Performance of Commercially Available Serological Screening Tests for Human T-Cell Lymphotropic Virus Infection in Brazil.

Serological screening for human T-cell lymphotropic virus type 1 (HTLV-1) is usually performed using enzyme-linked immunosorbent assay (ELISA), particle agglutination, or chemiluminescence assay kits. Due to an antigen matrix improvement entailing the use of new HTLV antigens and changes in the format of HTLV screening tests, as well as newly introduced chemiluminescence assays (CLIAs), a systematic evaluation of the accuracy of currently available commercial tests is warranted. We aimed to assess the performance of commercially available screening tests for HTLV infection diagnosis. A diagnostic accuracy study was conducted on a panel of 397 plasma samples: 200 HTLV-negative plasma samples, 170 HTLV-positive plasma samples, and 27 plasma samples indeterminate by Western blotting (WB). WB-indeterminate samples (i.e., those yielding no specific bands for HTLV-1 and/or HTLV-2) were assessed by PCR, and the results were used to compare agreement among the commercially available ELISA screening tests. For performance analysis, WB-indeterminate samples were excluded, resulting in a final study panel of 370 samples. Three ELISA kits (Murex HTLV-1/2 [Murex], anti-HTLV-1/2 SYM Solution [SYM Solution], and Gold ELISA HTLV-1/2 [Gold ELISA]) and one CLIA kit (Architect rHTLV-1/2) were evaluated. All screening tests demonstrated 100% sensitivity. Concerning the HTLV-negative samples, the SYM Solution and Gold ELISA kits had specificity values of >99.5%, while the Architect rHTLV-1/2 test presented 98.1% specificity, followed by Murex, which had a specificity of 92.0%. Regarding the 27 samples with WB-indeterminate results, after PCR confirmation, all ELISA kits showed 100% sensitivity but low specificity. Accuracy findings were corroborated by the use of Cohen's kappa value, which evidenced slight and fair agreement between PCR analysis and ELISAs for HTLV infection diagnosis. Based on the data, we believe that all evaluated tests can be safely used for HTLV infection screening.

Seroprevalence of HIV, HTLV, CMV, HBV and rubella virus infections in pregnant adolescents who received care in the city of Belém, Pará, Northern Brazil.

BACKGROUND: Prenatal tests are important for prevention of vertical transmission of various infectious agents. The objective of this study was to describe the prevalence of human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis B virus (HBV), cytomegalovirus (CMV), rubella virus and vaccination coverage against HBV in pregnant adolescents who received care in the city of Belém, Pará, Brazil. METHODS: A cross-sectional study was performed with 324 pregnant adolescents from 2009 to 2010. After the interview and blood collection, the patients were screened for antibodies and/or antigens against HIV-1/2, HTLV-1/2, CMV, rubella virus and HBV. The epidemiological variables were demonstrated using descriptive statistics with the G, χ2 and Fisher exact tests. RESULTS: The mean age of the participants was 15.8 years, and the majority (65.4%) had less than 6 years of education. The mean age at first intercourse was 14.4 years, and 60.8% reported having a partner aged between 12 and 14 years. The prevalence of HIV infection was 0.3%, and of HTLV infection was 0.6%. Regarding HBV, 0.6% of the participants had acute infection, 9.9% had a previous infection, 16.7% had vaccine immunity and 72.8% were susceptible to infection. The presence of anti-HBs was greater in adolescent between 12 and 14 years old (28.8%) while the anti-HBc was greater in adolescent between 15 and 18 years old (10.3%). Most of the adolescents presented the IgG antibody to CMV (96.3%) and rubella (92.3%). None of the participants had acute rubella infection, and 2.2% had anti-CMV IgM. CONCLUSIONS: This study is the first report of the seroepidemiology of infectious agents in a population of pregnant adolescents in the Northern region of Brazil. Most of the adolescents had low levels of education, were susceptible to HBV infection and had IgG antibodies to CMV and rubella virus. The prevalence of HBV, HIV and HTLV was similar to that reported in other regions of Brazil. However, the presence of these agents in this younger population reinforces the need for good prenatal follow-up and more comprehensive vaccination campaigns against HBV due to the large number of women susceptible to the virus.

No significant HTLV seroprevalence in German people who inject drugs.

