Micronutrient supplementation and T cell-mediated immune responses in patients with tuberculosis in Tanzania.

Limited studies exist regarding whether incorporating micronutrient supplements during tuberculosis (TB) treatment may improve cell-mediated immune response. We examined the effect of micronutrient supplementation on lymphocyte proliferation response to mycobacteria or T-cell mitogens in a randomized trial conducted on 423 patients with pulmonary TB. Eligible participants were randomly assigned to receive a daily dose of micronutrients (vitamins A, B-complex, C, E, and selenium) or placebo at the time of initiation of TB treatment. We found no overall effect of micronutrient supplements on lymphocyte proliferative responses to phytohaemagglutinin or purified protein derivatives in HIV-negative and HIV-positive TB patients. Of HIV-negative TB patients, the micronutrient group tended to show higher proliferative responses to concanavalin A than the placebo group, although the clinical relevance of this finding is not readily notable. The role of nutritional intervention in this vulnerable population remains an important area of future research.

Determinants of anemia in postpartum HIV-negative women in Dar es Salaam, Tanzania.

OBJECTIVE: The determinants of anemia during both pregnancy and postpartum recovery remain incompletely understood in sub-Saharan African women. SUBJECTS/METHODS: In a prospective cohort study among pregnant women, we assessed dietary, biochemical, anthropometric, infectious and sociodemographic factors at baseline. In multivariate Cox proportional hazards models, we examined predictors of incident anemia (hemoglobin <11 g/dl) and iron deficiency anemia (anemia plus mean corpuscular volume <80fL), and recovery from anemia and iron deficiency anemia through 18 months postpartum at antenatal clinics in Dar es Salaam, Tanzania between 2001 and 2005. A total of 2364 non-anemic pregnant women and 4884 anemic women were enrolled between 12 and 27 weeks of gestation. RESULTS: In total, 292 women developed anemia during the postpartum period and 165 developed iron deficiency anemia, whereas 2982 recovered from baseline anemia and 2044 from iron deficiency anemia. Risk factors for postpartum anemia were delivery complications (RR 1.6, 95% confidence interval (CI) 1.13, 2.22) and low postpartum CD4 cell count (RR 1.73, 95% CI 0.96, 3.17). Iron/folate supplementation during pregnancy had a protective relationship with the incidence of iron deficiency anemia. Absence of delivery complications, education status and iron/folate supplementation were positively associated with time to recovery from iron deficiency. CONCLUSION: Maternal nutritional status during pregnancy, prenatal iron/folate supplementation, perinatal care, and prevention and management of infections, such as malaria, are modifiable risk factors for the occurrence of, and recovery from, anemia.

Anemia in adults with tuberculosis is associated with HIV and anthropometric status in Dar es Salaam, Tanzania.

SETTING: Tuberculosis (TB) infected adults attending out-patient TB clinics in Dar es Salaam, Tanzania. OBJECTIVE: To examine the association of anemia with human immunodeficiency virus (HIV) co-infection, indicators of socio-economic status (SES) and anthropometric status in TB-infected adults. DESIGN: Cross-sectional data collection during screening for a clinical trial. RESULTS: Overall, 750 females and 1693 males participated in this study, of whom respectively 49% and 24% were co-infected with HIV-1. Hemoglobin levels were significantly lower in females than in males and in HIV-positive than in HIV-negative participants. HIV co-infection in this antiretroviral-naïve population was also associated with severe anemia (hemoglobin < 85 g/l) in both women (prevalence ratio [PR] = 2.07, 95%CI 1.65-2.59) and men (PR 3.45, 95%CI 2.66-4.47). Although severe anemia was negatively associated with indicators of SES, especially in males, adjustment for SES indicators only marginally changed its association with HIV co-infection. In both sexes, anemia was inversely associated with anthropometric status, independently of HIV infection and SES. CONCLUSION: Among TB-infected adults, anemia is strongly associated with HIV co-infection and anthropometric status, independently of SES indicators. As anemia is a risk factor for morbidity and mortality in both infections, the management of anemia in TB-HIV co-infected patients warrants special attention.

Prevalence of genotypic resistance to antiretroviral drugs in treatment-naive youths infected with diverse HIV type 1 subtypes and recombinant forms in Dar es Salaam, Tanzania.

