Fourth-generation Enzyme-linked Immunosorbent Assay Research Articles

Reduction in seroprevalence of viral transfusion-transmitted infections in southwest Nigeria in children with sickle cell disease using an enhanced screening strategy.

Blood transfusion is an integral component in the management of children and adults with sickle cell disease (SCD). Concerns about blood safety due to the high risk of bloodborne infections in sub-Saharan Africa limits the application of this cost-effective strategy in the management of individuals with SCD. In a single-centre, retrospective, longitudinal study in southwest Nigeria, we hypothesised that the use of stringent blood donor selection, along with very sensitive enzyme-linked immunosorbent assay (ELISA) screening methods would reduce transfusion-transmitted infections (TTIs). Among 45 002 eligible blood donors at the Lagos University Teaching Hospital in Nigeria, over a 5-year review period (2015-2019), the seroprevalence rate of viral TTIs was 9.83%. The seroprevalence rates for human immunodeficiency, hepatitis B, and hepatitis C viruses were 1.37%, 6.2%, and 2.25% respectively. Among 172 children with SCD, 71% (122/172) on regular blood transfusion and 29% (50/172) who had never been transfused or had less than two transfusions per lifetime, none acquired any TTIs using our enhanced screening approach during the study period. Thus, safe blood transfusion practices can be provided for children with SCD in sub-Saharan Africa with the use of stringent donor selection protocols and fourth-generation ELISA kits for TTI screening.

Nucleic Acid Test versus Enzyme Linked Section Immunosorbent Assay for Screening of Human Immunodeficiency Virus in Donated Blood Units: A Comparative Study at a Blood Centre in Western Rajasthan, India

Introduction: With a population of 1.3 billion people and a frequency of Human Immunodeficiency Virus (HIV) (0.17-0.29%), Hepatitis B Virus (3-4%), and Hepatitis C Virus (0.09-15%) in the general population, maintaining blood safety is a difficult undertaking in India. The fourth-generation Enzyme Linked Immunosorbent Assay (ELISA), which can be used in place of Nucleic Acid Amplification Test (NAT) testing in situations with limited resources, has been recommended as the minimal HIV test to increase the safety of blood transfusions. Aim: To compare the fourth generation ELISA with NAT in the screening of transfusion transmissible HIV infection in blood donors. Materials and Methods: A cross-sectional study was carried out at the Blood Centre, Department of Immuno-Haematology and Transfusion Medicine, Sardar Patel Medical College and Associated Groups of Hospitals, in Bikaner, Rajasthan, India. A total of 2000 voluntary and replacement blood donors were recruited consecutively between January 2020 to December 2021 (two years), and their samples were screened using fourthgeneration ELISA. All of these samples were sent to AIIMS in Jodhpur for NAT to identify HIV RNA, HCV RNA and HBV DNA. Results: In this study, when the fourth generation ELISA negative samples were subjected to NAT, no sample was found to be reactive for HIV in NAT, i.e. there was no NAT yield for HIV. Conclusion: As a bare minimum, the fourth-generation ELISA test should be used for blood donor screening and can be considered a cost-effective and reliable test in a resource limited setting. However, additional tests can be advocated for an additional layer of blood safety.

Internal quality control for HIV testing of blood donors - Dried tube specimen as a cost-effective alternative.

An important aspect of ensuring blood safety is the performance of mandatory serological testing for transfusion transmissible infections. The practice of internal quality control (IQC) in blood banks in India is nonuniform, especially the use of third-party materials. Cited reasons are cost, lack of access to control materials, and need for deep-freezers for storage, if prepared in-house. Validation of dried tube specimen (DTS) from HIV-positive plasma as a low-cost, stable material for use as IQC material in blood banks. Fresh-frozen plasma (FFP) prepared from four HIV-positive blood-donors were pooled. Equal numbers of seronegative FFPs were pooled. Twenty microlitre aliquots of plasma were made in micro-centrifuge tubes and air-dried overnight at room-temperature. These were stored in 2-8°C refrigerators and tested once weekly for 6 months on multiple platforms with different detection principles: Rapid tests, second-generation enzyme-linked immunosorbent assay (ELISA), fourth-generation ELISA, and fourth-generation Chemiluminescence immunoassay. The protocol was sustained over the next 6 months with decreased testing frequency to study the extended stability of DTS. A total of 139 positive-DTS and 139 negative-DTS were tested with 100% samples showing consistent results on all platforms over 1 year. There was mild deterioration in reaction strengths, which did not interfere in result interpretations. Plasma in form of DTS maintained stability when stored at 2-8°C for 1 year. This provides evidence that DTS can be a modality for the production of cost-effective, stable, in-house control material for resource-restricted countries.

