Via 7th Space :
" Serologic surveillance of Avian Influenza (AI) viruses is carried out by the hemagglutination inhibition (HI) test using reference reagents. This method is recommended by animal health organizations as a standard test to detect antigenic differences (subtypes) between circulating influenza virus, vaccine- and/or reference- strains.
However, significant discrepancies between reference antisera and field isolates have been observed during serosurveillance of influenza A viruses in pig and poultry farms. The objective of this study was to examine the effects of influenza virus genetic and antigenic drift on serologic testing using standard HI assays and reference reagents.
Low pathogenic AI H5N2 viruses isolated in Mexico between 1994 and 2008 were used for phylogenetic analysis of AI hemagglutinin genes and for serologic testing using antisera produced with year-specific AI virus isolates."
Showing posts with label 7th Space. Show all posts
Showing posts with label 7th Space. Show all posts
Tuesday, December 21, 2010
Thursday, November 11, 2010
Prospective study of avian influenza transmission to humans in Egypt
Via 7th Space and the BMC study is here :
" The highly pathogenic avian influenza (HPAI) H5N1 virus remains a public health threat and continues to cause outbreaks among poultry as well as human infections. Since its appearance, the virus has spread to numerous geographic areas and is now considered endemic in Egypt and other countries.
Most studies on human H5N1 cases were conducted to investigate outbreak situations and were not designed to address fundamental questions about the epidemiology of human infection with H5N1 viruses. Our objective for this study is to answer these questions by estimating the prevalence and incidence rates of human cases and determine associated risk and protective factors in areas where H5N1 viruses are endemic.
Methods: We designed a 3-year prospective cohort study of 1000 individuals of various exposure levels to poultry in Egypt.
At onset, we will collect sera to estimatebaseline antibody titers against AI viruses H4-H16. Two follow-up visits are scheduled at 1-year intervals following initial enrollment.
At follow-up, we will also collect sera to measure changes in antibody titers over time. Thus, annual prevalence rates as well as incidence rates of infection will be calculated."
" The highly pathogenic avian influenza (HPAI) H5N1 virus remains a public health threat and continues to cause outbreaks among poultry as well as human infections. Since its appearance, the virus has spread to numerous geographic areas and is now considered endemic in Egypt and other countries.
Most studies on human H5N1 cases were conducted to investigate outbreak situations and were not designed to address fundamental questions about the epidemiology of human infection with H5N1 viruses. Our objective for this study is to answer these questions by estimating the prevalence and incidence rates of human cases and determine associated risk and protective factors in areas where H5N1 viruses are endemic.
Methods: We designed a 3-year prospective cohort study of 1000 individuals of various exposure levels to poultry in Egypt.
At onset, we will collect sera to estimatebaseline antibody titers against AI viruses H4-H16. Two follow-up visits are scheduled at 1-year intervals following initial enrollment.
At follow-up, we will also collect sera to measure changes in antibody titers over time. Thus, annual prevalence rates as well as incidence rates of infection will be calculated."
Tuesday, July 13, 2010
Brazil : Mosquitoes infected with dengue viruses
Via 7th Space, a study on mosquitoes in Brazil :
" Dengue epidemics have been reported in Brazil since 1985. The scenery has worsened in the last decade because several serotypes are circulating and producing a hyper-endemic situation, with an increase of DHF/DSS cases as well as the number of fatalities.
Herein, we report dengue virus surveillance in mosquitoes using a Flavivirus genus-specic RT-Hemi-Nested-PCR assay. The mosquitoes (Culicidae, n=1700) collected in the Northeast, Southeast and South of Brazil, between 1999 and 2005, were grouped into 154 pools.Putative genomes of DENV-1, -2 and -3 were detected in 6 mosquito pools (3.8%).
One amplicon of putative DENV-1 was detected in a pool of Haemagogus leucocelaenus suggesting that this virus could be involved in a sylvatic cycle."
" Dengue epidemics have been reported in Brazil since 1985. The scenery has worsened in the last decade because several serotypes are circulating and producing a hyper-endemic situation, with an increase of DHF/DSS cases as well as the number of fatalities.
Herein, we report dengue virus surveillance in mosquitoes using a Flavivirus genus-specic RT-Hemi-Nested-PCR assay. The mosquitoes (Culicidae, n=1700) collected in the Northeast, Southeast and South of Brazil, between 1999 and 2005, were grouped into 154 pools.Putative genomes of DENV-1, -2 and -3 were detected in 6 mosquito pools (3.8%).
