Co-occurrence of bacteria and viruses and serotype distribution of Streptococcus pneumoniae in the nasopharynx of Tanzanian children below 2 years of age following introduction of the PCV13.

Introduction: Pneumococcal conjugate vaccines have reduced severe disease attributed to vaccine-type pneumococci in children. However, the effect is dependent on serotype distribution in the population and disease development may be influenced by co-occurrence of viral and bacterial pathogens in the nasopharynx. Methods: Following introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) in Tanzania we performed repeated cross-sectional surveys, including 775 children below 2 years of age attending primary healthcare centers. All children were sampled from nasopharynx and pneumococci were detected by single-target PCR. Pneumococcal serotypes/groups and presence of viruses and other bacteria were determined by two multiplex PCR assays. Results: The prevalence of PCV13 vaccine-type pneumococci decreased by 50%, but residual vaccine-types were still detected in 21% of the children 2 years after PCV13 introduction. An increase in the non-vaccine-type 15 BC was observed. Pneumococci were often co-occurring with Haemophilus influenzae, and detection of rhino/enterovirus was associated with higher pneumococcal load. Discussion: We conclude that presence of residual vaccine-type and emerging non-vaccine-type pneumococci in Tanzanian children demand continued pneumococcal surveillance. High co-occurrence of viral and bacterial pathogens may contribute to the disease burden and indicate the need of multiple public health interventions to improve child health in Tanzania.

Prevalence and factors associated with HIV and syphilis infection among children aged 0-36 months in Kilimanjaro, Tanzania: a community-based cross-sectional study.

BACKGROUND: Childhood mortality is high in sub-Saharan Africa. Mother-to-child transmission (MTCT) of HIV and congenital syphilis are among significant causes. Dual elimination of these two infections is one of the international goals. Community-based studies on the burden of HIV and syphilis among children will contribute to fine-tuning the interventions to achieve the elimination goal. This study aims to describe the prevalence of HIV and syphilis among children aged 0-36 months and associated factors in northern Tanzania. METHODS: This was a community-based cross-sectional study, which was conducted in all the seven districts of Kilimanjaro region. Multistage sampling was used, and a total of 2452 children aged 0 to 36 months and their primary caretakers were enrolled. Interviews were conducted with the mother/caretaker, and dried blood samples were collected from the children and processed for laboratory diagnosis of HIV and syphilis. HIV ELISA was first performed on all the samples. Positive samples of children < 18 months were confirmed using PCR. RESULTS: The prevalence of HIV among 2452 children aged 0-36 months was 1.7% (n = 42). There was a significant difference in the distribution of HIV by age of the child, maternal antenatal attendance, and breastfeeding history.The prevalence of syphilis was 0.4% (n = 10). Five of the children were more than 1 year old. All children with a positive test for syphilis were from Moshi rural district, and their mothers consumed alcohol. No child was co-infected with HIV and syphilis. CONCLUSIONS: Though the prevalence of the two infections was low, detecting syphilis in children suggests a missed opportunity in screening women during pregnancy. The region may be on track with the goal to achieve dual elimination of mother-to-child transmitted HIV and syphilis. However, efforts are needed to reduce missed opportunities for screening women for syphilis and HIV early in pregnancy and retesting at 3rd trimester/delivery. Strategies to improve testing for HIV-exposed children are needed.

Carriage of penicillin-non-susceptible pneumococci among children in northern Tanzania in the 13-valent pneumococcal vaccine era.

OBJECTIVES: To determine the antibiotic susceptibility and serotype distribution of colonizing Streptococcus pneumoniae in Tanzanian children. Serial cross-sectional surveys were performed following the national introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) in December 2012. METHODS: A total of 775 children less than 2 years of age were recruited at primary health centres in Moshi, Tanzania between 2013 and 2015, and samples were obtained from the nasopharynx. S. pneumoniae were isolated by culture and tested for antibiotic susceptibility by disc diffusion and E-test methods; molecular testing was used to determine serotype/group. RESULTS: Penicillin non-susceptibility in the isolated pneumococci increased significantly from 31% (36/116) in 2013, to 47% (30/64) in 2014 and 53% (32/60) in 2015. Non-susceptibility to amoxicillin/ampicillin and ceftriaxone was low (n=8 and n=9, respectively), while 97% (236/244) of the isolates were non-susceptible to trimethoprim-sulfamethoxazole. The majority of the children (54%, n=418) had been treated with antibiotics in the past 3 months, and amoxicillin/ampicillin were overall the most commonly used antibiotics. Carriage of penicillin-non-susceptible pneumococci was more common in children with many siblings. The prevalence of PCV13 serotypes among the detected serotypes/groups decreased from 56% (40/71) in 2013 to 23% (13/56) in 2015. CONCLUSIONS: Penicillin non-susceptibility in S. pneumoniae colonizing Tanzanian children increased during an observation period shortly after the introduction of PCV13. Measures to ensure rational use of antibiotics and more effective systems for surveillance of antibiotic resistance and serotype distribution are needed to assure continued effective treatment of pneumococcal disease.