Evaluation of the diagnostic performance and optimal cutoff value of a fourth-generation ELISA, VIDAS HIV-1/2 Duo Ultra assay, in a low-prevalence country

In this study, we described the largest analysis to date conducted with VIDAS® HIV Duo Ultra assay. Additionally, we analyzed the diagnostic performance and cutoff values (TV) of HIV Duo Ultra assay and total cost analysis for HIV testing. Of 11,642 enzyme-linked immunosorbent assay (ELISA)–positive samples referred to our center for confirmation, 2000 were positive with HIV Duo Ultra, and of these, 87% were HIV-1 positive and 0.6% were HIV-1 indeterminate with the confirmatory test. Overall, the false-positivity rate was 1.75% for HIV Duo Ultra assay. The sensitivity and specificity were 100% and 99.1%, respectively, when the TV was set at the recommended cutoff value. Even increasing the cutoff value four times, sensitivity and specificity remained high, pointing out that a TV of 0.99 is highly indicative of HIV positivity. Retesting samples with HIV Duo Ultra assay decreased 80% of the confirmatory tests, revealing a significant decrease of 78% in the total costs and reporting time.

HIV coinfections with tuberculosis among HIV-1 infected individuals in old cross river state, Nigeria

ABSTRACTHuman immunodeficiency virus (HIV) and Tuberculosis (TB) are two main global public health threats that dent development in low and middle-income countries. This study evaluated the HIV/TB co-infection rate among HIV-1 infected individuals in old Cross River State, Nigeria. A total of 417 HIV-infected individuals participated in this study, 241 (57.8%) from Calabar, Cross River State, Nigeria and 176 (42.2%) from Uyo, Akwa-Ibom State, Nigeria. The age range of the 417 HIV-1 positive individuals who participated in the study was 4–72 years with an average age of 39.1 years. Plasma samples were analyzed for HIV and TB using fourth-generation Enzyme-Linked immunosorbent Assay. The CD4 count was enumerated using the Partec CyFlow® Counter. Plasma viral loads (PVL) were determined using the Abbott Real-Time HIV-1 assay. Results showed that 230 (55.2%) of the participants were in the 31–45 years age range. The majority (67.4%) of the HIV-1 infected individuals were females and 32.6% were males. An overall prevalence of HIV/TB coinfection in Old Cross River State, Nigeria was 1.4%, with Akwa Ibom State (0.6%) and Cross River State (1.2%). A higher prevalence of HIV/TB coinfection was observed among females (1.8%) than in males (0.7%). Higher prevalences of HIV/TB coinfections was observed in patients above 45 years of age (2.2%), married (2.3%), tertiary education (1.8%) followed by those with secondary education (1.4%), traders and civil servants (3.1%), patients with CD4 counts 200–349 and ≥500 cells/μl (1.9%), and those with viral load <40 copies/mL (2.7%). This study confirmed the presence of HIV/TB co-infection in old Cross River State, Nigeria. Although the prevalence rate of HIV/TB coinfection was low, its presence alone among HIV-1 infected individuals makes it a major source of concern. This finding highlights the need for a well-structured approach to the management of co-infection, and this includes both the social and medical aspects of the problem.

A comparative study on fourth generation ELISA and rapid assay for diagnosing HIV infection in the high risk group

