Biological Sciences
Avian Flu
Avian flu, also known as avian influenza, is a highly contagious viral infection that primarily affects birds. It can also spread to humans and other animals, posing a significant public health concern. The virus can cause severe illness and has the potential to lead to outbreaks with serious implications for both animal and human populations.
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12 Key excerpts on "Avian Flu"
eBook - PDFPandemic Influenza
Emergency Planning and Community Preparedness
- Jeffrey R. Ryan(Author)
- 2008(Publication Date)
- CRC Press(Publisher)
3.2 WHAT IS INFLUENZA AND HOW DOES IT AFFECT US? Influenza is any illness caused by the influenza virus. Influenza viruses are highly infectious and significant human respiratory pathogens. Influenza viruses cause sea-sonal, endemic infections; sporadic, localized epidemics; and periodic, unpredictable pandemics (Taubenberger, Morens, 2008). As covered in chapter 2, the worst pandemic on record, the 1918 Spanish flu, killed approximately 50 million people worldwide. The layman is not likely to consider that influenza, or the flu, is actually a zoonotic disease. The recent emergence of bird flu due to the strain H5N1 out of the depths of Asia has brought that fact to the attention of the masses. Human infections caused by H5N1 highly pathogenic avian influenza viruses have raised concern about the emer-gence of another pandemic. Influenza viruses continue to be a major health threat in both endemic and pandemic forms. The rapid, continuous, and unpredictable nature of influenza viral evolution makes vaccine strategies and pandemic planning difficult. In order for us to truly know the enemy, we must understand and appreciate the connection between highly pathogenic avian influenza (HPAI) and human health. As most of us know, disease results when a pathogen encounters a susceptible host. In the case of influenza, a zoonotic triad exists between pathogen, host, and reservoir. Chapter 5 of this book goes into sufficient detail about the avian component of this dynamic of disease. However, some of that groundwork will also be discussed here. Mankind has always been challenged by pathogens and disease. In his thought-provoking book Guns, Germs, and Steel , Dr. Jared Diamond discussed the epide-miological transitions human societies have faced since their existence in family collectives: nomads or hunters and gatherers. Prior to the advent of agriculture more than 10,000 years ago, humans were affected mostly by parasitic diseases, which mostly affected individuals.
eBook - PDF- William Charney(Author)
- 2006(Publication Date)
- Routledge(Publisher)
Pandemic Flu The ongoing problems with regular flu vaccination will be compounded in the event of a pandemic outbreak — especially if the mortality or serious morbidity from the pandemic virus is greater than usual. This is why so many public health officials are alarmed about the possibility of so-called avian or bird flu, and in particular the H5N1 strain. Avian Flu virus is prevalent among waterfowl, including ducks, that can carry the virus without getting symptoms. H5N1 can also infect commercially grown chickens. In some East Asian countries the preponderance of chickens may be infected with H5N1. In the last few years, several cases of Avian Flu virus in humans have been identified. So far, human cases are believed to have been limited to farms in China, Thailand, Vietnam, Cambodia, Indonesia, and elsewhere in East Asia. At least 50 people have died from the disease. In small-farm production where people come in very close proximity with the animals they tend, the potential for animal to human transmission increases substantially. It is unclear in these cases whether the virus jumped directly from chicken to human or whether there were intermediary animals such as pigs that are also routinely kept on farms and whose genetic makeup may provide a bridge from birds to humans. Such jumps between animals are not rare, but usually the virus that jumps does not have the genetic capability of being transmittable from 282 Emerging Infectious Diseases human to human. Human to human transmission is a prerequisite for any large-scale outbreak and in order to have that ability, the virus must exchange genetic material with its new host or with other viruses in the host. In a couple of instances of reported Avian Flu in humans, several people in a household succumbed to the virus. This raised the specter that a mutation or genetic exchange had already occurred.