HIV Resistance and Prevention of Mother-to-Child Transmission Regimen in HIV-Infected Infants in Northern Tanzania.

Prevention of mother-to-child transmission (PMTCT) guidelines recommend that all HIV-infected pregnant women receive antiretroviral therapy (Option B) and HIV-infected infants should initiate therapy with a protease inhibitor-based regimen; however, implementation of these guidelines has lagged in many resource-limited settings. Tanzania only recently implemented these guidelines with little country-specific data to inform whether HIV non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance was present among infected infants under the Option A guidelines. This study aimed to identify primary resistance mutations in HIV-infected infants and to identify risk of nevirapine (NVP) resistance based on maternal and infant NVP exposure. Infant dried blood spots (DBSs) were sent to the zonal reference laboratory at Kilimanjaro Christian Medical Centre Clinical Laboratory and underwent DNA polymerase chain reaction testing for HIV as standard of care. Using the clinical laboratory registry, HIV-positive DBS cards, stored at ambient temperature, were identified and sent for further viral load testing, nucleotide sequencing, and analysis. Clinical information was obtained from the PMTCT clinical sites and the National PMTCT registry for information regarding maternal and infant demographics and PMTCT treatment regimen. Results demonstrated that infants exposed to NVP were more likely to have high level resistance mutations (HLRMs) to NVP than those infants not exposed to NVP (p = .002). The most common HLRMs to NVP were K103 N, Y181C, and Y188 L. HIV subtype A was most common, followed by subtype C. Approximately one-third of HIV-infected infants had documented referral to HIV care. This study demonstrated the ongoing need to scale up and strengthen points along the PMTCT continuum and supported the recommendation for all HIV-infected infants to initiate a lopinavir/ritonavir-based antiretroviral therapy regimen.

HIV-1 drug mutations in children from northern Tanzania.

OBJECTIVES: In resource-limited settings, it is a challenge to get quality clinical specimens due to poor infrastructure for their collection, transportation, processing and storage. Using dried blood spots (DBS) might be an alternative to plasma for HIV-1 drug resistance testing in this setting. The objectives of this study were to determine mutations associated with antiretroviral resistance among children <18 months old born to HIV-1-infected mothers enrolled in prevention of mother-to-child transmission services in northern Tanzania. PATIENTS AND METHODS: Kilimanjaro Christian Medical Center (KCMC) Clinical Laboratory is the zonal centre for early infant diagnosis using DBS in northern Tanzania. DBS were collected from January 2011 to December 2012. Mothers were kept on triple therapy and single-dose nevirapine before pregnancy and during labour, respectively. Infants were given single-dose nevirapine and most of them were breastfed. Genotypic resistance was determined in those with a viral load of >400 copies/mL. RESULTS: Genotypic resistance mutations were detected in 13 of 46 children (28%). HIV-1 genotypes were A1 (n = 27), C (n = 10), A/D (n = 4), D (n = 3) and CRF10_CD (n = 2). The median age was 12 weeks (IQR 6-28). The mean log10 viral load was 3.87 copies/mL (SD 0.995). All major mutations were detected in the reverse transcriptase gene and none in the protease gene region. The most frequent mutations were Y181C (n = 8) and K103N (n = 4), conferring resistance to non-nucleoside reverse transcriptase inhibitors. CONCLUSIONS: One-third of infants newly diagnosed with HIV in northern Tanzania harboured major drug resistance mutations to currently used antiretroviral regimens. These mutations were detected from DBS collected from the field and stored at room temperature. Surveillance of drug resistance among this population in resource-limited settings is warranted.

Evolution of human immunodeficiency virus type 1 serotypes in northern Tanzania: a retrospective study.

The HIV-1 epidemic in Tanzania is characterized by the circulation of heterogeneous virus subtypes. A retrospective study was conducted to determine the changing pattern of circulating HIV-1 subtypes in northern Tanzania. A peptide-binding enzyme immunoassay (PEIA) was employed to analyse 305 HIV-1 positive serum and plasma samples collected between 1985 and 2005. Samples were serotyped using synthetic peptides representing HIV-1 genotypes A-E derived from consensus gp120 V3 sequences. Plasma samples collected in 2005 were V3 genotyped for comparison with PEIA results. In 1985, serotypes A and D were co-circulating while serotype C was first detected in 1990. In 2001 and 2005, serotype C was the most prevalent, serotype A was stable, and serotype D was declining. PEIA is relatively rapid and simple to perform compared to molecular approaches, and is a valuable epidemiological tool in regions with limited resources. HIV-1 classification into serotypes based on antigenic V3 diversity may be a useful screening tool for the identification of HIV-1 variants with regard to diagnosis, treatment, disease progression and candidate vaccine development.