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Enzyme linked immunosorbent assay (ELISA) is a widely employed method for detecting HIV. Following its successful detection of HIV, the fourth generation ELISA was approved by FDA. The advantage of the FDA approved fourth generation ELISA is it detects p24 antigen, HIV 1&amp;amp;2 antibodies simultaneously and that too 5-7 days prior to conventional tests so that it detects HIV seroconversion earlier reducing its further spread.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; The study was conducted in a tertiary level medical centre after obtaining ethical approval. 200 patients from high risk group and their contacts were selected after a thorough physical examination and tests were done using fourth generation ELISA and rapid assay and these results were compared.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; As per our observations, the percentage of patients tested positive by fourth generation ELISA out of 200 subjects was 37% and negative was 63%. The detection rate of HIV positivity by rapid assay in high risk group was 11% and negative was 89%. The detection rate was also higher with fourth generation ELISA when various other parameters were compared.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; In this study, the percentage of HIV positivity detected by fourth generation ELISA was higher than that detected by rapid assay showing that fourth generation ELISA is a more sensitive test than rapid assay as well as a better diagnostic modality to opt for when coming to early detection in HIV. &lt;/p&gt;

A ten-year trend of human immunodeficiency virus infection in voluntary blood donors in the South Backa district of Vojvodina

Introduction. The first cases of human immunodeficiency virus infection and the first transmission of human immunodeficiency virus infection through blood transfusion in Vojvodina were registered in 1985. The aims of this study were to determine the ten-year trend of human immunodeficiency virus infection among blood donors in South Backa District of Vojvodina, routes of transmission and risk factors. Material and Methods. A retrospective study was conducted at the Blood Transfusion Institute of Vojvodina during 2009 - 2018, and human immunodeficijenca antigens and antibodies were analyzed. A total of 300 936 blood donor samples were screened using combined antibody-antigen tests (fourth generation enzyme-linked immunosorbent assay and chemiluminescence). Further testing included confirmatory immunoblot assay and molecular assay. Results. The overall human immunodeficiency virus seroprevalence was 3.7 per 100 000 donations. The number of blood donors found to be human immunodeficiency virus positive has increased during the study period showing a positive trend. The highest number of human immunodeficiency virus positive results was reported among blood donors aged 26-35 (36%) and 46-55 years (27%). The infection was more frequent in males. The leading rout of transmission was through unprotected sexual intercourse. Higher human immunodeficiency virus prevalence was among regular blood donors (73%). Conclusion. This study points to the importance of careful selection of blood donors and their education about risk behavior in order to reduce the risk of human immunodeficiency virus transmission. Concomitant use of sensitive serological and molecular tests is crucial to increase the blood safety.

Seroepidemiology of transfusion-transmitted infections among blood donors at a tertiary care center in Navi Mumbai, Maharashtra

Background: Blood is precious as well as scarce lifesaving medication. Proper screening of transfusion-transmitted infections (TTIs) such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), syphilis, and malarial parasite (MP) with appropriate methods is needed to ensure that the donated blood is made innocuous for transfusion. Objective: The aim of the study was to estimate the prevalence of TTI and their epidemiological aspects in blood donors in a hospital-based blood bank in Nerul, Navi Mumbai. Materials and Methods: A retrospective study of the total of 4708 donors was carried out from January 2015 to December 2018 year. Screening of HIV was done using the fourth-generation enzyme-linked immunosorbent assay (ELISA) and for hepatitis B surface antigen (HbsAg) and HCV by the third-generation ELISA kit. Testing for syphilis was done with rapid plasma reagin and MP was tested with rapid card test. Results: Voluntary donors were 4702 (99.9%) while replacement constituted for 6 (0.12%) number of cases. Among 4708 donors, 4079 (96%) were male and 629 (4%) were female. Among 66 (1.4%) transfusion transmitted diseases (TTD)-positive donors, the highest number of donors 28 (42%) belongs to 18–27 years of age group while the lowest 5 (2%) belonged to 48–57 years. Overall prevalence of HIV, HbsAg, HCV, syphilis, and MP was 0.08%, 1.1%, 0.2%, 0.04%, and 0.02%, respectively. Conclusion: The prevalence of TTD was more in males, in 18–27 age groups, and in voluntary donors. The most common TTI was HBV, followed by HCV, HIV, syphilis, and MP, respectively.

