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 199 records · Page 11Linked to original sources

PubMed1991

Complete seroconversion by low-dose intradermal injection of recombinant hepatitis B vaccine in hemodialysis patients.

The present study was undertaken to find out if the seroconversion rate of hemodialysis (HD) patients was enhanced by the intradermal (i.d.) inoculation of recombinant hepatitis B (HB) vaccine. Thirty-five HBs-Ag, HBs-Ab and HBc-Ag, HBc-Ab negative HD patients were divided into three groups: 14 patients in group I received 5 micrograms HBs Ag i.d. every 2 weeks, 13 patients in group II were given 2.5 micrograms HBs vaccine i.d. every 2 weeks, 5 times, then every week. The remaining 8 patients in group III were immunised with 10 micrograms HBs Ag every 4 weeks 5 times intramuscularly (i.m.), then 5 micrograms i.d., every 2 weeks until complete seroconversion. Antibody response to i.m. injection was poor and only 37.5% of patients developed anti-HBs at a titer of 10 mIU/ml or more at 16 weeks after the start of immunisation. However, this poor response was improved by i.d. injection. The time of seroconversion was significantly earlier and the rate of response was higher in group I. The poor response in group II was markedly improved by doubling the inoculation rate. Overall, 100% of seroconversion was finally obtained by multiple i.d. immunisation. However, the anti-HBs titers were lower in all patients and declined in some patients after the immunisation was stopped. The last seroconverted patient in each group lost protective antibody levels at the 39th week. These patients became antibody positive again at the 52nd week with a booster dose. We feel that the i.d. route remains a useful and cheaper method of obtaining prophylaxis against HBs in high-risk HD patients but it would seem to be prudent to monitor these patients serially to assess the persistence of anti-HBs in the serum.

Adult↗

PubMed2001

Late seroconversion in HIV-resistant Nairobi prostitutes despite pre-existing HIV-specific CD8+ responses.

Resistance to HIV infection in a small group of Kenyan sex workers is associated with CD8+-lymphocyte responses to HIV cytotoxic T-lymphocyte (CTL) epitopes. Eleven prostitutes meeting criteria for HIV resistance seroconverted between 1996 and 1999. The occurrence and specificity of preexisting HIV-1 epitope-specific responses were examined using the IFN-gamma enzyme-linked immunospot assay, and any epitopes recognized were cloned and sequenced from the infecting viral isolate. Immunologic and behavioral variables were compared between late seroconverters and persistently uninfected sex worker controls. HIV-1 CTL epitope responses were present in four of six cases, 5-18 months before seroconversion, and their presence was confirmed by bulk CTL culture. A possible viral escape mutation was found in one of six epitopes. The key epidemiologic correlate of late seroconversion was a reduction in sex work over the preceding year. In persistently uninfected controls, a break from sex work was associated with a loss of HIV-specific CD8+ responses. Late seroconversion may occur in HIV-1-resistant sex workers despite preceding HIV-specific CD8+ responses. Seroconversion generally occurs in the absence of detectable CTL escape mutations and may relate to the waning of HIV-specific CD8+ responses due to reduced antigenic exposure.

Adult↗

PubMed1998

Evaluation of a single dilution ELISA system for detection of seroconversion to bovine viral diarrhea virus, bovine respiratory syncytial virus, parainfluenza-3 virus, and infectious bovine rhinotracheitis virus: comparison with testing by virus neutralization and hemagglutination inhibition.

