Tobias Chirwa

Determinants of survival in very low birth weight neonates in a public sector hospital in Johannesburg

BackgroundAudit of disease and mortality patterns provides essential information for health budgeting and planning, as well as a benchmark for comparison. Neonatal mortality accounts for about 1/3 of deaths < 5 years of age and very low birth weight (VLBW) mortality for approximately 1/3 of neonatal mortality. Intervention programs must be based on reliable statistics applicable to the local setting; First World data cannot be used in a Third World setting. Many neonatal units participate in the Vermont Oxford Network (VON); limited resources prevent a significant number of large neonatal units from developing countries taking part, hence data from such units is lacking. The purpose of this study was to provide reliable, recent statistics relevant to a developing African country, useful for guiding neonatal interventions in that setting.MethodsThis was a retrospective chart review of 474 VLBW infants admitted within 24 hours of birth, between 1 July 2006 and 30 June 2007, to the neonatal unit of Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in Johannesburg, South Africa. Binary outcome logistic regression on individual variables and multiple logistic regression was done to identify those factors determining survival.ResultsOverall survival was 70.5%. Survival of infants below 1001 grams birth weight was 34.9% compared to 85.8% for those between 1001 and 1500 grams at birth. The main determinant of survival was birth weight with an adjusted survival odds ratio of 23.44 (95% CI: 11.22 - 49.00) for babies weighing between 1001 and 1500 grams compared to those weighing below 1001 grams. Other predictors of survival were gender (OR 3. 21; 95% CI 1.6 - 6.3), birth before arrival at the hospital (BBA) (OR 0.23; 95% CI: 0.08 - 0.69), necrotising enterocolitis (NEC) (OR 0.06; 95% CI: 0.02 - 0.20), hypotension (OR 0.05; 95% CI 0.01 - 0.21) and nasal continuous positive airways pressure (NCPAP) (OR 4.58; 95% CI 1.58 - 13.31).ConclusionsSurvival rates compare favourably with other developing countries, but can be improved; especially in infants < 1001 grams birth weight. Resources need to be allocated to preventing the birth of VLBW babies outside hospital, early neonatal resuscitation, provision of NCPAP and prevention of NEC.

Risk factors for HIV incidence in women participating in an HSV suppressive treatment trial in Tanzania

Objectives:A randomized, double-blind, placebo-controlled trial (RCT) of herpes simplex virus type 2 suppressive therapy with acyclovir 400 mg twice daily conducted among women in northwestern Tanzania reported a similar rate of HIV acquisition in both trial arms (Current Controlled Trials number ISRCTN35385041). Risk factors for HIV incidence were examined in the context of 3-monthly follow-up visits offering both voluntary counselling and testing and care for sexually transmitted infections. Design:Prospective cohort analysis of trial participants enrolled and followed for up to 30 months. Methods:Risk factors for HIV acquisition were analysed using Cox regression. Results:Overall, 821 herpes simplex virus type 2 seropositive, HIV seronegative women were randomized; 400 randomized to acyclovir and 421 to placebo; 659 (80.3%) completed follow-up. HIV incidence was 4.27 per 100 person-years. There was no overall impact of acyclovir on HIV incidence [hazard ratio = 1.01; 95% confidence interval (CI) 0.61–1.66]. HIV acquisition was independently associated with younger age at enrolment (age 16–19 vs. 30–35: hazard ratio = 4.02; 95% CI 1.67–9.68), alcohol consumption at enrolment (≥30 drinks/week vs. none: hazard ratio = 4.39, 95% CI 1.70–11.33), having paid sex within the previous 3 months (hazard ratio = 1.82, 95% CI 1.09–3.05), recent infection with gonorrhoea (hazard ratio = 3.62, 95% CI 1.62–8.08) and injections in the previous 3 months (hazard ratio = 3.45, 95% CI 1.62–7.34). There was some evidence of an association between HIV incidence and living in the recruitment community for less than 2 years (hazard ratio = 1.75, 95% CI 0.98–3.10) and exposure to hormonal contraception (hazard ratio = 1.60, 95% CI 0.93–2.76). Conclusion:A high incidence of HIV was observed in this trial cohort, especially in young women. Interventions are needed to address the risk associated with alcohol use and to sustain control of other sexually transmitted infections.