BACKGROUND: Although human T-lymphotropic virus (HTLV) is transmitted via the same routes as human immunodeficiency virus (HIV), its worldwide seroprevalence differs drastically because HTLV is transmitted mainly via infected cells rather than free virus. The sharing of needles and other equipment places people who inject drugs (PWID) at particularly high-risk for such blood-borne diseases. METHODS: To validate the methodology used to process and analyze the dried blood spots (DBS) utilized in the study, dried serum spots (DSS) with dilutions of sera from known HTLV infected individuals were analyzed by ELISA and Western blot. DBS collected between 2011 and 2015 from 2,077 PWID in eight German cities recruited by respondent-driven sampling were tested for HTLV-specific antibodies. RESULTS: The validation demonstrated that the use of DSS allowed identification of samples with even low titers of HTLV-specific antibodies, although a confirmatory Western blot with an additional venous blood sample would often be required. Despite numerous HIV and HCV positive individuals being identified within the study population, none tested positive for HTLV. CONCLUSION: While the HIV and HCV prevalences in German PWID are comparable to those in other European countries, the very low prevalence of HTLV reflects the situation in the general population.

[Relevance of safety measures to avoid HTLV transmission by transfusion in 2014]. / Pertinence des mesures sécuritaires transfusionnelles vis-à-vis du HTLV en 2014.

In high-income countries, the safety of blood transfusion related to viruses has reached a very high level, especially thanks to the implementation of multiple measures aimed at reducing the transfusion risk. The cost-effectiveness of these preventive measures is frequently discussed due to global financial resources, which are more and more limited. Hence, the revision of safety strategies is a key issue, especially when these strategies are redundant, as those implemented to avoid Human T-cell Lymphotropic Virus (HTLV) transmission, which are based on both antibodies screening and leucoreduction of blood products. The residual risk of the transmission of HTLV by transfusion has been recently estimated at 1 in 20 million donations (2010-2012) in France (excluding overseas territories). This estimation did not take into account the leucoreduction, which appears to be a very efficient preventive measure as the virus is strictly intra-cellular. To help decision-making, we have evaluated some parameters related to HTLV blood transmission. Firstly, the probability that an incident occurring during the leucoreduction process affects a HTLV-positive blood donation has been estimated at 1 in 178 million. Estimation of clinical consequences of HTLV-positive transfusions would affect 1 to 2 transfused-patients without leucoreduction, and one recipient every 192 years in case of 10% failures of the filtration method. Obviously, despite a risk, which appears to be controlled, HTLV screening will be disputed as soon as the efficiency of leucoreduction to totally prevent virus blood transmission will be proven and when pathogen inactivation methods are generalized to all blood cellular products.

Constitutive release of IFNγ and IL2 from peripheral blood mononuclear cells of rhesus macaques (Macaca mulatta) infected with simian T-lymphotropic virus type 1.

Simian T-cell lymphotropic viruses (STLV), the nonhuman primate counterparts of human T-cell lymphotropic viruses (HTLV), are endemic in many populations of African and Asian monkeys and apes. Although an etiologic link between STLV1 infection and lymphoproliferative disorders such as malignant lymphomas has been suggested in some nonhuman primate species, most STLV infections are inapparent, and infected animals remain clinically healthy. The retroviral transactivator, tax, is well known to increase transcription of viral and cellular genes, resulting in altered cytokine profiles. This study compared the cytokine profiles of peripheral blood mononuclear cell (PBMC) cultures from 25 STLV1-seropositive rhesus macaques (Macaca mulatta) with those of age- and sex-matched seronegative controls. IFNγ, TNFα, IL10, and IL2 levels in unstimulated PBMC culture supernatants were measured at 24, 48, and 72 h by using enzyme immunoassays. IFNγ concentrations were found significantly higher in the supernatants of PBMC cultures of seropositive monkeys as compared with seronegative controls. In addition, although IL2 concentrations were not significantly elevated in the supernatants of PBMC cultures of all seropositive monkeys as compared with all seronegative controls, IL2 levels were increased in a subset of 5 pairs. Increased constitutive cytokine release occurred in the absence of spontaneous proliferation. The increased constitutive release of IFNγ and IL2 suggests that STLV1 alters immune functions in infected but clinically healthy rhesus macaques and further characterizes STLV1 infection of rhesus macaques as a potential model for human HTLV1 infection.

