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Risk factors for the occurrence and spread of Highly Pathogenic Avian Influenza H5N1 in commercial poultry farms in Kano, Nigeria
AM Wakawa, PA Abdu, SB Oladele, L Sa’idu, SB Mohammed
Sokoto Journal of Veterinary Sciences , 2012,
Abstract: Outbreaks of Highly Pathogenic Avian Influenza (HPAI) subtype H5N1 occurred previously for three consecutive years, 2006, 2007 and 2008 in Kano State, Nigeria, causing heavy economic losses to farmers and the government. It was against this background that risk factors for the occurrence and spread of HPAI H5N1 among commercial poultry farms in the State were evaluated. A total of 64 farms comprising 32 affected (AF) and 32 non-affected (NAF) farms were enrolled for this study. Questionnaires were designed and administered to the selected farms through interviews with farm owners or farm managers during on-site visits. Information on flock profile including farm characteristics and environment, husbandry practices, biosecurity practices, farm trade practices and employee activities were obtained and analyzed. Pearson Chi square and Fisher’s exact tests were used to compare categorical variables. Values of p< 0.05 were considered significant. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to measure the strength and statistical significance of associations between the variables and occurrence and spread of HPAI H5N1 in commercial poultry farms in the State. The most significant risk factors were the presence of untreated surface water on farms (OR 18.6, 95%CI 2.24 – 154.34, p = 0.001), exchange of egg crates between traders and farmers (OR 12.1, 95%CI 1.43 – 102.61, p = 0.006), allowing egg crates of traders into poultry pens (OR 11.67, 95%CI 2.37 – 57.86, p = 0.001) and allowing rodents/wild birds access to poultry feed (OR 3.65, 95%CI 0.23 – 1.87, p = 0.024). It was recommended that veterinary inspection to enforce and encourage best biosecurity practices for the poultry farms should be introduced and sustained.
Risk factors for the occurrence and spread of Highly Pathogenic Avian Influenza H5N1 in commercial poultry farms in Kano, Nigeria
AM Wakawa,,PA Abdu,SB Oladele,L Sa’idu
Sokoto Journal of Veterinary Sciences , 2012,
Abstract: Outbreaks of Highly Pathogenic Avian Influenza (HPAI) subtype H5N1 occurred previously for three consecutive years, 2006, 2007 and 2008 in Kano State, Nigeria, causing heavy economic losses to farmers and the government. It was against this background that risk factors for the occurrence and spread of HPAI H5N1 among commercial poultry farms in the State were evaluated. A total of 64 farms comprising 32 affected (AF) and 32 non-affected (NAF) farms were enrolled for this study. Questionnaires were designed and administered to the selected farms through interviews with farm owners or farm managers during on-site visits. Information on flock profile including farm characteristics and environment, husbandry practices, biosecurity practices, farm trade practices and employee activities were obtained and analyzed. Pearson Chi square and Fisher’s exact tests were used to compare categorical variables. Values of p< 0.05 were considered significant. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to measure the strength and statistical significance of associations between the variables and occurrence and spread of HPAI H5N1 in commercial poultry farms in the State. The most significant risk factors were the presence of untreated surface water on farms (OR 18.6, 95%CI 2.24 – 154.34, p = 0.001), exchange of egg crates between traders and farmers (OR 12.1, 95%CI 1.43 – 102.61, p = 0.006), allowing egg crates of traders into poultry pens (OR 11.67, 95%CI 2.37 – 57.86, p = 0.001) and allowing rodents/wild birds access to poultry feed (OR 3.65, 95%CI 0.23 – 1.87, p = 0.024). It was recommended that veterinary inspection to enforce and encourage best biosecurity practices for the poultry farms should be introduced and sustained.
A Serological Survey of Antibodies to H5, H7 and H9 Avian Influenza Viruses amongst the Duck-Related Workers in Beijing, China  [PDF]
Peng Yang, Chunna Ma, Weixian Shi, Shujuan Cui, Guilan Lu, Xiaomin Peng, Daitao Zhang, Yimeng Liu, Huijie Liang, Yi Zhang, Li Zhang, Holly Seale, Quanyi Wang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050770
Abstract: The continued spread of highly pathogenic avian influenza (HPAI) viruses of H5 and H7 subtypes and low pathogenic avian influenza (LPAI) viruses of H5, H7 and H9 subtypes in birds and the subsequent infections in humans pose an ongoing pandemic threat. It has been proposed that poultry workers are at higher risk of exposure to HPAI or LPAI viruses and subsequently infection due to their repeated exposure to chickens or domestic waterfowl. The aim of this study was to examine the seroprevalence of antibodies against H5, H7 and H9 viruses amongst duck-related workers in Beijing, China and the risk factors associated with seropositivity. In March, 2011, 1741 participants were recruited from (1) commercial duck-breeding farms; (2) private duck-breeding farms; and (3) duck-slaughtering farms. Local villagers who bred ducks in their backyards were also recruited. A survey was administered by face-to-face interview, and blood samples were collected from subjects for antibody testing against H5, H7 and H9 viruses. We found that none of the subjects were seropositive for either H5 or H7 viruses, and only 0.7% (12/1741) had antibody against H9. A statistically significant difference in H9 antibody seroprevalence existed between the various categories of workers (P = 0.005), with the highest figures recorded amongst the villagers (1.7%). Independent risk factors associated with seropositivity toinfection with H9 virus included less frequent disinfection of worksite (OR, 5.13 [95% CI, 1.07–24.58]; P = 0.041; ≤ twice monthly versus>twice monthly) and handling ducks with wounds on hands (OR, 4.13 [95% CI, 1.26–13.57]; P = 0.019). Whilst the risk of infection with H5, H7 and H9 viruses appears to be low among duck-related workers in Beijing, China, ongoing monitoring of infection with the H9 virus is still warranted, especially amongst villagers who breed backyard ducks to monitor for any changes.
Comparative Serological Assays for the Study of H5 and H7 Avian Influenza Viruses  [PDF]
Eleonora Molesti,Adelaide Milani,Calogero Terregino,Giovanni Cattoli,Nigel J. Temperton
Influenza Research and Treatment , 2013, DOI: 10.1155/2013/286158
Abstract: The nature of influenza virus to randomly mutate and evolve into new types is an important challenge in the control of influenza infection. It is necessary to monitor virus evolution for a better understanding of the pandemic risk posed by certain variants as evidenced by the highly pathogenic avian influenza (HPAI) viruses. This has been clearly recognized in Egypt following the notification of the first HPAI H5N1 outbreak. The continuous circulation of the virus and the mass vaccination programme undertaken in poultry have resulted in a progressive genetic evolution and a significant antigenic drift near the major antigenic sites. In order to establish if vaccination is sufficient to provide significant intra- and interclade cross-protection, lentiviral pseudotypes derived from H5N1 HPAI viruses (A/Vietnam/1194/04, A/chicken/Egypt-1709-01/2007) and an antigenic drift variant (A/chicken/Egypt-1709-06-2008) were constructed and used in pseudotype-based neutralization assays (pp-NT). pp-NT data obtained was confirmed and correlated with HI and MN assays. A panel of pseudotypes belonging to influenza Groups 1 and 2, with a combination of reporter systems, was also employed for testing avian sera in order to support further application of pp-NT as an alternative valid assay that can improve avian vaccination efficacy testing, vaccine virus selection, and the reliability of reference sera. 1. Background Egypt faced its first H5N1 outbreak in 2006 where a highly pathogenic avian influenza (HPAI) virus was detected in poultry [1]. The strategy used by the Egyptian authorities to mitigate this relied on vaccinating poultry, depopulating infected areas, and increasing awareness and biosecurity levels. Despite these efforts, by 2008, the H5N1 virus had become endemic, and vaccine-escape variants have emerged despite commercial poultry vaccines exhibiting protection in laboratory settings [2]. For each year, from 2009 through 2012, Egypt has had more laboratory-confirmed human cases reported to the WHO than any other country, and global concern regarding Egyptian H5N1 influenza viruses is currently high, as some isolates have been reported to possess at least two mutations, of the 4 (or 5) needed to confer ferret-to-ferret airborne transmissibility [3]. Despite the mass vaccination program undertaken in poultry, the continuous circulation of the virus has resulted in a progressive genetic evolution and a significant antigenic drift with multiple mutations near the major antigenic sites [4]. To date, the WHO has identified 12 new H5N1 clades, and the Egyptian
Seroprevalence of Antibodies to Avian Influenza A (H5) and A (H9) Viruses among Market Poultry Workers, Hanoi, Vietnam, 2001  [PDF]
Timothy M. Uyeki, Doan C. Nguyen, Thomas Rowe, Xiuhua Lu, Jean Hu-Primmer, Lien P. Huynh, Nguyen L. K. Hang, Jacqueline M. Katz
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043948
Abstract: Background The frequency of avian influenza A virus infections among poultry workers is not well understood. Methods A seroprevalence study of market poultry workers and persons without occupational poultry exposure was conducted during 2001 in Hanoi, Vietnam. Sera were tested for avian influenza H5 and H9 antibodies by microneutralization and Western blot assays. Results Seroprevalence of H5 and H9 antibodies was 4% and 3% in poultry workers and 1% and 3.5% in non-poultry workers, respectively. Conclusions Seroprevalence of H5 and H9 antibodies was low among Hanoi market poultry workers in 2001, but can serve as a baseline for additional studies.
The Role of Avian Influenza, Newcastle Disease and Infectious Bronchitis Viruses During the Respiratory Disease Outbreak in Commercial Broiler Farms of Iran
M.M. Hadipour,G.H. Habibi, P. Golchin, M.R. Hadipourfard and N. Shayanpour
International Journal of Animal and Veterinary Advances , 2011,
Abstract: Avian influenza, newcastle disease and infectious bronchitis viruses are pathogens with economical importance in poultry industry. To determine the role of three mentioned viruses in respiratory diseases outbreak in Iranian broiler farms, 160 serum samples from 8 broiler flocks with respiratory disease symptoms were examined by Hemagglutination Inhibition (HI) and ELISA tests. None of these flocks received any of influenza A, newcastle disease and infectious bronchitis viruses vaccines. The overall antibody titres and seroprevalence of AIV H9 subtype, newcastle disease and infectious bronchitis viruses in this study were 7.6, 5.34 log2, 1123.12 log10 and 31.2, 18.47, 82.43%, respectively. The results revealed the important role of infectious bronchitis virus in respiratory disease outbreak in commercial broiler farms of Iran. Therefore, for preventing the IBV infection in the broiler farms, serotype of the new IBV isolates must regularly be determined.
Immunization of Chickens with Newcastle Disease Virus Expressing H5 Hemagglutinin Protects against Highly Pathogenic H5N1 Avian Influenza Viruses  [PDF]
Baibaswata Nayak, Subrat N. Rout, Sachin Kumar, Mohammed S. Khalil, Moustafa M. Fouda, Luay E. Ahmed, Kenneth C. Earhart, Daniel R. Perez, Peter L. Collins, Siba K. Samal
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006509
Abstract: Background Highly-pathogenic avian influenza virus (HPAIV) and Newcastle disease virus (NDV) are the two most important poultry viruses in the world. Natural low-virulence NDV strains have been used as vaccines over the past 70 years with proven track records. We have previously developed a reverse genetics system to produce low-virulent NDV vaccine strain LaSota from cloned cDNA. This system allows us to use NDV as a vaccine vector for other avian pathogens. Methodology/Principal Finding Here, we constructed two recombinant NDVs (rNDVs) each of which expresses the hemagglutinin (HA) gene of HPAIV H5N1strain A/Vietnam/1203/2004 from an added gene. In one, rNDV (rNDV-HA), the open reading frame (ORF) of HA gene was expressed without modification. In the second, rNDV (rNDV-HAF), the ORF was modified so that the transmembrane and cytoplasmic domains of the encoded HA gene were replaced with those of the NDV F protein. The insertion of either version of the HA ORF did not increase the virulence of the rNDV vector. The HA protein was found to be incorporated into the envelopes of both rNDV-HA and rNDV-HAF. However, there was an enhanced incorporation of the HA protein in rNDV-HAF. Chickens immunized with a single dose of either rNDV-HA or rNDV-HAF induced a high titer of HPAIV H5-specific antibodies and were completely protected against challenge with NDV as well as lethal challenges of both homologous and heterologous HPAIV H5N1. Conclusion and Significance Our results suggest that these chimeric viruses have potential as safe and effective bivalent vaccines against NDV and. HPAIV. These vaccines will be convenient and affordable, which will be highly beneficial to the poultry industry. Furthermore, immunization with these vaccines will permit serological differentiation of vaccinated and avian influenza field virus infected animals.
