Role of Culex and Anopheles mosquito species as potential vectors of rift valley fever virus in Sudan outbreak, 2007

<p>Abstract</p> <p>Background</p> <p>Rift Valley fever (RVF) is an acute febrile arthropod-borne viral disease of man and animals caused by a member of the <it>Phlebovirus </it>genus, one of the five genera in the family <it>Bunyaviridae</it>. RVF virus (RVFV) is transmitted between animals and human by mosquitoes, particularly those belonging to the <it>Culex, Anopheles </it>and <it>Aedes </it>genera.</p> <p>Methods</p> <p>Experiments were designed during RVF outbreak, 2007 in Sudan to provide an answer about many raised questions about the estimated role of vector in RVFV epidemiology. During this study, adult and immature mosquito species were collected from Khartoum and White Nile states, identified and species abundance was calculated. All samples were frozen individually for further virus detection. Total RNA was extracted from individual insects and RVF virus was detected from <it>Culex, Anopheles </it>and <it>Aedes </it>species using RT-PCR. In addition, data were collected about human cases up to November 24^th, 2007 to asses the situation of the disease in affected states. Furthermore, a historical background of the RVF outbreaks was discussed in relation to global climatic anomalies and incriminated vector species.</p> <p>Results</p> <p>A total of 978 mosquitoes, belonging to 3 genera and 7 species, were collected during Sudan outbreak, 2007. <it>Anopheles gambiae arabiensis </it>was the most frequent species (80.7%) in White Nile state. Meanwhile, <it>Cx. pipiens </it>complex was the most abundant species (91.2%) in Khartoum state. RT-PCR was used and successfully amplified 551 bp within the M segment of the tripartite negative-sense single stranded RNA genome of RVFV. The virus was detected in female, male and larval stages of <it>Culex </it>and <it>Anopheles </it>species. The most affected human age interval was 15-29 years old followed by ≥ 45 years old, 30-44 years old, and then 5-14 years old. Regarding to the profession, housewives followed by farmers, students, shepherd, workers and the free were more vulnerable to the infection. Furthermore, connection between human and entomological studies results in important human case-vulnerability relatedness findings.</p> <p>Conclusion</p> <p>Model performance, integrated with epidemiologic and environmental surveillance systems should be assessed systematically for RVF and other mosquito-borne diseases using historical epidemiologic and satellite monitoring data. Case management related interventions; health education and vector control efforts are extremely effective in preparedness for viral hemorrhagic fever and other seasonal outbreaks.</p

Preterm infants have significantly longer telomeres than their term born counterparts

There are well-established morbidities associated with preterm birth including respiratory, neurocognitive and developmental disorders. However several others have recently emerged that characterise an `aged' phenotype in the preterm infant by term-equivalent age. These include hypertension, insulin resistance and altered body fat distribution. Evidence shows that these morbidities persist into adult life, posing a significant public health concern. In this study, we measured relative telomere length in leukocytes as an indicator of biological ageing in 25 preterm infants at term equivalent age. Comparing our measurements with those from 22 preterm infants sampled at birth and from 31 term-born infants, we tested the hypothesis that by term equivalent age, preterm infants have significantly shorter telomeres (thus suggesting that they are prematurely aged). Our results demonstrate that relative telomere length is highly variable in newborn infants and is significantly negatively correlated with gestational age and birth weight in preterm infants. Further, longitudinal assessment in preterm infants who had telomere length measurements available at both birth and term age (n = 5) suggests that telomere attrition rate is negatively correlated with increasing gestational age. Contrary to our initial hypothesis however, relative telomere length was significantly shortest in the term born control group compared to both preterm groups and longest in the preterm at birth group. In addition, telomere lengths were not significantly different between preterm infants sampled at birth and those sampled at term equivalent age. These results indicate that other, as yet undetermined, factors may influence telomere length in the preterm born infant and raise the intriguing hypothesis that as preterm gestation declines, telomere attrition rate increases

Photoluminescence et niveaux localisés dans ZnTe dopé au phosphore

Zinc telluride is one of the semiconductors whose high luminescence efficiency in the green when suitably doped (Li or P). We have measured the Hall effect and the photoluminescence of ZnTe cristals containing 1017 to 5 x 1019 cm-3 phosphorous. The increase in the carrier concentration with rise of temperature in the range 30 < T < 300 K is due to thermal excitation of holes from an acceptor level whose depth, in the absence of screening, is 0.040 eV. The photoluminescence spectrum at 4 K contains a series of peaks separated by LO phonon with the non-phonon line (A) at 2.335 eV and another peak at 2.360 eV (B). The peak position, half width and integrated intensity of these two principal lines have been studied as a function of temperature between 4 and 300 K. We discuss our results on the basis of a recombination kinetics model and compare them with those previously published for ZnTe : Li (J. Physique Colloq. 35 (1974) C3-179). It is shown that the nature of the luminescent transitions is the same in both cases. The proposed electronic transitions are from the conduction band to an acceptor level (A) and from a donor level to the valence band (B).Le tellurure de zinc est un des semiconducteurs ayant un rendement élevé de luminescence dans le vert s'il est convenablement dopé (P ou Li). L'effet Hall et la photoluminescence ont été mesurés sur des cristaux de ZnTe contenant entre 1017 et 5 x 1019 cm-3 de phosphore. La croissance de la concentration de porteurs dans le domaine de température 30 < T < 300 K est due à l'excitation thermique des trous à partir d'un niveau accepteur dont la profondeur, en l'absence d'écrantage, est de 0,040 eV. Le spectre de photoluminescence à 4 K contient une série de pics séparés par phonons LO, dont l'émission non phononique se trouve à 2,335 eV (A), et un autre pic à 2,360 eV (B). La position énergétique, la largeur à mi-hauteur et l'intensité intégrée de ces deux raies principales ont été étudiées en fonction de la température entre 4 et 300 K. Nous discutons nos résultats sur la base d'un modèle de cinétique de recombinaison et les comparons avec ceux de ZnTe : Li publiés auparavant (J. Physique Colloq. 35 (1974) C3-179). Nous montrons que la nature des transitions de luminescence est la même pour les deux dopants. Les transitions électroniques proposées sont : bande de conduction-niveau accepteur (pic A) et niveau donneur-bande de valence (pic B)