Schistosoma antigens downmodulate the in vitro inflammatory response in individuals infected with human T cell lymphotropic virus type 1.

UNLABELLED: Human T cell lymphotropic virus type 1 (HTLV-1) is the causal agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). While the immune response to HTLV-1 infection is polarized to the Th1-type, chronic helminth infections drive the Th2- and T regulatory-type, and are able to downregulate the inflammatory response in some autoimmune diseases. OBJECTIVE: To evaluate whether Schistosoma spp. antigens alter the in vitro cytokine response in HTLV-1 infection. METHODS: The recombinant Schistosoma antigens Sm29 and ShTSP2 (tetraspanin) and PIII, a fraction of the Schistosoma mansoni adult worm antigen were added to peripheral blood mononuclear cell (PBMC) cultures of HTLV-1-infected individuals and the levels of interferon (IFN)-γ and interleukin (IL)-10 in the supernatants were measured using the ELISA sandwich technique. RESULTS: Compared to the levels of cytokine in nonstimulated cultures, the levels of IFN-γ were reduced in 50, 47 and 50% of patients by the presence of Sm29, ShTsp2 and PIII, respectively. The downregulation of IFN-γ production in the presence of Sm29 antigen was observed mainly in subjects who had lower basal levels of this cytokine. The levels of IL-10, however, increased by the addition of the three antigens in the cultures in 74, 62 and 44% of individuals, respectively. In addition, there was a decrease in the ratio of IFN-γ/IL-10 levels in cultures stimulated with Sm29 and ShTSP2 when compared to nonstimulated ones. CONCLUSIONS: The Schistosoma spp. antigens used in this study were able to downmodulate IFN-γ production in vitro in HTLV-1 infection. This may be associated with the increased levels of IL-10 induced by the antigens.

A comparison of human immunodeficiency virus, hepatitis C virus, hepatitis B virus, and human T-lymphotropic virus marker rates for directed versus volunteer blood donations to the American Red Cross during 2005 to 2010.

BACKGROUND: At most US blood centers, patients may still opt to choose specific donors to give blood for their anticipated transfusion needs. However, there is little evidence of improved safety with directed donation when compared to volunteer donation. STUDY DESIGN AND METHODS: The percentage of directed donations made to the American Red Cross (ARC) from 1995 to 2010 was determined. Infectious disease marker rates for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), and human T-lymphotropic virus (HTLV) were calculated for volunteer and directed donations made from 2005 to 2010. Odds ratios (ORs) were calculated to compare marker-positive rates of directed donations to volunteer donations. RESULTS: The percentage of donations from directed donors declined from 1.6% in 1995 to 0.12% in 2010. From 2005 to 2010, the ARC collected 38,894,782 volunteer and 69,869 directed donations. Rates of HIV, HCV, HBV, and HTLV for volunteer donations were 2.9, 32.2, 12.4, and 2.5 per 100,000 donations, respectively; for directed, the rates were 7.2, 93.0, 40.1, and 18.6 per 100,000. After demographics and first-time or repeat status were adjusted for, corresponding ORs of viral marker positivity in directed versus volunteer donations were not significant for HIV, HBV, or HTLV and significant for HCV (OR, 0.7; 95% confidence interval, 0.50-0.90). CONCLUSIONS: Directed donations have declined by 92% at the ARC since 1995, but have higher viral marker rates than volunteer donations. The difference can be explained in part by the effects of first-time or repeat status of the donors. Patients considering directed donation should be appropriately counseled about the potential risks.

Cost-effectiveness of additional blood screening tests in the Netherlands.

