No abstract

The incidence of colorectal cancer (CRC) is gradually rising in sub-Saharan Africa.This may be due to dietary changes associated with urbanisation, which may induce tumour-promoting gut microbiota composition and function. We compared faecal microbiota composition and activity in 10 rural and 10 urban Zimbabweans for evidence of a differential CRC risk. Dietary intake was assessed by a food frequency questionnaire. Faecal microbiota composition, metabolomic profile, functional microbial genes were analysed, and bile acids and short chain fatty acids quantified.Animal protein intake was higher among urban volunteers, but carbohydrate and fibre intake were similar. Bacteria related to Blautia obeum, Streptococcus bovis and Subdoligranulum variable were higher in urban residents, whereas bacteria related to Oscillospira guillermondii and Sporobacter termitidis were higher in rural volunteers. Faecal levels of primary bile acids, cholic acid and chenodeoxycholic acid (p<0.05), and secondary bile acids, deoxycholic acid (p<0.05) and ursodeoxycholic acid (p<0.001) were higher in urban residents. Faecal levels of acetate and propionate, but not butyrate, were higher in urban residents. The gut microbiota composition and activity among rural and urban Zimbabweans retain significant homogeneity (possibly due to retention of dietary fibre), but urban residents have subtle changes, which may indicate a higher CRC risk.

We have characterized the EV-like dermatosis of acquired HIV in 4 adolescents. Multiple HPV types were isolated in skin tissue samples, including β-HPV, but also high levels of HPV 1 and 2. ARV did not improve the EV eruption.

The interplay between hereditary and environmental factors in the causation of colorectal cancer in sub-Saharan Africa is poorly understood. We carried out a community based case-control study to identify the risk factors associated with colorectal cancer in Zimbabwe. We recruited 101 cases of colorectal cancer and 202 controls, matched for age, sex and domicile. Potential risk factors including family history, socioeconomic status, urbanization, diabetes mellitus and previous schistosomiasis were evaluated. Conditional logistic regression was used to estimate the odds ratios associated with the different factors. Cases were more likely to have a tertiary education (32.7 vs. 13.4%, P<0.001) and a higher income (18.8 vs. 6.9%, P=0.002). After multivariate analysis, diabetes mellitus [odds ratio (OR): 5.3; 95% confidence interval (CI): 1.4-19.9; P=0.012], previous urban domicile (OR: 2.8; 95% CI: 1.0-7.8; P=0.042), previous schistosomiasis (OR: 2.4; 95% CI: 1.4-4.2; P=0.001) and cancer in a first-degree relative (OR: 2.4; 95% CI: 1.2-4.8; P=0.018) were associated independently with colorectal cancer. Our findings suggest that family history, diabetes mellitus, previous schistosomiasis and approximation to a western lifestyle are the predominant associations with colorectal cancer in Africans. This offers opportunities for targeted prevention and hypothesis-driven research into the aetiology of colorectal cancer in this population.