Hypertension and traditional risk factors for cardiovascular diseases among treatment naïve HIV- infected adults initiating antiretroviral therapy in Urban Tanzania

BACKGROUND

Cardiovascular diseases (CVDs) have become an important cause of ill health and death among people living with HIV and/or AIDS (PLHIV) in the antiretroviral therapy (ART) era. There is scarce data on the burden of hypertension (HTN) and risk factors for CVDs among PLHIV in developing countries, including Tanzania during the ART era.

OBJECTIVE(S)

To determine the prevalence of HTN and risk factors for CVDs among ART naïve PLHIV initiating ART.

METHODS

We analysed baseline data of 430 clinical trial participants on the effect of low-dose aspirin on HIV disease progression among HIV-infected individuals initiating ART. HTN was the outcome CVD. Traditional risk factors for CVDs studied were age, alcohol consumption, cigarette smoking, individual and family history of CVDs, diabetes mellitus (DM), obesity/overweight, and dyslipidaemia. A generalized linear model (robust Poisson regression) was used to determine the predictors for HTN.

RESULTS

The median (IQR) age was 37 (28, 45) years. Females were the majority contributing 64.9% of all participants. The prevalence of HTN was 24.8%. The most prevalent risk factors for CVDs were dyslipidaemia (88.3%), alcohol consumption (49.3%), and overweight or obesity (29.1%). Being overweight or obese predicted the occurrence of HTN, aPR 1.60 (95% CI 1.16-2.21) while WHO HIV clinical stage 3 was protective against HTN, aPR 0.42(95% CI 0.18-0.97).

CONCLUSION

The prevalence of HTN and traditional risk factors for CVDs in the treatment naïve PLHIV initiating ART are significant. Identifying these risk factors and managing them at the time of ART initiation may lower future CVDs among PLHIV.

Colonization of Extended-spectrum β-lactamase producing Enterobacterales and meticillin-resistant S. aureus in the intensive care unit at a tertiary hospital in Tanzania: Implications for Infection control and prevention

Background

Multi-drug resistant (MDR) bacteria pose a major global threat to public-health and are of particular concern to hospitalized intensive care unit (ICU) patients. This study aimed at addressing the burden of MDR and the associated factors at admission to ICU.

Methods

This was a cross-sectional study conducted at the ICU of a tertiary hospital in Tanzania. Rectal and anterior nares swabs were collected within 48 hours of ICU admission to screen for extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) and meticillin-resistant Staphylococcus aureus (MRSA), respectively.

Results

The proportion of fecal carriage for ESBL-PE at admission to ICU was 54.54% (95% CI, 47.52–61.39), and nasal carriage for MRSA was 9.32% (95%CI, 5.67–14.93). The nasal MRSA colonization (OR = 1.52) and fecal carriage for ESBL-PE (OR=1.38) were more likely in participants who had received antibiotics before ICU admission than not, but association was not statistically significant. Hospitalization for ≥2 days (OR=1.18) was associated with fecal carriage of ESBL-PE, though not statistically significant. Overall, 66% and 73.5% of patients received antibiotics before and upon admission to ICU, respectively. Ceftriaxone, metronidazole and meropenem were commonly prescribed antibiotics. More than 84% of Enterobacterales were resistant to ciprofloxacin and trimethoprim-sulfamethoxazole, and 2.90% were resistant to meropenem. MRSA isolates showed a high rate of resistance to gentamicin and erythromycin.

Conclusion

MDR bacteria are common in patients admitted to ICU. To reduce the risk associated with MDR, we recommend use of simple screening methods to screen for MDR at ICU admission as part of infection control and prevention.

Frequent and Durable Anti-HIV Envelope VIV2 IgG Responses Induced by HIV-1 DNA Priming and HIV-MVA Boosting in Healthy Tanzanian Volunteers

We evaluated antibody responses to the human immunodeficiency virus (HIV) envelope variable regions 1 and 2 (V1V2) in 29 vaccinees who had received three HIV-1 DNA immunizations and two HIV-modified vaccinia virus Ankara (MVA) boosts in the phase I/II HIVIS03 vaccine trial. Twenty vaccinees received a third HIV-MVA boost after three years in the HIVIS06 trial. IgG and IgG antibody subclasses to gp70V1V2 proteins of HIV-1 A244, CN54, Consensus C, and Case A2 were analysed using an enzyme-linked immunosorbent assay (ELISA). Cyclic V2 peptides of A244, Consensus C, and MN were used in a surface plasmon resonance (SPR) assay. Four weeks after the second HIV-MVA, anti-V1V2 IgG antibodies to A244 were detected in 97% of HIVIS03 vaccinees, in 75% three years later, and in 95% after the third HIV-MVA. Anti-CN54 V1V2 IgG was detectable in 48% four weeks after the second HIV-MVA. The SPR data supported the findings. The IgG response was predominantly IgG1. Four weeks after the second HIV-MVA, 85% of vaccinees had IgG1 antibodies to V1V2 A244, which persisted in 25% for three-years. IgG3 and IgG4 antibodies to V1V2 A244 were rare. In conclusion, the HIV-DNA/MVA vaccine regimen induced durable V1V2 IgG antibody responses in a high proportion of vaccinees.

Induction of Identical IgG HIV-1 Envelope Epitope Recognition Patterns After Initial HIVIS-DNA/MVA-CMDR Immunization and a Late MVA-CMDR Boost

In the RV144 trial, to date the only HIV-1 vaccine efficacy trial demonstrating a modestly reduced risk of HIV-1 acquisition, antibody responses toward the HIV Envelope protein (Env) variable (V) 2 and V3 regions were shown to be correlated with a reduced risk of infection. These potentially protective antibody responses, in parallel with the vaccine efficacy, however, waned quickly. Dissecting vaccine-induced IgG recognition of antigenic regions and their variants within the HIV-1 Env from different vaccine trials will aid in designing future HIV-1 immunogens and vaccination schedules. We, therefore, analyzed the IgG response toward linear HIV-1 Env epitopes elicited by a multi-clade, multigene HIVIS-DNA priming, and heterologous recombinant modified vaccinia virus Ankara (MVA-CMDR) boosting regimen (HIVIS03) and assessed whether a late MVA-CMDR boost 3 years after completion of the initial vaccination schedule (HIVIS06) restored antibody responses toward these epitopes. Here we report that vaccination schedule in the HIVIS03 trial elicited IgG responses against linear epitopes within the V2 and V3 tip as well as against the gp41 immunodominant region in a high proportion of vaccinees. Antibodies against the V2 and gp41 Env regions were restricted to variants with close homology to the MVA-CMDR immunogen sequence, while V3 responses were more cross-reactive. Boosting with a late third MVA-CMDR after 3 years effectively restored waned IgG responses to linear Env epitopes and induced targeting of identical antigenic regions and variants comparable to the previous combined HIVIS-DNA/MVA-CMDR regimen. Our findings support the notion that anti-HIV-1 Env responses, associated with a reduced risk of infection in RV144, could be maintained by regular boosting with a single dose of MVA-CMDR.

Predictors of non adherence to antiretroviral therapy at an urban HIV care and treatment center in Tanzania

BACKGROUND

Measurement of adherence to antiretroviral therapy (ART) can serve as a proxy for virologic failure in resource-limited settings. The aim of this study was to determine the factors underlying nonadherence measured by three methods.

PATIENTS AND METHODS

This is a prospective longitudinal cohort of 220 patients on ART at Amana Hospital in Dar es Salaam, Tanzania. We measured adherence using a structured questionnaire combining a visual analog scale (VAS) and Swiss HIV Cohort Study Adherence Questionnaire (SHCS-AQ), pharmacy refill, and appointment keeping during four periods over 1 year. Overall adherence was calculated as the mean adherence for all time points over the 1 year of follow-up. At each time point, adherence was defined as achieving a validated cutoff for adherence previously defined for each method.

RESULTS

The proportion of overall adherence was 86.4% by VAS, 69% by SHCS-AQ, 79.8% by appointment keeping, and 51.8% by pharmacy refill. Forgetfulness was the major reported reason for patients to skip their medications. In multivariate analysis, significant predictors to good adherence were older age, less alcohol consumption, more advanced World Health Organization clinical staging, and having a lower body mass index with odds ratio (CI): 3.11 (1.55-6.93), 0.24 (0.09-0.62), 1.78 (1.14-2.84), and 0.93 (0.88-0.98), respectively.

CONCLUSION

We found relatively good adherence to ART in this setting. Barriers to adherence include young age and perception of well-being.

Erratum to: Prevalence of methicillin-resistant Staphylococcus aureus carriage on admission among patients attending regional hospitals in Dar es Salaam, Tanzania

Following publication of the original article [1], author Elia Mmbaga pointed out that her name had been misspelt as Elia Mbaga.

Prevalence of methicillin-resistant Staphylococcus aureus carriage on admission among patients attending regional hospitals in Dar es Salaam, Tanzania

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen responsible for hospital and community acquired infection. Colonization with MRSA is associated with a high risk of developing infection. This study aimed to determine the rate of MRSA carriage on admission and the associated risk factors among patients attending regional hospitals, in Dar es Salaam, Tanzania.

