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.

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.

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.

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.

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.

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).

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.

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.

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.

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%.

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.

Late postnatal transmission of human immunodeficiency virus type 1 infection from mothers to infants in Dar es Salaam, Tanzania

OBJECTIVE

To study late postnatal transmission of human immunodeficiency virus type 1 in a cohort of children born to HIV-1-seropositive mothers who delivered at Muhimbili Medical Centre in Dar es Salaam, Tanzania.

MATERIALS AND METHODS

Since 1991 a prospective cohort study of mother-to-child transmission of HIV-1 has been conducted at Muhimbili Medical Centre in Dar es Salaam. HIV-1-seropositive mothers and age-matched seronegative controls were recruited into the cohort at delivery together with their newborns. Diagnosis of HIV-1 infection in children was based on polymerase chain reaction, HIV-1 p24 antigen tests and HIV antibody tests. Late postnatal transmission was defined as HIV-1 infection occurring after 6 months of age in a child who was uninfected at 6 months of age and who had an HIV-1-seropositive mother. Children born to HIV-seronegative mothers were used as controls. Breast-feeding was universal in this cohort. CD4 and CD8 T lymphocytes were assayed by flow cytometry in the mothers.

RESULTS

Among 139 children born to HIV-1-seropositive mothers and known to be HIV-uninfected at 6 months of age, 8 children became HIV-1-infected at the end of their first year of life or later. No conversions were observed in children younger than 11 months. The 8 conversions were observed during a follow-up covering 1555 child months between 6 and 27 months of age corresponding to a conversion rate of 6.2 per 100 child years. Among 260 children with HIV-seronegative mothers no child became HIV-infected during the follow-up. The percentage of CD4 T lymphocytes was similar in mothers with early and late transmission but was significantly lower in transmitting than in nontransmitting mothers.

CONCLUSION

Because no HIV-1 infection occurred in children with HIV-seronegative mothers, we conclude that the observed infections at the end of the first year of life or later among children born to HIV-seropositive women were caused by late transmission from mother to child, most likely through breast-feeding.

Evaluation of T cell subsets by an immunocytochemical method compared to flow cytometry in four countries

The authors tested an alternative method for CD4 and CD8 T lymphocytes enumeration, the immunoalkaline phosphatase method (IA), in three African countries and in Denmark. The IA determinations from 136 HIV antibody positive and 105 HIV antibody negative individuals were compared to the corresponding results obtained by flow cytometry (FC) performed in the respective countries. The authors found good correspondence between the two methods for measurements of CD4 and CD8 T lymphocytes independent of serological status and geographical site. However, the CD4 and CD8 T lymphocytes values obtained by the two methods are not interchangeable as IA compared to FC consistently gives higher percentage of CD4 T lymphocytes, and lower percentage of CD8 T lymphocytes. Mean differences between the two methods did not differ between the three African countries indicating that the IA method provides systematic results. Replicate measurements suggested good correspondence between results obtained by IA. By using an IA level of < 300 CD4 T lymphocytes/microliter, the sensitivity was 81% and specificity 96% for detecting an FC level of < 200 CD4 T lymphocytes/microliter. Using an IA level of < 20% CD4 T lymphocytes, the sensitivity was 89% and specificity 95% for detecting an FC level of < 14% CD4 T lymphocytes. The FC and IA methods had the same internal correspondence between low absolute CD4 T cell count and low CD4 percentages; the sensitivity and specificity for detecting a low absolute CD4 T cell counts with a low CD4 percentage was 92% and 68% for FC and 91% and 73% for IA, respectively. The IA method is 10-fold cheaper than FC, is independent of advanced laboratory facilities, and does not need immediate processing of samples as blood smears can be stored for long periods. The IA method is therefore suitable for use in areas with limited resources and laboratory facilities where there is a need for immunological surveillance in hospital or community studies.