BACKGROUND: During the past decade, blood screening tests such as triplex nucleic acid amplification testing (NAT) and human T-cell lymphotropic virus type I or I (HTLV-I/II) antibody testing were added to existing serologic testing for hepatitis B virus (HBV), human immunodeficiency virus (HIV), and hepatitis C virus (HCV). In some low-prevalence regions these additional tests yielded disputable benefits that can be valuated by cost-effectiveness analyses (CEAs). CEAs are used to support decision making on implementation of medical technology. We present CEAs of selected additional screening tests that are not uniformly implemented in the EU. STUDY DESIGN AND METHODS: Cost-effectiveness was analyzed of: 1) HBV, HCV, and HIV triplex NAT in addition to serologic testing; 2) HTLV-I/II antibody test for all donors, for first-time donors only, and for pediatric recipients only; and 3) hepatitis A virus (HAV) for all donations. Disease progression of the studied viral infections was described in five Markov models. RESULTS: In the Netherlands, the incremental cost-effectiveness ratio (ICER) of triplex NAT is €5.20 million per quality-adjusted life-year (QALY) for testing minipools of six donation samples and €4.65 million/QALY for individual donation testing. The ICER for anti-HTLV-I/II is €45.2 million/QALY if testing all donations, €2.23 million/QALY if testing new donors only, and €27.0 million/QALY if testing blood products for pediatric patients only. The ICER of HAV NAT is €18.6 million/QALY. CONCLUSION: The resulting ICERs are very high, especially when compared to other health care interventions. Nevertheless, these screening tests are implemented in the Netherlands and elsewhere. Policy makers should reflect more explicit on the acceptability of costs and effects whenever additional blood screening tests are implemented.

New strain of human T lymphotropic virus (HTLV) type 3 in a Pygmy from Cameroon with peculiar HTLV serologic results.

A search for human T lymphotropic virus (HTLV) types 1 and 2 and related viruses was performed by serological and molecular means on samples obtained from 421 adult villagers from the southern Cameroon forest areas. One individual (a 56-year-old Baka Pygmy hunter) was found to be HTLV-3 infected; however, there was a low proviral load in blood cells. Complete sequence analysis of this virus (HTLV-3Lobak18) indicated a close relationship to human HTLV-3Pyl43 and simian STLV-3CTO604 strains. Plasma samples from Lobak18, the HTLV-3 infected individual, exhibited a peculiar "HTLV-2-like" pattern on Western blot analysis and were serologically untypeable by line immunoassay. These results were different from those for the 2 previously reported HTLV-3 strains, raising questions about serological confirmation of infection with such retroviruses.

Long-term serologic follow-up of blood donors with biologic false reactivity on an anti-human T-cell lymphotropic virus Types I and II chemiluminescent immunoassay and implications for donor management.

BACKGROUND: This study reports the results of the long-term serologic follow-up of blood donors who gave an index biologic false-reactive (BFR) result on an anti-human T-lymphotropic virus Types I and II (HTLV-I and -II) chemiluminescent immunoassay (ChLIA). STUDY DESIGN AND METHODS: All allogeneic whole-blood and apheresis donors who gave an index BFR result on a HTLV-I and -II ChLIA between May 10, 1997, and December 31, 2004, were included in the study. Donors were followed up for an additional 2 years until December 31, 2006. RESULTS: A total of 332 donors gave an index BFR donation during the study period. Donors were divided into five groups based on results of donations subsequent to the index BFR donation: 89 (26.8%) donors gave only nonreactive donations subsequent to the index BFR result, 56 (16.9%) donors gave only BFR donations, 43 (13.0%) gave one or more subsequent BFR donations before giving only nonreactive donations, 59 (17.8%) donors gave intermittent BFR and nonreactive donations, and 85 (25.6%) donors gave no further donations during the study period. The estimated mean duration of biologic false reactivity from the time of the index BFR donation in donors who gave only a single BFR result was 7.0 (1.4-42.75) months and 23.3 (4.1-92.25) months in those donors who gave several BFR results before giving nonreactive donations. Modeling of the data indicated that notification and deferral of donors after two consecutive BFR donations would result in the deferral of 143 of 332 (43.1%) of donors with an index BFR result while allowing donors to give three BFR results would reduce the number of deferred donors to 74 of 332 (22.3%). CONCLUSION: The results of this study indicate that although biologic false reactivity is usually transient, the time for resolution is variable. Allowing donors to give two or three BFR results before notification and deferral is one strategy that would substantially reduce the number of donors requiring deferral.

Use of replacement blood donors to study the epidemiology of major blood-borne viruses in the general population of Maputo, Mozambique.

