Diagnostic usefulness of five screening assays for HIV in an east African city where prevalence of infection is low.

Five commercial screening assays for HIV-1, evaluated for their usefulness in detecting infection in high-risk groups in the East African country of Djibouti, produced varying degrees of performance when compared to Western blot and immunofluorescence confirmatory assays. In this population with a low prevalence of HIV infection (16/599), two enzyme-linked immunosorbent assays (ELISA; Abbott and Elavia) and two rapid assays (cambridge latex agglutination and Du Pont's HIV-CHEK) exhibited less than optimal sensitivities. However, with the exception of Elavia, these assays displayed excellent specificities. The fifth test (Serodia gelatin agglutination) produced the highest sensitivity (0.938) and negative predictive value but the lowest specificity and positive predictive value of all five tests. False positive reactions, which occurred only with the Elavia and Serodia tests, could not be explained on the basis of early infection in patients or cross-reactions with the related retroviruses HIV-2 and HTLV-I. We conclude that none of the five tests alone is sufficient in this testing situation, but that a combination of tests could satisfy most requirements for identifying HIV-1 reactive and non-reactive sera.

Sensitivity of HIV-antibody assays determined by seroconversion panels.

OBJECTIVES: To determine the sensitivity of HIV-antibody assays for detecting low levels of HIV antibody using seroconversion and other panels containing plasma of varying titres. METHODS: Eight HIV-antibody assays, available under the World Health Organization bulk-procurement agreement, were evaluated on sets of sequential plasma samples derived from 11 individuals who had recently become HIV-infected (seroconversion panels). In addition, two non-seroconversion panels, consisting of low performance (titre) and mixed titre samples were used to further define the sensitivity of the assays. The eight assays included two rapid tests, one simple test, and five enzyme-linked immunosorbent assays (ELISA). RESULTS: On average, the eight assays detected antibody 0.5-4.8 days later than the reference test (Abbott HIV-1/HIV-2 3rd generation ELISA); these differences were statistically significant for six of the eight tests. All tests performed well on the low performance and mixed titre panels. All eight assays also had comparable sensitivity to that of the reference test on a large panel of known positive plasma. The additional risk of missing an infectious unit of blood during seroconversion by using the least sensitive rather than the reference test was estimated to be 1 in 7600 and 1 in 76 million at annual HIV incidence rates of 1 and 0.0001%, respectively. The cost of eliminating this additional risk by using the reference test is between US$ 15,150 and 151 million per unit detected at the above incidence rates. CONCLUSIONS: Although there are differences in sensitivity between the assays when used to test blood from individuals during the course of seroconversion, the differences are small, and all eight tests are appropriate for use as screening tests.

HIV-1 and hepatitis B transmission in Sudan.

A seroepidemiologic survey was conducted among 773 male soldiers living in five urban locations in Sudan to study the prevalence of and risk factors for HIV-1 and hepatitis B transmission. Twenty-eight per cent of the study population were born and raised in southern Sudan, an area bordering Kenya, Zaire and Uganda, whilst 72% of the study subjects were from northern Sudan. Seventy-eight per cent of the study population had serologic evidence of past hepatitis B infection, and 13 soldiers were confirmed positive for HIV-1 antibody. All 13 HIV-positive soldiers had recently been deployed in southern Sudan. Multivariate analysis indicated an association between living in southern Sudan and both hepatitis B (odds ratio 8.2) and HIV-1 infection (odds ratio 14). Additionally, sexual relations with prostitutes (odds ratio 1.5) and medical injections for schistosomiasis (odds ratio 2.72) were independent predictors of hepatitis B markers in this military population. The findings of this study suggest that sexual promiscuity is a risk factor for hepatitis B transmission in Sudan. They also indicate one possible route for the spread of HIV-1 from central to northern Africa.

Use of renal allografts from donors positive for hepatitis B core antibody confers minimal risk for subsequent development of clinical hepatitis B virus disease.

