Temporal trends in the incidence of HIV infection in antenatal clinic attendees in Addis Ababa, Ethiopia, 1995-2003.

BACKGROUND: The HIV incidence data are relevant in depicting the current dynamics and trend of the epidemic. Using a new laboratory method for HIV-1 incidence, we aimed at estimating a 10-year trend in HIV-1 incidence in Addis Ababa, Ethiopia. METHODS: We determined the temporal trends in HIV incidence based on a total of 7744 serum specimens from pregnant women who attended antenatal clinics in Addis Ababa between 1995 and 2003. HIV incidence was determined by IgG-capture HIV-1 BED incidence enzyme immunoassay following a validation using a well-characterized panel of serial serum specimens from subtype C-infected seroconverters. FINDINGS: Of the 1350 HIV+ specimens tested as part of the annual sentinel survey between 1995 and 2003, a total of 1332 (98.7%) were tested by BED HIV-1 incidence assay. The incidence rate of HIV-1 infection declined significantly from 7.7% (95% CI, 3.9-11.5%) in 1995 to 2.0% (95% CI, 0.7-3.3%) in 2003. Although there was a trend, amongst the age group of 15-29 years, in age-specific decline in incidence, it was not statistically significant. No change in HIV incidence rate was observed for the group aged above 30 years. INTERPRETATION: A corresponding decline in the incidence of HIV infection was observed with the decline in the prevalence of HIV infection between 1995 and 2003 in Addis Ababa City. Whether the declines were because of changes in sexual behaviours or other reasons needs to be explored. The BED HIV-1 incidence assay provides a valuable tool in obtaining information on recent HIV-1 infection.

Risk factors associated with failure of syndromic treatment of sexually transmitted diseases among women seeking primary care in Addis Ababa.

OBJECTIVE: To determine risk factors associated with the failure of syndromic management of sexually transmitted diseases (STDs) among women seeking treatment in primary healthcare centre in Addis Ababa, Ethiopia. METHODS: Women with symptomatic STDs seeking care in a health centre were prospectively enrolled. A total of 259 women were interviewed and underwent clinical examination; 106 were enrolled and received syndromic STD treatment and 91% returned for follow up. Logistic regression analysis was used to identify risk factors associated with treatment failure. RESULTS: Of the 106 women enrolled and presenting with symptomatic STDs 67% were HIV seropositive. Syndromic STD treatment did not result in clinical improvement in 30% of the women. Having genital ulcer disease, genital ulcer disease with genital discharge, genital warts, bacterial vaginosis and plasma HIV-1 load >10,000 copies RNA/ml or being HIV seropositive were all significantly associated with treatment failure. In multivariate analysis, however, only genital ulcer disease was significantly associated with treatment failure. CONCLUSION: In our setting, the association between HIV and genital ulcer disease caused by herpes may, therefore, be the reason for the failure of treatment.

The use of real-time PCR to identify Entamoeba histolytica and E. dispar infections in prisoners and primary-school children in Ethiopia.

In Ethiopia, it is generally unknown what proportion of the amoebic infections commonly found, by microscopy, in humans are caused by non-invasive Entamoeba dispar rather than the potentially invasive E. histolytica. Faecal samples were therefore collected from 363 primary-school students and 409 prisoners from various regions of Ethiopia. Each of these samples was checked for Entamoeba infection by the microscopical examination of formol-ether concentrates. DNA was then extracted from the 213 samples (27.6%) found Entamoeba-positive, and run in a real-time PCR with primers, based on the SSU-rRNA gene sequences of E. histolytica and E. dispar, that allow DNA from the two species to be distinguished. Although E. dispar DNA was identified in 195 (91.5%) of the 213 samples checked by PCR, no E. histolytica DNA was detected. This finding is consistent with the conclusion of a previous, smaller investigation: that many amoebic infections in Ethiopia are incorrectly attributed to E. histolytica and then treated, unnecessarily, with amoebicidal drugs.