Hepatitis C virus antibodies are absent among high risk group of health care workers in Damascus Hospital

Background and study aimsLiver disease caused by hepatitis C virus (HCV) is one of the most serious health issues worldwide. The prevalence of HCV among health care workers (HCWs) is higher than normal population. Our aim is to determine the seroprevalence of HCV among this high-risk group in Damascus Hospital, Syria in 2016. Subjects and methodsDuring March 2016, anonymous testing for HCV was offered to 150 residents and physicians from different departments (Surgery, otolaryngology, gastroenterology, anaesthesiology and laboratory) in Damascus Hospital using fourth-generation enzyme-linked immunosorbent assay (ELISA). In addition, each participant was interviewed and answered a comprehensive questionnaire which includes questions on potential hazards, risk factors and the level of awareness about the disease and its ways of transmission. ResultsSurprisingly, all samples tested negative for anti-HCV antibodies, though many participants were already exposed to many risk factors especially as HCWs. ConclusionHCV is not a main issue regarding its prevalence among HCWs in Damascus Hospital. Nevertheless, it is still necessary to develop a mandatory well-organized program to increase the awareness among HCWs and develop stricter prevention policies especially about bloodborne diseases transmitted occupationally.

Role of intrafamilial transmission in high prevalence of hepatitis C virus in Egypt.

BackgroundEgypt has the highest prevalence of hepatitis C virus (HCV) worldwide. Although an effective HCV treatment program has been adopted, it is estimated that the number of newly reported cases in Egypt is still high. Intrafamilial transmission may play a role in the high prevalence of HCV in Egypt. Identification of risk factors for the transmission of HCV may help in decreasing its prevalence and eliminating its infection.AimThe aim of this study was to estimate the prevalence of HCV infection among the household contacts of HCV patients and identify the possible risk factors associated with intrafamilial transmission.MethodsThis study was designed as a cohort study of 90 families of patients with confirmed chronic HCV and 38 families of non-HCV-infected persons. Diagnosis of HCV infection was performed by detection of HCV antibodies by fourth-generation enzyme-linked immunosorbent assay and confirmed by HCV RNA polymerase chain reaction. A pre-prepared questionnaire on risk factors was filled out by the participants. The prevalence of HCV was calculated, and univariate and multivariate analyses were carried out to identify the independent risk factors.ResultsAmong 90 positive-index families, 32 (35.6%) had contact persons with HCV infection compared to two of 38 (5.3%) negative-index families (P < 0.001, odds ratio [OR] = 9.9). Out of 257 index-positive contacts, 38 (14.8%) were infected compared to three of 75 (4%) of index-negative contacts (P = 0.01, OR = 4.3). Infection was associated with older age (6.9% of those aged <20 years, 10.4% of those aged 20–39 years, and 22% of those aged ≥40 years were infected) (P = 0.007). Husbands of infected wives were at a higher risk (33% infected) than wives (13.5%) and sons (16.9%) (P < 0.001). A history of hepatic encephalopathy was the independent predictor of intrafamilial transmission (P < 0.001, OR = 5.4).ConclusionIntrafamilial transmission was found to possibly play a major role in the high prevalence of HCV in Egypt. Transmission was associated with older age and contact with patients with hepatic encephalopathy and was high among husbands of infected wives.

Hepatitis C: an Overview of Various Laboratory Assays with their Mode of Diagnostic Cooperation.

This review describes in chronological order the different assays for hepatitis C virus (HCV) antibodies, for the core antigen and for the HCV-RNA. By ascending chronological order, the enzyme-linked immunosorbent assay (ELISA), rapid diagnostic tests (RDTs), HCV-Ab IgG avidity index (HCV AI), and Cy3-labeled microarray assay have been described for HCV antibodies in addition to ELISA for the total HCV core antigen (Ag). The recombinant immunoblot assay (RIBA) is a confirmatory test for HCV-Ab in blood, which is no longer needed due to the use of the sensitive third and fourth generation ELISA in addition to HCV-RNA detection by the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). ELISA and RIBA measure current and prior exposure to HCV infection, but cannot discriminate between the two. RT-PCR is performed after ELISA for the diagnosis of HCV infection whether acute, chronic, false positive or false negative ELISA. The cooperation between ELISA and RT-PCR in the diagnosis of HCV infection has been tabulated and discussed. HCV genotyping and subtyping testing is essential in pre-treatment evaluation of the patients for setting valuable treatment strategies and in understanding the epidemiology of the virus.