Results

A total of 258 patients were included in this study. Nasal swabs were collected on admission to the hospital and after 48 h of hospital stay for detection of MRSA. Of 258 patients enrolled, 89 (34.5%) were colonized with S. aureus and out them 22 (24.7%) were carriers of MRSA, giving an overall MRSA nasal carriage rate of 8.5% (22/258). One patient acquired MRSA while admitted in the hospital. Most of the S. aureus isolates 85 (95.5%) were resistant to penicillin. Resistance to gentamycin, ciprofloxacin, kanamycin, linezolid and mupirocin were 14.6, 11.2, 11.2, 3.4 and 1.1%, respectively. The prevalence of inducible clindamycin resistance, constitutive clindamycin resistance, MS phenotype (resistance to erythromycin alone), and multidrug resistance was 21.3, 3.4, 12.4, and 16.9%, respectively. We observed a statistically significant association between MRSA and multiple drugs resistance among S. aureus isolates (p = 0.001). Of the risk factors investigated none were statistically significant associated with MRSA.

Conclusion

There is a high prevalence of MRSA among patients on admission at the two municipal hospitals in Dar es Salaam. The high prevalence of MRSA and the increased rates of resistance to commonly used antimicrobials among MRSA isolates call for attention to the importance of including the screening of MRSA in our hospitals setting in order to prevent further spread of MRSA strains to other patients and to the communities. Control and prevention strategies should be emphasized including decolonization.

Three-Year Durability of Immune Responses Induced by HIV-DNA and HIV-Modified Vaccinia Virus Ankara and Effect of a Late HIV-Modified Vaccinia Virus Ankara Boost in Tanzanian Volunteers

We explored the duration of immune responses and the effect of a late third HIV-modified vaccinia virus Ankara (MVA) boost in HIV-DNA primed and HIV-MVA boosted Tanzanian volunteers. Twenty volunteers who had previously received three HIV-DNA and two HIV-MVA immunizations were given a third HIV-MVA immunization 3 years after the second HIV-MVA boost. At the time of the third HIV-MVA, 90% of the vaccinees had antibodies to HIV-1 subtype C gp140 (median titer 200) and 85% to subtype B gp160 (median titer 100). The majority of vaccinees had detectable antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies, 70% against CRF01_AE virus-infected cells (median titer 239) and 84% against CRF01_AE gp120-coated cells (median titer 499). A high proportion (74%) of vaccinees had IFN-γ ELISpot responses, 63% to Gag and 42% to Env, 3 years after the second HIV-MVA boost. After the third HIV-MVA, there was an increase in Env-binding antibodies and ADCC-mediating antibodies relative to the response seen at the time of the third HIV-MVA vaccination, p < .0001 and p < .05, respectively. The frequency of IFN-γ ELISpot responses increased to 95% against Gag or Env and 90% to both Gag and Env, p = .064 and p = .002, respectively. In conclusion, the HIV-DNA prime/HIV-MVA boost regimen elicited potent antibody and cellular immune responses with remarkable durability, and a third HIV-MVA immunization significantly boosted both antibody and cellular immune responses relative to the levels detected at the time of the third HIV-MVA, but not to higher levels than after the second HIV-MVA.

Boosting with Subtype C CN54rgp140 Protein Adjuvanted with Glucopyranosyl Lipid Adjuvant after Priming with HIV-DNA and HIV-MVA Is Safe and Enhances Immune Responses: A Phase I Trial

Background

A vaccine against HIV is widely considered the most effective and sustainable way of reducing new infections. We evaluated the safety and impact of boosting with subtype C CN54rgp140 envelope protein adjuvanted in glucopyranosyl lipid adjuvant (GLA-AF) in Tanzanian volunteers previously given three immunizations with HIV-DNA followed by two immunizations with recombinant modified vaccinia virus Ankara (HIV-MVA).

Methods

Forty volunteers (35 vaccinees and five placebo recipients) were given two CN54rgp140/GLA-AF immunizations 30–71 weeks after the last HIV-MVA vaccination. These immunizations were delivered intramuscularly four weeks apart.

Results

The vaccine was safe and well tolerated except for one episode of asymptomatic hypoglycaemia that was classified as severe adverse event. Two weeks after the second HIV-MVA vaccination 34 (97%) of the 35 previously vaccinated developed Env-specific binding antibodies, and 79% and 84% displayed IFN-γ ELISpot responses to Gag and Env, respectively. Binding antibodies to subtype C Env (included in HIV-DNA and protein boost), subtype B Env (included only in HIV-DNA) and CRF01_AE Env (included only in HIV-MVA) were significantly boosted by the CN54rgp140/GLA-AF immunizations. Functional antibodies detected using an infectious molecular clone virus/peripheral blood mononuclear cell neutralization assay, a pseudovirus/TZM-bl neutralization assay or by assays for antibody-dependent cellular cytotoxicity (ADCC) were not significantly boosted. In contrast, T-cell proliferative responses to subtype B MN antigen and IFN-γ ELISpot responses to Env peptides were significantly enhanced. Four volunteers not primed with HIV-DNA and HIV-MVA before the CN54rgp140/GLA-AF immunizations mounted an antibody response, while cell-mediated responses were rare. After the two Env subtype C protein immunizations, a trend towards higher median subtype C Env binding antibody titers was found in vaccinees who had received HIV-DNA and HIV-MVA prior to the two Env protein immunizations as compared to unprimed vaccinees (p = 0.07).

Conclusion

We report excellent tolerability, enhanced binding antibody responses and Env-specific cell-mediated immune responses but no ADCC antibody increase after two immunizations with a subtype C rgp140 protein adjuvanted in GLA-AF in healthy volunteers previously immunized with HIV-DNA and HIV-MVA.

Trial Registration

International Clinical Trials Registry PACTR2010050002122368

Potent functional antibody responses elicited by HIV-I DNA priming and boosting with heterologous HIV-1 recombinant MVA in healthy Tanzanian adults

Vaccine-induced HIV antibodies were evaluated in serum samples collected from healthy Tanzanian volunteers participating in a phase I/II placebo-controlled double blind trial using multi-clade, multigene HIV-DNA priming and recombinant modified vaccinia Ankara (HIV-MVA) virus boosting (HIVIS03). The HIV-DNA vaccine contained plasmids expressing HIV-1 gp160 subtypes A, B, C, Rev B, Gag A, B and RTmut B, and the recombinant HIV-MVA boost expressed CRF01_AE HIV-1 Env subtype E and Gag-Pol subtype A. While no neutralizing antibodies were detected using pseudoviruses in the TZM-bl cell assay, this prime-boost vaccination induced neutralizing antibodies in 83% of HIVIS03 vaccinees when a peripheral blood mononuclear cell (PBMC) assay using luciferase reporter-infectious molecular clones (LucR-IMC) was employed. The serum neutralizing activity was significantly (but not completely) reduced upon depletion of natural killer (NK) cells from PBMC (p=0.006), indicating a role for antibody-mediated Fcγ-receptor function. High levels of antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies against CRF01_AE and/or subtype B were subsequently demonstrated in 97% of the sera of vaccinees. The magnitude of ADCC-mediating antibodies against CM235 CRF01_AE IMC-infected cells correlated with neutralizing antibodies against CM235 in the IMC/PBMC assay. In conclusion, HIV-DNA priming, followed by two HIV-MVA boosts elicited potent ADCC responses in a high proportion of Tanzanian vaccinees. Our findings highlight the potential of HIV-DNA prime HIV-MVA boost vaccines for induction of functional antibody responses and suggest this vaccine regimen and ADCC studies as potentially important new avenues in HIV vaccine development.

Pharmacy refill adherence outperforms self-reported methods in predicting HIV therapy outcome in resource-limited settings

Background

Optimal adherence to antiretroviral therapy is critical to prevent HIV drug resistance (HIVDR) epidemic. The objective of the study was to investigate the best performing adherence assessment method for predicting virological failure in resource-limited settings (RLS).

Method

This study was a single-centre prospective cohort, enrolling 220 HIV-infected adult patients attending an HIV/AIDS Care and Treatment Centre in Dar es Salaam, Tanzania, in 2010. Pharmacy refill, self-report (via visual analog scale [VAS] and the Swiss HIV Cohort study-adherence questionnaire), pill count, and appointment keeping adherence measurements were taken.

Univariate logistic regression (LR) was done to explore a cut-off that gives a better trade-off between sensitivity and specificity, and a higher area under the curve (AUC) based on receiver operating characteristic curve in predicting virological failure. Additionally, the adherence models were evaluated by fitting multivariate LR with stepwise functions, decision trees, and random forests models, assessing 10-fold multiple cross validation (MCV). Patient factors associated with virological failure were determined using LR.

Results

Viral load measurements at baseline and one year after recruitment were available for 162 patients, of whom 55 (34%) had detectable viral load and 17 (10.5%) had immunological failure at one year after recruitment. The optimal cut-off points significantly predictive of virological failure were 95%, 80%, 95% and 90% for VAS, appointment keeping, pharmacy refill, and pill count adherence respectively. The AUC for these methods ranged from 0.52 to 0.61, with pharmacy refill giving the best performance at AUC 0.61.

Multivariate logistic regression with boost stepwise MCV had higher AUC (0.64) compared to all univariate adherence models, except pharmacy refill adherence univariate model, which was comparable to the multivariate model (AUC = 0.64). Decision trees and random forests models were inferior to boost stepwise model.

Pharmacy refill adherence (<95%) emerged as the best method for predicting virological failure. Other significant predictors in multivariate LR were having a baseline CD4 T lymphocytes count < 200 cells/μl, being unable to recall the diagnosis date, and a higher weight.

