Usutu virus in Africa.

Usutu virus (USUV) was discovered in South Africa in 1959. Since then, it has been reported in several African countries including Senegal, Central African Republic, Nigeria, Uganda, Burkina Faso, Cote d'Ivoire, and Morocco. In 2001, USUV has been identified for the first time outside of Africa, namely in Europe, where it caused a significant mortality among blackbirds in Vienna, Austria. In 2009, the first two human cases of USUV infection in Europe have been reported in Italy, causing encephalitis in immunocompromised patients. The host range in Africa includes mainly Culex mosquitoes, birds, and also humans with one benign and one severe case. Given its role as a potential human pathogen and the similar appearance compared with other emerging arboviruses, it is essential to investigate the natural history and ecology of USUV in Africa. In this regard, we review the emergence of USUV in Africa, summarizing data about isolations, host range, and potential vectors, which should help to improve our understanding of the factors underlying the circulation of USUV in Europe and Africa

Comparative full length genome sequence analysis of usutu virus isolates from Africa

Background: Usutu virus (USUV), a flavivirus belonging to the Japanese encephalitis serocomplex, was identified in South Africa in 1959 and reported for the first time in Europe in 2001. To date, full length genome sequences have been available only for the reference strain from South Africa and a single isolate from each of Austria, Hungary, and Italy. Methods: We sequenced four USUV isolates from Senegal and the Central African Republic (CAR) between 1974 and 2007 and compared the sequence data to USUV strains from Austria, Hungary, Italy, and South Africa using a Bayesian Markov chain Monte Carlo method. We further clarified the taxonomic status of a USUV strain isolated in CAR in 1969 and proposed earlier as a subtype of USUV due to an asymetric serological cross-reactivity with USUV reference strain. Results: A comparison of the four newly obtained USUV sequences with those from SouthAfrica_1959, Vienna_2001, Budapest_2005, and Italy_2009 revealed that they are all 96-99% and 99% similar at the nucleotide and amino acid levels, respectively. The phylogenetic relationships between these sequences indicated that a strain isolated in Senegal in 1993 is most closely related to the USUV strains detected in Europe. Analysis of a strain isolated from a human in CAR in 1981 (CAR_1981) revealed the presence of specific amino acid substitutions and a deletion in the 3′ noncoding region. This is the first fully sequenced human USUV isolate. The putative USUV subtype, CAR_1969, was 81% and 94% identical at the nucleotide and amino acid levels, respectively, compared to the other USUV strains. Our phylogenetic analyses support the serological identification of CAR_1969 as a subtype of USUV. Conclusions: In this study, we investigate the genetic diversity of USUV in Africa and the phylogenetic relationship of isolates from Africa and Europe for the first time. The results suggest a low genetic diversity within USUV, the existence of a distinct USUV subtype strain, and support the hypothesis that USUV was introduced to Europe from Africa. Further sequencing and analysis of USUV isolates from other African countries would contribute to a better understanding of its genetic diversity and geographic distribution

Antibiotic susceptibility profile of Streptococcus pneumoniae isolated from acute respiratory infection in Dakar: a cross sectional study

Streptococcus pneumoniae is a pathogen causing pneumonia, meningitis, otitis and bacteraemia. Nowadays, S. pneumoniae is developing antibacterial resistance, particularly for those with reduced susceptibility to penicillin. The objective of this study was to assess the susceptibility profile of S. pneumoniae strains isolated from acute respiratory infections (ARIs) in children younger than 5 years of age in Dakar, Senegal. S. pneumoniae strains were isolated from broncho-alveolar lavages (BALs), nasopharyngeal swabs, and middle ear secretion from children in the Paediatric Department of Abass Ndao University Teaching Hospital and Paediatric Department of Roi Baudouin Hospital in Dakar, Senegal. The strains were cultivated on Columbia agar supplemented with 5% of horse blood and gentamicin (6 mg/L). Antibiotic susceptibility testing was performed using E-test method. A total of 34 strains of S. pneumoniae were isolated and identified in this study, among them 7 strains (20.58%) showed penicillin-resistance. Antibiotics such as amoxicillin/clavulanic acid (MIC90=0.036 μg/mL), cefuroxim (MIC90=0.38 μg/mL), cefixim (MIC90=1.5 μg/mL), as well as macrolides (azithromycin MIC90=1.5 μg/mL, clarithromycin MIC90=0.125 μg/mL) and fluoroquinolone (levofloxacin MIC90=1 μg/mL, ofloxacin MIC90=2 μg/mL) were mostly active. However, all S. pneumoniae strains were resistant to sulfamethoxazole/trimethoprim (MIC90: 32 μg/mL). Except of S. pneumoniae strains penicillin-resistance or reduced susceptibility, most strains were susceptible to β-lactams antibiotics commonly used in ARI treatment. Continuous surveillance of antimicrobial resistance patterns of pneumococcus strains is still crucial for effective control of ARIs in children

Antibiotic Susceptibility of Isolated from Respiratory Tract Infections in Dakar, Senegal

Group A Streptococcus (GAS) is one of the major causes of respiratory tract infections. The objectives of this study were to identify isolates of S. pyogenes obtained from respiratory tract infections, and to assess their susceptibility to several antibiotics. A total of 40 strains were isolated and their susceptibility to 17 antibiotics was tested using a standard disk diffusion method. The minimum inhibitory concentrations (MICs) were determined using the E-test. All isolates were sensitive to β-lactam antibiotics including penicillin, amoxicillin, and cephalosporins. Macrolides remain active with the exception of spiramycin, which showed reduced susceptibility. Out of the 40 isolates, 100% of the isolates were resistant to tetracycline. Interestingly, isolates were sensitive to chloramphenicol, teicoplanin, vancomycine, and levofloxacin, providing potential alternative choices of treatment against infections with S. pyogenes