- Snežana Jovanovi?-?upi?, Muhammad Abubakar, Ay?e Emel Önal, Muhammad Kashif Saleemi, Ana Božovi?, Milena Krajnovic, Snežana Jovanović-Ćupić, Ayşe Emel Önal, Ana Božović, Snežana Jovanović-Ćupić, Muhammad Abubakar, Ayşe Emel Önal, Muhammad Kashif Saleemi, Ana Božović, Milena Krajnovic(Authors)
- 2020(Publication Date)
- IntechOpen(Publisher)
95 Chapter 7 Adequate Monitor of Avian Influenza Viral Infections and Foresight About Possibilities of Its Human Epidemic and Pandemic Infections Yuji Takemoto Abstract Avian influenza viruses are shared among wild birds and sometimes are shed from wild birds to domestic poultry and backyard domestic animals. Usually avian influenza viruses infect wild birds as asymptomatic or low pathogenesis and are stocked in birds, water, and soil. Accumulation of genetic changes of influenza viruses in hosts diversities the pathogenesis to hosts described as highly pathogenic avian influenza viruses and low pathogenic avian influenza viruses. Highly patho-genic avian influenza viruses being categorized among influenza A subtype viruses (H5, H7, H9) and different from low pathogenic avian influenza viruses cause severe illness and sudden increased deaths of wild birds, chicken, or other poultry. These infect from avian to humans. The adequate approaches of information and action for appearance of HPAI and LPAI viral infections in flock may prohibit the outbreak of avian to humans, which are mostly including quarantine of the infected area of the flock from surrounding laboratory tests for HPAI and LPAI viruses in early illness and antiviral treatments in humans. Keywords: zoonotic infection, antigenic drift, antigenic shift, influenza A virus strain 1. Introduction There are four types of influenza viruses, types A, B, C, and D, in the world. Influenza virus infection is zoonotic and sometimes restricted to specific spe-cies. Influenza A and B viruses mainly cause disease among humans, swine, and avian. Influenza C virus infects humans and swine but does not cause severe disease, and its infection to humans is rarely reported [1]. Influenza D viruses affect swine and cattle and are not known to cause sickness to humans [1]. Influenza B viruses infect humans and avian and cause epidemic in the limiting mild disease [2].
- Garg, Sudhi Ranjan(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
2 Avian Influenza C. Tosh and S. Nagarajan High Security Animal Disease Laboratory, Indian Veterinary Research Institute, Bhopal – 462 021 Avian influenza (AI) is primarily a disease of birds caused by Influenza A viruses and occasionally found in other species including humans. Influenza derived its name from the Italian word (meaning influence) in the year 1357 on the popular belief that the stars influence the development of flu. The first description of AI dates back to 1878 in Italy, when Perroncito described a contagious disease of poultry with high mortality and the disease was termed as “fowl plague” (Lupiani and Reddy 2009). The causative organism was identified as a virus in 1901 and classified under the influenza A virus group in 1955 (Horimoto and Kawaoka 2001). The term fowl plague was substituted with Highly Pathogenic Avian Influenza (HPAI) at the First International Symposium on Avian Influenza. The AI causes both direct and indirect loss to the poultry industry. Direct losses include losses due to high morbidity and mortality, loss of valuable genetic material, costs of depopulation and disposal, costs of quarantine and surveillance and compensation for the elimination of live birds etc. For example, direct transmission of H5N1 AI Virus (AIV) from birds to humans documented in 1997 in Hong Kong led to culling of more than 1.5 million chickens within a span of 3 days. Indirect losses are due to imposition of trade embargo on poultry and poultry products. In India, a single outbreak of H5N1 virus in a This ebook is exclusively for this university only. Cannot be resold/distributed. remote village of Manipur in 2007 resulted in a loss of over 0.5 per cent of GDP of the State (Kumar et al. 2008). The zoonotic potential and the subsequent fear of imminent pandemic led to culling of chickens wherever the infection of humans and birds occurred together.
eBook - PDF- Michael R. Conover, Rosanna M. Vail(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
(Courtesy of the CDC.) 400 Human Diseases from Wildlife avian influenza A viruses in wild birds, poultry, or humans. This monitoring allows local governments to quickly eliminate infected flocks, stop the movement of poul-try that may have been exposed to the virus, and close markets where live birds are sold. WHO has created the Global Outbreak Alert and Response Network, which is a collaboration of various governmental health agencies, institutions (e.g., Red Cross, Red Crescent, and medical colleges), and humanitarian organizations. Its mission is to pool global resources for the rapid identification, confirmation, and response to outbreaks of international importance (WHO 2005a). When the influenza virus is detected in domestic birds, the infected flock and any other flocks that had contact with it are culled and quarantine practices are imposed to contain the virus. For instance, countries in the European Union prohibit the movement of all live poultry and poultry products from within 2 miles (3 km) of where an infected bird was located; bird hunting is banned within this same area (Reperant et al. 2012). While quarantines or travel bans may only slow the arrival of influenza virus into a country rather than prevent it, the additional time allows health agencies to prepare (e.g., creating more vaccines). Furthermore, influenza pandem-ics are normally so contagious that health facilities are quickly overwhelmed by the sick. Any steps that can slow the pathogen’s spread through a population can reduce the number of patients requiring medical attention at any one point in time (OSHA 2006, CDC 2011a,b, 2012). 24.6.3 R EDUCING THE R ISK T HAT A P ERSON W ILL A CQUIRE I NFLUENZA FROM B IRDS OR P IGS According to the CDC, the best way for a person to avoid becoming infected during an outbreak in poultry is to avoid exposure to sick or dead birds. Poultry farmers and workers should use personal protective equipment.