Seroepidemiology of hepatitis B virus in Addis Ababa, Ethiopia: transmission patterns and vaccine control.

A community-based seroepidemiological survey of Addis Ababa, Ethiopia was conducted in 1994 to inform on the transmission dynamics and control of hepatitis B virus (HBV) infection. Venous blood from 4736 individuals under 50 years of age from 1262 households, selected using stratified cluster-sampling, was screened for HBV markers using commercial ELISAs. HBsAg prevalence was 7% (95 % CI 6-8), higher in males (9%; 7-10) than females (5%; 4-6). HBeAg prevalence in HBsAg positives was 23% (18-29), and less than 1% of women of childbearing age were HBeAg positive. Overall HBV seroprevalence (any marker), rose steadily with age to over 70% in 40-49 year olds, indicating significant childhood and adult transmission. Estimated instantaneous incidence was 3-4/100 susceptibles/year, higher in males than females in 0-4 year olds, and peaking in early childhood and young adults. The age at which 50% had evidence of infection was around 20 years, and the herd immunity threshold is approximated at 63-77%. Addis Ababa is of intermediate-high HBV endemicity, with negligible perinatal transmission. Our main findings are the identification of a significant difference between males and females in the age-acquisition of HBV infection, and marked differences between age groups in HBV incidence rates. These results should target future research studies of underlying risk factors. Furthermore, we generate a crude estimate of the level of coverage of HBV vaccine that would be required to eliminate the virus from the study population.

Seroepidemiology of measles in Addis Ababa, Ethiopia: implications for control through vaccination.

We undertook a representative survey of measles antibodies in Addis Ababa, Ethiopia 1994, to characterize immunity and transmission. Specific-antibody levels (IU/l) were determined by ELISA for 4654 sera from individuals aged 0-49 years (1805 < 15 years) collected by stratified household-cluster sampling. The proportion seronegative (< 100 IU/l) was 20% (95% CI: 16-25) in children 9-59 months old, declining to 9% (7-12) in 5-9 year olds, 5% (4-7) in 10-14 year olds, and < 1% in adults. The proportion of children (< 15 years old) with low-level antibody (100-255 IU/l) was 8% (7-10). Vaccination and an absence of a history of measles illness were strongly associated with low-level antibody. History of measles vaccination in 9 months to 14-year-old children was approximately 80%. We estimate a primary vaccine failure rate of 21% (12-34) and continued high measles incidence of 22 per 100 susceptibles (19-24) per annum. Our data support the introduction of campaign vaccination in the city in 1998, although higher routine vaccine coverage is required to sustain the impact. The implications of a high prevalence of low-level antibody are discussed.

No difference in in vitro susceptibility to HIV type 1 between high-risk HIV-negative Ethiopian commercial sex workers and low-risk control subjects.

Host factors such as increased beta-chemokine production, HIV-1 coreceptor expression level, and HIV-1 coreceptor polymorphism have been thought to influence susceptibility to HIV-1 infection. To determine the protective role of these factors in Ethiopians who remained HIV-1 uninfected, despite multiple high-risk sexual exposures, we studied 21 Ethiopian women who had been employed as commercial sex workers (CSWs) for five or more years. The HIV-1-resistant CSWs were compared with low-risk age-matched female controls who had a comparable CD4+ cell percentage and mean fluorescence intensity (MFI). Genetic polymorphism in the CCR5, CCR2b, or SDF-1 genes appeared not to be associated with resistance in the Ethiopian CSWs. Expression levels of CCR5 and CXCR4 on naive, memory, and total CD4+ T cells tended to be higher in the resistant CSWs, while the production of beta-chemokines RANTES, MIP-1alpha, and MIP-1beta by phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMCs) was lower compared with low-risk HIV-1 negative controls. In vitro susceptibility of PHA-stimulated PBMCs to primary, CCR5-restricted, Ethiopian HIV-1 isolates was comparable between resistant CSWs and low-risk controls. In vitro susceptibility was positively correlated to CD4+ cell mean fluorescence intensity and negatively correlated to CCR5 expression levels, suggesting that infection of PBMCs was primarily dependent on expression levels of CD4 and that CCR5 expression, above a certain threshold, did not further increase susceptibility. Our results show that coreceptor polymorphism, coreceptor expression levels, beta-chemokine production, and cellular resistance to in vitro HIV-1 infection are not associated with protection in high-risk HIV-1-negative Ethiopian CSWs.

