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Temperature Drops and the Onset of Severe Avian Influenza A H5N1 Virus Outbreaks  [PDF]
Chung-Ming Liu, Shu-Hua Lin, Ying-Chen Chen, Katherine Chun-Min Lin, Tsung-Shu Joseph Wu, Chwan-Chuen King
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000191
Abstract: Global influenza surveillance is one of the most effective strategies for containing outbreaks and preparing for a possible pandemic influenza. Since the end of 2003, highly pathogenic avian influenza viruses (HPAI) H5N1 have caused many outbreaks in poultries and wild birds from East Asia and have spread to at least 48 countries. For such a fast and wide-spreading virulent pathogen, prediction based on changes of micro- and macro-environment has rarely been evaluated. In this study, we are developing a new climatic approach by investigating the conditions that occurred before the H5N1 avian influenza outbreaks for early predicting future HPAI outbreaks and preventing pandemic disasters. The results show a temperature drop shortly before these outbreaks in birds in each of the Eurasian regions stricken in 2005 and 2006. Dust storms, like those that struck near China's Lake Qinghai around May 4, 2005, exacerbated the spread of this HPAI H5N1 virus, causing the deaths of a record number of wild birds and triggering the subsequent spread of H5N1. Weather monitoring could play an important role in the early warning of outbreaks of this potentially dangerous virus.
Movements of Wild Ruddy Shelducks in the Central Asian Flyway and Their Spatial Relationship to Outbreaks of Highly Pathogenic Avian Influenza H5N1  [PDF]
John Y. Takekawa,Diann J. Prosser,Bridget M. Collins,David C. Douglas,William M. Perry,Baoping Yan,Luo Ze,Yuansheng Hou,Fumin Lei,Tianxian Li,Yongdong Li,Scott H. Newman
Viruses , 2013, DOI: 10.3390/v5092129
Abstract: Highly pathogenic avian influenza H5N1 remains a serious concern for both poultry and human health. Wild waterfowl are considered to be the reservoir for low pathogenic avian influenza viruses; however, relatively little is known about their movement ecology in regions where HPAI H5N1 outbreaks regularly occur. We studied movements of the ruddy shelduck ( Tadorna ferruginea), a wild migratory waterfowl species that was infected in the 2005 Qinghai Lake outbreak. We defined their migration with Brownian Bridge utilization distribution models and their breeding and wintering grounds with fixed kernel home ranges. We correlated their movements with HPAI H5N1 outbreaks, poultry density, land cover, and latitude in the Central Asian Flyway. Our Akaike Information Criterion analysis indicated that outbreaks were correlated with land cover, latitude, and poultry density. Although shelduck movements were included in the top two models, they were not a top parameter selected in AIC c stepwise regression results. However, timing of outbreaks suggested that outbreaks in the flyway began during the winter in poultry with spillover to wild birds during the spring migration. Thus, studies of the movement ecology of wild birds in areas with persistent HPAI H5N1 outbreaks may contribute to understanding their role in transmission of this disease.
Development of Live-Attenuated Influenza Vaccines against Outbreaks of H5N1 Influenza  [PDF]
Dan Zheng,Yinglei Yi,Ze Chen
Viruses , 2012, DOI: 10.3390/v4123589
Abstract: Several global outbreaks of highly pathogenic avian influenza (HPAI) H5N1 virus have increased the urgency of developing effective and safe vaccines against H5N1. Compared with H5N1 inactivated vaccines used widely, H5N1 live-attenuated influenza vaccines (LAIVs) have advantages in vaccine efficacy, dose-saving formula, long-lasting effect, ease of administration and some cross-protective immunity. Furthermore, H5N1 LAIVs induce both humoral and cellular immune responses, especially including improved IgA production at the mucosa. The current trend of H5N1 LAIVs development is toward cold-adapted, temperature-sensitive or replication-defective vaccines, and moreover, H5N1 LAIVs plus mucosal adjuvants are promising candidates. This review provides an update on the advantages and development of H5N1 live-attenuated influenza vaccines.