Rotational Excitation of the CP(Χ2Σ+) Open Shell Molecule Due to Collision with He(1S)

International audiencePhosphorus bearing molecules have been discovered in the circumstellar and interstellar media. Modeling their abundance accurately requires computations of rate coefficients induced by collision with He and H 2 (i.e., the most abundant gaseous components). These calculations may be carried out by first determining highly accurate potential energy surface (PES) and cross sections. In this paper, we present the first PES of the CP(X 2 Σ +)-He(1 S) van der Waals collisional complex. The ab initio interaction potential was performed using the explicitly correlated restricted coupled cluster approach with simple, double, and perturbative triple excitation (RCCSD(T)−F12) in connection with the augmented-correlation consistent−polarized valence triple-ζ Gaussian basis set (aug-cc-pVTZ). The potential presents two minima of −18.62 cm −1 and −18.72 cm −1. From the PES obtained, we have computed state-to-state excitation cross sections of CP due to collision with He for energies up to 500 cm −1. Rotational transitions involving the fine-structure levels of the CP molecule were treated with a recoupling technique based on the scattering matrix calculated with the exact quantum mechanical close coupling method. Discussions on the propensity rules between the fine-structure levels were made and we found that the Δj = ΔN transitions are favored with respect to the Δj ≠ ΔN ones. The data presented in this paper may have a great impact on the accurate determination of the CP abundance in space

Trend in Antibiotic Resistance of and Strains Isolated from Community Acquired Respiratory Tract Infections in Dakar, Senegal between 2005 and 2008

Development of antibiotic resistance among common respiratory pathogens is a major cause of concern worldwide. Streptococcus pneumoniae and Haemophilus influenzae are among the most common respiratory pathogens. In this study, representative samples obtained from 3 different medical centers in Dakar, Senegal were subjected to antibiotic susceptibility testing. The samples were collected from 2005 to 2008 and the data obtained was compared to establish resistance patterns between the two years (i.e. 2005–2006 to 2007–2008). S. pneumoniae exhibited a significant increase in the resistance to azithromycin and the intermediate susceptibility to penicillin G and cotrimoxazole. H. influenzae also exhibited a significant increase in resistance to azithromycin and intermediate susceptibility to chloramphenicol. None of H. influenzae samples were resistant to amoxicillin/clavulanic acid, cephalosporin and fluroquinolones and most of the S. pneumoniae isolates demonstrated high susceptibility to the antibiotics tested. Results from this study will provide greater insights to antibiotic therapy during respiratory tract infections in Dakar, Senegal. This study also establishes the importance of continuous monitoring of antibiotic susceptibility patterns that are often region-specific

Datasets on extinction coefficients for free space optical link survey and optimization

Based on visibilities data recorded from 2004 to 2013, the minimum, maximum and mean values of extinction coefficients were determined and analyzed in a monthly basis, a yearly basis and also for the whole period of observation.The extinction coefficients data are obtained for the 1330 and 1550 nm optical wavelengths and may be used inter alia for range and availability analyses of optical link for different weather conditions. The data are collected in the region of Dakar, but approach and model of investigation can be reproduced for other regions in Sahel, and in the World, for optical metrology and allied fields of study

Rotational excitation of 36 ArH + by He at low temperature

International audienceIn this paper, we focus on the determination of the rotational excitation rate coefficients of the first observed molecule containing noble gas 36ArH+ isotope by He. Hence, we present the first potential energy surface (PES) of ArH+ −He van der Waals system. The interaction PES of the ArH+(X1Σ+)−He(1S) complex is calculated by the ab initio explicitly correlated coupled cluster with single, double, and perturbative triple excitation (CCSD(T)-F12) method in connection with the augmented correlation consistent triple zeta Gaussian basis (aug-cc-pVTZ). The interaction potential presents two global minima of 708.00 and 172.98 cm−1 below the ArH+(X1Σ+)–He(1S) dissociation limit. Using the PES obtained, we have computed integral inelastic cross-sections in the close-coupling approach among the first 11 rotational levels of ArH+ for energies up to 2500 cm−1. Downward rate coefficients were determined at low temperature (T ≤ 300 K). It is expected that the data worked out in this study may be beneficial for further astrophysical investigations as well as laboratory experiments

The excitation of CNCN in the interstellar medium: hyperfine resolved rate coefficients and non-LTE modelling

International audienceThe recent detections of CNCN and HNCCN+ are seen as further evidence of the large abundance of NCCN in the interstellar medium. The accurate determination of the abundance of these chemically related compounds from the observational spectra requires the prior calculation of collisional rate coefficients. In this work, we aimed at computing hyperfine resolved rate coefficients for the CNCN-He collisional system. First, we determined a new potential energy surface for the CNCN-He van der Waals complex from which we computed rotationally resolved excitation cross-sections for energies up to 800 cm(-1) using the quantum mechanical close-coupling approach. Then, hyperfine resolved transitions between the 30 low-lying pure rotational levels of CNCN were computed for temperatures ranging from 5 to 150 K using an improved infinite order sudden approach. The analysis of the scattering results showed a propensity rule in favour of Delta j = Delta F-1 = Delta F for the hyperfine transitions and a slight dominance of the odd Delta j transitions. Using these data, we carried out non-LTE radiative transfer calculations to simulate the excitation of CNCN in molecular clouds and to constrain the physical conditions of cold dark clouds. Preliminary results showed that the abundance of CNCN derived from observational spectra has to be revisited using these new collisional data