Conclusion

Pharmacy refill has the potential to predict virological failure and to identify patients to be considered for viral load monitoring and HIVDR testing in RLS.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-1035) contains supplementary material, which is available to authorized users.

Predominance of multi-drug resistant bacterial pathogens causing surgical site infections in Muhimbili National Hospital, Tanzania

Background

Surgical site infections (SSIs) remain a common and widespread problem contributing to a significant morbidity and mortality, attributed partly by the increase in antimicrobial resistance among the etiological agents. This study was done to determine the spectrum of bacterial isolates and their susceptibility patterns causing SSIs at Muhimbili National Hospital, Tanzania.

Methods

This descriptive cross sectional study was conducted between September, 2011 and February, 2012. Pus swabs or pus were cultured on blood agar (Oxoid, UK) and MacConkey agar (Oxoid, UK) and incubated aerobically at 37°C for 18–24 hours. Bacterial identification was done using API 20E and VITEK and antimicrobial susceptibility was determined by Kirby Bauer disc diffusion.

Results

Of the 100 patients, from whom wound swabs were collected, 90 (90%) had positive aerobic bacterial growth. A total of 147 pathogenic bacteria were isolated, including 114 (77.5%) gram negative and 33(22.5%) gram positive organisms. The most prevalent bacterial species were Pseudomonas aeruginosa (16.3%), followed by Staphylococcus aureus (12.2%) and Klebsiella pneumoniae (10.8%). Of the 18 S. aureus , 8 (44%) were methicillin resistant Staphylococcus aureus (MRSA) and three of them (17%) were carrying both MRSA and induced clindamycin resistance (ICR). Extended spectrum beta-lactamase (ESBL) producing Enterobacteriaceae were observed in 23 (79.3%) of the 29 isolates tested. Majority of Escherichia coli 12 (92.3%) and K. pneumoniae 11 (69%) isolates were ESBL producers. About 63% (93/147) were multiple-drug resistance (MDR) isolates, and the overall MDR among Gram positive and Gram negative bacteria was 60.6% (20/33) and 61.4%, (73/114), respectively. The prevalence of MDR for E. coli, A. baumannii and P. stuartii was 100% each. Majority (97%) of the Gram negative bacteria were resistant to more than four categories (classes) of antibiotics.

Conclusion

A high proportion (63%) of the isolates causing SSIs in this tertiary hospital were MDR, of which (90%) were resistant to more than four classes of antibiotics. In the light of these findings, an urgent and significant change in antibiotic prescription policy is required at this National hospital.

Predominance of Klebsiella pneumoniae ST14 carrying CTX-M-15 causing neonatal sepsis in Tanzania

Background

Klebsiella pneumoniae strains expressing ESBLs are a predominant cause of hospital acquired infections. Here we describe the molecular epidemiology of these isolates in a tertiary hospital in Tanzania, as potential pathogens for neonatal infections.

Methods

Between April 2009 and March 2010 all Klebsiella pneumoniae isolates with phenotypic expression Extended Spectrum Beta Lactamase (ESBL) were collected and characterized. Identification was done using in house biochemical tests in case of ambiguous results confirmation was done using API 20E. Susceptibility testing was determined using the disc diffusion method followed by specific PCR and sequencing to determine ESBL genes. Phylogenetic analysis, Pulse field gel electrophoresis (PFGE) and Multi-Locus sequence typing (MLST) to PFGE clusters representative isolates were performed to determine clones of the isolates. Conjugation and hybridization were performed to determine the location of blaCTX-M-15 gene.

Results

A total of 92 non- repetitive ESBL producing K. pneumoniae representing 50.3% of Klebsiella pneumoniae isolates were characterized. These isolates were from blood 61 (66%), wound swab 13 (14%), urine 12 (13%) and pus 6 (7%) were analyzed. Most blood culture strains originated from neonatal unit 39/61(64%) and 22 (36%) of the blood culture isolates were from neonatal ICU. All isolates were resistant to gentamicin and 54% were resistant to ciprofloxacin. Using a similarity index of 80%, the isolates were assigned to thirteen clusters based on PFGE patterns and contained sub-clusters with identical strains indicating clonal outbreaks. Cluster X5, X7 and X8, and X9 were grouped into ST48, ST14 and ST348 respectively. Based on gyrA PCR- RFLP phylogenetic analysis all isolates were grouped as KpI. The predominant ESBL allele detected was bla_CTX-M-15 which was found in 76% of isolates, followed by bla_TEM-104 (19%), bla_SHV-11 (3.2%) and bla_TEM-176 (2%). The bla_CTX-M-15 gene was located in multiple conjugative IncF plasmids ranging from 25 kb-485 kb in size.

Conclusion

The high prevalence of bla_CTX-M-15 observed among ESBL producing K. pneumoniae in Tanzania, is possibly due to the spread of a common IncFII 145 kb plasmid and of certain clones such as ST14 and ST48. Furthermore the 485 kb plasmid detected is the largest plasmid reported to carry bla_CTX-M-15 todate.

Plague in Tanzania: an overview

Human plague remains a public health concern in Tanzania despite its quiescence in most foci for years, considering the recurrence nature of the disease. Despite the long-standing history of this problem, there have not been recent reviews of the current knowledge on plague in Tanzania. This work aimed at providing a current overview of plague in Tanzania in terms of its introduction, potential reservoirs, possible causes of plague persistence and repeated outbreaks in the country. Plague is believed to have been introduced to Tanzania from the Middle East through Uganda with the first authentication in 1886. Xenopsylla brasiliensis, X. cheopis, Dinopsyllus lypusus, and Pulex irritans are among potential vectors while Lophuromys spp, Praomys delectorum, Graphiurus murinus, Lemniscomys striatus, Mastomys natalensis, and Rattus rattus may be the potential reservoirs. Plague persistence and repeated outbreaks in Tanzania are likely to be attributable to a complexity of factors including cultural, socio-economical, environmental and biological. Minimizing or preventing people's proximity to rodents is probably the most effective means of preventing plague outbreaks in humans in the future. In conclusion, much has been done on plague diagnosis in Tanzania. However, in order to achieve new insights into the features of plague epidemiology in the country, and to reorganize an effective control strategy, we recommend broader studies that will include the ecology of the pathogen, vectors and potential hosts, identifying the reservoirs, dynamics of infection and landscape ecology.

High nasal carriage of methicillin-resistant Staphylococcus aureus among healthy Tanzanian under-5 children

This study aimed to determine the prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) carriage, risk factors of colonization and antimicrobial susceptibility patterns of S. aureus strains. The study was conducted at the Muhimbili National Hospital in Dar es Salaam, Tanzania. Nasal swabs were obtained from children and S. aureus was isolated and identified using conventional culture methods. MRSA was screened and confirmed using the cefoxitin disk and multiplex real-time polymerase chain reaction, respectively. Antibiotic susceptibility was performed using the Kirby-Bauer disk diffusion method. MRSA isolates were further characterized by pulsed field gel electrophoresis (PFGE) profiling. Of 285 children included in the study, S. aureus was detected in 114 (40%). Of the 114 isolates, 12 (10.5%) were MRSA. PFGE results showed that these MRSA isolates are epidemiologically unrelated. Resistance of all S. aureus to trimethoprim-sulfamethoxazole, tetracycline, gentamicin, and ciprofloxacin was 65.8%, 23.7%, 27.2%, and 4.4%, respectively. No resistance to vancomycin was found. The prevalence of inducible clindamycin resistance, constitutive clindamycin resistance, MS phenotype (resistance to erythromycin alone), and multidrug resistance was 16.7%, 1.8%, 14.0%, and 16.8%, respectively. None of the risk factors examined was found to be significant. This is the first report of S. aureus and nasal carriage of MRSA and a high rate of S. aureus carriage was found in Tanzanian under-5 children. The study findings support the need for proper health education and effective infection control measures for healthcare workers.

Factors associated with flea infestation among the different rodent species in Mbulu and Karatu districts, northern Tanzania

Flea infection with the bacterium, Yersinia pestis is acquired from reservoirs which include several rodents and other small mammals. In areas that are endemic of plague, reservoirs of Y. pestis and various flea vectors are responsible for perpetuating existence of the disease. The objective of this cross sectional study was to investigate the magnitude and factors associated with flea infestation among different rodent species of northern Tanzania, where outbreaks of plague have been recently reported. House rodents were trapped with box traps, while field and forest rodents were trapped with Sherman live traps. Fleas were removed from the rodents by using shoe-shining brush and were identified to genus level. Among the captured rodents, Rattus rattus (26.5%), Lophuromys flavopunctatus (16.5%), Praomys delectorum (16.2%) and Mastomys natalensis (32.3%) were most abundant rodent species, accounting for 91% of all species. Altogether, 805 fleas belonging to nine species were collected from 61% of the captured rodents. The most common fleas were Xenopsylla spp.; Dinopsyllus spp and Ctenophthalmus spp. Fleas were found to be highly abundant in M. natalensis, R. rattus, P. delectorum and L .flavopunctatus. Most of rodents were heavily infested with various flea species. These flea species probably play an important role in the transmission of plague in these two districts. We conclude that rodent species was the most important risk factor associating with flea infestation among the rodent population. Therefore, measures for control and prevention of plague in this area should particularly target rodents associated with high intensity of flea infestation.

Predominance of methicillin resistant Staphylococcus aureus -ST88 and new ST1797 causing wound infection and abscesses

INTRODUCTION

Although there has been a worldwide emergence and spread of methicillin-resistant Staphylococcus aureus (MRSA), little is known about the molecular epidemiology of MRSA in Tanzania.