Different Environmental Drivers of Highly Pathogenic Avian Influenza H5N1 Outbreaks in Poultry and Wild Birds  [PDF]
Yali Si, Willem F. de Boer, Peng Gong
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053362
Abstract: A large number of highly pathogenic avian influenza (HPAI) H5N1 outbreaks in poultry and wild birds have been reported in Europe since 2005. Distinct spatial patterns in poultry and wild birds suggest that different environmental drivers and potentially different spread mechanisms are operating. However, previous studies found no difference between these two outbreak types when only the effect of physical environmental factors was analysed. The influence of physical and anthropogenic environmental variables and interactions between the two has only been investigated for wild bird outbreaks. We therefore tested the effect of these environmental factors on HPAI H5N1 outbreaks in poultry, and the potential spread mechanism, and discussed how these differ from those observed in wild birds. Logistic regression analyses were used to quantify the relationship between HPAI H5N1 outbreaks in poultry and environmental factors. Poultry outbreaks increased with an increasing human population density combined with close proximity to lakes or wetlands, increased temperatures and reduced precipitation during the cold season. A risk map was generated based on the identified key factors. In wild birds, outbreaks were strongly associated with an increased Normalized Difference Vegetation Index (NDVI) and lower elevation, though they were similarly affected by climatic conditions as poultry outbreaks. This is the first study that analyses the differences in environmental drivers and spread mechanisms between poultry and wild bird outbreaks. Outbreaks in poultry mostly occurred in areas where the location of farms or trade areas overlapped with habitats for wild birds, whereas outbreaks in wild birds were mainly found in areas where food and shelters are available. The different environmental drivers suggest that different spread mechanisms might be involved: HPAI H5N1 spread to poultry via both poultry and wild birds, whereas contact with wild birds alone seems to drive the outbreaks in wild birds.
Migration of Whooper Swans and Outbreaks of Highly Pathogenic Avian Influenza H5N1 Virus in Eastern Asia
Scott H. Newman,Samuel A. Iverson,John Y. Takekawa,Martin Gilbert,Diann J. Prosser,Nyambyar Batbayar,Tseveenmyadag Natsagdorj,David C. Douglas
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0005729
Abstract: Evaluating the potential involvement of wild avifauna in the emergence of highly pathogenic avian influenza H5N1 (hereafter H5N1) requires detailed analyses of temporal and spatial relationships between wild bird movements and disease emergence. The death of wild swans (Cygnus spp.) has been the first indicator of the presence of H5N1 in various Asian and European countries; however their role in the geographic spread of the disease remains poorly understood. We marked 10 whooper swans (Cygnus cygnus) with GPS transmitters in northeastern Mongolia during autumn 2006 and tracked their migratory movements in relation to H5N1 outbreaks. The prevalence of H5N1 outbreaks among poultry in eastern Asia during 2003–2007 peaked during winter, concurrent with whooper swan movements into regions of high poultry density. However outbreaks involving poultry were detected year round, indicating disease perpetuation independent of migratory waterbird presence. In contrast, H5N1 outbreaks involving whooper swans, as well as other migratory waterbirds that succumbed to the disease in eastern Asia, tended to occur during seasons (late spring and summer) and in habitats (areas of natural vegetation) where their potential for contact with poultry is very low to nonexistent. Given what is known about the susceptibility of swans to H5N1, and on the basis of the chronology and rates of whooper swan migration movements, we conclude that although there is broad spatial overlap between whooper swan distributions and H5N1 outbreak locations in eastern Asia, the likelihood of direct transmission between these groups is extremely low. Thus, our data support the hypothesis that swans are best viewed as sentinel species, and moreover, that in eastern Asia, it is most likely that their infections occurred through contact with asymptomatic migratory hosts (e.g., wild ducks) at or near their breeding grounds.
