Upper respiratory infections in a rural area with reduced malaria transmission in Senegal: a pathogens community study.

BACKGROUND: Acute Respiratory Infections (ARI) are common causes of febrile illnesses in many settings in Senegal. These infections are usually managed presumptively due to lack of appropriate diagnostic tools. This situation, can lead to poor management of febrile illness or antibiotic misuse. In addition, there are limited data on the spectrum of pathogens commonly responsible for these ARI. This study was conducted to explore the pathogens community among patients with acute respiratory infection in a rural area in Senegal. METHODS: A cross sectional study was conducted from August to December 2015. Children and adult patients attending Keur Socé health post for signs suggestive of acute respiratory infection were enrolled after providing inform consent. Eligible participants were recruited using a consecutive sampling method. Paired nose and throat swabs were collected for pathogen detection. Samples were processed using a multiplex PCR designed to identify 21 pathogens including both virus and bacteria. RESULTS: Two hundred and fifty patients participated in the study. Samples positivity rate was evaluated at 95.2% (238/250). Streptococcus pneumoniae was the predominant pathogen (74%) and was present in all months and all age-groups, followed by Staphylococcus aureus (28,8%) and rhinovirus (28,4%). Respiratory syncytial virus (RSV) was detected only among children under 5 years old in August and September while coronavirus was present in all age groups, during the months of October and December. CONCLUSION: This pilot study revealed a diversity of pathogens over the time and across all age groups, highlighting the need for further exploration. A pathogen community approach including both virus and bacteria at a larger scale becomes crucial for a better understanding of transmission dynamics at population level in order to help shape ARI control strategies.

Subtelomere organization in the genome of the microsporidian Encephalitozoon cuniculi: patterns of repeated sequences and physicochemical signatures.

BACKGROUND: The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with a small nuclear genome (2.9 Mbp) consisting of 11 chromosomes. Although each chromosome end is known to contain a single rDNA unit, the incomplete assembly of subtelomeric regions following sequencing of the genome identified only 3 of the 22 expected rDNA units. While chromosome end assembly remains a difficult process in most eukaryotic genomes, it is of significant importance for pathogens because these regions encode factors important for virulence and host evasion. RESULTS: Here we report the first complete assembly of E. cuniculi chromosome ends, and describe a novel mosaic structure of segmental duplications (EXT repeats) in these regions. EXT repeats range in size between 3.5 and 23.8 kbp and contain four multigene families encoding membrane associated proteins. Twenty-one recombination sites were identified in the sub-terminal region of E. cuniculi chromosomes. Our analysis suggests that these sites contribute to the diversity of chromosome ends organization through Double Strand Break repair mechanisms. The region containing EXT repeats at chromosome extremities can be differentiated based on gene composition, GC content, recombination sites density and chromosome landscape. CONCLUSION: Together this study provides the complete structure of the chromosome ends of E. cuniculi GB-M1, and identifies important factors, which could play a major role in parasite diversity and host-parasite interactions. Comparison with other eukaryotic genomes suggests that terminal regions could be distinguished precisely based on gene content, genetic instability and base composition biais. The diversity of processes assciated with chromosome extremities and their biological consequences, as they are presented in the present study, emphasize the fact that great effort will be necessary in the future to characterize more carefully these regions during whole genome sequencing efforts.

Multiyear persistence of 2 pandemic A/H1N1 influenza virus lineages in West Africa.

Our understanding of the global ecology of influenza viruses is impeded by historically low levels of viral surveillance in Africa. Increased genetic sequencing of African A/H1N1 pandemic influenza viruses during 2009-2013 revealed multiyear persistence of 2 viral lineages within West Africa, raising questions about the roles of reduced air traffic and the asynchrony of seasonal influenza epidemics among West African countries in the evolution of independent lineages. The potential for novel influenza virus lineages to evolve within Africa warrants intensified influenza surveillance in Africa and other understudied areas.

Respiratory viruses associated with patients older than 50 years presenting with ILI in Senegal, 2009 to 2011.