BACKGROUND: The risk associated with transplantation of renal allografts from hepatitis B virus core antibody-positive (HBcAb(+)), hepatitis B virus surface antigen-negative (HBsAg(-)) donors is not well defined. METHODS: Over 4 years, we performed 45 kidney transplants from IgG HBcAb(+), IgM HBcAb(-), HBsAg(-) donors into recipients with a history of prior hepatitis B virus (HBV) infection or reported vaccination. We examined HBV-related outcomes in these 45 patients, in comparison with 45 recipients of allografts from HBcAb(-) donors (matched for transplant type, date, and pretransplant HBV antibodies). We sought evidence for HBV transmission by testing posttransplant sera for the presence of HBcAb, hepatitis B virus surface antibody, and HBsAg. Additionally, we analyzed alanine aminotransferase profiles and allograft survival rates for all patients. RESULTS: No patient receiving an allograft from an HBcAb(+) donor developed clinical HBV infection. No patient receiving an allograft from an HBcAb(+) donor had HBsAg detected through retrospective testing of stored sera or through prospective routine clinical evaluation and care. However, among the HBcAb(+) kidney recipients, 27% developed new HBcAb and/or hepatitis B virus surface antibody after transplant; in contrast, only 4% of control patients developed new antibody responses (relative risk=4.94; confidence interval 1.07-22.83). Among the recipients of HBcAb(+) organs, 18% developed elevated transaminases after transplant, in comparison with 36% of the controls. No association was found between "seroconverter" status and elevated alanine aminotransferase profiles in either group. CONCLUSIONS: Transplantation of renal allografts from HBcAb(+), HBsAg(-) donors was not associated with clinically detectable HBV disease or antigenemia. However, recipients had a significantly increased risk of HBV seroconversion, consistent with exposure to HBV antigen. These results suggest that HBcAb(+) kidneys can be safely used if transplanted into appropriate recipients, but highlight the need for effective HBV vaccination and vaccine-response monitoring in potential recipients.

Specifics on the refinement and application of two serological assays for the detection of antibodies to HHV-8.

BACKGROUND: Serologic assays for the detection of antibodies to human herpesvirus type 8 (HHV-8) are important for epidemiological studies and to further investigate the proposed pathogenesis of the virus in cancer. Although a variety of assays are available, a lack of optimization and standardization makes their usefulness uncertain, and may be responsible for the controversy concerning the prevalence of infection. OBJECTIVES: To refine an indirect immunofluorescent assay (IFA) for the detection of latent antibodies and a recombinant ORF 65 ELISA for the detection of lytic antibodies in order to increase their ability to differentiate individuals at higher and lower risk for HHV-8 infection. STUDY DESIGN: Sera from Kaposi's sarcoma (KS) patients and blood donors (BDs) were used to modify assay parameters in an attempt to better discriminate between the two populations. Modifications included methods of substrate fixation, incubation times, sample dilution, and antigen/conjugate concentrations. RESULTS: Optimal modifications to the latent IFA included acetone fixation of substrate, and dilution of sera to 1:64 which enhanced detection of HHV-8 antibodies from 68 to 92% in the KS population. Similarly, successful refinement of the ORF 65 ELISA to increase the signal-to-noise ratio included the use of 88 ng of ORF 65 antigen per well and serum dilutions of 1:50. Optical density-to-cut-off ratios directly correlated with titers, thereby introducing a strategy to predict antibody concentrations. The ORF 65 ELISA and the latent IFA were both able to discriminate between the two populations but with different efficiencies. CONCLUSIONS: Although neither the latent IFA nor the ORF 65 ELISA produced perfect test indices, improvement in their performances was noted following the optimization strategies. The ELISA produced better detection of antibodies to the virus than the IFA and permitted prediction of sample titers, thus improving cost and time effectiveness.

Application of a rapid assay for detection of antibodies to human immunodeficiency virus in urine.

