Global spread of H5N1 in 2004
Encyclopedia
The global spread of H5N1 in bird
s is considered a significant pandemic
threat.
While prior H5N1
strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented. The current H5N1 strain is a fast-mutating
, highly pathogen
ic avian influenza virus (HPAI) found in multiple bird species. It is both epizootic (an epidemic in non-humans) and panzootic (a disease affecting animals of many species especially over a wide area). Unless otherwise indicated, "H5N1" in this article refers to the recent highly pathogenic strain of H5N1.
H5N1 caused flu outbreaks in 1959 and in 1991 but these strains were very different from the current highly pathogenic strain of H5N1. Evolution
from 1999 to 2002 created the Z genotype which became the dominant strain of highly pathogenic H5N1 in 2004.
In January 2004 a major new outbreak of H5N1
surfaced in Vietnam
and Thailand
's poultry
industry, and within weeks spread to ten countries and regions in Asia
, including Indonesia
, South Korea
, Japan
and China
. In October 2004 researchers discovered H5N1
is far more dangerous than previously believed because waterfowl
were directly spreading the highly pathogenic strain of H5N1
to chicken
s, crow
s, pigeons, and other birds and that it was increasing its ability to infect mammals as well. From this point on, avian influenza experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s is considered a significant pandemic
Influenza pandemic
An influenza pandemic is an epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the human population. In contrast to the regular seasonal epidemics of influenza, these pandemics occur irregularly, with the 1918 Spanish flu the most serious pandemic in...
threat.
While prior H5N1
H5N1
Influenza A virus subtype H5N1, also known as "bird flu", A or simply H5N1, is a subtype of the influenza A virus which can cause illness in humans and many other animal species...
strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented. The current H5N1 strain is a fast-mutating
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
, highly pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic avian influenza virus (HPAI) found in multiple bird species. It is both epizootic (an epidemic in non-humans) and panzootic (a disease affecting animals of many species especially over a wide area). Unless otherwise indicated, "H5N1" in this article refers to the recent highly pathogenic strain of H5N1.
H5N1 caused flu outbreaks in 1959 and in 1991 but these strains were very different from the current highly pathogenic strain of H5N1. Evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
from 1999 to 2002 created the Z genotype which became the dominant strain of highly pathogenic H5N1 in 2004.
In January 2004 a major new outbreak of H5N1
H5N1
Influenza A virus subtype H5N1, also known as "bird flu", A or simply H5N1, is a subtype of the influenza A virus which can cause illness in humans and many other animal species...
surfaced in Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
's poultry
Poultry
Poultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...
industry, and within weeks spread to ten countries and regions in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, including Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. In October 2004 researchers discovered H5N1
H5N1
Influenza A virus subtype H5N1, also known as "bird flu", A or simply H5N1, is a subtype of the influenza A virus which can cause illness in humans and many other animal species...
is far more dangerous than previously believed because waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
were directly spreading the highly pathogenic strain of H5N1
H5N1
Influenza A virus subtype H5N1, also known as "bird flu", A or simply H5N1, is a subtype of the influenza A virus which can cause illness in humans and many other animal species...
to chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s, crow
Crow
Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
s, pigeons, and other birds and that it was increasing its ability to infect mammals as well. From this point on, avian influenza experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.
January
- A major new outbreak of H5N1 surfaced in VietnamVietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
's poultryPoultryPoultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...
industry, and within weeks spread to ten countries and regions in AsiaAsiaAsia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, including IndonesiaIndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, South KoreaSouth KoreaThe Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and ChinaPeople's Republic of ChinaChina , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Intensive efforts were undertaken to slaughter chickenChickenThe chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s, duckDuckDuck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s and geese (over forty million chickens alone were slaughtered in high-infection areas), and the outbreak was contained by March, but the total human death toll in Vietnam and Thailand was twenty three people.
February
- "The Ministry of Public Health in Thailand has confirmed the country's tenth case of H5N1 infection."