A single-dilution quantitative enzyme-linked immunosorbent assay (ELISA) system, based on commercial ELISA kits, for the simultaneous detection of seroconversion to bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), parainfluenza-3 virus (PI3V), and infectious bovine rhinotracheitis virus (IBRV) was evaluated by testing acute and convalescent serum pairs from 564 cattle in 145 outbreaks of respiratory disease. Seroconversion to BVDV, BRSV, PI3V and IBRV was detected in 8.0%, 19.0%, 13.7%, and 7.4%, respectively, of serum pairs tested. Seroconversion was detected in 60.7% of herds and 34.6% of animals tested. Infection with 2 or more viruses was found in 46.6% of these herds and in 27.2% of these animals. The majority of BVDV infections (62%) were associated with other virus infections, suggesting that BVDV may potentiate infection with other agents rather than being a primary pathogen of the respiratory tract. The results were compared with those obtained by virus neutralization and hemagglutination inhibition testing, and the sensitivity, specificity, and overall correlation were calculated. Sensitivities of 92%, 95%, 100%, and 100% were obtained for BVDV, BRSV, PI3V, and IBRV, respectively. The corresponding specificity values were 89%, 92%, 86%, and 91%. The overall correlation for each virus was 90%, 93%, 90%, and 93%, respectively. These results demonstrate that this ELISA system may be used successfully to detect seroconversion in serum pairs, highlight the frequency of multiple viral infections in outbreaks of respiratory disease, and provide further evidence of an immunosuppressive role for BVDV infections.

Animals↗

PubMed1999

Isotype- and subclass-specific responses to infection and reinfection with parainfluenza-3 virus: comparison of the diagnostic potential of ELISAs detecting seroconversion and specific IgM and IgA.

Isotype- and subclass-specific indirect enzyme-linked immunosorbent assays were developed to detect parainfluenza-3 virus-specific IgG1, IgG2, IgM, and IgA responses. Sera were treated with protein G-agarose prior to testing for specific IgM and IgA to eliminate the possibility of false-positive results due to IgM-rheumatoid factor and to remove interisotypic competition due to specific IgG. IgM and IgA absorbance values were expressed as a percentage of the absorbance values of positive reference sera included on each plate (S/P%), and respective positive/negative threshold values of 15.0% and 28.0% were determined. The mean interval between experimental infection of 3 calves and initial detection of specific IgG1 and IgG2 responses was 8.0 and 9.3 days respectively, rising rapidly to an initial plateau 13.7 and 11.0 days postinfection (dpi). Reinfection of these calves at 30 dpi resulted in further rapid increases, with higher plateau values reached 13.0 (IgG1) and 13.7 (IgG2) days later. The mean interval between infection and the first positive IgM and IgA responses was 6.7 and 12.3 days, respectively. IgM S/P% values peaked at 13.0 dpi, with all 3 calves showing a secondary anamnestic response to reinfection, peaking 4.7 days later. The IgA response to initial infection was weak, with only 2 calves showing an obvious peak response at 15.0 dpi. A strong anamnestic IgA response to reinfection occurred in 2 calves, with a peak response 9.5 days later. Apparent biphasic and triphasic IgM and IgA responses were evident in some calves. Acute and convalescent serum samples from 80 calves involved in 17 outbreaks of respiratory disease were tested for specific IgM and IgA. Positive IgM results were detected in 15 outbreaks, with 71 sera from 44 calves testing positive. Although IgA-positive results were detected in the same 15 outbreaks, only 42 sera from 31 calves were positive. In a previous study, seroconversion was detected in 21 of these calves from 10 outbreaks. Thus the diagnostic potential of the assays was in the order IgM > IgA > seroconversion. The correlations between IgM and IgA, IgM and seroconversion, and IgA and seroconversion results for each calf were 73.8%, 58.8% and 62.5%, respectively.

Animals↗

PubMed2000

[Seroconversion study of Biken CAM-70 measles vaccine formulations].

OBJECTIVES: To compare seroconversion rates induced by Biken CAM-70 measles vaccines at different viral concentrations. METHODS: Healthy children aged 9 to 18 months from a primary health care unit in Rio de Janeiro, Brazil, and whose guardians agreed with their participation, were randomly assigned to receive one of the following vaccine formulations: 5,000, 1,000 or 200 CCID50 (50% Tissue Culture Infective Dose). The research team, participants, and data analysts were blinded to the type of vaccine administered. Pre- and post-vaccination antibody levels were assessed through Plaque Reduction Neutralization Test. Two interim data analyses were planned to assess unequivocal evidence of the superiority of one of the vaccine types. RESULTS: From 223 recruited children, 84% completed the whole course. Of them, 79% were less than 10 months of age, and 93% did not show detectable measles antibodies in pre-vaccination serum. Seroconversion (four-fold increase in antibody levels) in groups vaccinated with 5,000, 1,000 or 200 CCID50, were 82%, 55%, and 37% (p<0.0000), respectively. Differences in the mean concentration of post-vaccination antibodies were also substantial and statistically significant (p<0.000). Seroconversion rates (pooling data from all vaccine formulations) were 73% to children aged 10 months or more, and 53% in those below 10 months. CONCLUSIONS: Vaccines with concentrations below 5,000 CCID50 did not produce satisfactory seroconversion rates. The vaccine performance by age was consistent with that seen in other studies using Biken CAM-70 strain in which a sizable proportion of 9-month-old children failed to achieve full immunological response.