The use of rapid, simple tests to detect antibodies to human immunodeficiency virus (HIV) in urine could be valuable for several testing situations, such as in private offices, for epidemiologic surveys, and in developing countries. The authors evaluated the performance of the SUDS HIV type 1 test to detect antibody to HIV-1 peptides in urine. Test performance and applicability of the SUDS test were compared with a routine Food and Drug Administration-licensed enzyme-linked immunosorbent assay (ELISA) and Western blot using 139 serum and urine pairs collected from autopsy cases. Using a modified procedure when testing urine by the SUDS test, results indicated that a total of 15 serum/urine pairs were HIV-1 antibody positive by both the SUDS test and ELISA; all could be confirmed positive by Western blot. One sample produced discrepant results. The SUDS test produced no false-positive results when testing serum or urine, as compared with ELISA, and no false-negative results when compared with the Western blot. For optimal accuracy of detection of antibodies using urine, at least 100 microL of sample was required. By Western blot analysis, antibody profiles in urine were generally weaker than in serum, but confirmation of positivity was not compromised when larger volumes were used. The authors concluded that this rapid HIV-1 test, when used to detect antibodies to HIV-1 in urine, is accurate, easy to perform, and appropriate for use in certain testing situations.

Antigenic differentiation of Trypanosoma cruzi and Trypanosoma rangeli by means of monoclonal-hybridoma antibodies.

Sera from Balb/c mice, hyperimmunized with ruptured epimastigotes of either Trypanosoma cruzi or Trypanosoma rangeli, lacked species-specificity when assayed for antibodies by indirect immunofluorescent microscopy and by the enzyme-linked immunosorbent assay. However, when plasma cells from those mice were fused with syngeneic mouse plasmacytoma cells, many of the resultant hybridomas synthesized antibodies which were species-specific. Four clones are synthesizing antibodies specific for antigens of T. rangeli. These antigens are associated with the cytoplasm, plasma membrane and flagellum. One clone is synthesizing a specific anti-T. rangeli antibody which appears to be reactive with the entire surface of the epimastigote. Another clone is reactive with a subpopulation of epimastigotes, thus suggesting some antigenic variability among cultured forms. Two clones are synthesizing antibody specific for antigens of T. cruzi, one of which is confined to the cytoplasm.

Risk factors associated with a high seroprevalence of hepatitis C virus infection in Egyptian blood donors.

We performed serologic tests for hepatitis C virus (HCV) infection on sera obtained from 163 volunteer blood donors seen at one Cairo hospital. We found HCV infection in 36 donors (22%) measured by a second generation enzyme immunoassay. Thirty-five of these 36 positive sera were tested with a second generation recombinant immunoblot assay (RIBA-2); 22 (63%) were reactive and another 12 (34%) showed an indeterminate reaction. Overall, 13.6% (95% confidence interval [CI] = 8.3-18.9%) of these Egyptian blood donors were serologically confirmed to be infected with HCV. Of several demographic variables and medical risk factors examined, the serologically confirmed (RIBA-2 reactive) donors were significantly older than nonreactive donors, and the age-adjusted risk of being HCV-positive was significantly greater in individuals residing outside Cairo. A knowledge of having received injections, of having a history of schistosomiasis, or of having concomitant hepatitis B surface antigen or antibody were significantly associated with an increased risk of HCV-seropositivity; however, after adjusting for confounding demographic factors, only schistosomiasis (odds ratio = 8.9, 95% CI = 2.35-33.52) was significantly associated with HCV infection. The HCV seropositive rate of 13.6% among Egyptians is 5-35-fold higher than that reported from volunteer blood donors in other countries. Screening for HCV should be instituted in Egyptian blood banks. Blood banks that do not test for HCV should include a history of schistosomiasis in their exclusion criteria used for routine screening of blood donors.

Hepatitis E virus infection in eastern India.

Most cases of enterically transmitted non-A, non-B hepatitis in India have so far been attributed to hepatitis E virus (HEV) infection. Most of the documented studies of hepatitis have focused on the incidence of this disease in northern, western, and south central India. A small seroprevalence study was conducted in the eastern Indian city of Patna to assess the degree of HEV infection among acute sporadic hepatitis cases. Forty-two percent (24 of 57) of the cases of acute sporadic hepatitis were positive for anti-HEV antibodies. Absence of any serologic markers of hepatitis A, B, or E in 58% (33 of 57) of the cases with symptoms of acute hepatitis suggest that there may be as yet unidentified enterically transmitted viruses in this area.