One amplicon of putative DENV-1 was detected in a pool of Haemagogus leucocelaenus suggesting that this virus could be involved in a sylvatic cycle."
Friday, June 25, 2010
Sequence and phylogenetic analysis of H7N3 avian influenza viruses isolated from poultry in Pakistan 1995-2004
Via 7th Space :
" Avian influenza virus (AIV) infections have caused heavy economic losses to the poultry industry in Pakistan as well as numerous other regions worldwide. The first introduction of H7N3 AIV to Pakistan occurred during 1995, since then H7N3, H9N2 and H5N1 AIVs have each been sporadically isolated.
This report evaluates the genetic origin of the H7N3 viruses from Pakistan collected 1995-2004 and how they disseminated within the country. To accomplish this we produced whole genome sequences for 6 H7N3 viruses and data for the HA and NA genes of an additional 7 isolates.
All available sequence from H7N3 AIV from Pakistan was included in the analysis.
Results:
Phylogenetic analysis revealed that there were two introductions of H7 into Pakistan and one N3 introduction. Only one of the H7 introductions appears to have become established in poultry in Pakistan, while the other was isolated from two separate outbreaks 6 years apart.The data also shows that reassortment has occurred between H7N3 and H9N2 viruses in the field, likely during co-infection of poultry. Also, with the exception of these few reassortant isolates, all 8 genes in the predominant H7N3 virus lineage have evolved to be phylogenetically distinct."
" Avian influenza virus (AIV) infections have caused heavy economic losses to the poultry industry in Pakistan as well as numerous other regions worldwide. The first introduction of H7N3 AIV to Pakistan occurred during 1995, since then H7N3, H9N2 and H5N1 AIVs have each been sporadically isolated.
This report evaluates the genetic origin of the H7N3 viruses from Pakistan collected 1995-2004 and how they disseminated within the country. To accomplish this we produced whole genome sequences for 6 H7N3 viruses and data for the HA and NA genes of an additional 7 isolates.
All available sequence from H7N3 AIV from Pakistan was included in the analysis.
Results:
Phylogenetic analysis revealed that there were two introductions of H7 into Pakistan and one N3 introduction. Only one of the H7 introductions appears to have become established in poultry in Pakistan, while the other was isolated from two separate outbreaks 6 years apart.The data also shows that reassortment has occurred between H7N3 and H9N2 viruses in the field, likely during co-infection of poultry. Also, with the exception of these few reassortant isolates, all 8 genes in the predominant H7N3 virus lineage have evolved to be phylogenetically distinct."
Thursday, June 24, 2010
Mapping the risk of avian influenza in wild birds in the US
Via 7th Space :
" Avian influenza virus (AIV) is an important public health issue because pandemic influenza viruses in people have contained genes from viruses that infect birds. The H5 and H7 AIV subtypes have periodically mutated from low pathogenicity to high pathogenicity form.Analysis of the geographic distribution of AIV can identify areas where reassortment events might occur and how high pathogenicity influenza might travel if it enters wild bird populations in the US.
Modelling the number of AIV cases is important because the rate of co-infection with multiple AIV subtypes increases with the number of cases and co-infection is the source of reassortment events that give rise to new strains of influenza, which occurred before the 1968 pandemic.
Aquatic birds in the orders Anseriformes and Charadriiformes have been recognized as reservoirs of AIV since the 1970s. However, little is known about influenza prevalence in terrestrial birds in the order Passeriformes."
" Avian influenza virus (AIV) is an important public health issue because pandemic influenza viruses in people have contained genes from viruses that infect birds. The H5 and H7 AIV subtypes have periodically mutated from low pathogenicity to high pathogenicity form.Analysis of the geographic distribution of AIV can identify areas where reassortment events might occur and how high pathogenicity influenza might travel if it enters wild bird populations in the US.
Modelling the number of AIV cases is important because the rate of co-infection with multiple AIV subtypes increases with the number of cases and co-infection is the source of reassortment events that give rise to new strains of influenza, which occurred before the 1968 pandemic.
Aquatic birds in the orders Anseriformes and Charadriiformes have been recognized as reservoirs of AIV since the 1970s. However, little is known about influenza prevalence in terrestrial birds in the order Passeriformes."