BACKGROUND: In Africa, especially in West Africa, studies about the prevalence and diversity of respiratory viruses (influenza and others) in elderly people are largely lacking. In studies done elsewhere, it is well established that older people, when compared with younger adults, are at greater risk of significant morbidity and mortality from complications arising from influenza. The main aim of this study was to determine the prevalence and the diversity of respiratory viruses associated with ILI cases in adults over 50 years old in Senegal. METHODS: The recruitment period of this study was from January 2009 to December 2011. 232 patients aged 50 years and above presenting ILI cases were enrolled. Nasal-pharyngeal and/or oral pharyngeal swabs were collected from patients. RNA was extracted from 200 µl of each sample followed by a two-step real-time RT-PCR. The Anyplex™ II RV16 Detection kit was used for viral detection. The kit enabled the simultaneous detection of the presence of 16 respiratory viruses. RESULTS: 150 viruses were detected: influenza viruses (44.7%) and rhinoviruses (26.7%) were the most prevalent. We detected 13 human parainfluenza viruses (8.7%), 7 human respiratory syncytial viruses (4.7%), 6 coronaviruses (4%), 5 human metapneumoviruses (3.3%), 5 human adenoviruses (3.3%) and 1 human bocavirus (0.7%). 14 cases (6%) of dual virus infections and one triple viral detection case were encountered. 56 (56.6%) viruses detected were found in the 50-64 year old age group, 59 (76.6%; P < 0.001) from 65-74 year old age group and 35 (62.5%) were detected in the ≥75 year old age group. The viral co-infections were more frequent in the 65-74 age group (9/15). CONCLUSIONS: This pilot study demonstrates a variety of respiratory viruses in the elderly. It also highlights a high prevalence of these viruses in this age group. We speculate from these results that the impact of respiratory viruses other than influenza on the elderly has been considerably underestimated. A more exhaustive study seems necessary in order to provide a more complete picture of the burden of respiratory viruses on morbidity among adults over 50 years old in the sub-Saharan context.

Spread of Influenza A(H1N1) oseltamivir-resistant viruses in Africa in 2008 confirmed by multiple introductions in Senegal.

BACKGROUND: Among Influenza neuraminidase inhibitors (NAIs), oseltamivir corresponds to the most widely used agent to treat influenza disease. However since 2001, several cases of resistance to NAIs have been reported for circulating seasonal A(H1N1) Influenza viruses. A direct resistance mechanism may be invoked, involving critical mutations in the viral NA gene that prevent the drug binding to its target. Same phenomenon is reported for adamantanes drugs and mutations in the M2 channel protein gene of Influenza viruses. METHODS: Reverse-Transcription/Restriction Fragment Length Polymorphism (RT-PCR/RFLP) method, phenotypic testing for oseltamivir resistance, and sequencing of NA, HA and M2 genes were used in this study. Phylogenetic analyses were performed using BioEdit and Mega 5 softwares for alignment of sequences and phylogenetic trees building respectively. RESULTS: Using a simple RT-PCR/RFLP method, we found that the 86 seasonal A(H1N1) isolates from 2008 bear the oseltamivir resistance-associated mutation (H274Y) in the NA gene. In contrast all isolates isolated in Senegal in 2007 were sensitive to oseltamivir. These results were first confirmed by finding high IC50 values using a phenotypic testing for oseltamivir resistance, and secondly by sequencing the whole NA gene. Regarding M2 gene, no mutation associated to adamantanes resistance was characterized of the isolates. CONCLUSIONS: The present work provides evidence of circulation of drug-resistant seasonal A(H1N1) viruses during the 2008 influenza season (July to September) in Senegal. The results are in favor of multiple introductions of oseltamivir resistant viruses (ORV) A(H1N1) in Senegal.Phylogenetic analyses of isolates with complete sequences of N1 and HA1 genes showed that they belong to clade 2B and suggest sequential introductions in Africa.

Efficacy of a Russian-backbone live attenuated influenza vaccine among children in Senegal: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Live attenuated influenza vaccines have been shown to significantly reduce influenza in diverse populations of children, but no efficacy studies have been done in resource-poor tropical settings. In Senegal, we assessed the efficacy and safety of a live attenuated influenza vaccine based on Russian-derived master donor viruses and licensed as a single dose. METHODS: In this double-blind, placebo-controlled, parallel group, single-centre trial done near Niakhar, Senegal, generally healthy children aged 2-5 years were randomly allocated (2:1) to receive a single intranasal dose of masked trivalent live attenuated influenza vaccine or placebo. The allocation sequence was computer-generated by PATH with block sizes of three. The manufacturer provided vaccine and placebo in coded vials to preserve blinding. Participants were monitored through the predictable influenza season in Senegal for adverse events and signs and symptoms of influenza using weekly home visits and surveillance in clinics. The primary outcome was symptomatic laboratory-confirmed influenza caused by any strain and occurring from 15 days post-vaccination to the end of the study. The primary analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT01854632. FINDINGS: Between May 23, and July 1, 2013, 1761 children were randomly assigned, 1174 to receive live attenuated influenza vaccine and 587 to receive placebo. The per-protocol set included 1173 vaccinees and 584 placebo recipients followed up to Dec 20, 2013. Symptomatic influenza was laboratory-confirmed in 210 (18%) of 1173 recipients of live attenuated influenza vaccine and 105 (18%) of placebo recipients, giving a vaccine efficacy of 0·0% (95% CI -26·4 to 20·9). Adverse events were balanced between the study groups. Two girls who had received live attenuated influenza vaccine died, one due to anasarca 12 days postvaccination and one due to malnutrition 70 days postvaccination. INTERPRETATION: Live attenuated influenza vaccine was well tolerated in young children in Senegal, but did not provide protection against influenza. Further study in such populations, which might experience extended periods of influenza circulation, is warranted. FUNDING: US Centers for Disease Control and Prevention and Bill & Melinda Gates Foundation.