METHODOLOGY

In this study, we characterized MRSA strains isolated from clinical specimens at the Bugando Medical Centre, Tanzania, between January and December 2008. Of 160 S. aureus isolates from 600 clinical specimens, 24 (15%) were found to be MRSA. Besides molecular screening for the Panton Valentine leukocidin (PVL) genes by PCR, MRSA strains were further characterized by Multi-Locus Sequence Typing (MLST) and spa typing.

RESULTS

Despite considerable genetic diversity, the spa types t690 (29.1%) and t7231 (41.6%), as well as the sequence types (ST) 88 (54.2%) and 1797 (29.1%), were dominant among clinical isolates. The PVL genes were detected in 4 isolates; of these, 3 were found in ST 88 and one in ST1820. Resistance to erythromycin, clindamicin, gentamicin, tetracycline and co-trimoxazole was found in 45.8%, 62.5%, 41.6%, 45.8% and 50% of the strains, respectively.

CONCLUSION

We present the first thorough typing of MRSA at a Tanzanian hospital.  Despite considerable genetic diversity, ST88 was dominant among clinical isolates at the Bugando Medical Centre. Active and standardized surveillance of nosocomial MRSA infection should be conducted in the future to analyse the infection and transmission rates and implement effective control measures.

Broad and potent immune responses to a low dose intradermal HIV-1 DNA boosted with HIV-1 recombinant MVA among healthy adults in Tanzania

BACKGROUND

We conducted a phase I/II randomized placebo-controlled trial with the aim of exploring whether priming with a low intradermal dose of a multiclade, multigene HIV-1 DNA vaccine could improve the immunogenicity of the same vaccine given intramuscularly prior to boosting with a heterologous HIV-1 MVA among healthy adults in Dar es Salaam, Tanzania.

METHODS

Sixty HIV-uninfected volunteers were randomized to receive DNA plasmid vaccine 1mg intradermally (id), n=20, or 3.8mg intramuscularly (im), n=20, or placebo, n=20, using a needle-free injection device. DNA plasmids encoding HIV-1 genes gp160 subtype A, B, C; rev B; p17/p24 gag A, B and Rtmut B were given at weeks 0, 4 and 12. Recombinant MVA (10(8)pfu) expressing HIV-1 Env, Gag, Pol of CRF01_AE or placebo was administered im at month 9 and 21.

RESULTS

The vaccines were well tolerated. Two weeks after the third HIV-DNA injection, 22/38 (58%) vaccinees had IFN-γ ELISpot responses to Gag. Two weeks after the first HIV-MVA boost all 35 (100%) vaccinees responded to Gag and 31 (89%) to Env. Two to four weeks after the second HIV-MVA boost, 28/29 (97%) vaccinees had IFN-γ ELISpot responses, 27 (93%) to Gag and 23 (79%) to Env. The id-primed recipients had significantly higher responses to Env than im recipients. Intracellular cytokine staining for Gag-specific IFN-γ/IL-2 production showed both CD8(+) and CD4(+) T cell responses. All vaccinees had HIV-specific lymphoproliferative responses. All vaccinees reacted in diagnostic HIV serological tests and 26/29 (90%) had antibodies against gp160 after the second HIV-MVA boost. Furthermore, while all of 29 vaccinee sera were negative for neutralizing antibodies against clade B, C and CRF01_AE pseudoviruses in the TZM-bl neutralization assay, in a PBMC assay, the response rate ranged from 31% to 83% positives, depending upon the clade B or CRF01_AE virus tested.

CONCLUSIONS

This vaccine approach is safe and highly immunogenic. Low dose, id HIV-DNA priming elicited higher and broader cell-mediated immune responses to Env after HIV-MVA boost compared to a higher HIV-DNA priming dose given im. Three HIV-DNA priming immunizations followed by two HIV-MVA boosts efficiently induced Env-antibody responses.

Multiple ST clonal complexes, with a predominance of ST131, of Escherichia coli harbouring blaCTX-M-15 in a tertiary hospital in Tanzania

The molecular epidemiology of 32 non-duplicate, CTX-M-15 extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains, isolated from clinical samples, was investigated. Multilocus sequence typing revealed multiple sequence type clonal complexes: ST131 (12), ST405 (4), ST638 (3), ST38 (2), ST827 (2), ST224 (1), ST648 (1), ST46 (1) and two new sequence type clonal complexes (1845 and 1848) in 22 pulsed field gel electrophoresis clusters. The bla(CTX-M-15) gene was located on conjugative IncF plasmids. This is the first report of the worldwide emerging clonal complex ST131 linked to bla(CTX-M-15) in Tanzania and demonstrates the need for constant surveillance in developing countries to prevent the spread of these multiresistant isolates.

Antimicrobial resistance among producers and non-producers of extended spectrum beta-lactamases in urinary isolates at a tertiary Hospital in Tanzania

Background

Published data on the existence and magnitude of extended spectrum beta-lactamase (ESBL) production in urinary pathogens in local setting is limited. The aim of the present study was to determine the prevalence of antimicrobial resistance and ESBL production among Escherichia coli and Klebsiella spp from urine samples in a tertiary hospital. This was a cross sectional study conducted at Muhimbili National Hospital in Dar es Salaam, Tanzania.

Findings

A total of 270 E.coli and Klebsiella spp urinary pathogens from children and adults isolated from January to March 2010 were included in the study. E. coli and Klebsiella spp isolates were tested for antimicrobial susceptibility by the Clinical and Laboratory Standard Institute's disc diffusion method. These isolates were further screened for ESBL phenotype using cefotaxime and ceftazidime discs. Isolates with reduced sensitivity were confirmed using ESBL E-test strips. Of 270 isolates, 138 (51.1%) were E. coli and 132 (48.9%) were Klebsiella spp. ESBL was detected in 122 (45.2%) of all the isolates. ESBL- producing E. coli strains were significantly more resistance to cotrimoxazole (90.7%), ciprofloxacin (46.3%) and nalidixic acid (61.6%) than strains that did not produce ESBL (p < 0.05). Similarly, ESBL- producing Klebsiella spp strains were significantly more resistance to cotrimoxazole (92.6%), ciprofloxacin (25.0%), nalidixic acid (66.2%), and gentamicin (38.2%) than strains that did not produce ESBL (P < 0.05). Multi-drug resistance was found to be significantly (P < 0.05) more in ESBL producing isolates (90.5%) than non ESBL producers (68.9%). The occurrence of ESBL was significantly higher among isolates from inpatients than outpatients [95 (50.5%) vs. 27(32.9%)] (p = 0.008). The occurrence of ESBL was significantly higher among isolates from children than in adults [84 (54.9%) vs. 38(32.5%)] (p < 0.001).

Conclusions

High prevalence of ESBL-producing E. coli and Klebsiella spp strains was found among inpatients and children. Most of the ESBL- producing isolates were multi-drug resistant making available therapeutic choices limited. We recommend continued antibiotic surveillance as well comprehensive multi-center studies to address the emerging problem of ESBL-associated infections in order to preserve the continued usefulness of most antimicrobial drugs. Further more conducting molecular studies will help to evaluate the various ESBL types.

Maternal and neonatal colonisation of group B streptococcus at Muhimbili National Hospital in Dar es Salaam, Tanzania: prevalence, risk factors and antimicrobial resistance

BACKGROUND

Group B streptococcus (GBS), which asymptomatically colonises the vaginal and rectal areas of women, is the leading cause of septicemia, meningitis and pneumonia in neonates. In Tanzania no studies have been done on GBS colonisation of pregnant women and neonates. This study was conducted in Dar es Salaam, Tanzania to determine the prevalence of GBS colonisation among pregnant women, the neonatal colonisation rate and the antimicrobial susceptibility, thus providing essential information to formulate a policy for treatment and prevention regarding perinatal GBS diseases.

METHODS

This cross sectional study involved 300 pregnant women attending antenatal clinic and their newborns delivered at Muhimbili National Hospital (MNH) between October 2008 and March 2009. High vaginal, rectal, nasal, ear and umbilical swabs were cultured on Todd Hewitt Broth and in 5% sheep blood agar followed by identification of isolates using conventional methods and testing for their susceptibility to antimicrobial agents using the Kirby-Bauer method.

RESULTS

GBS colonisation was confirmed in 23% of pregnant women and 8.9% of neonates. A higher proportion of GBS were isolated from the vagina (12.3%) as compared to the rectum (5%). Prolonged duration of labour (>12 hrs) was significantly shown to influence GBS colonisation in neonates P < 0.05. Other risk factors such as prolonged rupture of membrane, intrapartum fever, low birth weight and HIV infection did not correlate with GBS colonisation. All isolates were sensitive to vancomycin and ampicillin. Resistance to clindamycin, erythromycin and penicillin G was found to 17.6%, 13% and 9.4%, respectively.

CONCLUSION

Our findings seem to suggest that a quarter of pregnant women attending ANC clinic at MNH and approximately 10% of their newborns are colonised with GBS. All isolates were found to be sensitive to vancomycin and ampicillin which seem to be the most effective antibiotics for the time being. However there is a need for continuous antibiotics surveillance of GBS to monitor trend of resistance. The high isolation frequency of GBS among pregnant women suggests routine antenatal screening at 35 to 37 weeks of gestation in order to provide antibiotic prophylaxis to GBS carrier.