Analysis of Variance↗

PubMed1992

Seroconversion to hepatitis C virus antibodies in patients with acute posttransfusion non-A, non-B hepatitis in Sweden with a second generation test.

28 patients with posttransfusion non-A, non-B (NANB) hepatitis in Stockholm, Sweden, were studied for seroconversion to hepatitis C virus antibodies (anti-HCV) and time lag to seroconversion by first and second generation tests. 15/28 patients (54%) seroconverted to anti-HCV with a first generation anti-HCV ELISA using C100-3 from the nonstructural (NS) region 4 of the HCV genome and 23 (82%) with a second generation anti-HCV ELISA including also antigens from the core and NS3 regions of the HCV genome. The mean time from onset of hepatitis to seroconversion was 6.1 weeks (0-18 weeks) with the first generation test and 2.3 weeks (0-7 weeks) with the second generation test. Development of chronic hepatitis was noticed in 14/23 (61%) patients who seroconverted to anti-HCV with the second generation ELISA and in none of 5 patients with posttransfusion NANB hepatitis who did not seroconvert. The inclusion of antigens from the core and NS3 regions of the HCV genome has increased the sensitivity of the second generation anti-HCV ELISA as compared to the first generation ELISA and also shortened the time lag to seroconversion in patients with posttransfusion hepatitis C. Patients with posttransfusion NANB hepatitis seroconverting seem more prone to develop chronic disease than patients not seroconverting.

Enzyme-Linked Immunosorbent Assay↗

PubMed2005

High level of hepatitis B virus DNA after HBeAg-to-anti-HBe seroconversion is related to coexistence of mutations in its precore and basal core promoter.

AIM: G1896A mutation in precore or A1762T/G1764A mutations in basal core promoter are suspected to be responsible for patients with detectable level of HBV DNA in serum after seroconversion from HBeAg to anti-HBe. However, G1896A variant has impaired, while A1762T/G1764A variant may have intact replication ability. They themselves or their coexistence status may play different roles in such meaningless seroconversion. For these reasons, the significances of these two types of mutations were comparatively investigated in this study. METHODS: One hundred and sixty-five sera with positive anti-HBe and HBV DNA were collected from different patients. Mutations of G1896A and A1762T/G1764A among these serum samples were detected using competitively differentiated PCR. HBV DNA was demonstrated using real-time quantitative PCR. RESULTS: G1896A and/or A1762T/G1764A mutations were detected in 89.1% (147/165) out of patients with detectable HBV DNA in serum after HBeAg-to-anti-HBe seroconversion. The positive rate of G1896A variants was significantly higher than that of A1762T/G1764A mutations (77.6% vs 50.3%, chi2 = 26.61, P<0.01). The coexistence positive rate of these two types of mutations was 38.8% (64/165). Coexistence mutations were found in 77.1% (64/83) out of sera with A1762T/G1764A mutations, and in 50.0% (64/128) out of sera with G1896A mutation. Compared with variants with G1896A mutation only, the coexistence mutations were predominant in patients with high level of serum HBV DNA, and related to higher total bilirubin, lower serum albumin and progressive liver diseases. CONCLUSION: The coexistence of G1896A mutation and A1762T/G1764A mutations is very common, and responsible for the major cases with high level of HBV DNA in serum and progressive liver diseases after HBeAg-to-anti-HBe seroconversion. This coexistence mutation variant may have higher pathogenicity and replication ability.

Adult↗

PubMed2004

Altered EBV viral load setpoint after HIV seroconversion is in accordance with lack of predictive value of EBV load for the occurrence of AIDS-related non-Hodgkin lymphoma.