Association of Schistosomiasis with False-Positive HIV Test Results in an African Adolescent Population

ABSTRACT This study was designed to investigate the factors associated with the high rate of false-positive test results observed with the 4th-generation Murex HIV Ag/Ab Combination EIA (enzyme immunoassay) within an adolescent and young-adult cohort in northwest Tanzania. (4th-generation assays by definition detect both HIV antigen and antibody.) The clinical and sociodemographic factors associated with false-positive HIV results were analyzed for 6,940 Tanzanian adolescents and young adults. A subsample of 284 Murex assay-negative and 240 false-positive serum samples were analyzed for immunological factors, including IgG antibodies to malaria and schistosoma parasites, heterophile antibodies, and rheumatoid factor (RF) titers. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). False-positive HIV test results were associated with evidence of other infections. False positivity was strongly associated with increasing levels of Schistosoma haematobium worm IgG1, with adolescents with optical densities in the top quartile being at the highest risk (adjusted OR = 40.7, 95% CI = 8.5 to 194.2 compared with the risk for those in the bottom quartile). False positivity was also significantly associated with increasing S. mansoni egg IgG1 titers and RF titers of ≥80 (adjusted OR = 8.2, 95% CI = 2.8 to 24.3). There was a significant negative association between Murex assay false positivity and the levels of S. mansoni worm IgG1 and IgG2 and Plasmodium falciparum IgG1 and IgG4. In Africa, endemic infections may affect the specificities of immunoassays for HIV infection. Caution should be used when the results of 4th-generation HIV test results are interpreted for African adolescent populations.

Bacterial vaginosis in female facility workers in north-western Tanzania: prevalence and risk factors

Objectives: To determine prevalence of, and risk factors for, bacterial vaginosis (BV) among herpes simplex virus (HSV) 2 seropositive Tanzanian women at enrolment into a randomised, placebo-controlled trial of HSV suppressive treatment. Methods: 1305 HSV-2 seropositive women aged 16–35 years working in bars, guesthouses and similar facilities were interviewed, examined and tested for HIV, syphilis, Neisseria gonorrhoeae, Chlamydia trachomatis, BV, candidiasis and trichomoniasis. Factors associated with BV were analysed using logistic regression to estimate odds ratios and 95% confidence intervals. Results: BV prevalence was 62.9%; prevalence of Nugent score 9–10 was 16.1%. Independent risk factors for BV were work facility type, fewer dependents, increasing alcohol consumption, sex in the last week (adjusted OR 2.03; 95% CI 1.57 to 2.62), using cloths or cotton wool for menstrual hygiene, HIV (adjusted OR 1.41; 95% CI 1.09 to 1.83) and Trichomonas vaginalis infection. There was no association between BV and the frequency or method of vaginal cleansing. However, BV was less prevalent among women who reported inserting substances to dry the vagina for sex (adjusted OR 0.44; 95% CI 0.25 to 0.75). Conclusion: BV was extremely prevalent among our study population of HSV-2 positive female facility workers in North-western Tanzania. Although recent sex was associated with increased BV prevalence, vaginal drying was associated with lower BV prevalence. Further studies of the effects of specific practices on vaginal flora are warranted.

Evaluating the potential of the sterile insect technique for malaria control: relative fitness and mating compatibility between laboratory colonized and a wild population of Anopheles arabiensis from the Kruger National Park, South Africa

BackgroundThe successful suppression of a target insect population using the sterile insect technique (SIT) partly depends on the premise that the laboratory insects used for mass rearing are genetically compatible with the target population, that the mating competitiveness of laboratory reared males is at least comparable to that of their wild counterparts, and that mass rearing and sterilization processes do not in themselves compromise male fitness to a degree that precludes them from successfully competing for mates in the wild. This study investigated the fitness and sexual cross-compatibility between samples of field collected and laboratory reared An. arabiensis under laboratory conditions.ResultsThe physiological and reproductive fitness of the MALPAN laboratory strain is not substantially modified with respect to the field population at Malahlapanga. Further, a high degree of mating compatibility between MALPAN and the Malahlapanga population was established based on cross-mating experiments. Lastly, the morphological characteristics of hybrid ovarian polytene chromosomes further support the contention that the MALPAN laboratory colony and the An. arabiensis population at Malahlapanga are genetically homogenous and therefore compatible.ConclusionsIt is concluded that the presence of a perennial and isolated population of An. arabiensis at Malahlapanga presents a unique opportunity for assessing the feasibility of SIT as a malaria vector control option. The MALPAN laboratory colony has retained sufficient enough measures of reproductive and physiological fitness to present as a suitable candidate for male sterilization, mass rearing and subsequent mass release of sterile males at Malahlapanga in order to further assess the feasibility of SIT in a field setting.

Microbicides Development Program, Tanzania-Baseline Characteristics of an Occupational Cohort and Reattendance at 3 Months

Objectives: To determine baseline characteristics of an occupational cohort of women in Mwanza City, Tanzania, and factors associated with reattendance at 3 months, in preparation for a microbicide trial. Study Design: One thousand five hundred seventy-three women aged 16–54 years working in food outlets and recreational facilities were enrolled, interviewed, and examined at community-based reproductive health clinics, provided specimens for HIV/STI and pregnancy testing, and attended 3 monthly clinical follow-up. Results: Baseline prevalence of HIV was 25.5%; pregnancy 9.7%; herpes simplex virus type-2 74.6%; active syphilis 10.2%, bacterial vaginosis 52.6%; gonorrhea 5.5%; chlamydia 5.9%; and trichomoniasis 12.3%. Reattendance at 3 months was 74.1% and was higher in older women, less mobile women, and in those who received an HIV-negative result at enrollment. Conclusions: Baseline characteristics of this occupational group suggest their suitability for microbicide trials. A screening round, locally appropriate informed consent procedures, and effective community tracing may help reduce losses to follow-up in such settings.