Factors associated with HIV-1 infection among sex workers of Addis Ababa, Ethiopia.

OBJECTIVE: To study the prevalence and risk factors for HIV infection among sex workers of Addis Ababa, Ethiopia. DESIGN AND METHODS: Cross-sectional survey on socio-demographic characteristics, behaviours, and HIV serological status of sex workers attending two health centres of Addis Ababa. RESULTS: HIV prevalence among sex workers was 274 of 372 (73.7%). Several factors were significantly associated with an increased risk of being HIV-infected [among others, working in 'shared rooms', high number of clients, use of injectable hormones, and positive Treponema pallidum particle agglutination (TPPA) serology], and others with a decreased risk (being born in Addis Ababa, high level of education, peer education on sex work, condom use, use of oral pill, and use of condoms for contraception). Of interest, sex workers who were using condoms for contraception were, compared with others, more likely to use condoms consistently (65 versus 24%, respectively; P < 0.001), and less likely to be HIV-infected (55 versus 86%, respectively; P < 0.001). In multivariate analysis [log-binomial model, giving estimates of the prevalence ratio (PR)], being born in Addis Ababa (PR = 0.74; 95% confidence interval (CI), 0.61-0.91), using condoms for contraception (PR = 0.73; 95% CI, 0.64-0.85), and a positive TPPA serology (PR = 1.21; 95% CI, 1.09-1.36), remained significantly associated with HIV infection. CONCLUSIONS: HIV prevalence was remarkably high among sex workers of Addis Ababa. Condom use was higher, and HIV prevalence lower, in sex workers using condoms not only for prevention of HIV and sexually transmitted diseases, but also for contraceptive purpose. This finding is of particular interest for its implications for prevention strategies among sex workers in the developing world.

Plasma levels of viro-immunological markers in HIV-infected and non-infected Ethiopians: correlation with cell surface activation markers.

Cross-sectional studies were conducted to measure soluble viral and immunological markers in plasma in order to determine the prognostic value of these markers for HIV disease progression in Ethiopians and to see their association with cell surface markers in HIV-1-infected and noninfected Ethiopians. Whole blood samples were collected from 52 HIV-1-negative Ethiopians, 32 HIV-1-positive Ethiopians with absolute CD4(+) T-cell count >200/microl whole blood and no AIDS defining conditions, and 39 HIV-positive Ethiopians with CD4(+) T-cell count <200/microl and/or AIDS defining conditions. Plasma levels of b(2)-microglobulin (b(2)m), soluble CD27 (sCD27), soluble tumor necrosis factor alpha receptor type II (sTNFR-II), IgG, IgA, IGE, and IL12 were elevated in HIV-1-infected individuals. The plasma levels of sTNFR-II, sCD27, b(2)m, IL12, and IgG were inversely correlated with numbers of CD4(+) T-cells, the proportion of naïve (CD45RA(+)CD27(+)) CD8(+) T-cells, and the proportion of CD8(+) T-cells expressing CD28 (CD8(+)CD28(+)) were positively correlated with the proportions of activated (HLA-DR(+)CD38(+)) CD4(+) T-cells, as well as activated (HLA-DR(+)CD38(+)) CD8(+) T-cells. A strong positive correlation was also observed when soluble immune markers were compared to each other. Multivariate regression analyses of soluble markers with numbers of CD4(+) T-cells showed that sCD27 is the best independent marker for CD4(+) T-cell decline in the HIV-1-infected Ethiopians. Our results indicate that measurement of soluble immune markers, which is relatively easy to perform, could be a good alternative to the quantification of T-cell subsets for monitoring HIV-1 disease progression in places where there is no facility for flow cytometric measurements.