In contrast to the situation in the post-transplant setting, in HIV-infected individuals an elevated EBV load is not predictive of EBV-related malignancies. To study whether a high EBV load is already a normal situation early in HIV infection and is not related to a decrease in immune function over time, we investigated EBV load and EBV-specific CD8(+) T cells approximately 1 year before and 1 year after HIV seroconversion. EBV load significantly increased after HIV seroconversion from 205 to 1002 copies/10(6) PBMC (p < 0.001), whereas no further increase in EBV load was observed between 1 and 5 years after HIV seroconversion (median, 1827-2478 copies/10(6) PBMC; p = 0.530). Interestingly, the absolute number of EBV lytic epitope, RAKFKQLL-specific CD8(+) T cells increased over HIV seroconversion (4.78 to 9.54/ micro l; p = 0.011). Furthermore, the fraction of CD27-negative effector, RAK-specific CD8(+) T cells tended to increase (from 12.2 to 17.31% CD27(-); p = 0.051), in accordance with Ag-driven differentiation. In conclusion, both virological and immunological data support the idea that a new EBV viral setpoint is reached early in HIV infection, probably by EBV reactivation, as suggested by the preferential increase in EBV lytic epitope-specific CD8(+) T cells. These data may thus help to explain the lack of predictive value of EBV load for the occurrence of AIDS-related lymphoma.

Adult↗

PubMed1995

Quantitation of HIV-1 RNA in plasma predicts outcome after seroconversion.

OBJECTIVE: To investigate the relation between the quantity of human immunodeficiency virus type 1 (HIV-1) RNA in plasma and the risk for the acquired immunodeficiency syndrome (AIDS) or a decline in the CD4+ T-cell count after seroconversion. DESIGN: Prospective study. PATIENTS: 62 homosexual men with documented HIV-1 seroconversion. SETTING: University outpatient setting. MEASUREMENTS: Clinical status, CD4+ T-cell counts, and plasma and serum samples were obtained every 6 months. Human immunodeficiency virus RNA in plasma was quantitated with a branched-DNA (bDNA) assay. Serum samples were assayed for neopterin, beta 2-microglobulin, and immune complex dissociated HIV-1 p24 antigen. RESULTS: 18 of 62 (29%) men developed AIDS; 21 (34%) had a significant decline in the CD4+ T-cell count without AIDS; and 23 (37%) had a stable CD4+ T-cell count. For each participant, HIV-1 RNA results were categorized into one of four groups: 1) detection of HIV-1 RNA (> 1 x 10(4) genome equivalents/mL [Eq/mL]) in all samples; 2) detection in most samples (> or = 50%); 3) detection in fewer than 50% of samples; and 4) detection in none of the samples. Detection of HIV-1 RNA in all or most samples was strongly associated with AIDS (16 of 18 patients) and a decline in the CD4+ T-cell count (13 of 21 patients) compared with a stable CD4+ T-cell count (4 of 23 patients; P < 0.001). Conversely, the absence of HIV-1 RNA (< 1 x 10(4) Eq/mL) in all or most samples was associated with stable CD4+ T-cell counts (19 of 23 patients) and a lower risk for AIDS or decline in the CD4+ T-cell count (10 of 39 patients; P < 0.001). In multivariate analysis of all laboratory values at the seroconversion visit, a plasma HIV-1 RNA level greater than 1 x 10(5) Eq/mL was the most powerful predictor of AIDS (odds ratio, 10.8; P = 0.01). CONCLUSIONS: Plasma HIV-1 RNA is a strong, CD4+ T-cell-independent predictor of a rapid progression to AIDS after HIV-1 seroconversion.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Cumulative incidence of hepatitis C seroconversion in a cohort of seronegative injecting drug users.