As human immunodeficiency virus (HIV) diversity may have an impact on both vaccine efficacy and drug resistance, it is important to have knowledge of circulating genetic variants. With widespread use of antiretroviral (ARV) drugs in Africa, one of the major potential challenges is the risk of emergence of ARV drug-resistant HIV strains. This study aimed to determine the circulating HIV subtypes and recombinant forms, as well as the prevalence of ARV drug resistance mutations, among 75 treatment-naive HIV-infected youths in Dar es Salaam, Tanzania. Gag (n = 48), partial pol (n = 44), and partial env (n = 35) sequencing was performed; all three regions were sequenced in 26 samples. Evidence of infection with recombinant viruses was found in 12 (46%) participants; AC recombinants were the most commonly detected and they were identified in six (23%) participants. Of individuals infected with nonrecombinant strains, subtype A was most commonly detected in seven (27%) participants, followed by subtype C detected in six (23%) participants and subtype D detected in one (4%) participant. Among the pol sequences from 44 individuals, three (7%) had resistance to nucleoside reverse transcriptase (RT) inhibitors and four (9%) had nonnucleoside RT inhibitor resistance mutations. Of these, three (7%) individuals were infected with viruses with cross-resistance mutations to both classes of RT inhibitors. These resistant mutations were all associated with drugs currently used in first-line therapy and in the prevention of vertical transmission. This high prevalence of resistance mutations is of considerable concern in apparently drug-naive populations as it may result in treatment failure and the spread of ARV-resistant strains.

Predictors of change in nutritional and hemoglobin status among adults treated for tuberculosis in Tanzania.

BACKGROUND: Patients with tuberculosis (TB) often suffer from profound malnutrition. OBJECTIVE: To examine the patterns and predictors of change in nutritional and hemoglobin status during and after TB treatment. METHODS: A total of 471 human immunodeficiency virus (HIV) positive and 416 HIV-negative adults with pulmonary TB were prospectively followed in Dar es Salaam, Tanzania. All patients received 8 months' TB treatment following enrollment. RESULTS: About 40% of HIV-positive and 47% of HIV-negative TB patients had body mass index (BMI) < 18.5 kg/m 2 at baseline, while about 94% of HIV-positive and 84% of HIV-negative participants were anemic at baseline. Both HIV-positive and HIV-negative patients experienced increases in BMI and hemoglobin concentrations over the course of TB treatment. Among HIV- positive patients, older age, low CD4 cell counts, and high viral load were independently associated with a smaller increase in BMI from baseline to 8 months. Fe- male sex, older age, low CD4 cell counts, previous TB infection and less money spent on food were independently associated with a smaller improvement in hemoglobin levels among HIV-positive patients during treatment. CONCLUSION: HIV-positive TB patients, especially those with low CD4 cell counts, showed poor nutritional recovery during TB treatment. Adequate nutritional support should be considered during TB treatment.

The use of total lymphocyte count as a surrogate for low CD4+ T lymphocyte cell counts among HIV-1-infected women in Tanzania.

BACKGROUND: Human Immunodeficiency Virus type 1 (HIV-1) infection leads to a progressive decline in CD4+ T-lymphocyte (CD4) cells. Initiation of prophylaxis against Opportunistic infections in adults (CD4% used for children) and antiretroviral therapy is usually based on CD4 cell counts, but CD4 cell counts measurement is not affordable in most African countries. OBJECTIVE: To examine whether total lymphocyte counts (TLC) may be used as proxies for low CD4 cell counts. DESIGN: Cross-sectional at baseline when women were pregnant and at least six months postpartum. METHODS: 1,078 HIV-1-infected pregnant women from Dar es Salaam, Tanzania were enrolled in a randomized clinical trial. A series of receiver operator characteristic (ROC) curves were created at baseline and at least 6 months postpartum and among women in WHO Stage 3 and above. The sensitivity and specificity of TLC and hemoglobin in predicting an absolute CD4 count < 200 cells/mm3 were determined for various clinically relevant cut points. RESULTS: TLC was not a good predictor of low CD4 cell counts during pregnancy or at least six months postpartum as exhibited by low ROC Area Under the Curve (AUCs) of .57 and .62 respectively. No other variable had the ability to predict CD4 < 200 cells/mm3. CONCLUSIONS: The use of TLC as a proxy for the estimation of low CD4 cell counts in a population of HIV-1-infected adults from sub-Saharan Africa was not substantiated. Inexpensive methods to quantify CD4 cell counts in Africa are needed.