The effect of HIV status on the clinical picture of leprosy: a prospective study in Ethiopia.

No major interaction between HIV infection and leprosy has been documented. The ALERT MDT Field Evaluation Study (AMFES) has allowed the examination of possible interactions in a prospective manner, although the total number of HIV-positive individuals was not high at 22 (3.8%) of 581 patients tested. There was an excess number of deaths in the HIV-positive group: 27% compared with 5.7% in the HIV-negative group, although the causes of death were not recorded (relative risk 4.8; 95% CI 2.2-10.2). HIV-positive individuals had a higher risk of ENL reactions (relative risk 5.2; 95% CI 1.7-15.9). Reversal reactions and neuritis (both acute and chronic) were not significantly influenced by HIV status, although there was a possible increase in recurrent reversal reactions in HIV-positive cases (relative risk 2.2; 95% CI 0.98-4.7). There was no evidence to suggest an increased risk of developing leprosy or of developing multibacillary rather than paucibacillary disease. There was no association between HIV positivity and the development of impairment.

Apelin, the natural ligand of the orphan seven-transmembrane receptor APJ, inhibits human immunodeficiency virus type 1 entry.

In addition to the CCR5 and CXCR4 chemokine receptors, a subset of primary human immunodeficiency virus type 1 (HIV-1) isolates can also use the seven-transmembrane-domain receptor APJ as a coreceptor. A previously identified ligand of APJ, apelin, specifically inhibited the entry of primary T-tropic and dualtropic HIV-1 isolates from different clades into cells expressing CD4 and APJ. Analysis of apelin analogues demonstrated that potent and specific antiviral activity was retained by a 13-residue, arginine-rich peptide. Antiviral potency was influenced by the integrity of methionine 75, which contributes to APJ-binding affinity, and by the retention of apelin residues 63 to 65. These studies demonstrate the ability of a small peptide ligand to block the function of APJ as an HIV-1 coreceptor, identify apelin sequences important for the inhibition, and provide new reagents for the investigation of the significance of APJ to HIV-1 infection and pathogenesis.

Sero-epidemiology of rubella in the urban population of Addis Ababa, Ethiopia.

We conducted a community-based cluster sample survey of rubella sero-epidemiology in Addis Ababa, Ethiopia in 1994. Among 4666 individuals for whom complete data were available, rubella antibody prevalence was 91% (95% confidence interval: 90, 92). On multivariable analysis, seroprevalence was lower among individuals who were resident in Addis Ababa for 1 year or less. Approx. 50% seroprevalence was attained by age 4 years, and the estimated average age at infection was 5.2 years. The highest age-specific force of infection was estimated to occur in 5- to 9-year-olds. The early age at infection corresponded with a low estimated incidence of congenital rubella syndrome (CRS) of 0.3 per 1000 live births, equivalent to nine cases of CRS in 1994. The predicted critical level of immunity for elimination of rubella via vaccination was 85-91%, requiring 89-96% coverage with a vaccine of 95% effectiveness. Unless very high coverage of rubella vaccine could be guaranteed, the introduction of childhood vaccination could increase the incidence of CRS in Addis Ababa.

Epidemiology of infections with intestinal parasites and human immunodeficiency virus (HIV) among sugar-estate residents in Ethiopia.

