Sub-Saharan Africa suffers from an excessively high endemicity of hepatitis B virus (HBV), but little is known about the prevalent genotypes. In this study, we investigated the PreS1/PreS2/S genes of 127 viruses obtained from 12 locations in Mali, Burkina Faso, Togo, Benin, Nigeria, Cameroon, and the Democratic Republic of Congo. Except for those obtained from the Cameroon HIV cohort (18/22 HBV genotype A), 96 of 105 sequences belonged to HBV genotype E (HBV/E), and viral DNA was very similar (1.67% diversity) throughout this vast HBV/E crescent, which spans 6000 km across Africa. The low diversity suggests that HBV/E may have a short evolutionary history. Considering a typical mutation rate of DNA viruses, it would take only 200 years for the strain diversity of HBV/E viruses to develop from a single introductory event. The relatively recent introduction of HBV/E into humans would also explain its conspicuous absence in the Americas, despite the forced immigration of slaves from west Africa, until the early 19th century. Infection during infancy is mostly associated with chronic carrier status, and this combination can account for the explosive spread of virtually identical viruses within a community, but whether other routes of long-range transmissions must be considered becomes an important question.

One hundred and twenty-two new hepatitis B virus (HBV) preC/C sequences and three complete genomes from three major countries in West Africa were analysed. The majority of sequences were of genotype E and the only other genotype found was genotype A. Although for genotype E sequences, the genetic diversity of the preC/C gene was about two to three times higher than that of the preS/S gene, it was still considerably lower than that for genotype A sequences. The HBV/E preC/C gene was related most closely to subgenotype D1 and D2 sequences. Evidence of recombination was found in two strains that were of genotype A in the preS/S gene and of genotype E in the preC/C gene. The genotype A strains from Cameroon, Mali and Nigeria could be divided phylogenetically into three subtypes, A3 and two new subtypes, tentatively designated A4 and A5. Each subtype presented a genetic diversity of 2?19-3?85 % and intersubtype distances of 4?47-5?97 %. Interestingly, one sample from Nigeria showed evidence of a triple recombination of genotypes E/D and A, separated by a genotype G-specific insert of 36 bp. Of 110 patients, 19 (17?3 %) showed a coinfection of genotypes A and E, mostly in human immunodeficiency virus-positive children from Cameroon. Thus, in Cameroon, where both genotypes coexist, 37 % of all individuals tested had mixed infections. The low genetic variability in the preC/C gene of genotype E supports our previous speculation about a relatively short evolutionary history of this genotype, in contrast to the subtype-rich African genotype A strains.

Sub-Saharan

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Abstract.Typhoid fever continues to pose a serious health challenge in developing countries. A reliable database on positive blood cultures is essential for prompt interventions. To generate reliable data on Salmonella enterica serovar Typhi (S. Typhi)–positive blood culture trends in typhoidal Salmonella in Nigeria alongside changing contextual factors and antimicrobial resistance patterns, a retrospective cohort study was conducted in two hospitals in Lagos between 1993 and 2015. Medical records of typhoid patients were reviewed for positive culture and antibiogram, using standard procedures and analyzed. Additional data were retrieved from a previous study in seven facilities in Abuja and three hospitals in Kano from 2008 to 2017 and 2013 to 2017, respectively. A declining trend in percent positivity of S. Typhi was observed in Abuja with more erratic trends in Lagos and Kano. In Lagos, more than 80% of the isolates from the entire study period exhibited multiple drug resistance with a generally increasing trend. Of the chosen contextual factors, improvements were recorded in female literacy, access to improved water supply, diarrheal mortality in children younger than 5 years, gross domestic product, and poverty while access to improved sanitation facilities decreased over time nationally. Typhoid fever still poses a serious health challenge in Nigeria and in antibiotic resistance, and is a major health security issue. A combined approach that includes the use of typhoid vaccines, improvements in sanitation, and safe water supply is essential.

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A total of 635 clinically diagnosed typhoid fever patients were bled from three different health institutions in the metropolis of Lagos, Nigeria over a period of 15 months, May 1997 to July 1998. Out of the total blood cultured, 101 (15.9% ) isolates of Salmonella species were isolated of which 68 (67.3% ) were S. typhi, 17 (16.8% ) and 16 (15.8% ) were S. paratyphi A and S. arizonae respectively. The overall isolation rate of S. typhi among patients is 10.7% , with most isolates 45.9% found among the severely-ill young adults, age group 1 6 -30 years. All isolates were subjected to anti-microbial susceptibility testing using 12 different antibiotics: chloramphenicol, ampicillin, cotrimoxazole, gentamicin, colistin sulfate, nalidixic acid, nitrofurantoin, cefotaxime, tetracycline, streptomycin, ofloxacin and ciprofloxacin. All the S. typhi and S. paratyphi A isolates showed resistance to two or more of the 10 of 12 antibiotics tested particularly the 3-first-line antibiotics commonly used (chloramphenicol, ampicillin and cotrim oxazole) in the treatment of typhoid fever in Nigeria. No isolate showed resistance to ofloxacin and ciprofloxacin, however, nalidixic acid and gentamicin showed a moderate and appreciable inhibition to most of our isolates.