The epidemiology of hepatitis C virus antibody in Yemen.

A cross-sectional survey of 348 subjects without evidence of liver disease was conducted to investigate the prevalence and risk factors for hepatitis C virus antibody (anti-HCV) seropositivity in the Yemen Arab Republic. The mean age of study subjects was 28.7 years (range 3-80), and 61% were males. Using commercial enzyme-linked immunosorbent assays (ELISA), 6.0% (95% confidence interval [CI] 3.8-9.1) of subjects were anti-HCV-positive, 13.5% were hepatitis B surface antigen-positive (HBsAg-positive), and 51.4% were positive for at least one serologic marker of prior hepatitis B infection. Nine (2.6%; 95% CI 1.2-4.9) of the 21 ELISA-positive sera were confirmed to be anti-HCV positive by a recombinant immunoblot assay. Anti-HCV seropositivity was significantly associated with age (odds ratio [OR] 2.0 for each 10-year increase in age) and prior surgery (OR 10.1), but was not associated with a history of prior blood transfusion or markers of hepatitis B infection. These preliminary data suggest that hepatitis C may pose a substantial health threat in Yemen.

Low prevalence of human immunodeficiency virus-1 (HIV-1), HIV-2, and human T cell lymphotropic virus-1 infection in Somalia.

A seroepidemiologic survey was conducted to determine the prevalence of human immunodeficiency virus type 1 (HIV-1), HIV-2, human T cell lymphotropic virus type I (HTLV-I), and Treponema pallidum infection among southern Somalis. Sera were collected from 1,269 study subjects in the urban area of the capital city, Mogadishu, and in the rural towns of Merka, Qoryoley, and Kismayo. The subjects included 57 prostitutes, 79 sexually transmitted disease (STD) patients, and 1,133 others, including outpatient and hospitalized patients with leprosy, tuberculosis, other infectious diseases, individuals from rehabilitation camps and secondary schools, and Ethiopian immigrants. Results indicated that none of the sera were positive for HIV-1 and HIV-2 by Western blot, but one was positive for HTLV-I. The prostitutes had a significantly higher prevalence of treponemal antibody (50.8%; P less than 0.0001) than either the STD patients (12.6%) or the other subjects (5.2%). Epidemiologic data indicated that 94% of the males and females were circumcised and only 2.6% of the males used condoms. Overall, the results of this study suggested a very low prevalence of HIV-1, HIV-2, and HTLV-I infections, especially among prostitutes and STD patients, who were considered at greatest risk of contracting these retroviral infections.

Hepatitis B and HIV in Sudan: a serosurvey for hepatitis B and human immunodeficiency virus antibodies among sexually active heterosexuals.

A serosurvey was conducted in Port Sudan and Suakin, Sudan in October and March 1987 to determine the prevalence and risk factors associated with the transmission of hepatitis B, human immunodeficiency virus type 1 (HIV-1), and syphilis among sexually active heterosexuals on the coast of Sudan. A total of 536 subjects, including 202 female prostitutes, 95 long-distance truck drivers, 103 soldiers, 72 Ethiopian refugees, and 54 Sudanese outpatients, were enrolled in the study. Seventy-eight percent (202/259) of the female study subjects were engaged in prostitution, and 57% (157/277) of the men admitted to prior sexual relations with prostitutes. Serologic markers for hepatitis B and syphilis were detected in 68% and 17% of the entire study population, respectively. In contrast, antibody to HIV-1 was detected in none of the 536 sera tested. Risk factors found to be independently predictive of hepatitis B infection by multivariate analysis included prostitution, positive serology for syphilis, and a history of anti-schistosomal therapy. The absence of HIV-1 infection among the prostitutes enrolled in this study is in marked contrast to the current AIDS epidemic in neighboring sub-Saharan countries, suggesting that HIV-1 has not been widely introduced on the coast of Sudan. The high prevalence of serologic markers to hepatitis B and syphilis, however, indicates a potential for HIV-1 in this region.

