Of the three genera of influenza viruses that cause human flu, two also cause influenza in pigs, with Influenzavirus A being common in pigs and Influenzavirus C being rare.Influenzavirus B has not been reported in pigs. Within Influenzavirus A and Influenzavirus C, the strains found in pigs and humans are largely distinct, although due to reassortment there have been transfers of genes among strains crossing swine, avian, and human species boundaries.
Influenza C
Influenza C viruses infect both humans and pigs, but do not infect birds. Transmission between pigs and humans have occurred in the past.For example, influenza C caused small outbreaks of a mild form of influenza amongst children in Japan and California.Due to its limited host range and the lack of genetic diversity in influenza C, this form of influenza does not cause pandemics in humans.
Influenza A
Swine influenza is known to be caused by influenza A subtypes H1N1,H1N2,H3N1, H3N2,and H2N3.In pigs, three influenza A virus subtypes (H1N1, H3N2, and H1N2) are the most common strains worldwide.In the United States, the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.
http://en.wikipedia.org
Showing posts with label influenza. Show all posts
Showing posts with label influenza. Show all posts
Tuesday, July 14, 2009
Sunday, July 5, 2009
Influenza
Influensa, biasanya dikenali sebagai flu, adalah penyakit menular burung dan mamalia yang disebabkan oleh virus RNA dari famili Orthomyxoviridae (virus influensa). Penyakit ini ditularkan dengan medium udara melalui bersin dari si penderita. Pada manusia, gejala umum yang terjadi adalah demam, sakit tenggorokan, sakit otot, sakit kepala, hidung tersumbat dan mengeluarkan cairan, batuk, lesu serta rasa tidak enak badan. Dalam kasus yang lebih buruk, influensa juga dapat menyebabkan terjadinya pneumonia, yang dapat mengakibatkan kematian terutama pada anak-anak dan orangtua.
Masa inkubasi
Masa penularan hingga terserang penyakit ini adalah 1-3 hari.
Gejala
Demam mendadak, asma, pilek, sakit kerongkongan, batuk, sakit otot dan sakit kepala, bersin-bersin.
Karantina atau pengasingan
Penderita dianjurkan agar mengasingkan diri atau dikarantina agar tidak menularkan penyakit hingga mereka merasa lebih sehat.
Pencegahan
Kaum lanjut usia atau mereka yang mengidap penyakit kronis dianjurkan diimunisasi. Tapi perlu adanya alternative lain dalam mengembangkan imunitas dalam tubuh sendiri, melalui makanan yang bergizi dan menjahui potensi-potensi yang menyebabkan influensa.
Mutasi virus influensa
Virus influensa cepat sekali bermutasi, sehingga setiap kali para ahli virus harus berusaha menemukan penangkal yang baru. Beberapa tahun yang lalu kita mengenal flu Hong Kong dan pada tahun 2005 merebak flu burung. Semua ini menunjukkan betapa sulitnya usaha penangkalan terhadap penyakit ini.
http://id.wikipedia.org
Thursday, June 11, 2009
World now at the start of 2009 influenza pandemic
Dr Margaret Chan
Director-General of the World Health Organization
Ladies and gentlemen,
In late April, WHO announced the emergence of a novel influenza A virus.
This particular H1N1 strain has not circulated previously in humans. The virus is entirely new.
The virus is contagious, spreading easily from one person to another, and from one country to another. As of today, nearly 30,000 confirmed cases have been reported in 74 countries.
This is only part of the picture. With few exceptions, countries with large numbers of cases are those with good surveillance and testing procedures in place.
Spread in several countries can no longer be...
traced to clearly-defined chains of human-to-human transmission. Further spread is considered inevitable.
I have conferred with leading influenza experts, virologists, and public health officials. In line with procedures set out in the International Health Regulations, I have sought guidance and advice from an Emergency Committee established for this purpose.
On the basis of available evidence, and these expert assessments of the evidence, the scientific criteria for an influenza pandemic have been met.
I have therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6.
The world is now at the start of the 2009 influenza pandemic.
We are in the earliest days of the pandemic. The virus is spreading under a close and careful watch.
No previous pandemic has been detected so early or watched so closely, in real-time, right at the very beginning. The world can now reap the benefits of investments, over the last five years, in pandemic preparedness.
We have a head start. This places us in a strong position. But it also creates a demand for advice and reassurance in the midst of limited data and considerable scientific uncertainty.