Study of prevalence of seropositivity in multi-transfused thalassemia patients - A hospital based study

Background: Thalassemia is an inherited hemoglobinopathy for which blood transfusion is an obligatory treatment. However, blood transfusion has its own adverse effects among which transfusion transmitted infections (TTIs) are major threat to the patients. Objective: To evaluate the seroprevalence of various TTIs in thalassemia patients. It also aims to correlate age group and prevalence of TTIs. Materials and Methods: In this study, a total of 55 beta thalassemia major patients attending C U Shah Medical College, Surendranagar, Gujarat, India, were screened for human immunodeficiency virus (HIV)-1 and HIV-2 IgG and IgM antibodies, hepatitis C virus (HCV) IgG antibody, HBsAg antigen, and IgG antibodies against Treponema pallidum using National AIDS Control Organization approved third generation enzyme-linked immunosorbent assay (ELISA) kits. Selected clinical, sociodemographic, and other characteristics were also recorded to understand the determinants of risks of these infections. Result: It was observed that of the total 55 patients, 2 (3.63%) were HIV reactive, 20 (36.36%) were HCV reactive, and none was found to be hepatitis B virus or venereal disease research laboratory reactive. Conclusion: To reduce the incidence of TTIs, especially HCV and HIV, stringent screening of donor should be done with fourth generation ELISA methods, polymerase chain reaction, or nucleic acid amplification techniques.

HIV-Positive–to–HIV-Positive Kidney Transplantation — Results at 3 to 5 Years

BackgroundThe outcome of kidney transplantation in human immunodeficiency virus (HIV)–positive patients who receive organs from HIV-negative donors has been reported to be similar to the outcome in HIV-negative recipients. We report the outcomes at 3 to 5 years in HIV-positive patients who received kidneys from HIV-positive deceased donors.MethodsWe conducted a prospective, nonrandomized study of kidney transplantation in HIV-infected patients who had a CD4 T-cell count of 200 per cubic millimeter or higher and an undetectable plasma HIV RNA level. All the patients were receiving antiretroviral therapy (ART). The patients received kidneys from deceased donors who tested positive for HIV with the use of fourth-generation enzyme-linked immunosorbent assay at the time of referral. All the donors either had received no ART previously or had received only first-line ART.ResultsFrom September 2008 through February 2014, a total of 27 HIV-positive patients underwent kidney transplantation. Survivors were followed for a median of 2.4 years. The rate of survival among the patients was 84% at 1 year, 84% at 3 years, and 74% at 5 years. The corresponding rates of graft survival were 93%, 84%, and 84%. (If a patient died with a functioning graft, the calculation was performed as if the graft had survived.) Rejection rates were 8% at 1 year and 22% at 3 years. HIV infection remained well controlled, with undetectable virus in blood after the transplantation.ConclusionsKidney transplantation from an HIV-positive donor appears to be an additional treatment option for HIV-infected patients requiring renal-replacement therapy. (Funded by Sanofi South Africa and the Roche Organ Transplantation Research Foundation.)

Hepatitis C Virus Prevalence in Haemodialysis Patients From Three Centers in Baghdad, Iraq: A Survey By Polymerase Chain Reaction and Serological Methods

Hepatitis C virus infection is a major health problem among haemodialysis patients in developing countries. Nosocomial transmission of HCV infection was a considerable route, particularly during the outbreaks of infection. To compare serological and molecular methods for detection of HCV infection serum samples were screened for anti-HCV antibodies using a fourth generation enzyme-linked immunosorbent assay (ELISA) and positive samples were confirmed by immunoblot assay. All seropositive and seronegative samples were screened for the presence of HCV-RNA by using reverse transcriptase PCR (RT-PCR). The overall prevalence was (41.10%) in the three centers (range: 26.05% to 62.82%) with higher prevalence in Al-Kadhimiya Teaching Hospital. All seropositive samples were tested by reverse transcriptase PCR, and 24/92 (26.09%) of confirmed samples were found to contain HCV-RNA. Additionally, 2/5 (40%) of immunoblot-indeterminate and 1/3 (33.33%) of immunoblot-negative samples were also found to be HCV-RNA positive. Also all seronegative samples were screened for the presence of HCV-RNA by using pooling strategy and 2/136 (1.47%) of anti-HCV negative samples were found to be HCV-RNA positive. Our data emphasize the need for stricter adherence to infection control measures in haemodialysis centers and reinforce the importance of screening by both PCR and serological methods at regular intervals to identify all HCV-infected patients.eng

Trends of transfusion transmissible diseases among blood donors at uttarakhand, India.

