1,971 research outputs found
Spatial modes for transmission of chikungunya virus during a large chikungunya outbreak in Italy. A modeling analysis
Background
The spatial spread of many mosquito-borne diseases occurs by focal spread at the scale of a few hundred meters and over longer distances due to human mobility. The relative contributions of different spatial scales for transmission of chikungunya virus require definition to improve outbreak vector control recommendations.
Methods
We analyzed data from a large chikungunya outbreak mediated by the mosquito Aedes albopictus in the Lazio region, Italy, consisting of 414 reported human cases between June and November 2017. Using dates of symptom onset, geographic coordinates of residence, and information from epidemiological questionnaires, we reconstructed transmission chains related to that outbreak.
Results
Focal spread (within 1 km) accounted for 54.9% of all cases, 15.8% were transmitted at a local scale (1–15 km) and the remaining 29.3% were exported from the main areas of chikungunya circulation in Lazio to longer distances such as Rome and other geographical areas. Seventy percent of focal infections (corresponding to 38% of the total 414 cases) were transmitted within a distance of 200 m (the buffer distance adopted by the national guidelines for insecticide spraying). Two main epidemic clusters were identified, with a radius expanding at a rate of 300–600 m per month. The majority of exported cases resulted in either sporadic or no further transmission in the region.
Conclusions
Evidence suggest that human mobility contributes to seeding a relevant number of secondary cases and new foci of transmission over several kilometers. Reactive vector control based on current guidelines might allow a significant number of secondary clusters in untreated areas, especially if the outbreak is not detected early. Existing policies and guidelines for control during outbreaks should recommend the prioritization of preventive measures in neighboring territories with known mobility flows to the main areas of transmission
Productividad del sábalo (Prochilodus lineatus) cultivado en estanques con diferentes tipos de fondo
El sábalo (Prochilodus lineatus) es la especie más importante para la pesca comercial y de subsistencia en Argentina. Sin embargo, hace algunos años alcanzó una situación de riesgo que motivó que el cultivo en cautiverio sea impulsado por diversos sectores públicos y privados debido al interés en la conservación ambiental. Este pez presenta un rápido crecimiento, elevada fecundidad y rusticidad. El objetivo del presente trabajo fue analizar comparativamente estanques de cultivo de P. lineatus con dos tipos de fondo, uno de cemento y otro de tierra, a fin de identificar alguna condición que influya sobre la productividad de la especie. Fueron utilizados 450 juveniles de 60 dÃas y 26 g de peso vivo promedio, a quienes se suministró alimento balanceado en base al 2% de la biomasa. Las variables de calidad de agua se registraron periódicamente, al igual que las biometrÃas, para ajustar la alimentación al crecimiento de los peces. El ensayo tuvo una duración de 340 dÃas. Los parámetros fÃsicoquÃmicos de calidad de agua permanecieron dentro de valores adecuados para la especie. Las variables productivas analizadas fueron: coeficiente de crecimiento especÃfico, biomasa total (donde se observaron diferencias significativas, p0,05). Los resultados obtenidos demuestran que los estanques con fondo de cemento no permiten que el sábalo se desarrolle como lo hace en estanques con fondo de tierra. Sin embargo, representan una alternativa para el cultivo de la especie, que deberÃa continuar evaluándose con el objeto de lograr el mantenimiento de una adecuada cantidad de material orgánico que satisfaga las necesidades de los peces en cultivo
Melanoma in the Italian population and regional environmental influences: A national retrospective survey on 2001–2008 hospitalization records
Objective: To assess the burden of regional environmental factors influencing the incidence of Melanoma in the Italian population and overcome the problem of partial population coverage by local cancer registries and thematic archives. Methods: We analyzed the Italian national hospitalization records from 2001 to 2008 provided by the Ministry of Health, excluding hospital re-admissions of the same patients, in order to assess the occurrence of Melanoma over a 8-year period. Data were presented by age groups (absolute number of cases from 20 to ≥80 years old) and per Region (rates per 100,000 inhabitants) for each year. Results: The overall number of new hospitalizations due to malignant Melanoma increased by 16.8% from 2001 (n = 4846) to 2008 (n = 5823), with the rate per 100,000 inhabitants passing from 10.5 to almost 12.0 at a national level. The majority of new diagnoses of malignant Melanoma was observed in two age groups: 61–70 years old (from 979 in 2001 up to 2109 in 2008, corresponding to 15.1 and 18.1 new cases per 100,000 inhabitants, respectively) and 71–80 years old (from 954 in 2001 up to 1141 in 2008, corresponding to 19.5 and 21.8 new cases per 100,000 inhabitants, respectively). The number of hospitalizations due to Melanoma increased in all age groups with the only exception of the youngest patients aged 20–30 years old. The highest increases over the 8-year period were observed in people aged ≥81 years old (+34%), 61–70 years old (+20%) and surprisingly in the age group 31–40 years old (+17%). Southern Regions showed lower hospitalization rates compared to Northern Italy and Region Lazio. The highest increases between 2001 and 2008 were observed in Trentino/Alto Adige, Friuli Venezia Giulia, Valla d’Aosta and Veneto Region. Conclusions: Hospitalizations due to malignant Melanoma in Italy seem to be influenced by environmental or population-related factors showing a decreasing incidence rate from the Northern to Southern Regions