Prevalence of multiresistant gram-negative organisms in a tertiary hospital in Mwanza, Tanzania

Background

Antimicrobial resistance is fast becoming a global concern with rapid increases in multidrug-resistant Gram negative organisms. The prevalence of extended spectrum beta-lactamase (ESBL)-producing clinical isolates increases the burden on implementing infectious disease management in low socio-economic regions. As incidence can vary widely between regions, this study was done to determine resistance patterns of Gram-negative organisms at Bugando Medical Center, a tertiary hospital in Mwanza, Tanzania.

Methods

A total of 800 clinical samples (urine, wound swab, pus, blood, aspirate, sputum etc) were processed over a period of 6 months. Gram-negative bacteria were identified using conventional in-house biochemical tests and susceptibility to common antibiotics done using disc diffusion methods. The disc approximation method was used to identify ESBL producers.

Results

A total of 377 Gram-negative bacteria (GNB) recovered from 377 clinical specimens were analyzed of which 76.9% were Enterobacteriaceae. Among all GNB, 110/377 (29.2%) were found to be ESBL producers. Species specific ESBLs rate among Klebsiella pneumoniae, Escherichia coli, Acinetobacter spp, Proteus spp and other enterobacteria were 63.7%, 24.4%, 17.7%, 6.4% and 27.9% respectively. A statistically significant higher number of inpatients 100/283 (35.3%) compared to 10/94 (10.6%) of outpatients had ESBL-producing organisms (p = 0.000023). Rates of resistances to gentamicin, tetracycline, sulphamethaxazole/trimethoprim and ciprofloxacin were significantly higher among ESBLs isolates than non-ESBL isolates (p = 0.000001).

Conclusion

ESBL producing organisms are common at BMC (Bugando Medical Center) and pose a challenge to antibiotic therapy. Successful implementation of a routine detection of ESBL production is essential in designing appropriate antibiotic prescribing policies and infection control intervention programmes.

Evaluation of simple rapid HIV assays and development of national rapid HIV test algorithms in Dar es Salaam, Tanzania

BACKGROUND

Suitable algorithms based on a combination of two or more simple rapid HIV assays have been shown to have a diagnostic accuracy comparable to double enzyme-linked immunosorbent assay (ELISA) or double ELISA with Western Blot strategies. The aims of this study were to evaluate the performance of five simple rapid HIV assays using whole blood samples from HIV-infected patients, pregnant women, voluntary counseling and testing attendees and blood donors, and to formulate an alternative confirmatory strategy based on rapid HIV testing algorithms suitable for use in Tanzania.

METHODS

Five rapid HIV assays: Determine HIV-1/2 (Inverness Medical), SD Bioline HIV 1/2 3.0 (Standard Diagnostics Inc.), First Response HIV Card 1-2.0 (PMC Medical India Pvt Ltd), HIV1/2 Stat-Pak Dipstick (Chembio Diagnostic System, Inc) and Uni-Gold HIV-1/2 (Trinity Biotech) were evaluated between June and September 2006 using 1433 whole blood samples from hospital patients, pregnant women, voluntary counseling and testing attendees and blood donors. All samples that were reactive on all or any of the five rapid assays and 10% of non-reactive samples were tested on a confirmatory Inno-Lia HIV I/II immunoblot assay (Immunogenetics).

RESULTS

Three hundred and ninety samples were confirmed HIV-1 antibody positive, while 1043 were HIV negative. The sensitivity at initial testing of Determine, SD Bioline and Uni-Gold was 100% (95% CI; 99.1-100) while First Response and Stat-Pak had sensitivity of 99.5% (95% CI; 98.2-99.9) and 97.7% (95% CI; 95.7-98.9), respectively, which increased to 100% (95% CI; 99.1-100) on repeat testing. The initial specificity of the Uni-Gold assay was 100% (95% CI; 99.6-100) while specificities were 99.6% (95% CI; 99-99.9), 99.4% (95% CI; 98.8-99.7), 99.6% (95% CI; 99-99.9) and 99.8% (95% CI; 99.3-99.9) for Determine, SD Bioline, First Response and Stat-Pak assays, respectively. There was no any sample which was concordantly false positive in Uni-Gold, Determine and SD Bioline assays.

CONCLUSION

An alternative confirmatory HIV testing strategy based on initial testing on either SD Bioline or Determine assays followed by testing of reactive samples on the Determine or SD Bioline gave 100% sensitivity (95% CI; 99.1-100) and 100% specificity (95% CI; 96-99.1) with Uni-Gold as tiebreaker for discordant results.

Surveillance of transmitted HIV drug resistance among women attending antenatal clinics in Dar es Salaam, Tanzania

Background

In resource-limited settings where antiretroviral treatment (ART) access is being scaled-up, the World Health Organization (WHO) recommends surveillance of transmitted HIV drug resistance (HIVDR). We used the WHO HIVDR threshold survey method to assess transmitted HIVDR in Dar es Salaam where ART was introduced in 1995 and where ∼11,000 people are currently on ART.

Methods

From November 2005 to February 2006, dried blood spot (DBS) specimens were made from remnant specimens collected during the national HIV serosurvey from 60 primagravidas <25 years old attending six antenatal clinics for routine syphilis testing. Genotyping was performed at the Centers for Disease Control and Prevention, Atlanta, Georgia, USA. Protease and reverse transcriptase drug resistance mutations were identified using the Stanford University HIV drug resistance database. We used the National Institutes of Health genotyping tool for HIV-1 subtyping. HIVDR prevalence categorization was based on the WHO threshold survey binomial sequential sampling method.

Results

Among the 60 eligible specimens collected, 50 DBS were successfully amplified using RT-PCR. Sequencing was performed on the first 39 specimens: 13 (33.3%) were subtype A1, 13 (33.3%) subtype C, and 4 (10.3%) subtype D, the remainder differed in the closest subtype based on protease versus reverse transcriptase. No resistance mutations were seen; HIVDR to all drug classes was categorized as <5%.

Conclusions

Our survey indicates that prevalence of transmitted HIVDR among recently infected pregnant women in Dar es Salaam is low (<5%). The survey should be repeated during the next HIV sentinel survey in Dar es Salaam and extended to other regions where ART is being scaled up.

Surveillance of transmitted HIV drug resistance among women attending antenatal clinics in Dar es Salaam, Tanzania

BACKGROUND

In resource-limited settings where antiretroviral treatment (ART) access is being scaled-up, the World Health Organization (WHO) recommends surveillance of transmitted HIV drug resistance (HIVDR). We used the WHO HIVDR threshold survey method to assess transmitted HIVDR in Dar es Salaam where ART was introduced in 1995 and where approximately 11,000 people are currently on ART.

METHODS

From November 2005 to February 2006, dried blood spot (DBS) specimens were made from remnant specimens collected during the national HIV serosurvey from 60 primagravidas <25 years old attending six antenatal clinics for routine syphilis testing. Genotyping was performed at the Centers for Disease Control and Prevention, Atlanta, Georgia, USA. Protease and reverse transcriptase drug resistance mutations were identified using the Stanford University HIV drug resistance database. We used the National Institutes of Health genotyping tool for HIV-1 subtyping. HIVDR prevalence categorization was based on the WHO threshold survey binomial sequential sampling method.

RESULTS

Among the 60 eligible specimens collected, 50 DBS were successfully amplified using RT-PCR. Sequencing was performed on the first 39 specimens: 13 (33.3%) were subtype A1, 13 (33.3%) subtype C, and 4 (10.3%) subtype D, the remainder differed in the closest subtype based on protease versus reverse transcriptase. No resistance mutations were seen; HIVDR to all drug classes was categorized as <5%.

CONCLUSIONS

Our survey indicates that prevalence of transmitted HIVDR among recently infected pregnant women in Dar es Salaam is low (<5/%). The survey should be repeated during the next HIV sentinel survey in Dar es Salaam and extended to other regions where ART is being scaled up.

Estimating and projecting HIV prevalence and AIDS deaths in Tanzania using antenatal surveillance data

Background

The Estimations and Projections Package (EPP 2005) for HIV/AIDS estimates and projects HIV prevalence, number of people living with HIV and new HIV infections and AIDS cases using antenatal clinic (ANC) surveillance data. The prevalence projection produced by EPP can be transferred to SPECTRUM, a demographic projectionmodel, to calculate the number of AIDS deaths. This paper presents estimates and projections of HIV prevalence, new cases of HIV infections and AIDS deaths in Tanzania between 2001 and 2010 using the EPP 2005 and SPECTRUM soft-wares on ANC data.

Methods

For this study we used; the 1985 – 2004 ANC data set, the 2005 UN population estimates for urban and rural adults, which is based on the 2002 population census, and results of the 2003 Tanzania HIV Indicator Survey. The ANC surveillance sites were categorized into urban and rural areas on the basis of the standard national definitions of urban and rural areas, which led to 40 urban and 35 rural clinic sites. The rural and urban epidemics were run independently by fitting the model to all data and on level fits.

Results

The national HIV prevalence increased from 0% in 1981 to a peak of 8.1% in 1995, and gradually decreased to 6.5% in 2004 which stabilized until 2010. The urban HIV epidemic increased from 0% in 1981 peaking at 12.6% in 1992 and leveled to between 10.9% and 11.8% from 2003 to 2010. The rural epidemic peaked in 1995 at 7.0% and gradually declined to 5.2% in 2004, and then stabilized at between 5.1% and 5.3% from 2005 to 2010. New infections are projected to rise steadily, resulting in 250,000 new cases in 2010. Deaths due to AIDS started in 1985 and rose steadily to reach 120,000 deaths in 2010, with more females dying than men.