Risky sexual practices among youth attending a sexually transmitted infection clinic in Dar es Salaam, Tanzania.

BACKGROUND: Youth have been reported to be at a higher risk of acquiring STIs with significant adverse health and social consequences. Knowledge on the prevailing risky practices is an essential tool to guide preventive strategies. METHODS: Youth aged between 18 and 25 years attending an STI clinic were recruited. Social, sexual and demographic characteristics were elicited using a structured standard questionnaire. Blood samples were tested for syphilis and HIV infections. Urethral, high vaginal and cervical swabs were screened for common STI agents. RESULTS: A total of 304 youth were studied with mean age of 21.5 and 20.3 years for males and females respectively. 63.5% of youth were seeking STI care. The mean age of coitache was 16.4 and 16.2 years for males and females respectively. The first sexual partner was significantly older in females compared to male youth (23.0 vs 16.8 years) (p < 0.01). 93.2% of male youth reported more than one sexual lifetime partner compared to 63.0% of the females. Only 50% of males compared to 43% of females had ever used a condom and fewer than 8.3% of female youth used other contraceptive methods. 27.1% of pregnancies were unplanned and 60% of abortions were induced. 42.0% of female youth had received gifts/money for sexual favours. The HIV prevalence was 15.3% and 7.5% for females and males respectively. The prevalence of other STIs was relatively low. Among male youth, use of alcohol or illicit drugs was associated with increased risk of HIV infection. However, the age of sexual initiation, number of sexual partners or the age of the first sexual partner were not associated with increased risk of being HIV infected. CONCLUSION: Most female youth seen at the STI clinic had their first sexual intercourse with older males. Youth were engaging in high risk unprotected sexual practices which were predisposing them to STIs and unplanned pregnancies. There is a great need to establish more youth-friendly reproductive health clinics, encourage consistent and correct use of condoms, delay in sexual debut and avoid older sexual partners in females.

Optimal blood mononuclear cell isolation procedures for gamma interferon enzyme-linked immunospot testing of healthy Swedish and Tanzanian subjects.

Determination of antigen-specific T-cell responses is an important part of vaccine assessment. High levels of recovery, viability, and functionality of peripheral blood mononuclear cells (PBMCs) are essential for reliable assessment of cell-mediated immune responses. Here, we sought to find the cell preparation technique best suited for two clinical vaccine trial sites: Stockholm, Sweden, and Dar es Salaam, Tanzania. Standard Ficoll-Paque gradient centrifugation, BD Vacutainer cell preparation tube (CPT), and Greiner Bio-One LeucoSep tube techniques were tested. Cell yield and viability were recorded. Gamma interferon (IFN-gamma) enzyme-linked immunospot (ELISPOT) testing was used to assess cell functionality. No differences in mean recovery or mean viability of fresh PBMCs were observed between Ficoll-Paque gradient centrifugation and CPT techniques as used in Stockholm. In Dar es Salaam, recovery of PBMCs isolated by use of the Ficoll-Paque gradient technique was higher than that seen with CPT (1.58 +/- 0.6 versus 1.34 +/- 0.4 million cells/ml of blood [P = 0.0469]), and the viability of PBMCs processed by Ficoll-Paque gradient was higher than that seen with CPT-purified cells (95.8% +/- 2.3% versus 92.6% +/- 4.8% [P = 0.0081]). Furthermore, LeucoSep cell separation gave higher levels of yield (1.10 +/- 0.3 versus 0.92 +/- 0.3 million cells/ml of blood [P = 0.0022]) and viability (95.7% +/- 2.0% versus 93.4% +/- 3.2% [P = 0.0012]) than Ficoll-Paque cell separation. The cells purified by the different techniques at the two sites performed equally well in IFN-gamma ELISPOT assays. Both techniques generated cell preparations with excellent yield, viability, and functionality in Stockholm. In Dar es Salaam, CPT did not perform as well as Ficoll-Paque separation. In a subsequent comparison, LeucoSep performed better than Ficoll-Paque separation. Our findings emphasize the need for on-site assessment of PBMC purification techniques for optimal evaluation of cell-mediated immune responses.