Photoluminescence et niveaux localisés dans ZnTe dopé au phosphore

Le tellurure de zinc est un des semiconducteurs ayant un rendement élevé de luminescence dans le vert s'il est convenablement dopé (P ou Li). L'effet Hall et la photoluminescence ont été mesurés sur des cristaux de ZnTe contenant entre 1017 et 5 x 1019 cm-3 de phosphore. La croissance de la concentration de porteurs dans le domaine de température 30 < T < 300 K est due à l'excitation thermique des trous à partir d'un niveau accepteur dont la profondeur, en l'absence d'écrantage, est de 0,040 eV. Le spectre de photoluminescence à 4 K contient une série de pics séparés par phonons LO, dont l'émission non phononique se trouve à 2,335 eV (A), et un autre pic à 2,360 eV (B). La position énergétique, la largeur à mi-hauteur et l'intensité intégrée de ces deux raies principales ont été étudiées en fonction de la température entre 4 et 300 K. Nous discutons nos résultats sur la base d'un modèle de cinétique de recombinaison et les comparons avec ceux de ZnTe : Li publiés auparavant (J. Physique Colloq. 35 (1974) C3-179). Nous montrons que la nature des transitions de luminescence est la même pour les deux dopants. Les transitions électroniques proposées sont : bande de conduction-niveau accepteur (pic A) et niveau donneur-bande de valence (pic B)

ÉTUDE DES SPECTRES DE PHOTOLUMINESCENCE DE ZnTe DOPÉ AU LITHIUM. NATURE DES TRANSITIONS

Les spectres de photoluminescence du tellurure de zinc dopé au lithium sont étudiés entre 4,2 K et 300 K. La concentration des porteurs dans les échantillons est vérifiée par mesures électriques. Les spectres de luminescence à 4,2 K sont étudiés en fonction de la concentration en Li entre 1017 et 1019 cm-3. Les variations d'énergie des raies de photoluminescence sont étudiees en fonction de la température. On met en évidence que les deux émissions à 2,336 eV ± 4 meV et 2,362 eV ± 8 meV, caractéristiques de ZnTe dopé au lithium, sont dues à la recombinaison de porteurs libres respectivement sur un niveau accepteur et un niveau donneur. Les variations d'intensité des raies d'émission en fonction de la température sont aussi déterminées. Un modèle des cinétiques de recombinaison basé sur l'interprétation ci-dessus, a permis une analyse semi-quantitative de l'intensité des émissions en fonction de la température. Le modèle a aussi permis de déterminer l'énergie d'ionisation du donneur (15 meV), de l'accepteur (47 meV) et l'énergie d'activation du processus non radiatif.The photoluminescence emission of Li-doped zinc telluride is studied between 4.2 K and 300 K. Concentration of carriers in the samples is also verified by electrical mesurements. The photoluminescence spectrum at 4.2 K is investigated as a function of Li concentration between 1017 and 1019 cm-3. The energy variations of the bands with temperature are studied. Evidences are obtained that the two emission bands at 2.336 eV ± 4meV, and 2.362 eV ± 8 meV, characteristic of Li-doped ZnTe, are due to free carrier recombination on an acceptor and a donor levels respectively. The intensity variations of the bands with temperature are also determined. A recombination kinetics model based on this interpretation has permitted semi-quantitative analysis of the temperature dependence of the two band intensities. The model also allows the determination of the donor ionization energy (15 meV), the acceptor ionization energy (47 meV) and the activation energy of the non radiative process (8 meV)

Genetic structure of the populations of Spilostethus pandurus in the wadis of the St Katherine Protectorate, South Sinai

The genetic diversity of Spilostethus pandurus was studied using RAPD markers in individuals sampled from four wadis within the St Katherine area. A total of 109 different RAPD bands were generated for the whole sample: site-specific bands occurred at low frequency. Even though there were many genetic differences among individuals within sites, the sites were statistically distinct. Thus even in thus fairly long-lived and apparently fairly mobile insect, there is evidence of genetic isolation among the wadis of this highly dissected environment. Keywords: aposematism, gene flow, genetic diversity, RAPD, Sinai Egyptian Journal of Biology Vol. 10 2008: pp. 87-9