A low energy core-collapse supernova without a hydrogen envelope
The final fate of massive stars depends on many factors, including mass,
rotation rate, magnetic fields and metallicity. Theory suggests that some
massive stars (initially greater than 25-30 solar masses) end up as Wolf-Rayet
stars which are deficient in hydrogen because of mass loss through strong
stellar winds. The most massive of these stars have cores which may form a
black hole and theory predicts that the resulting explosion produces ejecta of
low kinetic energy, a faint optical display and a small mass fraction of
radioactive nickel(1,2,3). An alternative origin for low energy supernovae is
the collapse of the oxygen-neon core of a relatively lowmass star (7-9 solar
masses) through electron capture(4,5). However no weak, hydrogen deficient,
core-collapse supernovae are known. Here we report that such faint, low energy
core-collapse supernovae do exist, and show that SN2008ha is the faintest
hydrogen poor supernova ever observed. We propose that other similar events
have been observed but they have been misclassified as peculiar thermonuclear
supernovae (sometimes labelled SN2002cx-like events(6)). This discovery could
link these faint supernovae to some long duration gamma-ray bursts. Extremely
faint, hydrogen-stripped core-collapse supernovae have been proposed to produce
those long gamma-ray bursts whose afterglows do not show evidence of
association with supernovae (7,8,9).Comment: Submitted 12 January 2009 - Accepted 24 March 200
SN 2006gy: was it really extra-ordinary?
We present an optical photometric and spectroscopic study of the very
luminous type IIn SN 2006gy for a time period spanning more than one year. In
photometry, a broad, bright (M_R~-21.7) peak characterizes all BVRI light
curves. Afterwards, a rapid luminosity fading is followed by a phase of slow
luminosity decline between day ~170 and ~237. At late phases (>237 days),
because of the large luminosity drop (>3 mag), only upper visibility limits are
obtained in the B, R and I bands. In the near-infrared, two K-band detections
on days 411 and 510 open new issues about dust formation or IR echoes
scenarios. At all epochs the spectra are characterized by the absence of broad
P-Cygni profiles and a multicomponent Halpha profile, which are the typical
signatures of type IIn SNe. After maximum, spectroscopic and photometric
similarities are found between SN 2006gy and bright, interaction-dominated SNe
(e.g. SN 1997cy, SN 1999E and SN 2002ic). This suggests that ejecta-CSM
interaction plays a key role in SN 2006gy about 6 to 8 months after maximum,
sustaining the late-time-light curve. Alternatively, the late luminosity may be
related to the radioactive decay of ~3M_sun of 56Ni. Models of the light curve
in the first 170 days suggest that the progenitor was a compact star (R~6-8
10^(12)cm, M_ej~5-14M_sun), and that the SN ejecta collided with massive
(6-10M_sun), opaque clumps of previously ejected material. These clumps do not
completely obscure the SN photosphere, so that at its peak the luminosity is
due both to the decay of 56Ni and to interaction with CSM. A supermassive star
is not required to explain the observational data, nor is an extra-ordinarily
large explosion energy.Comment: 33 pages, 8 figures. Accepted by ApJ. Paper with high-resolution
figures available at
http://web.oapd.inaf.it/supern/sn2006gy_astroph/agnoletto_2006gy.pd
SN 2004aw: Confirming Diversity of Type Ic Supernovae
Optical and near-infrared observations of the Type Ic supernova (SN) 2004aw
are presented, obtained from day -3 to day +413 with respect to the B-band
maximum. The photometric evolution is characterised by a comparatively slow
post-maximum decline of the light curves. The peaks in redder bands are
significantly delayed relative to the bluer bands, the I-band maximum occurring
8.4 days later than that in B. With an absolute peak magnitude of -18.02 in the
V band the SN can be considered fairly bright, but not exceptional. This also
holds for the U through I bolometric light curve, where SN 2004aw has a
position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN
2004aw provides a link between a normal Type Ic supernova like SN 1994I and the
group of broad-lined SNe Ic. The spectral evolution is rather slow, with a
spectrum at day +64 being still predominantly photospheric. The shape of the
nebular [O I] 6300,6364 line indicates a highly aspherical explosion. Helium
cannot be unambiguously identified in the spectra, even in the near-infrared.
Using an analytical description of the light curve peak we find that the total
mass of the ejecta in SN 2004aw is 3.5-8.0 M_Sun, significantly larger than in
SN 1994I, although not as large as in SN 1998bw. The same model suggests that
about 0.3 M_Sun of {56}Ni has been synthesised in the explosion. No connection
to a GRB can be firmly established.Comment: 22 pages, 15 figures, 6tables, LaTeX, MNRAS online-early, references
and affiliations updated, style correction
Hepatitis A virus strains circulating in the Campania region (2015-2018) assessed through bivalve biomonitoring and environmental surveillance
The genetic diversity of Hepatitis A Virus (HAV) circulating in the Campania Region in years 2015-2018 was investigated through the monitoring of sentinel bivalve shellfish and water matrices. Overall, 463 water samples (71 sewage samples, 353 coastal discharge waters, and 39 seawaters samples), and 746 bivalve shellfish samples were analyzed. Positivity for HAV was detected in 20/71 sewage samples, 14/353 coastal discharge waters, 5/39 seawaters, and 102/746 bivalve shellfish. Sixty-one of the positive samples were successfully sequenced and were characterized as genotype IA (n = 50) and IB (n = 11). The prevalent strain circulating in 2015 in both bivalves and waters was the IA strain responsible for the outbreak occurring around the same time in the Naples area. This variant was no longer identified in subsequent years (2017-2018) when, instead, appeared two of the IA variants of the multistate outbreak affecting men who have sex with men (MSM), VRD_521_2016, and RIVM-HAV16-090, with the former prevailing in both shellfish and water environments. HAV IB isolates were detected over the years in shellfish and in water matrices, but not in clinical samples, suggesting that this genotype had been circulating silently. An integrated surveillance system (environment/food/clinical cases) can be a useful tool to monitor changes in viral variants in the population, as well as an early warning system
The INTEGRAL/IBIS AGN catalogue I: X-ray absorption properties versus optical classification
In this work we present the most comprehensive INTEGRAL AGN sample which
lists 272 objects. Here we mainly use this sample to study the absorption
properties of active galaxies, to probe new AGN classes and to test the AGN
unification scheme. We find that half (48%) of the sample is absorbed while the
fraction of Compton thick AGN is small (~7%). In line with our previous
analysis, we have however shown that when the bias towards heavily absorbed
objects which are lost if weak and at large distance is removed, as it is
possible in the local Universe, the above fractions increase to become 80% and
17%. We also find that absorption is a function of source luminosity, which
implies some evolution in the obscuration properties of AGN. Few peculiar
classes, so far poorly studied in the hard X-ray band, have been detected and
studied for the first time such as 5 XBONG, 5 type 2 QSOs and 11 LINERs. In
terms of optical classification, our sample contains 57% of type 1 and 43% of
type 2 AGN; this subdivision is similar to that found in X-rays if unabsorbed
versus absorbed objects are considered, suggesting that the match between
optical and X-ray classification is overall good. Only a small percentage of
sources (12%) does not fulfill the expectation of the unified theory as we find
22 type 1 AGN which are absorbed and 10 type 2 AGN which are unabsorbed.
Studying in depth these outliers we found that most of the absorbed type 1 AGN
have X-ray spectra characterized by either complex or warm/ionized absorption
more likely due to ionized gas located in an accretion disk wind or in the
biconical structure associated to the central nucleus, therefore unrelated to
the toroidal structure. Among 10 type 2 AGN which resulted to be unabsorbed, at
most 3-4% is still eligible to be classified as a "true" type 2 AGN.Comment: 21 pages, 6 figures, 5 tables. Accepted for publication on MNRAS.
arXiv admin note: text overlap with arXiv:0709.2077 by other author
Human Herpesvirus-8 Infection Leads to Expansion of the Preimmune/Natural Effector B Cell Compartment
BACKGROUND: Human herpesvirus-8 (HHV-8) is the etiological agent of Kaposi's sarcoma (KS) and of some lymphoproliferative disorders of B cells. Most malignancies develop after long-lasting viral dormancy, and a preventing role for both humoral and cellular immune control is suggested by the high frequency of these pathologies in immunosuppressed patients. B cells, macrophages and dendritic cells of peripheral lymphoid organs and blood represent the major reservoir of HHV-8. Due to the dual role of B cells in HHV-8 infection, both as virus reservoir and as agents of humoral immune control, we analyzed the subset distribution and the functional state of peripheral blood B cells in HHV-8-infected individuals with and without cKS. METHODOLOGY/PRINCIPAL FINDINGS: Circulating B cells and their subsets were analyzed by 6-color flow cytometry in the following groups: 1- patients HHV-8 positive with classic KS (cKS) (n = 47); 2- subjects HHV-8 positive and cKS negative (HSP) (n = 10); 3- healthy controls, HHV-8 negative and cKS negative (HC) (n = 43). The number of B cells belonging to the preimmune/natural effector compartment, including transitional, pre-naïve, naïve and MZ-like subsets, was significantly higher among HHV-8 positive subjects, with or without cKS, while was comparable to healthy controls in the antigen-experienced T-cell dependent compartment. The increased number of preimmune/natural effector B cells was associated with increased resistance to spontaneous apoptosis, while it did not correlate with HHV-8 viral load. CONCLUSIONS/SIGNIFICANCE: Our results indicate that long-lasting HHV-8 infection promotes an imbalance in peripheral B cell subsets, perturbing the equilibrium between earlier and later steps of maturation and activation processes. This observation may broaden our understanding of the complex interplay between viral and immune factors leading HHV-8-infected individuals to develop HHV-8-associated malignancies
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