HIV co-infection, CD4 cell counts and clinical correlates of bacillary density in pulmonary tuberculosis.

BACKGROUND: Sputum microscopy for acid-fast bacilli (AFB) is the commonest diagnostic method for pulmonary tuberculosis (PTB) in developing countries. The method is reported to be less sensitive in human immunodeficiency virus (HIV) positive compared to negative patients. We determined the bacillary density in sputum of smear-positive PTB patients and related it to the patients' HIV status, CD4 cell count, clinical and demographic characteristics. METHODS: Three sputum samples per patient were examined using microscopy before initiating therapy. The AFB density was graded according to World Health Organization recommendations. The smear with the highest density was used. High bacillary density was defined as >10 AFB/field. HIV status and CD4 cell count were determined according to the national guidelines. RESULTS: Of 844 patients, 433 (51.3%) were HIV-positive. High bacillary density was significantly less common among HIV-positive (39.0%) than -negative (75.7%) patients (prevalence ratio 0.52; 95%CI 0.45-0.59, P < 0.0001). Among HIV-positive patients, the proportion of those with high bacillary density increased progressively with CD4 cell counts (P = 0.003). CONCLUSION: HIV is associated with lower AFB concentration in sputum. The AFB density falls with falling CD4 cell count. Microscopy for AFB in sputum may be less sensitive in diagnosing PTB when HIV infection is present, especially in severely immunocompromised patients.

Zinc supplementation to HIV-1-infected pregnant women: effects on maternal anthropometry, viral load, and early mother-to-child transmission.

OBJECTIVE: To examine the effect of zinc supplementation to HIV-1-infected pregnant women on viral load, early mother-to-child transmission of HIV (MTCT), and wasting. DESIGN: Double-blind placebo-controlled randomized clinical trial. SETTING: Antenatal clinic in Dar es Salaam, Tanzania. SUBJECTS: Four hundred HIV-1-infected pregnant women. METHODS: Women 12-27 weeks of gestation were randomly assigned to receive a daily oral dose of 25 mg zinc or placebo from the day of the first prenatal visit until 6 weeks postdelivery. Weight and mid-upper arm circumference (MUAC) were measured monthly. HIV status of the babies was assessed at birth and at 6 weeks postpartum. Viral load was assessed in a random sample of 100 women at baseline and at the end of the study. RESULTS: Zinc had no effects on maternal viral load or early MTCT. Supplementation was related to a significant threefold increase in the risk of wasting (reaching a MUAC value <22 cm) during an average 22 weeks of observation (RR=2.7, 95%CI=1.1, 6.4, P=0.03), and to a 4 mm decline in MUAC during the second trimester (P=0.02). CONCLUSIONS: Zinc supplementation to HIV-infected pregnant women offers no benefits on viral load or MTCT. The clinical relevance of an apparent decrease in MUAC associated with zinc supplementation is yet to be ascertained. These findings together with the lack of effect on fetal outcomes (reported previously) do not provide support for the addition of zinc supplements to the standard of prenatal care among HIV-infected women.

Wasting and body composition of adults with pulmonary tuberculosis in relation to HIV-1 coinfection, socioeconomic status, and severity of tuberculosis.