Birds can leave behind viral particles in their droppings, which then easily contaminate water; once there, influenza viral par- ticles may remain infectious for 100–200 days, depending on water temperature. Usually, avian influenza is not harmful to its bird host, but wide spread of the virus can easily occur because birds may travel for hundreds (or even thousands) of miles during migration. Recent identification of highly pathogenic strains of avian influenza in poultry has caused great concern for future potential of a dev- astating pandemic among humans, particularly with documentation of rapid vi- ral evolution, an increasing tendency for the virus to be found in new host species (such as migratory birds and mammals), and confirmed geographic spread of the virus from Asia to Africa, Europe, and the Middle East. Pigs may also play an important role in the biography of influenza. The re- spiratory tract of pigs contains receptors that bind both avian and human influenza viruses. It has been proposed that the genetic ‘‘reassortment’’ of avian and human influenza may occur in pigs, leading to a new and novel viral strain that can then be spread to mankind. CLASSIFICATION AND MORPHOLOGY OF THE INFLUENZA VIRUS Influenza has caused recurrent disease outbreaks for centuries, as has been well documented in our historical literature. Obviously, then, the virus has morphological characteristics that allow it to exist year after year. Medical 12 Influenza technology has now advanced enough for researchers to further classify the influenza virus in terms of size, shape, and function. Influenza belongs to a larger family of viruses called Orthomyxoviridae.
eBook - PDF- S. K. Lal, B. W. J. Mahy(Authors)
- 2006(Publication Date)
- S. Karger(Publisher)
Lal SK (ed): Emerging Viral Diseases of Southeast Asia. Issues Infect Dis. Basel, Karger, 2007, vol 4, pp 59–77 Avian Influenza H5N 1 Virus: An Emerging Global Pandemic Sunil K. Lal a , Vincent T.K. Chow b a Virology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India; b Programme in Infectious Diseases, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore Abstract The specter of avian influenza emerging from Asia and spreading all over the globe is causing deeper concern by the day. As we witness the H5N1 virus evolving and becoming increasingly dangerous, a major pandemic may be unavoidable. The bird flu virus has already claimed more than 140 lives worldwide as of August 2006. Should bird flu spark a global pandemic, several hundred million people could die within a matter of weeks, which is many times the number of deaths due to AIDS so far. This pathogen is completely differ-ent from seasonal influenza virus, which kills between 1 and 2 million people worldwide in a typical year. In the worst previous pandemic of 1918, more than 20 million humans died of the Spanish flu. The current bird flu virus has emerged from a pool of animals that have previously never infected humans implying that humans do not have antibodies to combat the infection. This virus also causes severe disease and high fatality within a short time span. The only remaining factor to enable the virus to cause a pandemic is if it acquires the capability of swift transmission among humans through coughing, sneezing or just a simple handshake! The evolving bird flu virus has already crossed the species barrier from chickens to other birds and mammals including pigs. Pigs possess flu virus receptors on their respiratory cells which are similar to human receptors.