Thanks to close monitoring, thorough investigations, and frank reporting from countries, we have some early snapshots depicting spread of the virus and the range of illness it can cause.
We know, too, that this early, patchy picture can change very quickly. The virus writes the rules and this one, like all influenza viruses, can change the rules, without rhyme or reason, at any time.
Globally, we have good reason to believe that this pandemic, at least in its early days, will be of moderate severity. As we know from experience, severity can vary, depending on many factors, from one country to another.
On present evidence, the overwhelming majority of patients experience mild symptoms and make a rapid and full recovery, often in the absence of any form of medical treatment.
Worldwide, the number of deaths is small. Each and every one of these deaths is tragic, and we have to brace ourselves to see more. However, we do not expect to see a sudden and dramatic jump in the number of severe or fatal infections.
We know that the novel H1N1 virus preferentially infects younger people. In nearly all areas with large and sustained outbreaks, the majority of cases have occurred in people under the age of 25 years.
In some of these countries, around 2% of cases have developed severe illness, often with very rapid progression to life-threatening pneumonia.
Most cases of severe and fatal infections have been in adults between the ages of 30 and 50 years.
This pattern is significantly different from that seen during epidemics of seasonal influenza, when most deaths occur in frail elderly people.
Many, though not all, severe cases have occurred in people with underlying chronic conditions. Based on limited, preliminary data, conditions most frequently seen include respiratory diseases, notably asthma, cardiovascular disease, diabetes, autoimmune disorders, and obesity.
At the same time, it is important to note that around one third to half of the severe and fatal infections are occurring in previously healthy young and middle-aged people.
Without question, pregnant women are at increased risk of complications. This heightened risk takes on added importance for a virus, like this one, that preferentially infects younger age groups.
Finally, and perhaps of greatest concern, we do not know how this virus will behave under conditions typically found in the developing world. To date, the vast majority of cases have been detected and investigated in comparatively well-off countries.
Let me underscore two of many reasons for this concern. First, more than 99% of maternal deaths, which are a marker of poor quality care during pregnancy and childbirth, occurs in the developing world.
Second, around 85% of the burden of chronic diseases is concentrated in low- and middle-income countries.
Although the pandemic appears to have moderate severity in comparatively well-off countries, it is prudent to anticipate a bleaker picture as the virus spreads to areas with limited resources, poor health care, and a high prevalence of underlying medical problems.
Ladies and gentlemen,
A characteristic feature of pandemics is their rapid spread to all parts of the world. In the previous century, this spread has typically taken around 6 to 9 months, even during times when most international travel was by ship or rail.
Countries should prepare to see cases, or the further spread of cases, in the near future. Countries where outbreaks appear to have peaked should prepare for a second wave of infection.
Guidance on specific protective and precautionary measures has been sent to ministries of health in all countries. Countries with no or only a few cases should remain vigilant.
Countries with widespread transmission should focus on the appropriate management of patients. The testing and investigation of patients should be limited, as such measures are resource intensive and can very quickly strain capacities.
WHO has been in close dialogue with influenza vaccine manufacturers. I understand that production of vaccines for seasonal influenza will be completed soon, and that full capacity will be available to ensure the largest possible supply of pandemic vaccine in the months to come.
Pending the availability of vaccines, several non-pharmaceutical interventions can confer some protection.
WHO continues to recommend no restrictions on travel and no border closures.
Influenza pandemics, whether moderate or severe, are remarkable events because of the almost universal susceptibility of the world’s population to infection.
We are all in this together, and we will all get through this, together.
Thank you.
http://www.who.int
Director-General of the World Health Organization
Ladies and gentlemen,
In late April, WHO announced the emergence of a novel influenza A virus.
This particular H1N1 strain has not circulated previously in humans. The virus is entirely new.
The virus is contagious, spreading easily from one person to another, and from one country to another. As of today, nearly 30,000 confirmed cases have been reported in 74 countries.
This is only part of the picture. With few exceptions, countries with large numbers of cases are those with good surveillance and testing procedures in place.
Spread in several countries can no longer be...
traced to clearly-defined chains of human-to-human transmission. Further spread is considered inevitable.
I have conferred with leading influenza experts, virologists, and public health officials. In line with procedures set out in the International Health Regulations, I have sought guidance and advice from an Emergency Committee established for this purpose.