OBJECTIVE: To examine the impact of HIV coinfection, socioeconomic status (SES) and severity of tuberculosis (TB) on the body composition and anthropometric status of adults with pulmonary TB. DESIGN: Cross-sectional study. SETTING: Five TB clinics in Dar es Salaam, Tanzania. SUBJECTS: A total of 2231 adult men and women diagnosed with pulmonary TB, prior to the initiation of anti-TB therapy. METHODS: We compared the distribution of anthropometric characteristics including body mass index (BMI), mid-upper arm circumference (MUAC), triceps skin-fold (TSF), and arm muscle circumference (AMC) by HIV status, SES characteristics, and indicators of TB severity (bacillary density in sputum and Karnofsky performance score). Similar comparisons were carried out with body composition variables from bioelectrical impedance analysis and albumin concentrations, in a subsample of 731 subjects. RESULTS: In multivariate analysis, HIV infection was significantly associated with lower MUAC and AMC in both men and women, but not with BMI or TSF. Compared to HIV-uninfected women, those who were HIV infected had lower body cell mass (BCM) (adjusted difference = -0.85 kg, P = 0.04), intracellular water (-0.68 l, P = 0.04), and phase angle (-0.52, P = 0.02). Albumin concentrations were significantly lower in both men and women infected with HIV. Among HIV-infected men, CD4 cell counts <200/mm(3) were related to lower intracellular water, BCM, fat-free mass and phase angle. Independent of HIV infection, BMI and MUAC were positively related to SES indicators and the Karnofsky performance score; and inversely related to bacillary density. CONCLUSIONS: HIV infection is associated with indicators of low lean body mass in adults with TB; socioeconomic factors and TB severity are important correlates of wasting, independent of HIV. SPONSORSHIP: The National Institute of Allergy and Infectious Diseases (UO1 AI 45441-01).

Estimation of CD4 T-lymphocyte counts from percent CD4 T-lymphocyte determinations in HIV-1-infected subjects in sub-Saharan Africa.

The relationship between CD4 percent and CD4 count has been reported to be different in industrialized countries compared to sub-Saharan Africa, where often only the former is reliable. CD4 determinations from an open cohort of hotel workers in Dar es Salaam followed between 1990 and 1998 were evaluated. T-lymphocyte determinations were offered once a year to 190 HIV-1 seropositive, 80 seroconverters and 495 sex and age matched HIV-seronegative subjects. After log transformation of the CD4 percent and CD4 counts a good fit to a linear regression curve was found, R(2) 0.697. The CD4 percent corresponding to a CD4 count of 200 cells/mm(3) was found to be 9.8%. CD4 percent determination can be useful to estimate CD4 counts, but needs to be locally standardized. The CD4 percent in Africa corresponding to AIDS defining CD4 counts seems to be lower than in the industrialized world.

Lymphocyte subset enumeration in HIV seronegative and HIV-1 seropositive adults in Dar es Salaam, Tanzania: determination of reference values in males and females and comparison of two flow cytometric methods.

The level of CD4(+) T-lymphocytes represents a useful marker with which to monitor the progression of HIV infection. Sex and geographical differences in the reference values of lymphocyte subsets have been reported. We have compared two flow cytometric methods (MultiSET and SimulSET) for the quantification of lymphocyte subsets using whole blood from 92 HIV seropositive and 241 seronegative adults, and determined the reference values of lymphocyte subsets in HIV seronegative Tanzanian subjects. In seronegative Tanzanian subjects, the percentages of CD3(+) and CD4(+) T-lymphocytes and the CD4(+):CD8(+) T-lymphocyte ratios were lower while the percentage of natural killer cells was higher compared to the levels of the corresponding parameters reported for Europeans. Seronegative Tanzanian females had significantly higher levels of CD3(+) and CD4(+) T-lymphocytes and CD4(+):CD8(+) T-lymphocyte ratios compared to seronegative males. The correlation coefficients of CD3(+), CD4(+) and CD8(+) T lymphocyte counts and percentages obtained by the two flow cytometric methods were high. The median values of the number of CD4(+) T-lymphocytes obtained by the two methods were not significantly different. In conclusion, determination of the reference values of lymphocyte subsets in HIV seronegative Tanzanian adults showed significant sex differences and differences in percentage values compared to those reported in certain other geographical areas. There was acceptable agreement in the levels of CD4(+) T-lymphocyte values obtained by the two flow cytometric methods.

Risk factors for syphilis among HIV-1 infected pregnant women in Dar es Salaam, Tanzania.

