECTIVE: Helicobacter pylori infections are acquired primarily during childhood. Nevertheless, infections also develop in the adult population and it is not clear how the cumulative effect of these infections occurs throughout life. With the aim to contribute to the current data on the evolution of H. pylori infection in the adult population of Spain, the incidence and prevalence rates in a population of women who went to the hospital for delivery were studied. SUBJECTS AND METHOD: The study considered the sero-conversion and sero-reversion of H. pylori antibodies in 1441 women from Gipuzkoa (Basque Country, Spain), between 15 and 41 years-old (mean 28.5 [3.4]). These women delivered after September 1989 and had a second childbirth 2 to 8 years later. A serum sample was obtained at the time of each childbirth. Results were determined by enzymoimmunoanalysis (Pyloriset EIA-G New, Finland). RESULTS: H pylori antibodies were detected in the first serum specimen of 648 women (45.0% prevalence). Twenty-four out of the 793 women who were initially seronegative underwent a seroconversion in successive years, and an annual infection rate of 0.77% (95% CI 0.49-1.14) was estimated. Twenty-six women, who were initially seropositive, yielded negative result in the second serum specimen, which led to an annual sero-reversion rate of 1.03% (95% CI 0.67-1.50). CONCLUSIONS: These results suggest that in our environment, infections by H. pylori occur with a moderate frequency in adults. The fact that the sero-reversion rate is similar to or higher than the sero-conversion one suggests that the prevalence of H. pylori infection in the adult population is currently decreasing.

Adolescent↗

PubMedDate not supplied

Seroconversion for Helicobacter pylori in adults from Brazil.

We studied, prospectively, seroconversion for Helicobacter pylori in adults from a developing country and investigated risk factors for the acquisition of the microorganism in this population. A group of 213 volunteers of low socioeconomic level from a district in the metropolitan area of Belo Horizonte, south-east Brazil was evaluated. Anti-H. pylori IgG antibodies were measured by ELISA using Cobas Core anti-H. pylori EIA (Roche) in serum samples collected in 1992 and in 1997. The subjects were interviewed and sociodemographic data were collected. A total of 174 (81.7%) subjects presented anti-H. pylori antibodies on the occasion of the first visit. During 56 months of follow-up, 2 of 39 seronegative adults converted to seropositive with an annual infection rate of 1.1%, and 2 of 174 seropositive subjects reverted to seronegative (0.2%/year). The prevalence of infection increased significantly with age and an inverse association was observed between prevalence of infection and educational level. In conclusion, the results of the present study demonstrate that in a developing country there is a low but continuous risk of H. pylori infection in adulthood.

Adolescent↗

PubMed1985

Acute encephalopathy coincident with seroconversion for anti-HTLV-III.

Acute encephalopathy was associated with the appearance of antibodies to human T-lymphotropic virus (HTLV-III) in two patients. A third patient showed seroconversion for anti-HTLV-III, but the temporal association was not established so precisely. The illness was characterised by a prodromal period of up to 2 weeks, characterised by pyrexia, general malaise, and changes of mood. The encephalopathy culminated in epileptiform seizures in two of the patients. Electroencephalographic changes were compatible with viral encephalitis, and cerebrospinal-fluid pleocytosis was minimal. Neurological signs and symptoms resolved quickly in all patients, and no residual central-nervous-system sequelae were apparent.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Female to male transmission of human immunodeficiency virus type 1: risk factors for seroconversion in men.

To determine the frequency and risk factors for female to male sexual transmission of human immunodeficiency virus type 1 (HIV-1), a prospective study was carried out in 422 men who had acquired a sexually transmitted disease (STD) from a group of prostitutes with a prevalence of HIV-1 infection of 85%. The initial seroprevalence of HIV among the men was 12%. 24 of 293 (8.2%) initially seronegative men seroconverted to HIV-1. Newly acquired infection was independently associated with frequent prostitute contact (risk ratio 3.2, 95% confidence interval 1.2-8.1), with the acquisition of genital ulcer disease (risk ratio 4.7, 95% confidence interval 1.3-17.0), and with being uncircumcised (risk ratio 8.2, 95% confidence interval 3.0-23.0). 96% of documented seroconversions occurred in men with one or both of the latter two risk factors. In a subgroup of 73 seronegative men who reported a single prostitute sexual contact, the frequency of HIV-1 infection was 8.2% during 12 weeks of observation. No man without a genital ulcer seroconverted. A cumulative 43% of uncircumcised men who acquired an ulcer seroconverted to HIV-1 after a single sexual exposure. These data indicate an extremely high rate of female to male transmission of HIV-1 in the presence of STD and confirm a causal relation between lack of male circumcision, genital ulcer disease, and susceptibility to HIV-1 infection.