The seroprevalence rates of human immunodeficiency virus (HIV), human T-cell leukemia/lymphoma virus (HTLV), hepatitis B virus (HBV), hepatitis D virus (HDV), and hepatitis C virus (HCV) in Mozambique are poorly documented. The epidemiology of these infections was studied in the Maputo region. All donors attending the blood bank during the study period were interviewed and underwent serological and molecular tests for markers of virus exposure. Thus, 1,578 consecutive replacement blood donors were investigated, as they undergo no selection (other than their relation with a patient needing a transfusion), and may thus provide reliable estimates of the prevalence rates in the general population. The age-standardized prevalence rates among 15- to 49-year-old men and women were, respectively, 12.3 and 15.4% for HIV and 0.9 and 1.2% for HTLV. Low educational status (P = 0.014) and tattooing/scarification (P = 0.023) were predictive of HIV infection in multivariate analysis. The age-adjusted prevalence rates of markers of hepatotropic virus among men and women were, respectively, 10.6 and 4.5% for hepatitis B surface antigen (HBsAg), 1.2 and 1.0% for anti-HCV, and 0 and 0% for anti-HDV. Two percent of donors had viral co-infections, involving most frequently the combination of HIV and HBsAg +. A significant association was found between anti-HIV and anti-HBc (P = 0.012). HBsAg was associated with the place of birth (P = 0.011) and a history of transfusion (P = 0.069). Smokers had higher seroprevalence rates than nonsmokers for HIV (P < 0.0001) and HBsAg (P = 0.045). Genotype A was the most frequent HBV genotype (86.3%) followed by E and D. HCV genotypes were 1a, 1b, 3a, and 5a. These results show that HBV vaccination and HIV-preventive measures need to be reinforced in Mozambique.

Prevalence of viral markers among first-time Arab blood donors in Kuwait.

BACKGROUND: The aim of this study was to assess the effect of blood donation modes on the prevalence of viral markers among Arab first-time blood donors in Kuwait. STUDY DESIGN AND METHODS: Donor ethnic background was classified as Kuwaiti nationals and non-Kuwaiti Arabs. A total of 26,874 donors were screened in 2002 for the following viral markers: hepatitis C virus antibody (anti-HCV), hepatitis B surface antigen (HBsAg), anti-hepatitis B core antigen (HBc), human immunodeficiency virus-1 and -2 antibody (anti-HIV-1 and -2), HIV p24, and human T lymphotropic virus-I and -II antibody (anti-HTLVI/II). All samples positive for the presence of anti-HBc were tested for anti-HBs. Among these donors, 12,798 were first-time donors of which 74 percent were replacement and 26 percent were volunteers. RESULTS: The prevalence of HCV among replacement donors was significantly higher than the volunteer group. The difference between the two modes of blood donations, however, was not significant for HBsAg. The prevalence of anti-HCV among Kuwaiti national and non-Kuwaiti Arab first-time donors was 0.8 and 5.4 percent, respectively, whereas the prevalence of HBsAg was 1.1 and 3.5 percent, respectively, with the difference being significant at a p level of <0.0001. The difference observed for prevalence of anti-HBc among Kuwaiti national and non-Kuwaiti Arab donors (17 and 33.3%, respectively) was significant (p < 0.0001). Among first-time donors, 13.7 percent were positive for the presence of anti-HBs, indicating that 13.7 percent of the total Arab donor population might have had a previous infection and possible immunity to hepatitis B virus (HBV). CONCLUSION: A high prevalence of HBV and HCV was found among non-Kuwaiti Arab donors. The prevalence of anti-HCV was only significantly higher among replacement versus volunteer first-time donors. Therefore, there is a need to develop a strategic plan that incorporates the diverse background of the blood donors living in Kuwait.

Identification in gelada baboons (Theropithecus gelada) of a distinct simian T-cell lymphotropic virus type 3 with a broad range of Western blot reactivity.