Conclusion

The fact that the number of new infections is projected to increase steadily to reach 250,000 per year in 2010 calls for more concerted efforts to combat the spread of HIV infection particularly in the rural areas where the infrastructure needed for prevention programmes such as counseling and testing, condom accessibility and AIDS information is less developed.

Surveillance of HIV and syphilis infections among antenatal clinic attendees in Tanzania-2003/2004

BACKGROUND

This paper presents the prevalence of human immunodeficiency virus (HIV) and syphilis infections among women attending antenatal clinics (ANC) in Tanzania obtained during the 2003/2004 ANC surveillance.

METHODS

Ten geographical regions; six of them were involved in a previous survey, while the remaining four were freshly selected on the basis of having the largest population among the remaining 20 regions. For each region, six ANC were selected, two from each of three strata (urban, peri-urban and rural). Three of the sites did not participate, resulting into 57 surveyed clinics. 17,813 women who were attending the chosen clinics for the first time for any pregnancy between October 2003 and January 2004. Patient particulars were obtained by interview and blood specimens were drawn for HIV and syphilis testing. HIV testing was done anonymously and the results were unlinked.

RESULTS

Of the 17,813 women screened for HIV, 1,545 (8.7% (95% CI = 8.3-9.1)) tested positive with the highest prevalence in women aged 25-34 years (11%), being higher among single women (9.7%) than married women (8.6%) (p < 0.07), and increased with level of education from 5.2% among women with no education to 9.3% among those at least primary education (p < 0.001). Prevalence ranged from 4.8% (95% CI = 3.8%-9.8%) in Kagera to 15.3% (95% CI = 13.9%-16.8%) in Mbeya and was; 3.7%, 4.7%, 9.1%, 11.2% and 15.3% for rural, semi-urban, road side, urban and 15.3% border clinics, respectively (p < 0.001). Of the 17,323 women screened for syphilis, 1265 (7.3% (95%CI = 6.9-7.7)) were positive, with highest prevalence in the age group 35-49 yrs (10.4%) (p < 0.001), and being higher among women with no education than those with some education (9.8% versus 6.8%) (p < 0.0001), but marital status had no influence. Prevalence ranged from 2.1% (95% CI = 1.4%-3.0%) in Kigoma to 14.9% (95% CI = 13.3%-16.6%) in Kagera and was 16.0% (95% CI = 13.3-18.9), 10.5% (95% CI = 9.5-11.5) and 5.8% (95% CI = 5.4-6.3) for roadside, rural and urban clinics, respectively. Syphilis and HIV co-infection was seen in 130/17813 (0.7%).

CONCLUSION

The high HIV prevalence observed among the ANC clinic attendees in Tanzania call for expansion of current voluntary counselling and testing (VCT) services and access to antiretroviral drugs (ARV) in the clinics. There is also a need for modification of obstetric practices and infant feeding options in HIV infection in order to prevent mother to child transmission of HIV. To increase uptake to HIV testing the opt-out strategy in which all clients are offered HIV testing is recommended in order to meet the needs of as many pregnant women as possible.

Seroprevalence of human immunodeficiency virus, hepatitis B and C viruses and syphilis infections among blood donors at the Muhimbili National Hospital in Dar es Salaam, Tanzania

Background

According to the latest Tanzanian National AIDS Control Programme (NACP) report a total of 147,271 individuals donated blood during the year 2002. However, blood safety remains an issue of major concern in transfusion medicine in Tanzania where national blood transfusion services and policies, appropriate infrastructure, trained personnel and financial resources are inadequate. Most of the donated blood is screened for HIV alone.

Methods

We determined among blood donors at Muhimbili National Hospital (MNH), the seroprevalence of human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B surface antigen (HBsAg) and syphilis by donor type, sex and age and to determine association, if any, in the occurrence of the pathogens. The sample included 1599 consecutive donors, 1424(89.1%) males and 175 (10.9%) females, who donated blood between April 2004 and May, 2005. Most of them 1125 (70.4%) were replacement donors and a few 474 (29.6%) voluntary donors. Their age (in years) ranged from 16 to 69, and most (72.2%) were between 20–39 years.

Results

Two hundred and fifty four (15.9%) of the donated blood had serological evidence of infection with at least one pathogen and 28 (1.8%) had multiple infections. The current seroprevalence of HIV, HBsAg, HCV and syphilis among blood donors at MNH in Dar es Salaam was found to be 3.8%, 8.8%, 1.5% and 4.7%, respectively. Respective seroprevalences among HIV seronegative blood donors were 8.7% for HBV, 1.6% for HCV and 4.6% for syphilis. The differences in the prevalence of HIV and syphilis infections between replacement and voluntary donors were statistically significant (P < 0.05). Syphilis was the only infection that occurred more frequently among HIV infected (12.1%) than non-infected (4.6%) blood donors (P < 0.05), and whose prevalence increased with age (X² = 58.5 df = 5, P < 0.001). There were no significant sex differences in the occurrence of pathogens. Finally, there were significant associations in the occurrence of HBsAg and syphilis (OR = 2.2, 95% CI 1.1.-4.2) and HIV and syphilis (OR = 2.2, 95% CI 1.0–5.3).

Conclusion

The high (15.9%) seroprevalence of blood-borne infections in blood donated at MNH calls for routine screening of blood donors for HBV, HCV, HIV and syphilis and for strict selection criteria of donors, with emphasis on getting young voluntary donors and for establishment of strict guidelines for blood transfusions.

Tetanus immunity among pregnant women attending antenatal care in Dar es Salaam, Tanzania

This study was conducted to investigate immunity to tetanus among pregnant women with verbal histories or documentation of having been vaccinated under the current five-dose tetanus toxoid (TT) schedule. It examined sera from 176 pregnant women attending antenatal care at Muhimbili Medical Centre in Dar es Salaam, Tanzania. Tetanus antitoxin level of 0.1 IU/ml was considered protective. Our findings show that 94.9% of women had tetanus antitoxin > or = 0.1 IU/ml. Multivariate analysis revealed that time after last vaccination, TT doses received and TT vaccination status explained 7.5%, 5.7% and 2.3% of variations in tetanus antitoxin levels respectively. Pregnant women with non-protective levels of tetanus antitoxin (5.1%) pose great risks of neonatal tetanus to their newborns and are also susceptible to maternal tetanus. Proper keeping of TT vaccination records is vitally important to avoid hyper-immunisation.

Immunity to tetanus in male adults in Dar es Salaam, Tanzania

OBJECTIVE

To determine immunity to tetanus in male blood donors with previous diphtheria-pertussis-tetanus (DPT)/tetanus toxoid (TT) vaccination.

DESIGN

A cross sectional study, conducted in September 1999.

SETTING

Blood bank, Muhimbili Medical Centre, Dar es Salaam, Tanzania.

METHODS

Using an antigen competition ELISA technique, serum tetanus anti-toxin levels in two hundred male blood donors were determined.

RESULTS

Vaccination history was absent in 43 (21.5%) blood donors, whereas 60 (30%) and 97 (48.5%) reported childhood DPT and TT vaccination, respectively. Tetanus anti-toxin was undetectable in 47 (23.5%) blood donors and the levels were below that considered protective (> or = 0.1 IU/ml) in 25 (12.5%). Among those with undetectable level, 43 (91.5%) had no vaccination history. Time after last DPT/TT vaccination correlated significantly with tetanus anti-toxin levels (r2=-0.331, p=0.001). In multivariate analysis, TT doses received and time after last vaccination explained 4.8% and 29.4%, respectively, of the variations in tetanus anti-toxin levels.

CONCLUSION

Seventy two (36%) male blood donors were susceptible to tetanus and the susceptibility was highest from 48 years. A regular TT booster dose at 10 yearly intervals is recommended to provide adequate and long lasting immunity in male adults. Proper keeping of vaccination records is emphasised.

Affordable CD4+ T cell counts by flow cytometry. II. The use of fixed whole blood in resource-poor settings

We tested the feasibility and precision of affordable CD4+ T cell counting in resource-poor settings using a recently standardised fixative, TransFix in whole blood (WB) by flow cytometry (FCM). The precision of the assays was established under optimal conditions for single-platform FCM such as the volumetric CytoronAbsolute and the bead-based FACSCan. Fresh WB samples from HIV-seropositive and seronegative patients were tested in Tanzania and South Africa, fixed and sent to the UK for reanalysis 7 days later. Correlation, bias and limits of agreements were analysed by linear regression and the Bland-Altman test. Absolute CD4+ T cell counts remained stable for at least 10 days when TransFix was added to WB in 1:10 dilution at 20-25 degrees C, and for 7 days when added in 1:10 or 1:5 dilution to samples stored to mimic 'tropical' conditions at 37 degrees C. Higher temperatures such as 42 degrees C were tolerated for only short periods since the recovery had decreased to 63% by day 3. The reproducibility of lymphocyte subset analysis remained unchanged by TransFix with coefficient of variations <6% for all T cell subsets. Absolute CD4+ T cell counts and CD4+ T cell % values on fixed samples in the UK showed a high correlation with the results using fresh samples in Tanzania (r=0.993 and 0.969, respectively) and with the samples handled in Johannesburg (r=0.991 and 0.981) with minimal bias. Primary CD4 gating using only a single CD4 antibody also remained accurate in TransFixed samples (r=0.999). Thus, TransFix permits optimal fixation and transport of WB samples in the developing world for FCM to local regional laboratories and for quality assurance in international centres. When used together with inexpensive primary CD4 gating, TransFix will allow reliable and affordable CD4+ T cell counting by FCM in resource-poor settings.