Hepatitis C in Peru: risk factors for infection, potential iatrogenic transmission, and genotype distribution.

A large seroepidemiologic and genotyping study of hepatitis C virus (HCV) was conducted in Lima, Peru, during the periods of 1986 to 1993 (cohort A) and 1994 (cohort B). Anti-HCV seroprevalence rates were 15.6% (216 of 1,389) and 11.7% (168 of 1,438), respectively. Low rates were seen among volunteer blood donors (1.1% and 0.8%). Anti-HCV rates were much higher among patients undergoing hemodialysis (43.7% and 59.3%), hemophiliacs (60.0% and 83.3%), in those more than 39 years old (18.2% and 26.0%), in females (25.0% and 27.4%), and in less-educated persons (16.9%). Age- and gender-adjusted risk factors in cohort B included blood transfusion history (adjusted odds ratio [AOR] = 29.8), prior organ transplantation (AOR = 9.1) or a history of hepatitis (AOR = 4.9), previous hospitalization (AOR = 3.7), a history of intravenous drug use (AOR = 3.5), prior major surgery (AOR = 2.6), a history of acupuncture (AOR = 2.1), previous dental procedures (AOR = 1.2), and prior medical injections (AOR = 1.04). The most prevalent HCV genotype was type 1 (86%), followed by type 3 (10%) and type 2 (2%). Transmission through unsafe injection-related and medical/dental procedures appears to play an important role in HCV infection among Peruvians.

Time for HIV-1/HIV-2 combination tests?

We should like to report the case of an individual in the Middle East infected with HIV-2 whose serum was negative by our routine ELISA tests for HIV-1. We propose that screening for HIV-2, in addition to HIV-1, be performed on individuals who are clinically determined to be at risk for HIV infection. Commercially available HIV-1/HIV-2 combination tests may serve to identify both infectious agents.

Enhanced chemiluminescence as a means of increasing the sensitivity of western blot assays for HIV antibody.

Chemiluminescence indicator systems offer several advantages for diagnostic assays and have been used successfully to increase the sensitivity of antibody and antigen assays. A technique of enhanced chemiluminescence (ECL) was applied as a replacement for routine chromogenic substrates on HIV-1 Western blots. The results indicated that the enhanced chemiluminescence detection system increased the sensitivity by greater than 10-fold over routine chromogenic indicator systems when testing diluted, reactive sera. When testing 9 seroconversion panels, the use of ECL indicated that early detection of HIV infection was elicited in six panels up to 31 days (average 11.4 days) prior to detection by routine FDA-licensed Western blots, and could be detected in all panels up to 43 days (average 18.8 days) prior to detection by in-house Western blots. In no case was the ECL Western blot system less sensitive than any of the chromogenic Western blots, and in several cases the maximum potential of the ECL system for early detection of antibody could not be determined. The ECL system was capable of detecting antibodies to envelope antigens at a 20-fold increase over chromogenic Western blots. The time of detection of seropositivity by the ECL Western blot was equal to that of most ELISAs in 5 panels and was 31 days earlier than ELISA in one panel. Permanent documentation of Western blot profiles was accomplished using a simple instamatic camera system capable of detecting the chemiluminescence signal, and blots could be re-probed using a second sample.(ABSTRACT TRUNCATED AT 250 WORDS)

HHV-6 in Djibouti--an epidemiological survey in young adults.

Human herpesvirus type six (HHV-6), previously called human B-cell lymphotropic virus (HBLV), was first isolated in 1986 from patients with various lymphoproliferative disorders, some related to the acquired immunodeficiency syndrome. In order to investigate the epidemiology of HHV-6 in the Horn of Africa, we studied 281 young adults living in the city of Djibouti during June 1988. Of these, 181 belonged to various groups at risk for human immunodeficiency virus (HIV), while 100 represented the normal young adult population. Sera were screened and titrated for antibodies against HHV-6 by an indirect fluorescent antibody assay. The percentage seropositivity for HHV-6 was 71 in the normal population, 75 in the population at risk for HIV, and 93 in the population of subjects with a confirmed positive HIV Western blot. Mean titres of positive sera were similar in all population groups. No correlation existed between HHV-6 seropositivity and age, sex, tribe, habitat, and risk factors for HIV. A positive correlation was noted between HHV-6 and patients complaining of fatigue.