eBook - PDF- Edward Tabor(Author)
- 2006(Publication Date)
- Elsevier Science(Publisher)
As of this writing (April 2006), there have been more than 200 laboratory-confirmed cases of avian influenza H5N1 infections in humans reported in nine countries, more than 100 of which resulted in death ( WHO, 2006b ). These events have highlighted the potential for another influenza pandemic. What causes a pandemic and how does it arise? What can be done to limit the devastating effects a pandemic usually brings and how prepared are we to meet such challenges? An examination of the biology of the avian influenza viruses and their relationship with their animal hosts may shed light on these questions. Virology Classification Influenza viruses are enveloped viruses with a segmented genome. They are in the virus family Orthomyxoviridae . Three types of influenza virus have been described, designated as influenza A, B, and C, based on the antigenicity of two of their internal proteins, the nucleoprotein (NP) and matrix (M) protein ( Lamb and Krug, 2001 ). Influenza B and C viruses mainly infect humans, while influenza A viruses infect a wide variety of avian and mammalian species, including humans, pigs, sea mammals, and horses. Influenza viral proteins Influenza A and B viruses possess eight single-stranded negative-sense RNA seg-ments that encode structural and nonstructural proteins. Hemagglutinin (HA), a surface glycoprotein that mediates viral entry by binding to sialic acid residues on host cells, is the main target of the protective humoral immune responses in the human host. Neuraminidase (NA) is the other major surface glycoprotein, whose enzymatic function allows the release of newly formed virions, permits the spread of infectious virus from cell to cell, and keeps newly budding virions from aggre-gating at the host cell surface. This catalytic function of the NA protein is the target of the anti-influenza virus drugs oseltamivir and zanamivir; although these A.L. Suguitan, Jr., K. Subbarao 98
eBook - PDFViral Diagnostics
Advances and Applications
- Robert S. Marks, Leslie Lobel, Amadou Sall, Robert S. Marks, Leslie Lobel, Amadou Sall(Authors)
- 2014(Publication Date)
- Jenny Stanford Publishing(Publisher)
The following are examined in this chapter: the historical course of H5N1-induced disease in humans and birds, mechanisms for human-to-human transmission, viral recombination in humans and animals, and extant immunity to disease in humans. These factors should be carefully considered in assessing the risk of a new pandemic based on some variant of the currently circulating clades of HPAI H5N1. An H5N1 pandemic appears unlikely, but systematic near real-time surveillance for severe respiratory or gastrointestinal symptoms in humans and animals is warranted, to identify disease-causing organisms that have the potential to cause pandemics or panzootics. 6.2 The Nature of Influenza A Predisposes It to Pandemics Influenza A, B, and C virus types are members of the family Orthomyxoviridae , all negative-sense RNA viruses possessing a segmented genome divided into either eight or nine strands. One genus of Orthomyxoviridae contains influenza A and B, and a second contains influenza C. While these influenza types obviously share structural properties, their host ranges are dramatically different, with types B and C being almost exclusively human pathogens (on occasion found in pigs and seals); IAVs have a wide host range—wild birds, pigs, horses, seals and whales, and poultry. Influenza viruses routinely undergo mutational changes during host cell transcription of viral RNA. Such mutations may or may not result in a viable virus, but if they do, a virus with a changed host range or pathogenic potential may emerge. In this chapter, we consider an IAV first recognized to cause severe disease in birds about a decade ago and that has been touted as a potential cause of another pandemic (glossary of terms), perhaps with consequences as severe as the devastating pandemic of 1918. The arguments advanced for this concern are detailed later and shall be analyzed in the context of the knowledge of influenza immunology in humans and the experimental literature on host
- Dongyou Liu(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
21 3 3.1 INTRODUCTION The genus Influenzavirus A contains a number of segmented, single-stranded, negative sense RNA viruses that are further separated into 17 hemagglutinin (H or HA) subtypes and 9 neuraminidase (N or NA) subtypes. As members of the genus Influenzavirus A are adapted in wild aquatic birds (natural reservoir host), they are commonly known as avian influ-enza viruses (or “avian influenza,” “bird flu”). Among these viruses, several subtypes (e.g., H1N1, H2N2, H3N2, H5N1) are highly pathogenic, with the tendency to induce signifi-cant mortality in domestic fowls as well as serious diseases in humans. Hence, they are frequently referred to as highly pathogenic avian influenza viruses (HPAI). In particular, highly pathogenic avian influenza A (H5N1) virus (HPAI H5N1, sometimes shortened to H5N1) is highly contagious and deadly to domestic poultry. Being capable of direct transmission from poultry to humans, and airborne transmission between mammals, this virus has been respon-sible for causing sporadic, severe illness in humans and many animal species. After first appearing in Asia in 1997, HPAI H5N1 has created global concern as a potential pandemic threat. Between 2003 and 2011, this virus was responsible for a total of 566 confirmed human cases and 332 deaths. On the other hand, avian influenza subtype H7N9 virus is gener-ally considered as of low pathogenicity affecting birds only and has not been implicated in human outbreaks. However, between February and November 2013, 138 patients have been confirmed in eastern China provinces with avian influ-enza virus subtype H7N9 infection, resulting in 45 casualties. This chapter focuses on HPAI H5N1 as well as the newly emerged H7N9, in relation to its classification, morphology, biology, epidemiology, clinical features, pathogenesis, identifi-cation, diagnosis, treatment, and prevention.