AIM: To measure the cumulative incidence of hepatitis C virus seroconversion over a two year period in a group of seronegative injecting drug users. METHODS: The study involved follow-up, in 1996, of a cohort (n=85) of injecting drug users identified as hepatitis C virus seronegative in 1994. Participants were interviewed about risk factors for hepatitis C. A blood sample was also taken for anti-hepatitis C virus antibody and hepatitis C virus RNA testing. RESULTS: Forty-four participants were interviewed and 39 gave blood for testing. Most (80%) were aged 29 years or under and two thirds (n=26) were male. Around half reported borrowing (49%) or lending (57%) needles and syringes since 1994 and both of these behaviours were associated with seroconversion. The majority (88%) also reported sharing other injecting equipment. Nine were anti-hepatitis C virus positive giving a seroconversion rate over two years of 23% (13 per 100 person years). Four out of the nine seropositive specimens tested were also hepatitis C virus RNA positive. CONCLUSIONS: This study demonstrates a high rate of recent hepatitis C virus seroconversion amongst a group of New Zealand injecting drug users. Transmission of hepatitis C virus appears to be unabated by current control measures. These findings confirm the need to develop more effective policy and practices to prevent further spread, not just of hepatitis C, but of other blood-borne viruses in injecting drug user populations.

Adolescent↗

PubMed2006

[A prospective cohort study on human immunodeficiency virus and syphilis seroconversion among injecting drug users].

OBJECTIVE: To study the rate of human immunodeficiency virus (HIV) seroconversion, HIV transmission and related risk factors among injecting drug users (IDUs) in an area of Sichuan province. METHODS: In November 2002, a community-based baseline survey was conducted to recruit 333 HIV-seronegative IDUs for a prospective cohort study in Xichang county of Sichuan province, China. Follow-up visits were carried out every 6 months to study the situation of drug use, sexual behaviors of the IDUs and blood specimens were collected to test for antibodies against HIV and syphilis. RESULTS: During a 24-month follow-up period, cohort retention rate and HIV incidence were 75.7% and 2.53 per 100 person-years [95% confidence interval (CI): 1.10-3.97)], respectively. Multivariate Poisson regression model showed that risk factors which were significantly associated with HIV seroconversion would include: ethnicity (RR = 12.42; 95% CI: 2.72-56.74, P = 0.0012) and needle or syringe sharing in the past 3 months (RR = 4.06; 95% CI: 1.29-12.81, P = 0.0168). Syphilis seroconversion in this cohort was 4.71 per 100 person-years (95% CI: 2.59-6.82). In multivariate Poisson regression being female (RR = 4.42; 95% CI: 1.78-10.99, P = 0.0014) appeared to be the only factor which was significantly associated with syphilis seroconversion. CONCLUSION: Our study results showed that there was a rapid transmission of HIV and syphilis among IDUs in Sichuan province, suggesting that effective intervention should be urgently taken.

Cohort Studies↗

PubMed1991

Late seroconversion to hepatitis B in a Somali village indicates the important role of venereal transmission.

Hepatitis B virus (HBV) markers were investigated in a cross-sectional study in 1985 on sera from 84% of the 648 inhabitants in a rural Somali village. The prevalence of HBV markers increased with age, from 9.7% in subjects less than 12 years old, to 38% in the age group 12-19 years, and to 68% in adults. HBV markers were more common in boys less than 12 years old, 13%, than in girls of the same age group, 5.8% (P less than 0.05). A rapid increase of HBV markers started at adolescence in both sexes. The female cohort showed their highest seroconversion rate during their second decade of life, while the male cohort seroconverted more rapidly in the third decade. Thus, an initially more rapid seroconversion among boys was reversed when the females reached reproductive age, and no sex difference in marker frequencies was observed in the age group 12-19 years. There was a steady increase of HBV markers during the reproductive years in both sexes. The frequencies of HBsAg, as well as total markers, were significantly higher in adult males than females, 14 vs 5.6%, and 77 vs 62%, respectively. HBV markers were more frequent in wives of HBV positive husbands than in those married to HBV negative husbands. No increased marker prevalence was observed among siblings of HBV positive children, nor among their mothers, which disproved the role of vertical and early horizontal transmission. In 1989 the four-year rate of seroconversion was investigated in villagers who were seronegative in 1985. On testing 158 sera from 319 individuals, the seroconversion rate was significantly lower among those younger than 12 years in 1985 compared to those in the older age group, 5 vs 17%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Age for measles immunization seroconversion after measles vaccination at 6-8 months of age--a randomized controlled trial.