Acquired Immunodeficiency Syndrome↗

PubMed2004

[Eruptive pseudo-angiomatosis associated with enterovirus seroconversion].

BACKGROUND: Eruptive pseudo-angiomatosis is a benign, acute dermatosis, mostly associated with a viral infection. Skin lesions consist of angioma-like papules, scattered over the skin. Involution is usually spontaneous and swift. CASE-REPORT: We report a case of eruptive pseudo-angiomatosis, which occurred in an immunocompetent 18 year-old adult together with acute gastroenteritis and enterovirus seroconversion. DISCUSSION: Eruptive pseudo-angiomatosis was described for the first time in 1969 in 4 children and then several pediatric cases were reported. Recently, 9 eruptive pseudo-angiomatosis in adults have been described. Our case had some particularities: it occurred in an immunocompetent adult and the skin lesions were angioma-like.

Adolescent↗

PubMed1997

Reactivity of a new HIV-1 group O third generation A-HIV-1/-2 assay with an unusual HIV-1 seroconversion panel and HIV-1 group O/group M subtyped samples.

It was shown previously that about 97% of the anti-HIV-1 group O strain-positive samples were detected by crossreaction with native HIV-1 gp160 (Van Binsbergen et al., Evaluation of a new third generation anti-HIV-1/anti-HIV-2 assay with increased sensitivity for HIV-1 group O, J. Virol. Methods 60 (1996) 131-137). Fourteen out of 17 new anti-HIV-1 group O positive samples, selected with the Enzygnost HIV-1/2 plus assay, were already reactive when tested with HIV-1 gp160. When tested by the Vironostika HIV Uni-Form II plus O microELISA all 17 samples were reactive, demonstrating the necessity to implement an HIV-1 group O-specific antigen in the assay. On the other hand, it was surprisingly found that 40 out of 43 (93%) of anti-HIV-1 group M-positive samples, belonging to strain A, B, C, D, E or F, were detected by crossreaction with the HIV-1 group O (strain ANT70) synthetic peptide incorporated in the Vironostika HIV Uni-Form II plus O. Only HIV-1 subtype D-positive samples did not react with this peptide, presumably because of the presence of a histidine residue in the immunodominant region of HIV-1 subtype D gp41. Both crossreactions make the Vironostika HIV Uni-Form II plus O microELISA also sensitive for anti-HIV-1-positive samples originating from different geographical regions and resulting from different HIV-1 subtype infections. With an unusual seroconversion panel in which p24 Ag was present persistently, many anti-HIV-1/-2 assays produce alternating positive/negative results in anti-HIV antibody-positive bleeds. It was shown that the use of viral p24 and gp160 in a direct sandwich, allowing detection of anti-HIV IgG and IgM, explains the identification of all anti-HIV-positive bleeds by the Vironostika HIV Uni-Form II plus O. The high sensitivity of the plus O assay was confirmed with clinical samples of a so-called anti-HIV-1 low titer panel. The specificity of the Vironostika HIV Uni-Form II plus O determined in five blood transfusion centers, based on 135070 tests, was 99.97%.

AIDS Serodiagnosis↗

PubMed1998

Evaluation of 14 commercial HIV-1/HIV-2 antibody assays using serum panels of different geographical origin and clinical stage including a unique seroconversion panel.