Intestinal parasitic infections could play an important role in the progression of infection with human immunodeficiency virus (HIV), by further disturbing the immune system whilst it is already engaged in the fight against HIV. HIV and intestinal parasitic infections were investigated in 1239, randomly selected individuals, aged 15-54 years, living on a sugar estate in central Ethiopia. Intestinal parasites were identified in faecal samples (one/subject) using direct, concentration, and (for Strongyloides stercoralis larvae) Baermann methods. HIV serological status was determined using ELISA, with ELISA-positive samples confirmed as positive by western blotting. Most (70.1%) of the subjects were infected with at least one intestinal parasite and 3.1% were seropositive (but asymptomatic) for HIV. The intestinal parasites identified in the study population were amoebic parasites (Entamoeba histolytica/Enta. dispar) (24.6%), hookworms (23.8%), Ascaris lumbricoides (22.2%), Trichuris trichiura (19.5%), S. stercoralis (13.0%), Taenia saginata (4.5%), Giardia lamblia (3.0%), and Enterobius vermicularis (1.3%). Overall, the HIV-positives were no more or less likely to carry intestinal parasites than the HIV-negatives (76.2% v. 69.9%; P > 0.05). However, when each parasite was considered separately, amoebic parasites were found to be more common in the HIV-positives than the HIV-negatives (43.7% v. 24.0%; P < 0.05). This difference remained significant in a multivariate analysis, after controlling for the socio-demographic characteristics of the study participants. In conclusion, there was moderate interaction between intestinal parasites and HIV at the asymptomatic stage of HIV infection. The observed association between amoebic and HIV infections requires confirmation in a prospective study, allowing for the analysis of biological mechanisms involved in the association.

Nonradioactive techniques for measurement of in vitro T-cell proliferation: alternatives to the [(3)H]thymidine incorporation assay.

T-cell proliferation is an important in vitro parameter of in vivo immune function and has been used as a prognostic marker of human immunodeficiency virus type 1 (HIV-1) disease progression. The proliferative capacity of T cells in response to various stimuli is commonly determined by a radioactive assay based on incorporation of [(3)H]thymidine ([(3)H]TdR) into newly generated DNA. In order to assess techniques for application in laboratories where radioactive facilities are not present, two alternative methods were tested and compared to the [(3)H]TdR assay as a "gold standard." As an alternative, T-cell proliferation was measured by flow cytometric assessment of CD38 expression on T cells and by an enzyme-linked immunosorbent assay (ELISA) based on bromo-2'-deoxyuridine (BrdU) incorporation. Peripheral blood mononuclear cells (PBMCs), either in whole blood or Ficoll-Isopaque separated, from a total of 26 HIV-1-positive and 18 HIV-1-negative Dutch individuals were stimulated with CD3 monoclonal antibody (MAb) alone, a combination of CD3 and CD28 MAbs, or phytohemagglutinin. BrdU incorporation after 3 days of stimulation with a combination of CD3 and CD28 MAbs correlated excellently with the [(3)H]TdR incorporation in both study groups (HIV-1 positives, r = 0.96; HIV-1 negatives, r = 0.83). A significant correlation of absolute numbers of T cells expressing CD38 with [(3)H]TdR incorporation, both in HIV-1-positive (r = 0.96) and HIV-1-negative (r = 0.84) individuals, was also observed under these conditions. The results of this study indicate that determination of both the number of CD38-positive T cells and BrdU incorporation can be used as alternative techniques to measure the in vitro T-cell proliferative capacity. The measurement of CD38 expression on T cells provides the additional possibility to further characterize the proliferating T-cell subsets for expression of other surface markers.

Epidemiology of HIV and Schistosoma mansoni infections among sugar-estate residents in Ethiopia.