The objective of the study was to compare the effectiveness of measles vaccine by seroconversion in vaccinated children with non-vaccinated children of 6 to 8 months age group in a city slum community so as to study the feasibility of advancing the age of immunization. Live attenuated lyophilized Schwartz strain of measles vaccine was used. Hemagglutination inhibition (HI) antibody was estimated. Seroconversion was defined as either the conversion of negative to positive or a two fold rise in titre. One hundred and thirty two children completed the study. There was no difference in the age, sex and nutritional status between vaccinated and non-vaccinated groups (p greater than 0.7). The seroconversion rate in the vaccinated group was 65% and in the non-vaccinated group was 26%. The age, sex and nutritional status did not significantly affect the seroconversion. Our data suggest that immunization with measles vaccine may be effective as early as 6 months of age. Immunization at 6 months may be needed at least for children in densely populated areas like cities and towns.

Age Factors↗

PubMed1990

No association between herpes simplex virus type-2 seropositivity or anogenital lesions and HIV seroconversion among homosexual men.

Recent reports have suggested that HSV-2 infection and associated anogenital ulcerations represent an important risk factor for acquisition of HIV infection. Although this is an appealing biological hypothesis, inferences drawn for homosexual men, as well as other at-risk populations, must be made after careful consideration of methods to control for potential confounding data. This report utilized a nested case-control study in which 49 homosexual HIV seroconverters were compared to 49 homosexual seronegative men matched on the prior level of receptive anal intercourse. No differences were observed for prior HSV-2 infection, since 21/49 (43%) of matched HIV seronegative men were HSV-2 antibody positive and 21/49 (43%) of HIV seroconverters were HSV-2 antibody positive at the visit 6 months before HIV seroconversion (odds ratio of 1.0, 95% confidence limits of 0.3-2.9) Similar findings were also observed for prior HSV-1 infection. Both self-reported symptoms and physical exam findings suggestive of HSV infection were rare during the 12 months prior to seroconversion and not associated with HIV seroconversion. These data do not support HSV-2 as a risk factor for seroconversion to HIV among homosexual men studied. These results should not be generalized to heterosexual transmission of HIV, particularly in Africa, where both an increased prevalence of genital ulcerative diseases and different etiologies have been observed.

Adult↗

PubMed1989

Incidence of human immunodeficiency virus seroconversion in US Navy and Marine Corps personnel, 1986 through 1988.

From 1986 through 1988, the US Navy and US Marine Corps administered 1,956,631 enzyme-linked immunosorbent assay screening tests for antibodies to the human immunodeficiency virus to 1,070,511 active-duty enlisted and officer personnel. This study identified all persons who had an initial test with negative results. This population was then followed up and those who later tested positive for human immunodeficiency virus were identified as seroconverters. There were 582 seroconversions identified from a total of 987,479 person-years at risk. The age adjusted seroconversion rate and 95% Poisson confidence intervals for navy personnel was 0.69 per 1000 person-years (95% confidence interval, 0.63 to 0.76). Age-adjusted rates in men were 5.0 times those of women. Age-adjusted rates in blacks were 3.7 times those of whites. The age-adjusted seroconversion rate in Marine Corps personnel was 0.28 per 1000 person-years (95% confidence interval, 0.22 to 0.36). Similar demographic patterns were present in the Marine Corps and the US Navy. This study is one of the first reports of incidence of human immunodeficiency virus seroconversion by demographic characteristics in a large, young, and apparently healthy population.

Adolescent↗

PubMed1987

1986 update of HIV seroprevalence, seroconversion, AIDS incidence, and immunologic correlates of HIV infection in patients with hemophilia A and B.