The performance of 14 commercially available HIV-1/2 antibody assays were compared using well-characterized serum panels containing in total 1500 1800 sera. The panels included consecutive HIV-negative blood donor sera from Sweden, unselected blood donor and patient sera from Tanzania and unselected sera from outpatient clinics in Guinea-Bissau. Furthermore selected HIV-1 antibody positive sera from Sweden and Tanzania and HIV-2 antibody positive sera from Guinea-Bissau were included in the panels. The HIV-1 antibody positive sera were from individuals at various stages of HIV infection, from primary infection, to asymptomatic phase and late stage disease. 12 of the 14 assays identified correctly all HIV-1 and HIV-2 antibody positive sera. One Tanzanian HIV-1 antibody positive sample with complete banding pattern on Western blot was not detected by two of the ELISAs employing synthetic peptides. There were small differences in sensitivity between the assays when used for analysis of seroconversion panels. The most sensitive assay, Abbott IMx HIV-1/HIV-2 III Plus detected antibodies in all nine samples collected from four individuals during the first week after onset of symptoms of primary HIV-1 infection. Most of the assays became reactive during the second week after onset of symptoms and the least sensitive assays were reactive from the third week. The assays showed a high specificity ranging from 99.2 to 100% when used for analysis of Swedish blood donor sera, while most of the assays showed a significantly lower specificity, 91.9-99.6%, when used for testing African specimens.

AIDS Serodiagnosis↗

PubMed2003

Antigen dependent adverse reactions and seroconversion of a tick-borne encephalitis vaccine in children.

Two randomized, double blind dose comparison studies were conducted in 595 children in Austria and Germany with an albumin-free and thiomersal-free tick-borne encephalitis (TBE) vaccine. Vaccinated subjects of an age between 6 months and 12 years randomly assigned received either the full adult dose or half the adult dose. Results from vaccinated children under 1 year of age at the time of the first vaccination (159 subjects) showed an age dependent immune response. There were significantly fewer adverse systemic events (e.g. fever reactions). In children who received only half the adult dose, while seroconversion was not significantly different (93% versus 98%) after the second vaccination, and 100% for both groups after the third vaccination. Based on these results, it is recommended to vaccinate children between the ages of 1 and 12 years with half the adult dose.

Aging↗

PubMed1997

Seroconversion of a trivalent measles, mumps, and rubella vaccine in children aged 9 and 15 months.

The serological response to MMR vaccine was evaluated in 109 9-month-old infants having no history of measles vaccination, and in 98 15-month-old children who had received monocomponent measles immunisation at 9 months. The combined vaccine contained Schwarz, Urabe Am9, and Wistar RA 27/3 live attenuated virus strains. Preimmunisation antibody levels were extremely low for the 9-month-old children, indicating that maternally-transmitted antibodies do not persist at this age. In the case of mumps, preimmunisation antibody levels were significantly higher in the 15-month-old than in the 9-month-old group. A difference between groups in terms of postimmunisation antibody titres was observed only for rubella, with titres being significantly higher in the older group. Seroconversion rates were high in both groups and no serious events attributable to vaccination were observed. The MMR vaccine can thus be administered to children as young as 9 months of age. Evidence for the efficacy of a two-dose schedule, i.e. at 9 and 15 months, is presented.

Aging↗

PubMed2001

Hiv-associated nephropathy occurring before HIV antibody seroconversion.

It currently is thought that human immunodeficiency virus-associated nephropathy (HIVAN) occurs late in the course of HIV infection. Although HIVAN may be the presenting manifestation of acquired immunodeficiency syndrome (AIDS), it usually occurs after a prolonged period of viral infection often associated with high levels of HIV viremia. The patient described here developed HIVAN as a manifestation of acute retroviral syndrome. A 41-year-old black man presented with nephrotic range proteinuria, renal insufficiency, and acute gastrointestinal and pulmonary symptoms. He recently had been treated for primary syphilis. Two HIV serologic tests, performed 3 months apart, were negative. Renal biopsy was consistent with HIVAN. After the biopsy, the patient was discovered to have more than 700,000 viral copies per mL in his blood. CD4(+) count was greater than 500/mm(3). Six weeks later, enzyme-linked immunosorbent assay and Western blot analyses for HIV antibody became positive. HIVAN can occur early in the course of HIV infection, even during acute infection before seroconversion, and prolonged exposure to virus is not necessary for this renal involvement to occur in the susceptible host.

AIDS-Associated Nephropathy↗

PubMed1997

Effect of maternally acquired Aujeszky's disease (pseudorabies) virus-specific antibody in pigs on establishment of latency and seroconversion to differential glycoproteins after low dose challenge.