Haemolytic E. coli Associated with the Outbreaks of Avian Influenza [H5N1] in Nigeria
H.M. Kazeem,D.F. Adene,L Sa’idu,P.A. Abdu,A.M. Wakawa,C.N. Kwanashie,P.H. Mamman,J. Adamu,M.Y. Fatihu,T. Joannis
Journal of Animal and Veterinary Advances , 2012,
Abstract: Avian Influenza (AI) strain H5N1 outbreak with very high mortality in 2 commercial poultry farms in Nigeria was subjected to further laboratory investigations to document all contributory etiological factors. Tissues from flocks on the farms located over 200 km apart were sampled for bacteriology. Haemolytic E. coli and an unidentified Gram variable rod were isolated from the first farm; Pasteurella haemolytica and haemolytic E. coli were isolated from the second farm. Antibiotic susceptibility test showed haemolytic E. coli was resistant to 6, partially to 3 and fully susceptible to Enrofloxacin (Tarivid ). Pasteurella haemolytica was resistant to 5 and susceptible to 3 antibiotics. The unidentified Gram variable pleomorph was sensitive to 10 antibiotics used. The isolation of haemolytic E. coli, in avian influenza outbreaks with high degree of antibiotic resistance is hereby documented.
Outbreaks of Highly Pathogenic Avian Influenza (H5N1) in Bauchi State, Nigeria
Mohammed Bello,Bala Musa Lukshi,Mohammed Sanusi
International Journal of Poultry Science , 2008,
Abstract: Natural outbreaks of highly pathogenic avian influenza disease were recorded in 19 farms in Bauchi State, Nigeria, between February and May, 2006. The disease was diagnosed by the National Veterinary Research Institute, Vom, Nigeria and the Food and Agriculture Organisation Reference Laboratory in Padova, Italy. Nine avian species of different ages and sexes involved in the outbreaks included commercial and local chickens, ostriches, emus, guinea fowls, geese, pigeons, turkeys, ducks and crowned cranes. A total number of 176,426 birds were lost, which constituted about 1.5% of the total poultry population in the state. Of these, 67,058 (38%) died naturally of the disease, while 109,368 (62%) were destroyed in order to stamp out the disease. Clinical signs and post-mortem findings of the disease included cyanotic comb and wattles, dyspnoea, subcutaneous haemorrhages, regression and necrosis of ovaries. All blood samples obtained from personnel involved in the containment of the disease in the state and screened for H5N1 virus were negative. In conclusion, the potential risk of human infection by the virus in the state exists and the present outbreaks caused serious socio-economic damage, which adversely affected the livelihood of poultry farmers and the poultry business in the state.
Modeling and Roles of Meteorological Factors in Outbreaks of Highly Pathogenic Avian Influenza H5N1  [PDF]
Paritosh K. Biswas, Md. Zohorul Islam, Nitish C. Debnath, Mat Yamage
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098471
Abstract: The highly pathogenic avian influenza A virus subtype H5N1 (HPAI H5N1) is a deadly zoonotic pathogen. Its persistence in poultry in several countries is a potential threat: a mutant or genetically reassorted progenitor might cause a human pandemic. Its world-wide eradication from poultry is important to protect public health. The global trend of outbreaks of influenza attributable to HPAI H5N1 shows a clear seasonality. Meteorological factors might be associated with such trend but have not been studied. For the first time, we analyze the role of meteorological factors in the occurrences of HPAI outbreaks in Bangladesh. We employed autoregressive integrated moving average (ARIMA) and multiplicative seasonal autoregressive integrated moving average (SARIMA) to assess the roles of different meteorological factors in outbreaks of HPAI. Outbreaks were modeled best when multiplicative seasonality was incorporated. Incorporation of any meteorological variable(s) as inputs did not improve the performance of any multivariable models, but relative humidity (RH) was a significant covariate in several ARIMA and SARIMA models with different autoregressive and moving average orders. The variable cloud cover was also a significant covariate in two SARIMA models, but air temperature along with RH might be a predictor when moving average (MA) order at lag 1 month is considered.