Antibodies to simian T-cell lymphotropic virus (STLV) were found in serum or plasma from 12 of 23 (52.2 %) gelada baboons (Theropithecus gelada) captive in US zoos. A variety of Western blot (WB) profiles was seen in the 12 seroreactive samples, including human T-cell lymphotropic virus (HTLV)-1-like (n=5, 41.7 %), HTLV-2-like (n=1, 8.3 %), HTLV-untypable (n=4, 33.3 %) and indeterminate (n=2, 16.6 %) profiles. Phylogenetic analysis of tax or env sequences that had been PCR amplified from peripheral blood lymphocyte DNA available from nine seropositive geladas showed that four were infected with identical STLV-1s; these sequences clustered with STLV-1 from Celebes macaques and probably represent recent cross-species infections. The tax sequences from the five remaining geladas were also identical and clustered with STLV-3. Analysis of the complete STLV-3 genome (8917 bp) from one gelada, TGE-2117, revealed that it is unique, sharing only 62 % similarity with HTLV-1/ATK and HTLV-2/Mo. STLV-3/TGE-2117 was closest genetically to STLV-3 from an Eritrean baboon (STLV-3/PH969, 95.6 %) but more distant from STLV-3s from red-capped mangabeys from Cameroon and Nigeria (STLV-3/CTO-604, 87.7 %, and STLV-3/CTO-NG409, 87.2 %, respectively) and Senegalese baboons (STLV-3/PPA-F3, 88.4 %). The genetic relatedness of STLV-3/TGE-2117 to STLV-3 was confirmed by phylogenetic analysis of a concatenated gag-pol-env-tax sequence (6795 bp). An ancient origin of 73 628-109 809 years ago for STLV-3 was estimated by molecular clock analysis of third-codon positions of gag-pol-env-tax sequences. LTR sequences from five STLV-3-positive geladas were >99 % identical and clustered with that from a Papio anubisxP. hamadryas hybrid Ethiopian baboon, suggesting a common source of STLV-3 in these sympatric animals. LTR sequences obtained 20 years apart from a mother-infant pair were identical, providing evidence of both mother-to-offspring transmission and a high genetic stability of STLV-3. Since STLV-3-infected primates show a range of HTLV-like WB profiles and have an ancient origin, further studies using STLV-3-specific testing are required to determine whether STLV-3 infects humans, especially in regions of Africa where STLV-3 is endemic.

Evaluation of HTLV-I removal by filtration of blood cell components in a routine setting.

BACKGROUND: WBC depletion by filtration may prevent the transmission of HTLV-I, which requires cell-to-cell contact. The removal of HTLV-I-infected cells in routinely filtered blood cell components was measured. STUDY DESIGN AND METHODS: The study was conducted in Martinique where systematic screening for HTLV-I and -II and universal leukoreduction are mandatory. HTLV-I was quantified by use of real-time PCR in 8 RBC units and 4 PLT concentrates before and after filtration. HTLV-I proviral load in PBMNCs was determined in five of the eight HTLV-I-infected blood donors. RESULTS: The amount of MNC-associated HTLV-I DNA in RBC units before filtration was 21 x 10(6)+/- 29 x 10(6) copies (mean +/- SD). HTLV-I was detected in 4 of 8 RBC units after filtration, with a number of copies in the MNC fraction ranging from 20 to 140, following a 4.9 to 5.8 log reduction. Flow cytometry analysis performed in 2 of the filtered RBC units containing detectable HTLV-I showed suboptimal and out-of-range leukoreduction (0.56 x 10(6) and 1.22 x 10(6) residual WBCs). HTLV was not detected in filtered RBCs from the blood donor with the highest percentage of HTLV-I-infected PBMCs (9%). CONCLUSION: This study confirms that HTLV-I-infected cells can be detected in filtered blood cell components and shows that optimal leukoreduction is critical for HTLV-I removal.

[Prevalence of HBV, HCV, HIV and HTLV in autologous blood donors in France between 1993 and 2000]. / Prévalence des virus des hépatites B et C, du VIH et de l'HTLV chez les candidats à une transfusion autologue programmée en France, 1993-2000.