eBook - PDF- H. -D. Klenk, M. N. Matrosovich, J. Stech, W. Preiser(Authors)
- 2008(Publication Date)
- S. Karger(Publisher)
Klenk H-D, Matrosovich MN, Stech J (eds): Avian Influenza. Monogr Virol. Basel, Karger, 2008, vol 27, pp 101–117 History of Research on Avian Influenza Christoph Scholtissek Linden, Germany Abstract This chapter on the history of avian influenza viruses starts at the beginning of the 20th century with the description of early fundamental experiments on the characterization and replication of fowl plague virus before it was recognized as an influenza A virus. Virus replication is explained using molecular approaches, and the importance of the cleavability of the hemagglutinin for starting the infection, for pathogenicity, organ tropism, and outbreaks is a central theme. The role of host factors for specific modifications of viral components for understanding species specificity is discussed as well as virus genetics leading to the con-cept of a segmented genome which helps to explain reassortments and creation of pandemic viruses. Studies on the ecology revealed a huge reservoir of avian influenza viruses in waterfowl in evolutionary stasis, from which from time to time an avian virus arises to pass the species barrier to mammals, explain-ing well the disastrous pandemic of 1918–1919. Possible outbreaks of future pandemics and how they might be dealt with are also discussed. Copyright © 2008 S. Karger AG, Basel Introduction Influenza has a long recorded history, dating back to 412 BC at least when Hippocrates described a typical human influenza epidemic in Greece. Avian influenza, initially called fowl plague (Hühnerpest, peste aviaire), was discovered much later. In the second half of the 19th century there were severe outbreaks of fowl plague in Northern Italy exhibiting symptoms that were distinct from those of fowl cholera, leading Centanni [1] in 1901 to characterize the causative agent as a virus. The agent was found to pass bacterial filters and could be passaged ‘indefinitely’ through chicken.
eBook - PDF- Dongyou Liu(Author)
- 2009(Publication Date)
- CRC Press(Publisher)
Perroncito, E. Epizoozia tifoide nei gallinacei. Ann. Accad. Agric. Torino , 21, 87, 126, 1878. 2. Capua, I. and Marangon S. Control of avian influenza in poul-try. Emerg. Infect . Dis ., 12, 1319, 2006. 3. Perdue, M.L. and Swayne, D.E. Public health risk from avian influenza viruses. Avian Dis ., 49, 317, 2005. 4. Cattoli, G. and Terregino, C. New perspectives in avian influ-enza diagnosis. Zoonoses Public Health, 55, 24, 2008. 5. Fouchier, R.A.M. et al. Characterization of a novel influenza A virus hemagglutinin subtype (H16) obtained from black-headed gulls. J. Virol., 79, 2814, 2005. 6. Olsen, B. et al. Global patterns of influenza A virus in wild birds. Science , 312, 384, 2006. 7. EFSA (European Food Safety Authority), Scientific report of the scientific panel on biological hazards on “Food as a pos-sible source of infection with highly pathogenic avian influ-enza viruses for humans and other mammals”.. EFSA J ., 74, 1, 2006. Also available online at www.efsa.eu.int 8. Capua, I. and Alexander, D.J. Human implications of avian influenza viruses and Paramyxoviruses. Eur. J. Clin. Microbiol. Infect. Dis ., 23, 1, 2004. 9. Rott, R. The pathogenic determinant of influenza virus. Vet. Microbiol ., 33, 303, 1992. 10. Vey, M. et al. Haemagglutinin activation of pathogenic avian influenza viruses of serotype H7 requires the recognition motif R-X-R/K-R. Virology , 188, 408, 1992. 11. Senne D.A. et al. Survey of the haemagglutinin (HA) cleavage site sequence of H5 and H7 avian influenza viruses: amino acid sequence at the cleavage site as a marker of pathogenicity potential. Avian Dis ., 40, 425, 1996. 12. Suarez, D.L. et al. Recombination resulting in virulence shift in avian influenza outbreak. Emerg. Infect. Dis ., 10, 1, 2004. 13. Pasick, J., Handel, K. and Robinson, J. Intersegmental recom-bination between the haemagglutinin and matrix genes was responsible for the emergence of a highly pathogenic H7N3 avian influenza virus in British Columbia.
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