On the basis of available evidence, and these expert assessments of the evidence, the scientific criteria for an influenza pandemic have been met.
I have therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6.
The world is now at the start of the 2009 influenza pandemic.
We are in the earliest days of the pandemic. The virus is spreading under a close and careful watch.
No previous pandemic has been detected so early or watched so closely, in real-time, right at the very beginning. The world can now reap the benefits of investments, over the last five years, in pandemic preparedness.
We have a head start. This places us in a strong position. But it also creates a demand for advice and reassurance in the midst of limited data and considerable scientific uncertainty.
Thanks to close monitoring, thorough investigations, and frank reporting from countries, we have some early snapshots depicting spread of the virus and the range of illness it can cause.
We know, too, that this early, patchy picture can change very quickly. The virus writes the rules and this one, like all influenza viruses, can change the rules, without rhyme or reason, at any time.
Globally, we have good reason to believe that this pandemic, at least in its early days, will be of moderate severity. As we know from experience, severity can vary, depending on many factors, from one country to another.
On present evidence, the overwhelming majority of patients experience mild symptoms and make a rapid and full recovery, often in the absence of any form of medical treatment.
Worldwide, the number of deaths is small. Each and every one of these deaths is tragic, and we have to brace ourselves to see more. However, we do not expect to see a sudden and dramatic jump in the number of severe or fatal infections.
We know that the novel H1N1 virus preferentially infects younger people. In nearly all areas with large and sustained outbreaks, the majority of cases have occurred in people under the age of 25 years.
In some of these countries, around 2% of cases have developed severe illness, often with very rapid progression to life-threatening pneumonia.
Most cases of severe and fatal infections have been in adults between the ages of 30 and 50 years.
This pattern is significantly different from that seen during epidemics of seasonal influenza, when most deaths occur in frail elderly people.
Many, though not all, severe cases have occurred in people with underlying chronic conditions. Based on limited, preliminary data, conditions most frequently seen include respiratory diseases, notably asthma, cardiovascular disease, diabetes, autoimmune disorders, and obesity.
At the same time, it is important to note that around one third to half of the severe and fatal infections are occurring in previously healthy young and middle-aged people.
Without question, pregnant women are at increased risk of complications. This heightened risk takes on added importance for a virus, like this one, that preferentially infects younger age groups.
Finally, and perhaps of greatest concern, we do not know how this virus will behave under conditions typically found in the developing world. To date, the vast majority of cases have been detected and investigated in comparatively well-off countries.
Let me underscore two of many reasons for this concern. First, more than 99% of maternal deaths, which are a marker of poor quality care during pregnancy and childbirth, occurs in the developing world.
Second, around 85% of the burden of chronic diseases is concentrated in low- and middle-income countries.
Although the pandemic appears to have moderate severity in comparatively well-off countries, it is prudent to anticipate a bleaker picture as the virus spreads to areas with limited resources, poor health care, and a high prevalence of underlying medical problems.
Ladies and gentlemen,
A characteristic feature of pandemics is their rapid spread to all parts of the world. In the previous century, this spread has typically taken around 6 to 9 months, even during times when most international travel was by ship or rail.
Countries should prepare to see cases, or the further spread of cases, in the near future. Countries where outbreaks appear to have peaked should prepare for a second wave of infection.
Guidance on specific protective and precautionary measures has been sent to ministries of health in all countries. Countries with no or only a few cases should remain vigilant.
Countries with widespread transmission should focus on the appropriate management of patients. The testing and investigation of patients should be limited, as such measures are resource intensive and can very quickly strain capacities.
WHO has been in close dialogue with influenza vaccine manufacturers. I understand that production of vaccines for seasonal influenza will be completed soon, and that full capacity will be available to ensure the largest possible supply of pandemic vaccine in the months to come.
Pending the availability of vaccines, several non-pharmaceutical interventions can confer some protection.
WHO continues to recommend no restrictions on travel and no border closures.
Influenza pandemics, whether moderate or severe, are remarkable events because of the almost universal susceptibility of the world’s population to infection.
We are all in this together, and we will all get through this, together.
Thank you.
http://www.who.int
Friday, May 22, 2009
Confirmed cases of swine influenza A (H1N1) virus in three countries in the WHO European Region
On 27 April 2009, National Focal Points (NFPs) for the International Health Regulations (IHR) informed WHO/Europe about the detection of four confirmed cases of swine influenza A (H1N1) virus infection: two cases...
each in Spain and the United Kingdom. On 28 April 2009, the NFP of Israel reported an additional confirmed case.