July
- Fresh outbreaks in poultry were confirmed in AyutthayaAyutthaya ProvincePhra Nakhon Si Ayutthaya is one of the central provinces of Thailand. Neighboring provinces are Ang Thong, Lop Buri, Saraburi, Pathum Thani, Nonthaburi, Nakhon Pathom and Suphan Buri....
and Pathumthani provinces of ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, and Chaohu city in AnhuiAnhuiAnhui is a province in the People's Republic of China. Located in eastern China across the basins of the Yangtze River and the Huai River, it borders Jiangsu to the east, Zhejiang to the southeast, Jiangxi to the south, Hubei to the southwest, Henan to the northwest, and Shandong for a tiny...
, ChinaPeople's Republic of ChinaChina , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Research identifies the dominant strain of H5N1 as the "Z genotype".
August
- Avian flu was confirmed in Kampung Pasir, KelantanKelantanKelantan is a state of Malaysia. The capital and royal seat is Kota Bharu. The Arabic honorific of the state is Darul Naim, ....
, Malaysia. Two chickens were confirmed to be carrying H5N1. As a result SingaporeSingaporeSingapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
has imposed a ban on the importation of chickens and poultry products. Similarly the EU has imposed a ban on Malaysian poultry products. A cull of all poultry has been ordered by the Malaysian government within a 10 km radius of the location of this outbreak. These moves appear to have been successful and since then, Singapore has lifted the ban and Malaysia has requested the OIEOffice international des épizootiesThe World Organisation for Animal Health is the intergovernmental organisation responsible for improving animal health worldwide and was created by an international agreement as the International Office of Epizootics on 25 January 1924...
declare Malaysian poultry bird flu free.
October
- Researchers discover H5N1 is far more dangerous than previously believed. "In the past, outbreaks of highly pathogenic avian influenza in poultry began following the primary introduction of a virus, of low pathogenicity, probably carried by a wild bird. The virus then required several months of circulation in domestic poultry in order to mutate from a form causing very mild disease to a form causing highly pathogenic disease, with a mortality approaching 100%. Only viruses of the H5 and H7 subtypes are capable of mutating to cause highly pathogenic disease. In the present outbreaks, however, asymptomatic domestic ducks can directly introduce the virus, in its highly pathogenic form, to poultry flocks." Limiting this conclusion to domestic waterfowlWaterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
proved to be wishful thinking, as in later months it became clear that nondomestic waterfowlWaterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
were also directly spreading the highly pathogenic strain of H5N1 to chickenChickenThe chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s, crowCrowCrows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
s, pigeons, and other birds and that it was increasing its ability to infect mammals as well. From this point on, avian influenza experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.
November
- The U.S.United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
's National Institutes of HealthNational Institutes of HealthThe National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
's (NIH) National Institute of Allergy and Infectious DiseasesNational Institute of Allergy and Infectious DiseasesThe National Institute of Allergy and Infectious Diseases is one of the 27 institutes and centers that make up the National Institutes of Health , an agency of the United States Department of Health and Human Services...
's (NIAID) Influenza Genome Sequencing ProjectInfluenza Genome Sequencing ProjectThe Influenza Genome Sequencing Project is an American-based genome project aimed at improving the availability of genomic sequence data from influenza viruses and related information....
to provide complete sequence data for selected human and avian influenza isolates begins.
See also
- Global spread of H5N1 in 2005Global spread of H5N1 in 2005The global spread of H5N1 in birds is considered a significant pandemic threat.While prior H5N1 strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented...
- Global spread of H5N1 in 2006Global spread of H5N1 in 2006The global spread of H5N1 in birds is considered a significant pandemic threat.While prior H5N1 strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented...
- Global spread of H5N1 in 2007Global spread of H5N1 in 2007The global spread of H5N1 in birds is considered a significant pandemic threat.While prior H5N1 strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented...