Teste Repositóri
2014-01-01
Resultados de pesquisa
Foram encontrados 10 registos.
People vaccinated against influenza develop hemagglutination inhibition (HAI) antibodies (Ab) that bind to the virus and neutralize it. Ab titer levels are variable depending on factors insufficiently studied, and tend to decrease over time.
In the present study, we analyzed antibodies responses before and after influenza vaccination in nurses working in a hospital, with the aim of:
-identifying seroconversion rates to trivalent influenza vaccine one month after immunization;
-evaluating if, six months after vaccination, influenza HAI Ab titer fall comparing to one-month post vaccination HAI Ab titer;
-studying the association between the lack of HAI Ab response (seroconversion) assessed one month after immunization and:
∘past influenza vaccinations,
∘baseline (before vaccination) HAI Ab titer,
∘baseline (before vaccination)...
A research project on antiviral drug resistance of influenza viruses circulating in Portugal has been carried out since 2007. Here, the first results obtained regarding the evaluation of susceptibility to amantadine and oseltamivir are presented. Information about antiviral prescription and exposure was available through the National Influenza Surveillance Programme. Amantadine susceptibility was evaluated by
pyrosequencing for known resistance markers on 178 influenza A strains from 2004/2005 to 2006/2007. Susceptibility to oseltamivir was evaluated by 50% inhibitory concentration determination on 340 virus strains from 2004/2005 to 2008/2009, 134 of which were further analyzed by sequencing of the neuraminidase gene. This study revealed that influenza antiviral drugs were rarely prescribed at national level. Resistance to amantadine...
Human adenoviruses (AdVs) typically cause mild illnesses in otherwise healthy hosts. We investigated a pediatric outbreak of acute respiratory infection with fatal outcomes that occurred in Lisbon, Portugal, in 2004.Biological specimens were collected from 83 children attending two nurseries, a kinesiotherapy clinic, and the household of a nanny. Adenovirus infection was confirmed in 48 children by PCR and virus isolation. Most(96%) isolates were classified as being of subspecies B1. Phylogenetic analysis of fiber and hexon gene sequences revealed that most infants were infected with AdV serotype 3 (AdV3) strains. Infants attending one nursery harbored a new recombinant strain containing an AdV serotype 7 hexon and serotype 3 fiber (AdV7/3). Both the AdV3 and the AdV7/3 strains caused fatal infections. Two different serotype 3 strains ...
In Portugal, influenza surveillance is achieved
through the National Influenza Surveillance Programme
(NISP), in close collaboration with other
European and global surveillance networks. The
NISP integrates epidemiological, clinical and
virological data based on the information collected
by a Network of Sentinel Medical Practitioners
and by a network of Emergency Units of
Hospitals and Health Care Centres. In this study,
genetic and antigenic characterization of influenza
A viruses of the A/Fujian/411/2002 lineage,
isolated during the 2003/2004 and 2004/2005
influenza winter seasons, in the context of the
NISP, are described. Antigenic analysis of A/
Fujian/411/2002-like viruses, first detected and
isolated during the 2003/2004 winter season,
revealed a close similarity with the reference
strains A/Kumamoto/102/2002 an...
As infecções por vírus influenza são uma importante causa de morbilidade em todos os
grupos etários e estão associados a uma elevada mortalidade nos idosos e nos
indivíduos pertencentes a grupos de risco.
No presente estudo analisaram-se os dados da vigilância epidemiológica da gripe durante
o Inverno de 2000/2001. Os dados clínicos, epidemiológicos e virológicos referentes
aos casos de síndroma gripal foram recolhidos através do Programa Nacional de
Vigilância da Gripe que se desenvolve em colaboração com a Direcção Geral da Saúde
e integra a informação obtida a partir das redes Médicos-Sentinela e Serviços de
Urgência. A análise dos dados recolhidos mostram que, durante a época de Inverno de
2000/2001, a actividade gripal foi baixa, sendo o período epidémico curto e de pequena
intensidade e duração. As taxas de incidência d...