Low prevalence of HIV infection in Djibouti--has the AIDS epidemic come to a stop at the Horn of Africa?

To determine if the HIV-epidemic had reached Djibouti by autumn 1987, we investigated 645 subjects belonging to various risk groups; 150 were patients with a disease compatible with acquired immune deficiency or with a mycobacterial infection, 115 were young males having a sexually transmitted disease, 295 were female prostitutes, and 69 were villagers from a rural area; the remaining 16 belonged to other groups. All subjects answered an epidemiological questionnaire and had their serum tested for evidence of HIV antibodies. Eight sera were HIV-antibody positive by both ELISA and Western blot. Of these, 2 were from young men while 6 were from young women who admitted to prostitution. This accounts for an HIV seropositivity rate of 2.0% +/- 1.6% in the prostitute population. Also, one antibody-positive subject was positive for circulating HIV antigen. Seven of the seropositive individuals had no general complaints or abnormal clinical signs. The eighth subject was a 28 year old man in hospital for pneumonia. We conclude that in Djibouti, in late 1987, the prevalence of both AIDS and HIV infection in high risk individuals was much lower than that reported from other East African countries.

Viral hepatitis markers in Djibouti: an epidemiological survey.

A serosurvey involving 656 individuals revealed that hepatitis A infection was virtually universal in Djibouti in 1987, and more than half of the people investigated had serum markers of hepatitis B infection. The rate of chronic HBsAg carriers was 7.3% and was higher for males than for females. Both HBsAg and anti-HBs positivity rates were directly related to increasing age. No uniform mechanism could be found to account for transmission of the hepatitis B virus, and no correlation was noted between HBV-marker status and sexual promiscuity or the classic blood exposure risks. However, a significant association existed between the abuse of khat and the chronic HBsAg carrier state.

Serological evidence for human immunodeficiency virus type 2 in east Africa.

Infection by human immunodeficiency virus type 2 (HIV-2) has not previously been described in North or East Africa. We examined over 1200 sera of high-risk individuals from three North/East African countries for antibodies to HIV-2. Results indicated that 17 were repeatedly reactive by ELISA; 4 were confirmed by Western blot. Of the 4 confirmed, 2 produced strong reactions to the envelope antigens of HIV-2 but not of HIV-1. One of these subjects was a foreigner from Senegal who was tested while in Egypt and one was a Djiboutian prostitute who was infected presumably prior to October 1987. We conclude that HIV-2 has been introduced into this region and that specific testing of selected individuals for HIV-2 is warranted.

Prevalence of HIV-1 and oral lesions in pregnant women in rural Malawi.

OBJECTIVE: Whether oral lesions were associated with human immunodeficiency virus-type 1 (HIV-1) status in a cohort of pregnant Malawian women was studied. STUDY DESIGN: Six hundred thirty-eight women participated in a randomized prospective study at 3 prenatal clinics in a rural area of southern Malawi. Oral examinations, followed by collection of oral fluid specimens with an HIV-1 oral specimen collection device, were performed. The specimens were tested for antibodies against HIV-1. RESULTS: Sixty-one oral lesions were found in 60 participants. While traditional HIV-1 associated lesions were rare, benign migratory glossitis was unexpectedly common (6%). Oral hairy leukoplakia was significantly more common among women who were HIV-1 positive than among women who were HIV-1 negative. An HIV-1 prevalence rate of 21.8% was estimated among the women, with the highest rate of HIV-1 infection (34.1%) among women aged 25 to 29 years. CONCLUSION: Stratifying lesions showed a small number of oral hairy leukoplakia to be markers for HIV-1. A high seroprevalence was found in this rural cohort, but there were unexpectedly few oral lesions. The relatively few oral lesions diagnosed may indicate a recent infection with HIV.