Bayesian analysis of zero inflated spatiotemporal HIV/TB child mortality data through the INLA and SPDE approaches: Applied to data observed between 1992 and 2010 in rural North East South Africa.

Highlights ► South Africas HIV/TB burden in children and modelling which results in mortality risk maps. ► Analyses of hierarchical spatiotemporal data with zero inflated outcomes. ► Resolving the “Big N” on Gaussian fields (GF) by converting to Gaussian Markov Random Fields (GMRF). ► Use of fast and accurate approximate Bayesian algorithms, i.e. INLA and SPDE in lieu of MCMC. ► Medical or natural assumptions driven modelling that informs further research and policy.

Adult deaths and the future: a cause-specific analysis of adult deaths from a longitudinal study in rural Tanzania 2003–2007

Objectives  To determine patterns and risk factors for cause‐specific adult mortality in rural southern Tanzania.

Nosocomial Outbreak of New Delhi Metallo-β-Lactamase-1-Producing Gram-Negative Bacteria in South Africa: A Case-Control Study.

Objective New Delhi metallo-β-lactamase (NDM)-producing Gram-negative bacteria have spread globally and pose a significant public health threat. There is a need to better define risk factors and outcomes of NDM-1 clinical infection. We assessed risk factors for nosocomial infection with NDM-1-producers and associated in-hospital mortality. Methods A matched case-control study was conducted during a nosocomial outbreak of NDM-1-producers in an adult intensive care unit (ICU) in South Africa. All patients from whom NDM-1-producers were identified were considered (n=105). Cases included patients admitted during the study period in whom NDM-1 producing Gram-negative bacteria were isolated from clinical specimens collected ≥48 hours after admission, and where surveillance definitions for healthcare-associated infections were met. Controls were matched for age, sex, date of hospital admission and intensive-care admission. Conditional logistic regression was used to identify risk factors for NDM-1 clinical infection and associated in-hospital mortality. Findings 38 cases and 68 controls were included. Klebsiella pneumoniae was the most common NDM-1-producer (28/38, 74%). Cases had longer mean hospital stays (44.0 vs. 13.3 days; P < 0.001) and ICU stays (32.5 vs. 8.3 days; P < 0.001). Adjusting for co-morbid disease, the in-hospital mortality of cases was significantly higher than controls (55.3% vs. 14.7%; AOR, 11.29; P < 0.001). Higher Charlson co-morbidity index score (5.2 vs. 4.1; AOR, 1.59; P = 0.005), mechanical ventilation days (7.47 vs. 0.94 days; AOR, 1.32; P = 0.003) and piperacillin/tazobactam exposure (11.03 vs. 1.05 doses; AOR, 1.08; P = 0.013) were identified as risk factors on multivariate analysis. Cases had a significantly higher likelihood of in-hospital mortality when the NDM-1-producer was Klebsiella pneumoniae (AOR, 16.57; P = 0.007), or when they had a bloodstream infection (AOR, 8.84; P = 0.041). Conclusion NDM-1 infection is associated with significant in-hospital mortality. Risk factors for hospital-associated infection include the presence of co-morbid disease, mechanical ventilation and piperacillin/tazobactam exposure.

Are Women Who Work in Bars, Guesthouses and Similar Facilities a Suitable Study Population for Vaginal Microbicide Trials in Africa?

Background A feasibility study was conducted to investigate whether an occupational at-risk cohort of women in Mwanza, Tanzania are a suitable study population for future phase III vaginal microbicide trials. Methodology/Principal Findings 1573 women aged 16–54 y working in traditional and modern bars, restaurants, hotels, guesthouses or as local food-handlers were enrolled at community-based reproductive health clinics, provided specimens for HIV/STI and pregnancy testing, and asked to attend three-monthly clinical follow-up visits for 12-months. HIV positive and negative women were eligible to enter the feasibility study and to receive free reproductive health services at any time. HIV prevalence at baseline was 26.5% (417/1573). HIV incidence among 1156 sero-negative women attending at baseline was 2.9/100PYs. Among 1020 HIV sero-negative, non-pregnant women, HIV incidence was 2.0/100PYs, HSV-2 incidence 12.7/100PYs and pregnancy rate 17.8/100PYs. Retention at three-months was 76.3% (778/1020). Among 771 HIV sero-negative, non-pregnant women attending at three-months, subsequent follow-up at 6, 9 and 12-months was 83.7%, 79.6%, and 72.1% respectively. Older women, those who had not moved home or changed their place of work in the last year, and women working in traditional bars or as local food handlers had the highest re-attendance. Conclusions/Significance Women working in food outlets and recreational facilities in Tanzania and other parts of Africa may be a suitable study population for microbicide and other HIV prevention trials. Effective locally-appropriate strategies to address high pregnancy rates and early losses to follow-up are essential to minimise risk to clinical trials in these settings.