The epidemiological surveillance of autologous blood donors has been carried out in France since 1993. The number of autologous donors increased regularly from 1993 to 1997 but has decreased during the last three years to become less than 50,000 in 2000. The sex-ratio was stable over time (0.85 male for 1 female). The population of autologous donors grew older between 1993 and 2000: the proportion of those aged under 50 years old decreased from 29% in 1993 to 18% in 2000 while the proportion of those over 69 increased from 22 to 34%. Between 1993 and 2000, HbsAg prevalence decreased by a factor of 2.5 and HCV prevalence by a factor of 5. For HIV, a slight decrease was observed and the prevalence of HTLV was stable over time. In 2000, HCV prevalence (0.23%) was two times higher than HBsAg prevalence (0.12%), fifteen times higher than HTLV prevalence in Continental France (0.015%) and one hundred times higher than HIV prevalence (0.002%). The prevalence was similar in men and women for HCV, about two times higher in men than in women for HBsAg and three times higher for HIV. On the contrary, HTLV prevalence was about two times higher in women than in men. HBsAg and HCV prevalence rates were also calculated by age group. The prevalence rates for HBsAg increased up to the 30-39 age group among women and the 40-49 age group among men; then the rates decreased but were higher in men than in women. For HCV, while the prevalence increased continuously with age among women, a peak was reached for men in the 30-39 age group followed by a decrease up to the 50-59 age group and the prevalence was stable afterwards. The very low level of the current risk of transmitting viral infections by homologous transfusion and technical changes in autologous transfusion seem to be the two main factors that contributed to the recent decline in the number of autologous donors. The decrease in HBsAg and anti-HCV prevalence between 1993 and 2000 is multifactorial, but the drop observed for HCV is probably linked to a decrease in HCV prevalence of the general population over the last ten years.

Seroprevalence of HIV and HTLV in a representative sample of the Spanish population.

HIV and HTLV seroprevalence was determined by means of unlinked anonymous testing of 2144 sera, originally obtained from primary care patients by representative sampling of the Spanish population aged 15-39 years in 1996. HIV-1 seroprevalence was 4.3 per 1000 population in the 15-39 years age group [95% confidence interval (CI), 1.5-10.7] and 5.6 per 1000 (95% CI, 1.8-15.3) in the 20-39 years age group. Seroprevalence proved higher in males and urban residents. No antibodies to HIV-2 and HTLV-I were detected in any of the sera studied. However, presence of antibodies to HTLV-II was confirmed in one serum sample, while HTLV seroreactivity, though detected in another, could not be typed. The two HTLV-positive results equated to a seroprevalence of 1.9 per 1000 in the 20-39 years age group (95% CI, 0.3-8.6). HIV-I seroprevalence was consistent with previous estimates yielded by back-calculation. The level of HTLV seroprevalence found suggests endemicity.

[Controlled viral risks]. / Les risques viraux maîtrisés.

The prevalence of virological markers in blood donors has been continuously decreasing since the implementation, as soon as they were available, of serological screening methods. In 1998, the prevalences (per 10,000 donations) were 0.17 for antibody to HIV, 0.08 for antibody to HTLV, 2.23 for HBs Ag and 2.52 for antibody to HCV. The values are of course higher in new donors when compared to regular donors: approximately five-fold for HIV, 50-fold for HCV and 300-fold for HBs Ag. The remaining major questions concern the residual risk due to infectious donations which could escape the preventive measures. It seems evident that the major risk is imputable mainly to donations collected during the window period. During the 1996-1998 period, the residual risk for HIV was one out of 1,350,000 donations, 0 for HTLV, one out of 375,000 for HCV, and one out of 220,000 for HBV. A few cases of 'immuno-silent' patients have been reported. They remain exceptional. The first data collected after implementation of Nucleic Acid Technology (NAT) confirm the very low residual risk. The molecular epidemiology of the concerned viruses applied to the evaluation of screening assays highlighted the impact of the genetic diversity on the efficiency of these assays. This is particularly evident for HIV and HBV. The recent introduction of leucodepletion probably brought an important contribution in diminishing the risk of transmission of leucotropic viruses such as cytomegalovirus, Epstein-Barr viruses, human herpesviruses 6 and 7, and HTLV. If the purification process of plasma derived medicinal products including inactivation procedures permits confidence in the elimination of infectivity due to enveloped viruses, the detection of nucleic acid sequences derived from naked viruses in plasma pools may greatly contribute to their safety.

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study.

BACKGROUND: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals. All samples were coded and distributed to each of four independent testing laboratories for polymerase chain reaction analysis to detect sequences of the HTLV-I or HTLV-II tax gene, using detailed procedures specified by the laboratory reporting the original observation. Each laboratory also tested a dilution panel of a plasmid containing HTLV-I tax to determine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted detection of as few as 1 to 10 copies of the tax gene. However, HTLV-I tax sequences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this population of 100 blood donors negative for anti-HTLV-I.