Few studies have examined the interaction between schistosomiasis and infection with human immunodeficiency virus (HIV). The overlap between the two infections, and the effect of HIV infection on the egg output and worm load of individuals co-infected with Schistosoma mansoni, were therefore investigated in a sugar estate in central Ethiopia. The 1239 subjects were selected by stratified sampling of residents aged 15-54 years. The intensities of infection with S. mansoni were measured as egg output in stools (all subjects) and as the concentration of circulating cathodic antigen (CCA) in urine (a proxy for worm load, measured in 287 subjects). Schistosome infection was detected in 358 subjects [adjusted prevalence (AP) = 31.4%] and HIV infection in 52 (AP = 3.1%). The two infections clustered into different populations of the estate: the schistosome infections were predominantly found in the camps, and primarily affected young people (aged < 20 years) and those working in the field, whereas the HIV epidemic was found in the main village, primarily affecting those aged > 20 years and those who had recently arrived on the estate. Schistosome infection was detected in 348 of the 1187 HIV-negatives (AP = 31.6%) and 10 of the 52 HIV-positives (AP = 25.1%; P > 0.05). Schistosoma mansoni egg output was significantly lower in the HIV-positives than in the HIV-negatives (Mann-Whitney test; P = 0.03; ratio of geometric means = 0.74), and remained so after controlling for potential confounders (gender, age, and residence). However, CCA concentrations (i.e. worm loads) were found to be similar for these two groups, after controlling for potential confounders (age, gender, residence, and duration of residence).

Immunohematological reference ranges for adult Ethiopians.

A cross-sectional survey was carried out with 485 healthy working adult Ethiopians who are participating in a cohort study on the progression of human immunodeficiency virus type 1 (HIV-1) infection to establish hematological reference ranges for adult HIV-negative Ethiopians. In addition, enumeration of absolute numbers and percentages of leukocyte subsets was performed for 142 randomly selected HIV-negative individuals. Immunological results were compared to those of 1,356 healthy HIV-negative Dutch blood donor controls. Immunohematological mean values, medians, and 95th percentile reference ranges were established. Mean values were as follows: leukocyte (WBC) counts, 6.1 x 10(9)/liter (both genders); erythrocyte counts, 5.1 x 10(12)/liter (males) and 4.5 x 10(12)/liter (females); hemoglobin, 16.1 (male) and 14.3 (female) g/dl; hematocrit, 48.3% (male) and 42.0% (female); platelets, 205 x 10(9)/liter (both genders); monocytes, 343/microl; granulocytes, 3, 057/microl; lymphocytes, 1,857/microl; CD4 T cells, 775/microl; CD8 T cells, 747/microl; CD4/CD8 T-cell ratio, 1.2; T cells, 1, 555/microl; B cells, 191/microl; and NK cells, 250/microl. The major conclusions follow. (i) The WBC and platelet values of healthy HIV-negative Ethiopians are lower than the adopted reference values of Ethiopia. (ii) The absolute CD4 T-cell counts of healthy HIV-negative Ethiopians are considerably lower than those of the Dutch controls, while the opposite is true for the absolute CD8 T-cell counts. This results in a significantly reduced CD4/CD8 T-cell ratio for healthy Ethiopians, compared to the ratio for Dutch controls.

Evaluation of the World Health Organization staging system for HIV infection and disease in Ethiopia: association between clinical stages and laboratory markers.