A cohort of 181 patients with hemophilia A (149) and hemophilia B (32) cared for at the Hemophilia Center of Western Pennsylvania was followed to determine human immunodeficiency virus (HIV) seroprevalence, seroconversion rate, and clinical and immunologic correlates of HIV infection. By December 1986, 82 (45%) were HIV seropositive, and of these, ten (12%) had developed AIDS, 28 (34%) had symptomatic HIV infection (CDC class III, IV), of whom 14 (17%) had AIDS-related complex (ARC), and 44 (54%) had asymptomatic HIV infection (CDC class II). The HIV seropositive group included 82% of those treated with factor VIII concentrate (97% severe, 5% moderate), 48% of those treated with factor IX concentrate (92% severe, 8% moderate), 10% of those treated with cryoprecipitate (67% severe, 33% moderate), and none of those treated with fresh frozen plasma. Based on 77 serially sampled HIV seropositive hemophiliacs (1977 to 1986), peak seroconversion occurred in 1982, with 14% (11 of 77) occurring since 1984. With increasing time from seroconversion, both T4 lymphocyte number and function (the latter measured by growth in soft agar [T colony assay]) progressively declined; T4 number declined to 135 +/- 26/mm3 (SEM), and colony count declined 1193 +/- 537 (control 3851 +/- 387) by 5 years after seroconversion. In those developing AIDS, total T4 fell below 100/mm3 (33 +/- 8/mm3) at diagnosis. In this cohort, the overall AIDS incidence is 5.5% (12% among the HIV seropositive) and in those seropositive 5 or more years, the AIDS incidence approaches 32%.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Incidence and risk factors for human T-lymphotropic virus type II seroconversion among injecting drug users in Baltimore, Maryland, U.S.A.

To determine the incidence of and risk factors for human T-lymphotropic virus, type II (HTLV-II) seroconversion among injecting drug users (IDUs), specimens from IDUs recruited into the ALIVE Study in 1988/1989 were assayed at baseline for antibody to HTLV with use of enzyme immunoassay and Western blot. Participants were monitored semiannually with venipuncture and interviews. In 1992, the most recent sera of HTLV-negative participants were tested for HTLV with use of enzyme immunoassay and confirmed and typed by Western blot. For positive cases, assays were then performed for all intervening visits to determine the calendar time of seroconversion. Incidence rates were estimated using person-time. Risk factor analysis used a nested case-control design, with up to seven controls per case matched by time of study entry and duration of follow-up. At baseline, 251 HTLV-positive, 22 indeterminate, and 2,574 HTLV-seronegative IDUs were identified. Follow-up of the seronegative IDUs identified 38 seroconverters (all HTLV-II) over 5,813.6 person-years, for a rate of 0.7/100 person-years. Median lag time for seroconversion was 6.8 months. Factors associated with HTLV-II seroconversion included a specific needle-sharing practice called "backloading" within the previous 6 months [odds ratio (OR) = 6.52; 95% confidence interval (CI) = 1.94-21.95] and a baseline history of receiving money for sex (OR = 3.36; 95% CI = 1.32-8.57). Of those with more than one sex partner in the past 6 months, women were more likely than men to seroconvert (OR = 5.77; 95% CI = 1.33-25.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

HIV seroconversion in Thai hemophiliacs up to 1991.

In Thailand, the anti-HIV screening in the donor blood was started in 1987 and was compulsory nationwide in February 1989. Sixty-six hemophilia A and 10 hemophilia B patients who received approximately six million units of factor VIII and IX in the form of fresh frozen plasma, frozen cryoprecipitate, cryoprecipitate removed plasma, fresh dry plasma and factor concentrate during 1976 to 1991 were tested for anti-HIV since 1987. The age ranged from 1-39 year (mean +/- SD = 15 +/- 7.3). The anti-HIV test was performed by ELISA and/or gel agglutination and confirmed by Western blot analysis. The patients would be checked 1-2 times per year and as necessary. A total of 174 tests for the first, second, third, fourth, fifth and sixth tests were studied in 76, 49, 27, 14, 5 and 3 patients respectively during 1987 to 1991. The prevalence of HIV seroconversion in the year 1987, 1988, 1989, 1990 and 1991 was 2.2% (1/45), 1.9% (1/53), 1.6% (1/63), 1.5% (1/67) and 3.9% (3/76) respectively. Three HIV seroconversion were found in the first, fourth and fifth anti-HIV test in 3 hemophilia A patients who received massive infusion of blood components during orthopedic corrective surgery. One case of HIV seroconversion found in 1987 was transmitted by HIV unscreened blood while 2 cases in 1991 by anti-HIV seronegative blood whose donors were in the window period of HIV infection. The prevalence of HIV seroconversion in Thai hemophiliacs is much lower than those in western countries.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