Evaluation of several adjuvants in avian influenza vaccine to chickens and ducks
Chun G Liu, Ming Liu, Fei Liu, Da F Liu, Yun Zhang, Wei Q Pan, Hao Chen, Chun H Wan, En C Sun, Hong T Li, Wen H Xiang
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-321
Abstract: H5 subtype highly pathogenic avian influenza (HPAI) viruses could cause severe disease and enormous economical loss to poultry farms. They could also cross the species barrier to infect mammals. In particular, the direct transmission of avian influenza viruses to humans without the pigs as "vessel" might be seriously endangered the poultry industry and human health [1-3]. It is very important to strengthen bird influenza surveillance, prevention and control work. The main control strategies for H5N1 subtype HPAI involve increased bio-security, surveillance, and vaccination, however, the vaccination is an effective and economic strategy in controlling the prevalence of this disastrous disease. At present, the widely used conventional inactivated H5 subtype bird influenza virus is from allantoic fluids of embryonated chicken eggs. It is necessary to solve many problems in vaccine development, including the difficulty in vaccine strains construction by conventional method [4], the serious byproducts pollution from embryonated chicken eggs in vaccines production progress, and the difficulty to differentiate nature infected and routine immunized birds. A new type of vaccine production system which could replace embryonated chicken eggs and differentiate between the infected and the immunized birds is urgent need.The modern molecular biological techniques provide a new approach for new type of influenza vaccine design [5]. Compare to traditional vaccine development, the new influenza vaccine development trend should have the same or no less protective effects, saving times in the vaccine production process, alleviating environmental pollution, providing a higher levels of bio-security.The reverse genetics H5N3 (rH5N3) avian influenza vaccine strain was successfully constructed by the reverse genetics technique [6]. The prepared rH5N3 vaccine strain, which could discriminate the infected birds from the immunized birds by N3 marker [7,8], can replicate effectively in MDCK c
Reassortant between Human-Like H3N2 and Avian H5 Subtype Influenza A Viruses in Pigs: A Potential Public Health Risk  [PDF]
Yanlong Cong,Guangmei Wang,Zhenhong Guan,Shuang Chang,Quanpeng Zhang,Guilian Yang,Weili Wang,Qingfeng Meng,Weiming Ren,Chunfeng Wang,Zhuang Ding
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012591
Abstract: Human-like H3N2 influenza viruses have repeatedly been transmitted to domestic pigs in different regions of the world, but it is still uncertain whether any of these variants could become established in pig populations. The fact that different subtypes of influenza viruses have been detected in pigs makes them an ideal candidate for the genesis of a possible reassortant virus with both human and avian origins. However, the determination of whether pigs can act as a “mixing vessel” for a possible future pandemic virus is still pending an answer. This prompted us to gather the epidemiological information and investigate the genetic evolution of swine influenza viruses in Jilin, China.
Generation High Yield Vaccine Strain Wholly Derived from Avian Influenza Viruses by Reverse Genetics
利用反向遗传学技术构建H5亚型禽流感高产疫苗株

LIU Ming,ZHANG Yun,LIU Chun-Guo,PAN Wei-Qi,LIU Chao-Nan,YANG Tao,
刘明
,张云,刘春国,潘蔚绮,刘超男,杨涛

生物工程学报 , 2006,
Abstract: Highly pathogenic avian influenza A (HPAI) viruses of the H5N1 subtypes caused enormous economical loss to poultry farms in China and Southeastern Asian countries. The vaccination program is a reliable strategy in controlling the prevalence of these disastrous diseases. The six internal genes of the high-yield influenza virus A/Goose/Dalian/3/01 (H9N2), the hemagglutinin (HA) gene of A/Goose/HLJ/QFY/04 (H5N1) strain, and the neuraminidase gene from A/Duck/Germany/1215/73 (H2N3) reference strain were amplified by RT-PCR technique. The HA gene was modified by the deletion of four basic amino acids of the connecting peptide between HA1 and HA2. Eight gene expressing plasmids were constructed, and the recombinant virus rH5N3 was generated by cells transfection. The infection of chicken embryos and the challenge tests involving chickens demonstrated that the recombinant H5N3 (rH5N3) influenza virus is avirulent. The allantoic fluids of rH5N3-infected eggs contain high-titer influenza viruses with hemagglutination unit of 1:2048, which are eight times those of the parental H5N1 virus. The rH5N3 oil-emulsified vaccine could induce hemagglutination inhibition (HI) antibodies in chickens in 2 weeks post-vaccination, and maximum geometric mean HI-titer were observed 4 approximately 5 weeks post-vaccination and were kept under observation for 18 weeks. The rH5N3-vaccinated chickens were fully protected against morbidity and mortality of the lethal challenge of the H5N1 HPAI viruses, A/Goose/Guangdong/1/96 and A/Goose/HLJ/QFY/04, which had 8 years expansion and differences among multiple amino acids in HA protein. The N3 neuraminidase protein marker makes it possible to distinguish between H5N1 infected- and H5N3 vaccinated animals.
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