Context:Blood can save lives; however, it can be a source of transfusion transmitted diseases if proper screening of donated blood is not done. It is now mandatory to screen all donated blood units, whether replacement or voluntary for five transfusion transmitted diseases-namely human immunodeficiency virus (HIV), hepatitis B and C, syphilis, and malaria.Aims:The present study was done to study the prevalence of infectious disease markers among donors at the blood bank of a tertiary care center.Settings and Design:A total of 53,069 donors donated blood over 11 years. The number of replacement and voluntary donors was 41,710 and 11,359, respectively.Materials and Methods:Screening of blood units was done by enzyme-linked immunosorbent assay (ELISA) method for HIV and hepatitis B and C. HIV testing was done using fourth generation ELISA kits. Syphilis was tested by latex agglutination assay and malaria was tested using slide method up to the year 2008-2009 and by rapid immunochromatographic assay after that.Results:The mean percentage of these infections per year was found to be 0.2, 1.2, 0.9, 0.3, and 0.002% for HIV, hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV), syphilis, and malarial parasite (MP), respectively.Conclusions:The risk of transfusion transmissible infection (TTI) today is low but supply of safe blood depends on proper donor selection and sensitive screening tests.

Risk of Transfusion-Transmitted Human Parvovirus B19 Infection in Anyigba and Lokoja, Kogi State – Nigeria

Risk of Transfusion-Transmitted Human Parvovirus B19 Infection in Anyigba and Lokoja, Kogi State – Nigeria

A prospective study for prevalence and/or development of transfusion-transmitted infections in multiply transfused thalassemia major patients

Objective:To evaluate the rate of seropositivity to hepatitis B and C and Human Immunodeficiency Virus (HIV) infections among children with β-thalassemia major receiving multiple transfusions in Ahmedabad, India, compared with healthy controls.Materials and Methods:The study was performed during January 2007 to January 2009 on multi-transfused children suffering with β-thalassemia major registered in the Prathama Blood Centre, Ahmedabad; Jeevandeep hospital, Ahmedabad; and Red Cross Blood Centre, Ahmedabad, and investigated for the prevalence and development of transfusion-transmitted infections. Hepatitis B surface Antigen (HBsAg), anti-Hepatitis C Virus (HCV) Antibodies (Ab), and HIV Ab were checked using a fourth-generation Enzyme-Linked Immunosorbent Assay (ELISA). Positive tests were confirmed by western blots. Healthy blood donors were used for the control group.Results:Hepatitis B surface antigen, anti-HCV Ab, and HIV Ab were positive in one of 96 (1.04%; 95% Confidence Interval (CI) = 0.17–1.3), 24 of 96 (25%; 95% CI = 11.4–14.2), and one of 96 (1.04%; 95% CI = 0.12–1.3), respectively. The rate of anti-HCV Ab was significantly higher in multi-transfused children suffering with β-thalassemia major. In thalassemia patients, the rate of positive anti-HCV Ab was significantly higher than that for positive HBsAg (P<0.001) and HIV Ab (P<0.001).Conclusion:It is concluded that HCV is the current major problem in multi-transfused children with thalassemia major and more careful pretransfusion screening of blood for anti-HCV must be introduced in blood centers.

Cost-Effectiveness of Nucleic Acid Amplification Tests for Identifying Acute HIV Infections