This study investigated whether (1) passively immune pigs could become latently infected after challenge with low doses of wild type pseudorabies virus (PRV) and (2) if seroconversion to PRV could be consistently detected using two commercially available differential diagnostic ELISAs. Three litters of piglets with passively acquired PRV serum neutralizing (SN) antibody (geometric mean titers 47.03 to 95.10) were challenged at 6 to 12 days of age with 236 to 500 TCID50 of Shope strain virus; pigs were vaccinated at 11 weeks of age with a commercially available genetically engineered vaccine (TK- gE- gG- Iowa S62 strain PRV). Vaccination was intended to reduce the risk of reactivation of latent infection resulting in spread of virulent PRV infection to previously uninfected pigs during the experiment. Vaccination at this age also approximated common field practices in infected herds. After 15 weeks, all challenged pigs were seropositive on the PRV glycoprotein (g or gp) E differential ELISA but were seronegative on the gG differential ELISA. All three challenge groups had pigs that were latently infected as evidenced by the detection of PRV DNA by polymerase chain reaction (PCR) assay of their trigeminal ganglia (TG). There was a significant inverse relationship observed for age at challenge and the proportion of PCR positive pigs in the group 15 weeks postchallenge (p = 0.0004). This trend was independent of the passively acquired PRV SN antibody titers at challenge. In this study, passively acquired antibody did not provide protection against establishment of latent infection in piglets after exposure to low doses of virulent PRV. These latent infections were detected serologically by only one of two available differential diagnostic ELISA.

Analysis of Variance↗

PubMed2006

HIV seroconversion in a woman preparing for assisted reproduction: an inherent risk in caring for HIV-serodiscordant couples.

A woman preparing to undergo IVF and intracytoplasmic sperm injection to avoid horizontal viral transmission of HIV from her seropositive husband was discovered to be HIV seropositive, presumably secondary to a condom break or unprotected intercourse. Had this event occurred after treatment, the sperm-washing technique used to avoid infection would have undoubtedly been called into question. Nearly all HIV-serodiscordant couples are sexually active and therefore at risk for transmitting infection, either due to improper condom use or unprotected intercourse. Physicians willing to treat HIV-serodiscordant couples must accept the inevitability of viral transmission in occasional individuals. Furthermore, it should not be presumed that all patients who experience seroconversions after either intrauterine insemination or IVF procedures do so as a result of inadequacies in the sperm preparation technique.

Adult↗

PubMed1998

The rate of CD4 decline as a determinant of progression to AIDS independent of the most recent CD4 count. The Italian Seroconversion Study.

The data of two cohort studies of HIV-infected individuals were used to examine whether the rate of CD4 decline is a determinant of HIV progression, independent of the most recent CD4 count. Time from seroconversion to clinical AIDS was the main outcome measure. Rates of CD4 decline were estimated using the ordinary least squares regression method. AIDS incidences were compared in individuals who had previously experienced either a steeper or a less steep rate of CD4 decline. Cox proportional hazards model including a time-dependent covariate for the rate of CD4 decline was performed. The rate of prior CD4 decline was significantly associated with the risk of developing AIDS independently from the most recent CD4 count, with a 2% increase in hazard of AIDS (P < 0.01) for a difference of 10 cells/mm3 in the estimated yearly drop in CD4 count. This finding gives scientific credit to the belief that individuals with a prior steeper CD4 decline consistently have a higher subsequent risk of developing AIDS than those with a less steep prior decline.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Serum IgG antibodies to human herpesvirus-6 (HHV-6) do not predict the progression of HIV disease to AIDS. Italian Seroconversion Study group.