OBJECTIVE: To study the association between the clinical axis of the World Health Organization (WHO) staging system of HIV infection and disease and laboratory markers in HIV-infected Ethiopians. DESIGN: Cross-sectional study. METHODS: Clinical manifestations and stage of HIV-positive individuals participating in a cohort study of HIV infection progression, and of HIV-positive patients hospitalized with suspicion of AIDS, were compared to CD4+ T-cell count and viral load. RESULTS: Of the 86 HIV-positive participants of the cohort study, 53 (62%), 16 (19%), 16 (19%), and one (1.2%) were in stage 1, 2, 3 and 4, respectively. Minor weight loss (n = 15) and pulmonary tuberculosis (n = 9) were the most commonly diagnosed conditions among the 38 (44%) symptomatic HIV-positive individuals. Although 23 (27%) HIV-positive participants had CD4+ T-cell counts less than 200 x 10(6)/l, only one was in clinical stage 4. Among 79 hospitalized HIV-positive patients, 15 (19%) and 64 (81%) were in stage 3 and 4, respectively. The majority (83.5%) had CD4+ T-cell counts < 200 x 10(6)/l. Individuals at stage 3 had lower CD4+ T-cell counts and higher viral loads when seen in hospital as compared to cohort participants (P = 0.06 and 0.008, respectively). When grouping the two study populations, the median CD4+ T-cell count decreased (337, 262, 225, 126, and 78 x 10(6)/l, P< 0.01), and the median viral load increased (4.08, 3.89, 4.47, 5.65, and 5.65 log10 copies/ml, P < 0.01), with increasing clinical stage of HIV infection (1, 2, 3 cohort, 3 hospital, and 4, respectively). Median CD4+ T-cell counts were remarkably low in HIV-negative participants (749 x 10(6)/l), and in HIV-positive participants at stage 1 and 2 (337 and 262 x 10(6)/l, respectively). CONCLUSIONS: There was a good correlation between WHO clinical stages and biological markers. CD4+ T-cell counts were low in Ethiopians, particularly during early stages of HIV-1 infection, and preliminary reference values at different stages of HIV-1 infection were determined. In HIV-infected Ethiopians, lymphocyte counts less than 1,000 x 10(6)/l in non-hospitalized individuals, and less than 2,000 x 10(6)/l in hospitalized patients, had high positive predictive value, but low sensitivity, in identifying subjects with low CD4+ T-cell counts (< 200 x 10(6)/l) who would benefit from chemoprophylaxis of opportunistic infections. The on-going longitudinal study will be useful to confirm the prognostic value of the WHO staging system.

Reduced naive and increased activated CD4 and CD8 cells in healthy adult Ethiopians compared with their Dutch counterparts.

To assess possible differences in immune status, proportions and absolute numbers of subsets of CD4+ and CD8+ T cells were compared between HIV- healthy Ethiopians (n = 52) and HIV- Dutch (n = 60). Both proportions and absolute numbers of naive CD4+ and CD8+ T cells were found to be significantly reduced in HIV Ethiopians compared with HIV- Dutch subjects. Also, both proportions and absolute numbers of the effector CD8+ T cell population as well as the CD4+CD45RA-CD27- and CD8+CD45RA-CD27- T cell populations were increased in Ethiopians. Finally, both proportions and absolute numbers of CD4+ and CD8+ T cells expressing CD28 were significantly reduced in Ethiopians versus Dutch. In addition, the possible association between the described subsets and HIV status was studied by comparing the above 52 HIV- individuals with 32 HIV+ Ethiopians with CD4 counts > 200/microliter and/or no AIDS-defining conditions and 39 HIV+ Ethiopians with CD4 counts < 200/microliter or with AIDS-defining conditions. There was a gradual increase of activated CD4+ and CD8+ T cells, a decrease of CD8+ T cells expressing CD28 and a decrease of effector CD8+ T cells when moving from HIV- to AIDS. Furthermore, a decrease of naive CD8+ T cells and an increase of memory CD8+ T cells in AIDS patients were observed. These results suggest a generally and persistently activated immune system in HIV- Ethiopians. The potential consequences of this are discussed, in relation to HIV infection.

Evaluation of the Eiken latex agglutination test for anti-Toxoplasma antibodies and seroprevalence of Toxoplasma infection among factory workers in Addis Ababa, Ethiopia.

Sera from 170 factory workers aged 18-45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti-Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti-Toxoplasma antibodies was 80.0% (95% confidence interval 73.9-86.1%). The sensitivity and specificity of the Eiken latex agglutination test were 96.3% and 97.1%, respectively, showing its validity for the detection of anti-Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74.2% versus 83.3%, P > 0.05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected (P < 0.001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti-Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.