Spatial and Temporal Association of Outbreaks of H5N1 Influenza Virus Infection in Wild Birds with the 0°C Isotherm  [PDF]
Leslie A. Reperant ,Neven S. Fu?kar,Albert D. M. E. Osterhaus,Andrew P. Dobson,Thijs Kuiken
PLOS Pathogens , 2010, DOI: 10.1371/journal.ppat.1000854
Abstract: Wild bird movements and aggregations following spells of cold weather may have resulted in the spread of highly pathogenic avian influenza virus (HPAIV) H5N1 in Europe during the winter of 2005–2006. Waterbirds are constrained in winter to areas where bodies of water remain unfrozen in order to feed. On the one hand, waterbirds may choose to winter as close as possible to their breeding grounds in order to conserve energy for subsequent reproduction, and may be displaced by cold fronts. On the other hand, waterbirds may choose to winter in regions where adverse weather conditions are rare, and may be slowed by cold fronts upon their journey back to the breeding grounds, which typically starts before the end of winter. Waterbirds will thus tend to aggregate along cold fronts close to the 0°C isotherm during winter, creating conditions that favour HPAIV H5N1 transmission and spread. We determined that the occurrence of outbreaks of HPAIV H5N1 infection in waterbirds in Europe during the winter of 2005–2006 was associated with temperatures close to 0°C. The analysis suggests a significant spatial and temporal association of outbreaks caused by HPAIV H5N1 in wild birds with maximum surface air temperatures of 0°C–2°C on the day of the outbreaks and the two preceding days. At locations where waterbird census data have been collected since 1990, maximum mallard counts occurred when average and maximum surface air temperatures were 0°C and 3°C, respectively. Overall, the abundance of mallards (Anas platyrhynchos) and common pochards (Aythya ferina) was highest when surface air temperatures were lower than the mean temperatures of the region investigated. The analysis implies that waterbird movements associated with cold weather, and congregation of waterbirds along the 0°C isotherm likely contributed to the spread and geographical distribution of outbreaks of HPAIV H5N1 infection in wild birds in Europe during the winter of 2005–2006.
Spatio-Temporal Magnitude and Direction of Highly Pathogenic Avian Influenza (H5N1) Outbreaks in Bangladesh  [PDF]
Syed S. U. Ahmed, Annette K. Ersb?ll, Paritosh K. Biswas, Jens P. Christensen, Nils Toft
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024324
Abstract: Background The number of outbreaks of HPAI-H5N1 reported by Bangladesh from 2007 through 2011 placed the country among the highest reported numbers worldwide. However, so far, the understanding of the epidemic progression, direction, intensity, persistence and risk variation of HPAI-H5N1 outbreaks over space and time in Bangladesh remains limited. Methodology/Principal Findings To determine the magnitude and spatial pattern of the highly pathogenic avian influenza A subtype H5N1 virus outbreaks over space and time in poultry from 2007 to 2009 in Bangladesh, we applied descriptive and analytical spatial statistics. Temporal distribution of the outbreaks revealed three independent waves of outbreaks that were clustered during winter and spring. The descriptive analyses revealed that the magnitude of the second wave was the highest as compared to the first and third waves. Exploratory mapping of the infected flocks revealed that the highest intensity and magnitude of the outbreaks was systematic and persistent in an oblique line that connects south-east to north-west through the central part of the country. The line follows the Brahmaputra-Meghna river system, the junction between Central Asian and East Asian flyways, and the major poultry trading route in Bangladesh. Moreover, several important migratory bird areas were identified along the line. Geostatistical analysis revealed significant latitudinal directions of outbreak progressions that have similarity to the detected line of intensity and magnitude. Conclusion/Significance The line of magnitude and direction indicate the necessity of mobilizing maximum resources on this line to strengthen the existing surveillance.
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