As a consequence of immune pressure, influenza
virus hemagglutinin presents some of its amino acids
under positive selection. Several authors have reported the
existence of influenza A hemagglutinin codons under positive
selective pressure (PSP). In this framework, the present
work objectives were to demonstrate the presence of PSP
and evaluate its effects on Victoria- and Yamagata-like
influenza B viruses. Methodology adopted consisted in
estimating the acceptance rate of nonsynonymous substitutions
(ω = dN/dS) that describe the strength of selective
pressure and identifying codons that may be positively
selected, applying a set of continuous-time Markov chain
codon-substitution models. Two groups of HA1 sequences
(140 from Yamagata and 60 from Victoria lineage) were
used. All the model maximum-likelihood estimates were
...
BACKGROUND: Genetic changes in influenza surface and internal genes can alter viral fitness and virulence. Mutation trend analysis and antiviral drug susceptibility profiling of A(H1N1)pdm09 viruses is essential for risk assessment of emergent strains and disease management.
OBJECTIVE: To profile genomic signatures and antiviral drug resistance of A(H1N1)pdm09 viruses and to discuss the potential role of mutated residues in human host adaptation and virulence.
STUDY DESIGN: A(H1N1)pdm09 viruses circulating in Portugal during pandemic and post-pandemic periods and 2009/2010 season. Viruses were isolated in MDCK-SIAT1 cell culture and subjected to mutation analysis of surface and internal proteins, and to antiviral drug susceptibility profiling.
RESULTS: The A(H1N1)pdm09 strains circulating during the epidemic period in Portugal...
Influenza viral infections are an important cause of morbidity in all age groups and are associated with a high mortality rate amongst the elderly and in risk groups. The current study analyses data from the epidemiological surveillance of influenza during the 2000/2001-winter season. Clinical, epidemiological and virological data relative to cases of influenza syndrome were collected via the National Influenza Surveillance Scheme, in collaboration with the General Directory of Health and integrates the information obtained by the Network of Sentinel Medical Practitioners and Emergency Units. The data analysis hereby obtained shows a low influenza activity during the 2000/2001-winter season, with an epidemiological period characterized by small duration and intensity. The incidence rate of influenza-like illnesses increased above the b...
Although many archeo-epidemiological studies have assessed the mortality impact of the 1918-19 influenza pandemic, detailed estimates are not available for Portugal. We applied negative binomial models to monthly mortality data from respiratory and all-causes at the national and district-level from Portugal, 1916-1922. Influenza-related excess mortality was computed as the difference between observed and expected deaths. Poisson regression was used to estimate the association between geographic, socio-demographic factors and excess mortality. Two waves of pandemic influenza were identified between July 1918-January 1919 and April- May 1919, representing an excess all-cause death rate of 195.7 per 10,000. All districts of Portugal were affected. The pandemic hit earlier in southeastern districts and the main cities, while excess mortali...
Abstract
Nucleotide sequences of the HA1 subunit of influenza B viruses isolated in Portugal between 1994 and 2003 influenza winter seasons were analyzed by the Neighbor-Joining algorithm and rates of HA1 evolution estimated by linear regression. From 1994 to 2002, all influenza B viruses studied were of the Yamagata lineage. Strains isolated from 1994 to 1996, 1996 to 1999, and 1999 to 2002 revealed a high similarity with B/Beijing/184/93, B/Yamanashi/166/98, and B/Sichuan/379/99, respectively, and strains isolated during 1994-1995, 1996-1997, and 1998-1999 clustered in more than one branch of the phylogenetic tree. Victoria-related strains reappeared during 2002/2003 and formed only one branch in the phylogenetic tree revealing a closer relationship to B/Shandong/7/97. Evolutionary rates for strains from the Yamagata lineage were es...