Prevalence of reverse transcriptase and protease mutations associated with antiretroviral drug resistance among drug-naïve HIV-1 infected pregnant women in Kagera and Kilimanjaro regions, Tanzania.

BACKGROUND: Access to antiretroviral drugs for HIV-1 infection has increased in sub-Saharan Africa (SSA) during the past few years. Mutations in the HIV-1 genome are often associated with treatment failure as indicated by viral replication and elevated levels of virus in the blood. Mutations conferring resistance to antiretroviral drugs are based on comparing gene sequences with corresponding consensus sequences of HIV-1 subtype B that represents only 10% of the AIDS pandemic. The HIV pandemic in SSA is characterized by high viral genetic diversity. Before antiretroviral drugs become more widely available, it is important to characterize baseline naturally occurring genetic mutations and polymorphisms associated with antiretroviral drug resistance among circulating HIV-1 subtypes. METHODS: The prevalence of mutations associated with antiretroviral drug resistance in protease (PR) and reverse transcriptase (RT) regions among antiretroviral treatment-naïve HIV-1 infected pregnant women was investigated in Bukoba (Kagera) and Moshi (Kilimanjaro) municipalities, Tanzania, between September and December 2005. The HIV-1 pol gene was amplified using primers recognizing conserved viral sequences and sequenced employing BigDye chemistry from 100 HIV-1 seropositive treatment-naïve pregnant women and 61 HIV-1 seropositive women who had received a single dose of Nevirapine (sdNVP). Positions 1-350 of the RT and 1-99 of the PR genes were analyzed for mutations based on the Stanford University HIV Drug Resistance Database. RESULTS: HIV-1 subtypes A, C, D, CRF10_CD and Unique Recombinant Forms (URF) were detected. Primary mutations associated with NRTI and NNRTI resistance were detected among 3% and 4% of treatment-naïve strains, respectively. Primary mutations associated with NRTI and NNRTI resistance were detected in 1.6% and 11.5% of women who had received sdNVP, respectively. None of the primary mutations associated with PI resistance was found. Polymorphisms detected in RT and PR sequences were mainly mutations that are found in the consensus sequences of non-B subtypes CONCLUSION: Based on the WHO HIV Drug Resistance Research Network Threshold of less than 5%, the baseline prevalence of primary mutations among treatment-naïve HIV-1 infected pregnant women in Kagera and Kilimanjaro regions was low. The significance of HIV-1 subtype B polymorphic positions with respect to antiretroviral resistance identified among the prevalent HIV-1 subtypes is unknown. More studies addressing the correlation between polymorphic mutations, antiretroviral resistance and clinical outcome are warranted in regions where non-B subtypes are prevalent.

Diversity of human immunodeficiency virus type 1 subtypes in Kagera and Kilimanjaro regions, Tanzania.

A strategy to prevent the spread of HIV-1 worldwide is complicated by the high genetic diversity of the virus. To gain a better understanding of the HIV-1 genetic diversity in Tanzania, a molecular epidemiological investigation was conducted in Kagera and Kilimanjaro regions. While several studies have addressed HIV-1 subtypes in Tanzania, this is the first study to describe the virus subtypes circulating in Kagera. The Kagera region is the epicenter of the HIV-1 epidemic in Africa, and it was therefore of interest to compare the prevalence of HIV subtypes in this region and Kilimanjaro. Blood samples were obtained from 246 HIV-1-infected pregnant women attending antenatal clinics. Plasma HIV-1 RNA was extracted, amplified, and sequenced in the env C2V3 and/or pol regions from 209 samples. Based on the analysis of env C2V3 and pol sequences, 47.4% had concordant subtypes, 19.1% were discordant indicating recombination, and for 33.5% sequences were obtained for only one region. The distribution HIV-1 subtypes based on the phylogenetic analysis of paired env C2V3/ pol sequences in Kagera region was A/A (27.8%), C/C (29.6%), D/D (16.7%), and unique recombinant forms (25.9%), and in Kilimanjaro region was A/A (32.9%), C/C (25.9%), D/D (10.6%), CRF10_CD (1.2%), and unique recombinant forms (29.4%). The env C2V3 subsubtype A2 and env C2V3/pol CRF10_CD were also observed indicating that these recombinants are circulating in Tanzania. The high diversity of HIV-1 subtypes and the high prevalence of recombinants demonstrated in this study necessitate expanded and continuous monitoring of the epidemic in Tanzania. The trend may have implications for current national control strategies against the HIV-1 epidemic.