Molecular epidemiology of hepatitis B virus infection in Tanzania.

Despite the significant public health problems associated with hepatitis B virus (HBV) in sub-Saharan Africa, many countries in this region do not have systematic HBV surveillance or genetic information on HBV circulating locally. Here, we report on the genetic characterization of 772 HBV strains from Tanzania. Phylogenetic analysis of the S-gene sequences showed prevalence of HBV genotype A (HBV/A, n=671, 86.9 %), followed by genotypes D (HBV/D, n=95, 12.3 %) and E (HBV/E, n=6, 0.8 %). All HBV/A sequences were further classified into subtype A1, while the HBV/D sequences were assigned to a new cluster. Among the Tanzanian sequences, 84 % of HBV/A1 and 94 % of HBV/D were unique. The Tanzanian and global HBV/A1 sequences were compared and were completely intermixed in the phylogenetic tree, with the Tanzanian sequences frequently generating long terminal branches, indicating a long history of HBV/A1 infections in the country. The time to the most recent common ancestor was estimated to be 188 years ago [95 % highest posterior density (HPD): 132 to 265 years] for HBV/A1 and 127 years ago (95 % HPD: 79 to 192 years) for HBV/D. The Bayesian skyline plot showed that the number of transmissions 'exploded' exponentially between 1960-1970 for HBV/A1 and 1970-1990 for HBV/D, with the effective population of HBV/A1 having expanded twice as much as that of HBV/D. The data suggest that Tanzania is at least a part of the geographic origin of the HBV/A1 subtype. A recent increase in the transmission rate and significant HBV genetic diversity should be taken into consideration when devising public health interventions to control HBV infections in Tanzania.

Effects of delayed sample processing and freezing on serum concentrations of selected nutritional indicators.

BACKGROUND: Environmental conditions during sample processing, shipping, and storage are often suboptimal, particularly in less developed countries. We used samples from US volunteers to investigate the effects of delayed whole blood (WB) processing and delayed freezing of serum on selected nutritional indicators. METHODS: WB tubes (n = 35) were either stored at 32 degrees C for up to 3 days before serum separation or centrifuged within 2 h of collection; serum samples were stored at 11 degrees C for up to 14 days to simulate delayed shipping. We assessed analyte stability by comparing results with data from optimally prepared/stored serum samples (<2 h on the clot, frozen at -70 degrees C) and by using clinical-acceptability criteria based on combined analytical imprecision and intraindividual biologic variability. RESULTS: Clinically acceptable changes in concentration varied from 3%-15%. Delayed WB processing did not unacceptably affect concentrations of carotenoids and vitamins B(12), D, and E; however, we obtained clinically unacceptable changes for ferritin (+9%), soluble transferrin receptor (sTfR) (+5%), and folate (-30%) after 1 day, and for vitamin A (-10%) after 3 days. Delayed freezing of serum did not affect concentrations of ferritin, sTfR, carotenoids, and vitamins A, B(12), and E; however, we obtained clinically unacceptable changes for vitamins C (-20%) and D (+7%) after 7 days and for folate after 14 days (-22%). CONCLUSIONS: Despite substantial delays in WB processing or in the freezing of serum samples, most nutritional indicators showed remarkable stability. This information is important for both the design of field studies and the use of residual samples subjected to suboptimal preanalytical factors.

A randomized, 4-month mango and fat supplementation trial improved vitamin A status among young Gambian children.

Supplementation with carotene-rich fruits may be an effective and sustainable approach to prevent vitamin A deficiency. To test the effectiveness of mango supplementation, 176 Gambian children, aged 2 to 7 y, were randomly assigned to one of four treatments: 75 g of dried mango containing approximately 150 micro g retinol activity equivalents with (MF) or without (M) 5 g of fat, 5 d/wk for 4 mo or 60,000 micro g of vitamin A (A) or placebo (P) capsule at baseline. After 4 mo, plasma beta-carotene was greater in both the M (P < 0.05) and MF (P = 0.07) groups compared with the P group. After controlling for baseline plasma retinol, elevated acute phase proteins and age, plasma retinol concentrations in the A and MF, but not M, groups were higher than in the P group at the end of the study (P < 0.01). Increases in retinol concentrations, however, were small in both groups. These results support the use of dietary supplementation with dried mangoes and a source of fat as one of several concurrent strategies that can be used to help maintain vitamin A status of children in developing countries where there is a severe seasonal shortage of carotenoid-rich foods.