Sunday, June 6, 2010
Evaluating the control of HPAIV H5N1 in Vietnam
From 7th Space Interactive :
" Currently, the highly pathogenic avian influenza virus (HPAIV) of the subtype H5N1 is believed to have reached an endemic cycle in Vietnam. We used routine surveillance data on HPAIV H5N1 poultry outbreaks in Vietnam to estimate and compare the within-flock reproductive number of infection (R0) for periods before (second epidemic wave, 2004-5; depopulation-based disease control) and during (fourth epidemic wave, beginning 2007; vaccination-based disease control) vaccination.
Results: Our results show that infected premises (IPs) in the initial (exponential) phases of outbreak periods have the highest R0 estimates.
The IPs reported during the outbreak period when depopulation-based disease control was implemented had higher R0 estimates than IPs reported during the outbreak period when vaccination-based disease control was used. In the latter period, in some flocks of a defined size and species composition, within-flock transmission estimates were not significantly below the threshold for transmission.
Conclusions: Our results indicate that the current control policy based on depopulation plus vaccination has protected the majority of poultry flocks against infection.
However, in some flocks the determinants associated with suboptimal protection need to be further investigated as these may explain the current pattern of infection in animal and human populations."
" Currently, the highly pathogenic avian influenza virus (HPAIV) of the subtype H5N1 is believed to have reached an endemic cycle in Vietnam. We used routine surveillance data on HPAIV H5N1 poultry outbreaks in Vietnam to estimate and compare the within-flock reproductive number of infection (R0) for periods before (second epidemic wave, 2004-5; depopulation-based disease control) and during (fourth epidemic wave, beginning 2007; vaccination-based disease control) vaccination.
Results: Our results show that infected premises (IPs) in the initial (exponential) phases of outbreak periods have the highest R0 estimates.
The IPs reported during the outbreak period when depopulation-based disease control was implemented had higher R0 estimates than IPs reported during the outbreak period when vaccination-based disease control was used. In the latter period, in some flocks of a defined size and species composition, within-flock transmission estimates were not significantly below the threshold for transmission.
Conclusions: Our results indicate that the current control policy based on depopulation plus vaccination has protected the majority of poultry flocks against infection.
However, in some flocks the determinants associated with suboptimal protection need to be further investigated as these may explain the current pattern of infection in animal and human populations."
Friday, May 28, 2010
Hong Kong : SFH visits local poultry farms
Via 7th Space :
" Hong Kong (HKSAR) : The Secretary for Food and Health, Dr York Chow, visited two poultry farms in Yuen Long this afternoon (May 27) to see for himself the implementation of biosecurity measures on the farms and understand the business situation of poultry farmers. Accompanied by the Permanent Secretary for Food and Health (Food), Mrs Marion Lai, and the Acting Director of Agriculture, Fisheries and Conservation, Dr Leung Siu-fai, Dr Chow first visited a poultry farm that makes use of enclosed farm sheds. The farm has installed an evaporative cooling system in poultry rearing.
Dr Chow then visited a traditional poultry farm, and noted that the farm has upgraded its biosecurity measures, including the addition of disinfection facilities and the installation of sturdy and non-malleable bird nets, to prevent wild birds from entering the farm sheds. Dr Chow also enquired about the recent business situation of the two poultry farmers. Most local poultry farms rear poultry in traditional open or semi-open type sheds with complementary biosecurity facilities."
" Hong Kong (HKSAR) : The Secretary for Food and Health, Dr York Chow, visited two poultry farms in Yuen Long this afternoon (May 27) to see for himself the implementation of biosecurity measures on the farms and understand the business situation of poultry farmers. Accompanied by the Permanent Secretary for Food and Health (Food), Mrs Marion Lai, and the Acting Director of Agriculture, Fisheries and Conservation, Dr Leung Siu-fai, Dr Chow first visited a poultry farm that makes use of enclosed farm sheds. The farm has installed an evaporative cooling system in poultry rearing.
Dr Chow then visited a traditional poultry farm, and noted that the farm has upgraded its biosecurity measures, including the addition of disinfection facilities and the installation of sturdy and non-malleable bird nets, to prevent wild birds from entering the farm sheds. Dr Chow also enquired about the recent business situation of the two poultry farmers. Most local poultry farms rear poultry in traditional open or semi-open type sheds with complementary biosecurity facilities."
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