Antibodies to tetanus toxoid in women of childbearing age in Dar es Salaam and Bagamoyo, Tanzania

Our aim was to determine tetanus immunity in women of childbearing age (15-44 years) with histories and/or documentation of having been vaccinated with Tetanus Toxoid (TT) under the Expanded Programme on Immunization in Dar es Salaam and Bagamoyo, Tanzania. Using an ELISA technique, serum levels of TT antibody, antibody avidity and distribution of TT IgG subclass antibodies were determined in 207 apparently healthy women. A TT antibody level of 0.1 IU/ml was considered protective. 99% and 100% of women in Dar es Salaam and Bagamoyo, respectively, had a TT antibody level > or = 0.1 IU/ml. Anti-toxin binding avidity was found to be high in most of the women. In addition to TT IgG3 subclass antibody, TT IgG1 subclass antibody was the most dominant subclass type. A substantial number of women also had TT IgG2 and TT IgG4 subclass antibody responses. A better recording system on TT immunization is recommended to avoid hyper-immunization of women and to optimize the cost-effectiveness of the immunization programme.

Levels and avidity of antibodies to tetanus toxoid in children aged 1-15 years in Dar es Salaam and Bagamoyo, Tanzania

A study was undertaken to determine the serological response in children (aged 1-15 years) immunized with diphtheria-pertussis-tetanus vaccine (DPT) alone or with a tetanus toxoid (TT) booster dose under the Expanded Programme on Immunization in Dar es Salaam and Bagamoyo, Tanzania. Using an ELISA technique, serum levels of anti-TT antibody, antibody avidity and anti-TT IgG subclasses were determined in 138 apparently healthy children. Our findings revealed that 94.7% and 98% of children aged 1-5 years in Dar es Salaam and Bagamoyo, respectively, had anti-TT antibody levels above that considered protective (> or = 0.1 IU/ml). Among 6-15-year-old children, 53.3% in Dar es Salaam and 55% in Bagamoyo had anti-TT antibody levels > or = 0.1 IU/ml. The avidity index of anti-TT antibodies was high in most of the younger children, 84.2% in Dar es Salaam and 92% in Bagamoyo. Significantly fewer older children in Dar es Salaam and Bagamoyo (53.3% and 50%, respectively) had high avidity index antibodies. The predominant anti-TT IgG subclasses were IgG1 and IgG3. It is concluded that the current DPT immunization schedule provides adequate tetanus immunity for children under 5. However, about half of the older children had no protection against tetanus.

Risk factors for HIV-1 seroprevalence among family planning clients in Dar es Salaam, Tanzania

Between March and September of 1995, women receiving family planning (FP) services in three large clinics in Dar es Salaam, Tanzania were invited to participate in a cross-sectional study. Consenting women were interviewed to obtain information about HIV risk factors, and blood for HIV testing was collected. The prevalence of HIV was 16.9% (95% CI: 14.4%-19.3%). The risk of HIV increased significantly with age. Compared with married women, the risk of HIV was significantly higher among cohabiting women (age-adjusted OR = 2.3; 95% CI = 1.5-3.5) and among women who were single, divorced or widowed (age-adjusted OR = 2.3; 95% CI = 1.2-4.4). The risk of HIV was also significantly higher among hotel workers (age-adjusted OR = 4.3; 95% CI = 1.4-12.9). Women with laboratory evidence of sexually transmitted diseases were at increased risk of HIV. This study shows that HIV is a major public health problem among FP clients in Tanzania. Innovative HIV interventions are needed to reduce further spread of HIV infection.

Immunoglobulin profile in HIV-1 infected children in Dar es Salaam

OBJECTIVE

To determine immunoglobulin levels in HIV-1 seronegative and HIV-1 seropositive children at different clinical stages of HIV infection.

DESIGN

Cross-sectional study.

SETTING

Lugalo and Mwanayamala mother and child clinics in Dar es Salaam.

SUBJECTS

Two hundred and ninety-nine children aged 18 months to five years.

MAIN OUTCOME MEASURES

Estimation of immunoglobulin classes (IgG, IgA, IgM, IgD and IgE).

RESULTS

Mean serum levels of all immunoglobulin classes were significantly higher (p < 0.0001) among the HIV-1 seropositive children (IgG = 22.9 g/l, IgA = 2.2 g/l, IgM 2.7 g/l, IgD 101.5 IU/ml and IgE 887.7 IU/ml) than among the HIV-1 seronegative children (IgG = 11.3 g/l, IgA = 1.0 g/l, IgM = 1.5 g/l, IgD = 27.8 UI/ml and IgE 341.3 UI/ml). The percentages of HIV-infected children with immunoglobulin concentrations above mean level were 83% for IgG, 77% for IgA, 78% for IgM, 73% for IgD and 78% for IgE.

CONCLUSION

HIV seropositive children have higher levels of immunoglobulin than seronegative children. There was no correlation between the levels of immunoglobulin classes and CDC clinical staging.

Serum levels of measles IgG antibody activity in children under 5 years in Dar-es-Salaam, Tanzania

Measles IgG antibody levels were estimated in sera from 685 Tanzanian children, 374 (54.6%) boys and 311 (45.4%) girls aged 18 months to 5 years, using an enzyme-linked immunosorbent assay (ELISA). The children were screened for HIV-1 and 2 antibodies using ELISA, and reactive sera were confirmed by Western blot. Nutritional status was assessed by anthropometry. Overall measles vaccination coverage was 98.8%. Measles antibody activity was not detected in 41 (6.0%) children, and ten (1.5%) had antibody levels below 200 mIU/ml, the cut-off level considered to be protective. The non-reactive samples were from one unvaccinated child, one child with unknown vaccination status and 39 vaccinated children. Measles IgG antibody levels were higher in girls (3452.1 mIU/ml) than in boys (2928.2 mIU/ml) (p = 0.02). Higher mean levels were found in children with a history of low birthweight (< 2.5 kg) (p = 0.03). There were no significant differences in measles antibody levels with regard to variations in nutritional status. No correlation (r2 = 0.002) was found between antibody levels and time elapsed since vaccination. In a multivariable logistic regression analysis, children who were HIV-seropositive (n = 9) were more likely to have non-protective antibody levels < 200 mIU/ml (OR = 5.85; 95% CI: 1.37-24.93).

Prevalence of transfusion-associated viral infections and syphilis among blood donors in Muhimbili Medical Centre, Dar es Salaam, Tanzania

OBJECTIVE

To determine the seroprevalence of the main transfusion-associated viral infections and syphilis among blood donors in Muhimbili Medical Centre, Dar es salaam, Tanzania.

DESIGN

Cross sectional study.

SETTING

The blood bank unit of Muhimbili Medical Centre in Dar es salaam, Tanzania.

SUBJECTS

A consecutive sample of 300 blood donors.

INVESTIGATIONS

Search for the presence of antibodies to: human immunodeficiency virus (anti-HIV), hepatitis C virus (anti-HCV), hepatitis B surface antigen (anti-HBs), human T-lymphotropic virus type 1 (anti-HTLV-1), syphilis and for hepatitis B surface antigen (HbsAg).

RESULTS

The overall frequency of anti-HIV, anti-HCV, anti-HBs, HbsAg, anti-HTLV-1, and syphilis antibodies were 8.7%, 8%, 20%, 11%, 0%, and 12.7%, respectively. Among the HIV seronegative donors, the frequency of anti-HCV, anti-HBs, HBsAg, anti-HTLV-1, and syphilis antibodies were 8.8%, 22%, 11%, 0%, and 10.9%, respectively. HIV-seropositive donors had an increased risk for being positive for syphilis antibodies (OR = 3.6, 95% CI 1.4-9.0) and HBsAg (OR = 4.0, 95% CI 1.0-18.8), but not anti-HCV (OR = 0.9, 95% CI 0.86-0.97), anti-HBs (OR = 1.0, 95% CI 0.2-5.3) or anti-HTLV-1 (OR = 0.0).

CONCLUSION

Donor blood including that from HIV-seronegative donors, has high frequency of HCV, HBV, and syphilis antibodies but not anti-HTLV-1. A significant association exists in the occurrence of HIV, HBV and syphilis; and due to the association of syphilis and HIV, clients with history of sexually transmitted disease should be excluded during donor selection. From these observations were recommend: (i) routine screening of donor blood for HIV, HCV, HBV, and syphilis antibodies but not HTLV-1 and; (ii) a larger study to generate more accurate estimates of the magnitude the transfusion-transmissible infectious diseases.

Evaluation of sexually transmitted diseases diagnostic algorithms among family planning clients in Dar es Salaam, Tanzania

OBJECTIVES

To determine the prevalence of sexually transmitted diseases (STDs) and to assess the validity of STD screening approaches among family planning clients in Dar es Salaam, Tanzania.

METHODS

Between March and September 1995, information about sociodemographic characteristics, contraceptive use, sexual behaviour, and medical history was obtained from consenting women (n = 908). After interview, blood and genital specimens were collected for diagnosis of STDs and HIV. Based on the information obtained at interview and clinical examination, STD diagnostic algorithms were developed and validated.