Recent trends on bacterial resistance to antibiotics

Antimicrobial resistance has become a major medical and public health problem. The main factor responsible for development and spread of bacterial resistance is injudicious use of antimicrobial agents which has resulted in most gram positive and gram negative bacteria continuously developing resistance to the antimicrobials in regular use at different time periods. In East Africa, among E. coli in urinary tract infections, more than 80% are currently resistant to ampicillin, cotrimoxazole and tetracycline while more than 80% of the isolates are still susceptible to nitrofurantoin, gentamicin and third generation cephalosporins. Penicillin G resistant strains of pneumococci were first reported in 1967 but had gradually increased to about 20% in 1991. Among group A streptococci, all natural strains are still sensitive to penicillin G while resistance to tetracycline has reached alarming proportions. In Tanzania, more than 65% of N. gonorrhoeae isolates are beta-lactamase producers, however, spectinomycin, second and third generation cephalosporins and ciprofloxacin are effective against most strains. Vibrio cholerae 01 strains resistant to multiple antibiotics are widely spread globally, however, there are recent reports indicating that withdrawal of the drugs can lead to loss of the antibiotic resistance factors. Despite varied susceptibility of N. meningitidis strains world wide, isolates in Tanzania are still susceptible to commonly available drugs including penicillin G and chloramphenicol. Available methods for control of spread of bacterial resistance include rational use of antimicrobial agents including control in animal husbandry, change to newer antimicrobials, rotational use of drugs and constant surveillance for emerging bacterial resistance.

Predictive markers for mother-to-child transmission of HIV-1 in Dar es Salaam, Tanzania

The aim of this study was to determine immunological factors associated with increased risk of mother-to-child transmission of HIV-1 that could be used as predictive markers in Tanzanian women. One hundred and thirty-eight HIV-1-seropositive and 117-seronegative mothers and their newborns were recruited at delivery and followed up at Muhimbili Medical Centre in Dar es Salaam, Tanzania. Blood specimens from the mothers were analyzed for HIV-1 p24 antigen, beta 2-microglobulin (B2M), T-lymphocyte subsets, and presence of viral DNA in blood mononuclear cells by the polymerase chain reaction (PCR). Among 138 seropositive mothers, 30 (21.7%) had transmitted HIV-1 to their children, as shown by a positive PCR in the child. The vertical transmission rate was significantly higher in women with a percentage of CD4 lymphocytes < or = 20 (eight of 24, 33%) or a level of B2M > or = 2 mg/L (21 of 62, 34%) than in women with a higher percentage of CD4 lymphocytes (10 of 73, 14%) or a lower level of B2M (eight of 57, 14%) (p = 0.034 and 0.018, respectively). In eight of 18 (44%) transmitting mothers the percentage of CD4 lymphocytes was < or = 20, and in 21 of 29 (72%) transmitting mothers the B2M level was > or = 2 mg/L. In women with both a low percentage of CD4 lymphocytes (< or = 20) and a high level of B2M (> or = 2 mg/L), the vertical transmission rate was 54%.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the WHO human immunodeficiency virus (HIV) antibody testing strategy for the diagnosis of HIV infection

OBJECTIVE

To evaluate a WHO testing strategy based on the use of two consecutive enzyme-linked immunosorbent assays (ELISA) as an alternative to ELISA followed by Western blotting (WB) for the serologic diagnosis of HIV infection.

STUDY DESIGN

The study was of 2069 consecutive serum specimens from patients suspected of HIV infection received for HIV diagnostic testing at the HIV laboratory, Muhimbili Medical Centre, Dar es Salaam. The strategy involved testing all sera with Behring indirect anti-HIV 1 + 2 peptide ELISA, followed by Wellcozyme anti-HIV-1 recombinant competitive ELISA on those sera reactive by the first ELISA. WB was done on a sample of the sera reactive on both ELISAs and on all those giving discordant results on the two ELISAs. Of the 2069 sera tested, 837 (40.5%) were negative on the first ELISA, 1172 (56.6%) were reactive on both ELISAs and 60 (2.9%) were initially reactive on the first test but not on the second assay.

RESULTS

Of the 1172 sera reactive on both ELISAs, 329 (28.1%) were tested by WB. The diagnostic accuracy of the WHO alternative testing strategy using WB confirmation as the 'gold' standard was as follows: sensitivity 99.4% (326/328), specificity 99.7%, (893/896), positive predictive value 99.1% (328/331) and negative predictive value 99.8% (893/895). Repeated testing by ELISA of the sera which initially gave discordant results on the two ELISAs increased the sensitivity to 100%. Three sera giving false positive reactions on both ELISAs became negative on both ELISAs after retesting. In order to achieve a specificity and a positive predictive value of 100%, it would have been necessary to subject all sera reacting on both ELISAs to retesting on one ELISA.

CONCLUSIONS

A second ELISA based on different antigens and a different test principle compared with the first ELISA could be used as an alternative to the WB assay for confirmation of HIV antibodies. However, some modifications of the WHO strategy for diagnostic HIV antibody testing were required in order to maximize the diagnostic accuracy.