This study was conducted to determine the risk factors for recent (active) syphilis among HIV-1 seropositive pregnant women (N = 1058) in Dar es Salaam, Tanzania, Recruitment of study participants (N = 1058) was done between April 1995 and June 1997 at four main prenatal clinics in Dar es Salaam city. Study subjects were interviewed to obtain information about potential risk factors, and blood and genital specimens were collected for detection of syphilis and other genital infections. The prevalence of active syphilis was 5.9%. After adjusting for other risk factors, women without their own source of income had a 50% lower risk of syphilis (OR = 0.5, 95% CI: 0.3-0.9). The risk of active syphilis was significantly increased among women with genital ulceration on examination (OR = 8.4, 95% CI: 1.5-47.7), and in those with trichomoniasis (OR = 2.2, 95% CI: 1.2-3.8). HIV-related immunodeficiency was not associated with increased risk of syphilis. These results show that syphilis and other genital infections are a major problem among HIV infected women. Prevention of syphilis and other genital infections is urgently needed in this population.

Monitoring of HIV-1 infection prevalence and trends in the general population using pregnant women as a sentinel population: 9 years experience from the Kagera region of Tanzania.

In the Kagera region of Tanzania, a population-based study was initiated in 1987 followed by the establishment of antenatal-clinic-based sentinel surveillance system in the town of Bukoba in 1990. Repeat studies in both populations in Bukoba in 1993 and 1996 made it possible to study the dynamics of HIV infection prevalence and incidence in the area. This study aims at comparing the findings from this sentinel surveillance system with those of cross-sectional studies in the general population to assess its validity in estimating HIV prevalence and their trends in the general population. A multistage cluster sampling technique was used in the population-based studies whereas the antenatal-clinic-based population was obtained by consecutively recruiting antenatal care attenders coming for the first time during a given pregnancy. Antibodies against HIV infection were tested using two independent enzyme-linked immunosorbent assay (ELISA) antibody detection tests. Unlinked anonymous testing strategy was adopted for the sentinel population. Age-adjusted prevalence among antenatal care attenders decreased from 22.4% (95% confidence interval [CI], 20.6-25.2) in 1990 to 16.1% (95% CI, 15.9-18.8) in 1993 and further to 13.7% (95% CI, 11.8-14.3) in 1996. These results closely resemble those of the general population of adult women in the clinic's catchment area (the town of Bukoba) where the age-adjusted prevalence of 29.1% (95% CI, 24.4-34.6) in 1987 showed a decrease in the studies in 1993 18.7% (95% CI, 15.1-23.0) and in 1996 14.9% (95% CI, 12.0-17.1). The study indicates that general population trend estimates can be generated using sentinel surveillance data based on pregnant women visiting an antenatal clinic for the first time during a given pregnancy. The benefits of using this group outweigh its limitations that are brought about by possible selection bias. Continued surveillance of the epidemic based on antenatal care patients as a sentinel population is therefore recommended.

Antimicrobial susceptibility pattern of Vibrio cholerae O1 strains during two cholera outbreaks in Dar es Salaam, Tanzania.

OBJECTIVE: To determine and compare the antimicrobial susceptibility patterns of Vibrio cholerae 01 strains, which were isolated in two cholera epidemics in 1997 and 1999 in Dar es Salaam. METHODS: V. cholerae 01 strains isolated from patients with cholera in Dar es Salaam city during 1997 (94 isolates) and 1999 (87 isolates) were stored on nutrient agar slants at room temperature and antimicrobial susceptibility pattern was determined, using Kirby Bauer method. SETTING: Department of Microbiology and Immunology, Muhimbili Medical Centre, Dar es Salaam, Tanzania. RESULTS: A total of 181 V. cholerae 01 strains were studied during two epidemic periods when tetracycline or erythromycin was used for treatment of patients with severe disease. Among the 94 V. cholerae 01 strains isolated in 1997; 98.6%, 93.6%, 83%, 81.9%, 36.2%, 35.5%, 3.2% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, nalidixic acid, chloramphenicol and trimethoprim/sulphamethoxazole, respectively. Among the 87 V. cholerae 01 isolates collected in 1999, 100%, 58.6%, 46.0%, 46%, 47.1%, 19.5%, 3.4% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, chloramphenicol, nalidixic acid and trimethoprim/sulphamethoxazole, respectively. Between 1997 and 1999, there was a significant increase in the proportion of V. cholerae 01 isolates resistant to tetracycline, ampicillin, nalidixic acid and to erythromycin but there was no change for susceptibility to ciprofloxacin and trimethoprim/sulphamethoxazole. CONCLUSION: Significant proportion of V. cholerae 01 strains in Dar es Salaam were resistant to commonly used antimicrobial agents during the two years of the study. Therefore, there is a great need to control the utilisation of antimicrobial agents in cholera control, in addition to continuing carrying out surveillance of antimicrobial resistance as a guide to choice of antimicrobial treatment. Rotational use of the available drugs with regular monitoring of susceptibility may contribute to continuing usefulness of such drugs.