We read with interest the study by Gous et al. (2) evaluating the utility of HIV nucleic acid amplification tests (NAAT) of pooled HIV seronegative serum samples to identify acute HIV infections (AHI). Four of 3,005 seronegative sera were identified as RNA positive by 211 NAAT at a cost of $7.16 per sample over and above the cost of HIV serology alone. The multitude of benefits from early diagnosis of HIV infection are undisputed; however, the most meaningful value to determine feasibility is the cost per additional case identified that would have been missed by antibody testing alone. In this study, this cost was $5,392. Furthermore, careful consideration needs to be given to the possibility of false-positive NAAT results. Various RNA assays cause occasional false-positive results, mostly reporting low viral load values (6, 7, 8) but rarely even >10,000 copies/ml (1). The paper does not discuss this possibility. One of the four positive samples had a very low viral load of 84 copies/ml; given the small input volume of only 100 μl, this is unlikely to cause a positive pool. Two others had viral loads of 3,430 and 11,900 copies/ml. Such low levels are unexpected in AHI and may suggest false positives. If only two instead of four samples were truly positive, the prevalence rate would be halved and the cost per additional case identified would double to $10,784. Finally, it is unclear why a fourth-generation enzyme-linked immunosorbent assay (ELISA) (combined antigen/antibody detection) is negative in the presence of a viral load as high as 1.87 × 106 copies/ml. HIV viral load and p24 levels in the peripheral blood correlate well (9), and the Abbott AxSym fourth-generation HIV assay used by Gous et al. is very sensitive (4). During two evaluations, this assay never reported a negative result at viral loads in excess of 8 × 104 copies/ml (5, 10). However, a second diagnostic window may occasionally cause false-negative results in combined antigen/antibody tests. Another study of pooled NAAT following third-generation ELISA testing established that this strategy will be cost-effective only in settings with a very high HIV incidence (3). Using fourth-generation ELISAs, better at detecting acute HIV infections, may further reduce cost-effectiveness. The same study highlighted the need for timely delivery of NAAT results, as a public health benefit results from decreasing the potential for transmission due to high infectivity during AHI. It was calculated that the cost-effectiveness of pooled NAAT screening may be improved when notifications of all positive results are made within 7 days, although it may still be beyond generally accepted threshold values. The title of the study by Gous et al. asks a difficult question, especially under circumstances where resource constraints not only impact the technical aspects of testing but also the logistics. The answer should not only take the cost of laboratory testing, reporting, and clinical management into account but also the ability of the astute physician to retain a high index of suspicion and consequently repeat serological tests, which may eliminate or at least decrease the necessity for NAAT.

Baja prevalencia de la infección por el virus de la hepatitis C en una población de reclusos, Maracaibo, Venezuela

The high risk behaviors observed in prison centers have favored the transmission of hepatitis C virus infection. The main risk factor to acquire hepatitis C virus infection seems to be the use of intravenous drugs. In Venezuela, the prevalence of the infection in these centers is unknown since studies of the hepatitis C virus there are lacking. The aim of this study was to determine the prevalence of hepatitis C virus and the risk factors involved in the transmission in prisoner populations. A sample of 200 prisoners was studied from Sabaneta Jail, Maracaibo, Venezuela. The ages were between 18-69 years (average +/- DS: 31.6+/-9.9 years). Serum samples were tested by a fourth generation enzyme-linked immunosorbent assay ELISA and a confirmatory assay INNO-LIA. Both kits were from Innogenetic Laboratories N.V. (Belgium). Viral RNA was tested by the reverse transcription polymerase chain reaction technique (RT-PCR). The ELISA assay determined a hepatitis C virus prevalence of 5.0% (10/200); 3/200 (1.5%) individuals were positive by both INNO-LIA and RT-PCR tests. The observed prevalence of hepatitis C virus antibodies in this population was very low, suggesting a low circulation of the virus in this environment and a low level of associated risk behaviors.

Evaluation of a new fourth generation enzyme-linked immunosorbent assay, the LG HIV Ag–Ab Plus, with a combined HIV p24 antigen and anti-HIV-1/2/O screening test

The LG HIV Ag–Ab Plus, a new fourth generation diagnostic assay for HIV infection, was evaluated in comparison to the Enzygnost HIV Integral, an established fourth generation HIV assay. The LG assay showed 100% sensitivity with 109 samples with anti-HIV-1, anti-HIV-2 or anti-HIV-1 group O reactivity. It also detected correctly all 51 positives on three BBI performance panels, slightly outperforming the Enzygnost HIV Integral, which detected 50. The specificity of the LG HIV Ag–Ab Plus was 99.9% with 999 sera from healthy blood donors, which was slightly inferior to the performance of the Enzygnost HIV Integral, which had 100% specificity. The LG assay showed 100% specificity with 81 specimens with underlying diseases including hepatitis B, demonstrating a low risk of cross-reactivity with other infections. The reduction of the diagnostic window by the LG HIV Ag–Ab Plus, compared to a third generation HIV assay, was 6.3 days. The LG assay also showed sufficiently high intra-person and inter-person reproducibility. The overall performance of this new fourth generation HIV assay was adequate for screening and diagnosis of HIV infection.