OBJECTIVES: To evaluate if different levels of human herpesvirus 6 (HHV-6) antibodies can predict HIV disease progression. DESIGN: Longitudinal study of individuals with a documented date of HIV seroconversion. SETTING: Clinical centers located throughout Italy. PATIENTS: Individuals who serconverted for HIV between 1983 and 1995 in Italy. METHODS: Sera were tested for IgG antibodies to HHV-6 using a commercial enzyme immunoassay. A serum sample with an optical density (OD) > or =242 (i.e. the mean value of 10 negative controls +4x standard deviation) was considered as HHV-6 positive; the progression of HIV disease was evaluated estimating the relative hazards (RH) of AIDS (by Cox models) for individuals with higher levels vs. lower levels of HHV-6 antibodies or considering levels of antibodies based on 10% increase of the distribution (deciles). Rates of CD4 decline fitting linear regression were also estimated. RESULTS: A total of 381 persons were followed for a median time of 4 years (range: 0.15-9 years) following the date of collection of the serum sample. The median OD value of HHV-6 antibodies was 306, with an interquartile range of 241-440 and a range of 48-2330. A slight inverse correlation was found between HHV-6 antibody levels and age of the individual at the time of serum collection (Spearman rank correlation coefficient, -0.16; p = 0.0013). No association was found between HHV-6 and CD4 level or between HHV-6 and CD8 level at the date of serum collection. The unadjusted RH of progression to AIDS was 0.63 (95% CI: 0.42-0.96) for HHV-6 positive individuals vs. HHV-6 negative; when adjusting for possible confounders (CD4, age, pre-AIDS HIV-related pathologies at the date of sera collection, and previous anti-herpes treatment), the RH of AIDS increased to 0.80 (95% CI: 0.51-1.23). No particular association with HIV disease progression was found when using the deciles of the distribution of HHV-6 antibodies. The median CD4 cell loss was 5.0x10(6) cells/l per month among HHV-6 positive individuals and 5.7x10(6) cells/l per month among the others. CONCLUSIONS: The presence of high levels of HHV-6 antibodies does not seem to predict the clinical or immunologic progression of HIV disease.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Incidence and risk factors for hepatitis C seroconversion in hemodialysis: a prospective study. The UCL Collaborative Group.

To delineate the incidence and risk factors for seroconversion (SC) for HCV, from May 1991 to November 1992 we followed all 401 patients (no i.v. drug abusers) dialyzed in 15 Belgian hemodialysis (HD) units, none of which isolates anti-HCV (+) patients. The sensitive ELISA II test was performed in the same laboratory for all patients. ELISA II (+) sera were considered truly positive if specific antibodies were detected by RIBA II against at least one HCV antigen. Blood transfusions given from 12 months prior to inclusion in the study, dialyzer reuse and frequency of dialysis monitor sterilization were recorded. In May 1991, prevalence of truly positive ELISA II tests averaged 13.5% (54/399). During the three consecutive six-month periods, ELISA II became truly positive in 3 of 305 (1%), 4 of 314 (1.3%) and 1 of 313 (0.3%) patients, respectively, which was an average yearly incidence of 1.7%. SC was preceded (1 to 6 months) in all cases by an unexplained, unprecedented increase in the alanine aminotransferase level. The mean monthly rate of transfusions was significantly higher (P < 0.001) in eight patients with SC (0.7 +/- 0.6 U) than in 393 patients without SC (0.1 +/- 0.01 U). However, three of eight patients with SC had not been transfused at all. SC was observed in only 3 of 13 units (1, 3 and 4 cases, respectively) dialyzing ELISA (+) patients. In the unit with three SC, patients were always assigned a fixed station: SC was observed only in patients dialyzed next to an ELISA II (+) patient (3 of 8 vs. 0 of 30, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2002

Lamivudine treatment for reverse seroconversion of hepatitis B 4 years after allogeneic bone marrow transplantation.

Reverse seroconversion of hepatitis B virus (HBV) after allogeneic BMT is rare. We present a case of HBV reactivation late after allogeneic BMT which responded well to lamivudine therapy. A 35-year-old woman with CML received an allogeneic BMT. Before BMT, the patient had immunity to HBV, with serum antibodies against hepatitis B surface antigen (HBsAb), and the donor was completely negative for HBV. Four years after BMT, acute hepatitis occurred with a detectable level of HBV-DNA. Lamivudine rapidly reduced transaminase and bilirubin levels, and serum HBV-DNA decreased to negative. Retrospective analysis revealed that there had been a gradual decrease in serum HBsAb titers after BMT. Administration of lamivudine immediately after HBV replication may be more effective than vaccination of hepatitis B surface antigen-negative donors before BMT.

Adult↗