The accuracy of an alternative confirmatory strategy for detection of antibodies to HIV-1: experience from a regional laboratory in Kagera, Tanzania.

BACKGROUND: Constant improvement of HIV tests often results in withdrawal of poorer quality tests by the manufacturing companies. It is thus often necessary to evaluate new HIV testing kits and modify the existing testing strategies. OBJECTIVES: To evaluate an alternative HIV antibody testing strategy which involves consecutive testing of sera by two enzyme-linked immunosorbent assays (ELISA), which both are recombinant antigen-based but utilise different test principles, followed by re-testing of sera giving discordant results. STUDY DESIGN: Sera (n = 1558) from a cross-sectional study of the HIV-1 seroprevalence in the Kagera region of Tanzania were tested using two ELISAs in parallel: Enzygnost anti-HIV-1/2 plus and Wellcozyme HIV-1 recombinant. Western blot analysis was done on all concordantly reactive and repeatedly discordant reactive samples as well as on 10% of concordantly ELISA negative sera. RESULTS: Two hundred and four sera (13.1%) were confirmed HIV-1-antibody positive. Both ELISAs had a sensitivity of 100%. The specificities of the ELISAs at initial and repeated testing were 99.8 and 99.9%, respectively, for Enzygnost and 97.7 and 99.5%, respectively, for Wellcozyme. None of the sera was concordantly false positive in both ELISAs. The mean ratio of the optical density of a sample to the cut off value of the test run (OD/CO ratio) was lower for samples giving false positive reactions than for confirmed HIV-1-antibody-positive samples. It is therefore important to interpret with caution HIV antibody ELISA test results on samples giving low OD/CO ratios. None of 10% of randomly selected concordantly ELISA negative sera gave a positive Western blot reaction. CONCLUSIONS: This field evaluation of an HIV antibody testing strategy involving the use of a recombinant antigen-based sandwich ELISA (Enzygnost) followed by a recombinant antigen-based competitive ELISA (Wellcozyme) showed that it had a sensitivity and specificity of 100%.

Antimicrobial susceptibillty of Staphylococcus aureus strains at Muhimbili Medical Centre, Tanzania.

OBJECTIVE: To determine the antimicrobial susceptibility pattern of S. aureus isolates including the presence of methicillin resistant S. aureus strains. DESIGN: Cross-sectional study. SETTING: Department of Microbiology and Immunology, Muhimbili Medical Centre, Dar es Salaam, Tanzania between October 1997 and March 1998. PATIENTS: Two hundred and sixty patients consisting of 67 neonates, 114 children aged 18 years and below and 79 adults. MAIN OUTCOME MEASURES: Antimicrobial susceptibility to tetracycline, erythromycin, cefuroxime, methicillin and penicillin G and presence of mec A gene. RESULTS: Among the S. aureus strains, 97.3%, 68.1%, 37.3% and 6.5% were sensitive to cefuroxime, erythromycin, tetracycline and penicillin G respectively. Only one (0.4%) S. aureus isolate was resistant to methicillin using both the E test and presence of mec A gene. There was no significant difference between the sensitive S. aureus isolates from the neonates, children and adults. CONCLUSION: S. aureus strains are becoming more resistant to commonly used antimicrobial agents, the prevalence of methicillin resistant S. aureus strains in our study population is low compared with reported studies.

Immunological profile of endemic and epidemic Kaposi's sarcoma patients in Dar-es-Salaam, Tanzania.