RESULTS

The prevalence of STDs was HIV (16.9%), gonococcal and/or chlamydial cervicitis (8.2%), and Trichomonas vaginalis and/or Candida albicans (27.2%). The risk of cervicitis was increased among unmarried women and among women with a husband < or = 25 years of age and women having more than one sex partners in the past 3 months or a new sex partner during the past month. Most women with cervicitis (62.2%) and vaginitis (67.6%) were asymptomatic. A screening strategy for cervicitis based on symptoms had a sensitivity of 29.7%, a specificity of 84.1%, and a positive predictive value (PPV) of 15.9%. The corresponding figures for an algorithm based on clinical signs were 20.3%, 90.2%, and 15.6%. The sensitivity of a simple risk assessment algorithm ranged from 20.3% to 73%. An approach based on both risk assessment (risk score > or = 1) and clinical signs (cervical mucopus and friability) had a sensitivity of 37.8%, a specificity of 87.5%, and a PPV of 21.4%. A syndromic approach for vaginitis resulted in a higher sensitivity than the approach based on the type of vaginal discharge.

CONCLUSION

Although there is no single screening strategy for cervicitis which can be advocated for large scale application, risk assessment might be the only cost effective strategy for identifying women with cervicitis in family planning clinics in Tanzania.

The incidence of HIV infection among women using family planning methods in Dar es Salaam, Tanzania

OBJECTIVES

To determine the risk factors for HIV seroconversion and assess the association between contraceptive use and HIV infection among women attending three large family planning clinics in Dar es Salaam, Tanzania.

DESIGN

Prospective cohort study.

METHODS

Between 1992 and 1995, 2471 HIV-negative women were followed prospectively. Information about sociodemographic characteristics, sexual behavior, contraceptive use and other risk factors was collected at recruitment and updated at follow-up visits. At the end of the study, specimens were collected for HIV testing and laboratory diagnosis of sexually transmitted diseases.

RESULTS

The overall HIV incidence was 3.4 per 100 person-years [95% confidence interval (Cl), 2.6-4.1]. The risk of HIV seroconversion decreased with increasing age (P=0.04, test for trend). Women reporting three or more sex partners during the follow-up period had the highest risk of HIV [age-adjusted relative risk (RR), 4.89; 95% Cl, 2.61-9.17]. Having an uncircumcised husband was associated with a significantly increased risk of HIV (age-adjusted RR, 3.60; 95% Cl, 1.12-11.59). The risk of HIV was also significantly increased among women with gonorrhoea (age-adjusted RR, 3.51; 95% Cl, 1.60-7.71) and candidiasis at baseline (age-adjusted RR, 1.98; 95% Cl, 1.17-3.33) and among women reporting alcohol consumption during the follow-up period. After controlling for other risk factors, the risk of HIV infection amongst users of oral contraceptive, intrauterine device and injectable contraceptive was not significantly increased. Similarly, there was no significant trend associated with increasing duration of use of any of these contraceptive methods.

CONCLUSION

These findings confirm that a large number of new HIV infections continue to occur in this population. Reassuringly, no significant association was observed between HIV and use of specific contraceptive methods. Interventions to reduce further spread of HIV are still urgently needed.

Association between carriage of oral yeasts, malnutrition and HIV-1 infection among Tanzanian children aged 18 months to 5 years

The objective was to determine whether there is an association between carriage of oral yeasts, malnutrition and HIV-1 infection among Tanzanian children. A case-control study design within a cross-sectional study was used, and the outcome was carriage of oral yeasts. The exposure variables were malnutrition and HIV-1 antibody, and confounders to be adjusted for were age, sex, and breastfeeding. The study was carried out in Dar-es-Salaam, Tanzania, in two maternal and child health (MCH) clinics that offer routine medical checkups to all expectant mothers and children aged between 0 and 5 years in the catchment area. A total of 882 children aged between 18 months and 5 years participated. Smears from the tongue and buccal mucosa were examined for oral yeasts. Malnutrition was categorized according to standards on the MCH chart and World Health Organization/Centers for Disease Control (WHO/CDC) standards as weight-for-height (wasted), weight-for-age (underweight), and height-for-age (stunted). HIV-1 infection was determined by an enzyme-linked immunosorbent assay. Reactive sera were confirmed by Western Blot. About 27% of the children were slightly or severely malnourished according to standards on the MCH chart. According to WHO/CDC standards, 2.6% were wasted, 16.3% were underweight, and 29.6% were stunted. Fourteen (1.6%) were seropositive for HIV-1 antibody. Hyphal forms and blastospores were much more frequent among children infected with HIV-1 with odds ratios ranging from 3.8 (95% CI: 1.3;11.2) to 6.2 (95% CI: 2.1;18.4) depending on categorization of malnutrition. Malnutrition was a risk factor, too, albeit to a much lesser and insignificant degree. The study supports our previous findings that malnutrition may predispose to carriage of oral yeasts and subsequent infection. However, in this study population HIV infection was clearly the predominant risk factor.

Nutritional status of under fives attending maternal and child health clinics in Dar es Salaam, Tanzania

We designed a study to assess the nutritional status of children under five years of age attending MCH clinics in Dar es Salaam. This was a cross-sectional anthropometric study involving children 6-24 months who from July to August 1993 were attending Magomeni MCH clinic and those aged 18 months to five years who were attending Lugalo and Mwananyamala MCH clinics for routine growth monitoring and for vaccination between May to August 1994. The data collected included age, birthweight, sex, weight, height, breastfeeding status and HIV-1 serostatus. Of the 1854 children enrolled (961 boys and 893 girls) 31.6% were stunted, 14.6% were underweight and 2.9% were wasted. The highest percentage of stunting and wasting was observed between 11 and 25 months and 36 to 40 months. Of the 849 children tested for HIV-1, 14 (1.7%) were seropositive and two out of 770 (0.3%) were born with low weight. HIV seropositivity and low birthweight were both associated with stunting and wasting. We conclude that malnutrition is still a sizeable problem among children attending urban MCH clinics in Dar es Salaam especially among those aged less than three years, to whom special malnutrition control strategies should be targeted. There is also a need to identify factors responsible for the observed decline in MCH attendance with age and correct the situation.

Immunohaematological findings in healthy and HIV-1 infected adults in Dar es Salaam, Tanzania

In order to assess the prognostic value of lymphocyte subsets and immune activation markers in HIV-1 infected Tanzanian patients, peripheral white blood cell(WBC) count, total lymphocytes, CD4+ and CD8+ T-lymphocytes and Beta-2 microglobulin (B-2M) concentrations were determined among healthy HIV-1 seronegative Tanzanian blood donors and in infected Tanzania individuals in different clinical stages of HIV-1 infection. CD4+ T-lymphocytes, CD8+ T-lymphocyte percentages, CD4:CD8 lymphocyte ratios and the concentrations of B-2M were strongly correlated with the clinical stages of HIV-1 infection. These results suggest that B-2M could be a useful prognostic marker in HIV-1 infection in settings where T-lymphocyte subset determinations cannot be done.

Evaluation of the FACScount, TRAx CD4 and Dynabeads methods for CD4 lymphocyte determination

A study to evaluate the performance of the FACScount, TRAx CD4 and Dynabeads methods for the determination of CD4+ T lymphocyte subset levels was conducted in Tanzania as part of a World Health Organization (WHO) collaborative multicenter field evaluation of alternative methodologies for the enumeration of CD4+ T lymphocytes. The objective was to compare the performance of these alternative methods in a developing country setting, against that of flow cytometry as the reference standard. T lymphocyte subset levels were determined in 91 HIV seronegative and 98 HIV-1 seropositive adults using the three alternative methods. CD4+ and CD8+ T lymphocyte counts were determined by all methods except for TRAx CD4 enzyme linked immunosorbent assay (ELISA) which measures CD4+ T lymphocyte levels only. Linear regression analysis was done to correlate the counts obtained by the alternative methods to those obtained by flow cytometry. The overall correlation coefficients of FACScount and Dynabeads CD4+ and CD8+ T lymphocyte counts with those of flow cytometry were high (r > 0.9). A lower correlation (r = 0.631) was obtained when TRAx CD4+ ELISA counts were compared to those of the reference method. These results show that two of these alternative methodologies are suitable for the determination of CD4+ and CD8+ T lymphocyte counts with the use of African blood samples. Since the methods are simpler and cheaper than flow cytometry, they provide an alternative option for the enumeration of T lymphocyte subsets in laboratories with limited facilities.

Biotypes of oral Candida albicans isolates in a Tanzanian child population

Although biotypes of Candida albicans from adult populations, especially in the West, have been described, there are no data either from a child population, or from the African continent. Hence a total of 200 oral C. albicans isolates from Tanzanian children aged 6-24 months were biotyped using two commercially available API micromethod kit systems and a boric acid resistance test. The predominant biotypes, which comprised two thirds of the organisms isolated, were J1S (19.5%), A1S (16.0%), J1R (14.5%), A1R (9.5%) and P1R (7.5%). In total, 16 new biotypes comprising 44 (22%) isolates which have not hitherto been described were found in this Tanzanian population and, of these, the P1R biotype predominated with 15 (7.5%) isolates. There was no significant association between predominant biotypes (with clusters > or = 15 isolates) and age, gender, breast feeding and malnutrition. These data indicate that the biotype profile of C. albicans isolates may differ in paediatric and adult populations, and/or global distribution of various subtypes of this common opportunistic pathogen.