A comparison of oral fluid and serum for the detection of rubella-specific antibodies in a community study in Addis Ababa, Ethiopia.

OBJECTIVE: To assess the utility of oral fluid compared with serum for the determination of age-prevalence of rubella-specific antibodies in an urban African community setting. METHOD: Paired serum and oral fluid samples were collected from 439 individuals aged 0-49 years in Addis Ababa, Ethiopia, as part of a larger seroepidemiological survey in 1994. Oral fluid was sampled using a simple sponge device that was well accepted by subjects of all ages; venous blood was collected by Vacutainer system. We measured rubella-specific antibodies in serum by the Radial Haemolysis (RH) test, supported by two confirmatory assays, and in oral fluid by IgG antibody-capture radioimmunoassay (GACRIA). RESULTS: Sensitivity and specificity of oral fluid results compared to serum were 89% and 76%, respectively. Sensitivity declined from 96% in age group 0-19 years to 90% in age group 20-29 and 78% in age group 30-49. Specificity was 86% in 0-9 year olds contrasting with 61% in older groups (10-49 years). The positive predictive value of an oral fluid sample was high in all age groups (range 92-100%), while the negative predictive value declined from > or =80% in those aged <10 years to <10% in those aged > or =30 years. Serum confirmatory tests suggested a proportion of false serum RH negatives, increasing with age, indicating a need to standardize serum as well as oral fluid tests. CONCLUSION: In the community setting of a developing country, oral fluid surveys could be useful to estimate age-prevalence of rubella immunity and identify rubella-susceptible children for follow-up. Further work is required to simplify assays and sample processing, improve assay sensitivity and estimate assay specificity more precisely, and compare and standardise collection methods suitable for surveillance of a variety of childhood viral infections.

Age- and sex-specific HIV-1 prevalence in the urban community setting of Addis Ababa, Ethiopia.

OBJECTIVE: To estimate the age and sex-specific prevalence of HIV infection in the population of Addis Ababa, Ethiopia. DESIGN: Two-stage cluster sampling of the population aged 0-49 years of Addis Ababa, using kebeles (urban dwelling associations) as clusters. METHODS: The sera used for this study were collected in an earlier study (1994) on the rate of acquisition of antibodies against measles, rubella, and hepatitis B. After separate approvals were obtained from the institutional ethics committees, sera were tested by enzyme-linked immunosorbent assay confirmed by Western blot. Age- and sex-specific HIV prevalence rates were estimated. The prevalence of HIV in men and women over 15 years of age was compared by calculating age-standardized HIV prevalence, using the age distribution of the census population as the standard. A time-dependent catalytic model was used to obtain crude estimates of HIV incidence from age-prevalence data. RESULTS: A total of 3853 sera were available for analysis. The prevalence of HIV in adults was 6.0% [95% confidence interval (CI), 4.5-7.4%] for men and 6.9% (95% CI, 5.3-8.5%) for women, with peak prevalence in the 25-29 year age group of 16.3 and 11.8%, respectively. After standardization for age using the direct method, the HIV prevalence ratio comparing adult men with women was 0.97:1 (95% CI, 0.70:1 - 1.35:1). Three children aged less than 5 years were HIV-positive. The prevalence of HIV among adults ranged from 0-21.3% in different clusters, indicating the heterogeneity of the spread of HIV in the city. HIV prevalence estimates among the antenatal clinic patients of Addis Ababa in 1996 far exceeded the estimates obtained during the community survey, particularly in the youngest age group (15-24 years). Estimates of HIV incidence (per susceptible person per annum) for the age group 16-22 years ranged from 1.3-2.25% for men and from 2.1-2.4% for women. CONCLUSION: By 1994, a substantial proportion of the adult population of Addis Ababa was infected with HIV. Promotion of behavioural changes and the control of sexually transmitted diseases should be strongly supported to limit the spread of the HIV epidemic in Ethiopia.