Kaposi's sarcoma (KS) presents in four clinicopathological types namely classical/sporadic (CKS), endemic African (EKS), iatrogenic (IKS) and that associated with AIDS (AKS). Recently a putative herpes virus (HHV-8) was described and shown to be present in all four types of KS. The immunological status of patients with EKS has been conflicting. In this study total leucocyte counts, total lymphocyte counts and lymphocyte subsets of patients with EKS and AKS were determined by flow cytometry and compared to those of healthy HIV-1 seronegative controls. Results show that 50% of EKS lesions were of nodular type. Patients with EKS had significantly lower levels of CD4+ T- lymphocytes and CD4:CD8 ratio but significantly higher CD8+ T-lymphocytes compared to controls. Patients with AKS had significantly lower levels of CD4+ T-lymphocytes and also CD4:CD8 ratios but significantly higher percentage of CD8+ T-lymphocytes when compared with EKS patients. These findings indicate that in both forms of KS there is a certain degree of immunological disturbance which is more conspicuous in AKS because of HIV infection and suggests that HIV-1 acts synergistically with the aetiological agent (HHV-8) to cause a more aggressive type of KS.

Decline in the prevalence of HIV-1 infection in young women in the Kagera region of Tanzania.

In northwestern Tanzania, a population-based survey of HIV-1 infection in the Kagera region in 1987 demonstrated a high prevalence (24.2%) in adults of Bukoba town, whereas it was lower (10.0%) in the surrounding rural district of Bukoba. In 1993 and 1996, population-based cross-sectional studies were carried out in urban and rural Bukoba districts, respectively, to monitor the time trend in the prevalence of HIV-1 infection in the region. In both studies, a multistage cluster sampling technique was adopted in selecting study individuals. Consenting individuals between 15 and 54 years of age were interviewed using a structured questionnaire. Following individual counseling, blood samples were drawn and tested for HIV infection using enzyme-linked immunosorbent assay (ELISA) antibody detection tests. The overall age-adjusted HIV-1 seroprevalence in urban Bukoba decreased from 24.2% (134 of 553) in 1987 to 18.3% (118 of 653) in 1993 (p = .008). The age-adjusted gender-specific prevalence declined significantly in women, from 29.1% (95 of 325) to 18.7% (74 of 395; p = .0009). Except for men > or = 35 years of age, whose prevalence appeared to have an upward trend between the two studies, all other age groups in both genders had a downward trend; this finding was most significant in women between 15 and 24 years of age (from 27.6% to 11.2%; p = .0004). For the rural population, the overall prevalence decreased from 10.0% (54 of 538) in 1987 to 6.8% (118 of 1728) in 1996 (p = .01). Except for rural women between 15 and 24 years of age whose prevalence decreased from 9.7% (12 of 124) to 3.1% (12 of 383; p = .002), other age groups in the rural populations showed no change in prevalence. Ongoing interventions in this area leading to behavioral change may have contributed to this observation. An incidence study is under way to confirm this observation and to investigate the factors that are responsible for the decline in the HIV-1 prevalence.

PIP: A population-based survey of HIV-1 infection conducted in northwestern Tanzania's Kagera region in 1987 identified a 24.2% HIV prevalence among adults in Bukoba town and a prevalence of 10.0% in the surrounding rural district. In response to these findings, various interventions and community support activities (e.g., IEC, condom distribution, spiritual counseling, home-based care for AIDS patients, and the supply of safe blood for transfusion) were initiated. Additional population-based cross-sectional studies were conducted in the region in 1993 (urban population) and 1996 (rural population) to assess HIV prevalence trends over time. The overall age-adjusted HIV-1 seroprevalence among adults in urban Bukoba decreased from 24.2% in 1987 to 18.3% in 1993; most significant was the decline among women, from 29.1% in 1987 to 18.7% in 1993. With the exception of men 35 years of age and above, whose prevalence showed an upward trend between studies, all other age groups and both genders had a downward trend; this trend was most significant among women 15-24 years of age (from 27.6% to 11.2%). For the rural population, overall HIV-1 seroprevalence declined from 10.0% in 1987 to 6.8% in 1996. With the exception of rural women 15-24 years of age, whose prevalence decreased from 9.7% to 3.1%, other age groups showed no significant change in prevalence. An incidence study is underway to confirm these trends and identify the specific interventions responsible for the decline in HIV-1 prevalence.