The five people with confirmed cases in the WHO European Region presented with mild illness and had recently returned from travel in Mexico. As of 27 April 2009, 43 additional people in 8 countries in the Region were under investigation for infection.
Situation in the European Region
The reports of confirmed cases from Israel, Spain and the United Kingdom reflect important steps taken by the national authorities to ensure early detection and response in association with the evolving situation in the Americas. National authorities are advised to intensify surveillance efforts for the early detection of people who may be infected with swine influenza A (H1N1) virus and may transmit the infection to others.
On 27 April 2009, the WHO Regional Director for Europe, Dr Marc Danzon, informed the health ministers, chief medical officers and NFPs in the Region of WHO/Europe’s response. He acknowledged that cooperation between WHO and national and international counterparts was crucial in preparing for and responding to the potential spread of swine influenza A (H1N1) virus in the European Region.
WHO/Europe is working closely with the Directorate-General for Health and Consumers of the European Commission and the European Centre for Disease Prevention and Control. Similarly, WHO is in close consultation with development partners, United Nations agencies and other international organizations (including those involved in trade and travel), and manufacturers of vaccines, drugs, diagnostic equipment and personal protection equipment.
Global situation
The five cases in the WHO European Region are the first confirmed cases identified outside the Americas. The WHO headquarters web pages on swine influenza offer additional information on the global situation, including Canada, Mexico and the United States of America.
Change in pandemic alert level
On 27 April 2009, the second meeting of the Emergency Committee was convened as stipulated under the IHR. Following the Committee’s advice, the WHO Director-General, Dr Margaret Chan, decided to change the current phase of pandemic alert from level 3 to level 4.
This decision was based primarily on epidemiological data demonstrating human-to-human transmission and the ability of the virus to cause community-level outbreaks. As further information becomes available, WHO may decide either to revert to phase 3 or to raise the level of alert further.
The outcome of the Emergency Committee’s meeting included recommendations to countries not to close borders or to restrict international travel. It is considered prudent for people who are ill to delay international travel and for those developing symptoms following international travel to seek medical attention. In addition, WHO will facilitate the process needed to develop a vaccine effective against the A (H1N1) virus.
WHO published interim guidance for the surveillance of human infection with swine influenza A (H1N1) virus, including case definition and requirements for reporting to WHO, on 27 April 2009.
each in Spain and the United Kingdom. On 28 April 2009, the NFP of Israel reported an additional confirmed case.
The five people with confirmed cases in the WHO European Region presented with mild illness and had recently returned from travel in Mexico. As of 27 April 2009, 43 additional people in 8 countries in the Region were under investigation for infection.
Situation in the European Region
The reports of confirmed cases from Israel, Spain and the United Kingdom reflect important steps taken by the national authorities to ensure early detection and response in association with the evolving situation in the Americas. National authorities are advised to intensify surveillance efforts for the early detection of people who may be infected with swine influenza A (H1N1) virus and may transmit the infection to others.
On 27 April 2009, the WHO Regional Director for Europe, Dr Marc Danzon, informed the health ministers, chief medical officers and NFPs in the Region of WHO/Europe’s response. He acknowledged that cooperation between WHO and national and international counterparts was crucial in preparing for and responding to the potential spread of swine influenza A (H1N1) virus in the European Region.
WHO/Europe is working closely with the Directorate-General for Health and Consumers of the European Commission and the European Centre for Disease Prevention and Control. Similarly, WHO is in close consultation with development partners, United Nations agencies and other international organizations (including those involved in trade and travel), and manufacturers of vaccines, drugs, diagnostic equipment and personal protection equipment.
Global situation
The five cases in the WHO European Region are the first confirmed cases identified outside the Americas. The WHO headquarters web pages on swine influenza offer additional information on the global situation, including Canada, Mexico and the United States of America.
Change in pandemic alert level
On 27 April 2009, the second meeting of the Emergency Committee was convened as stipulated under the IHR. Following the Committee’s advice, the WHO Director-General, Dr Margaret Chan, decided to change the current phase of pandemic alert from level 3 to level 4.
This decision was based primarily on epidemiological data demonstrating human-to-human transmission and the ability of the virus to cause community-level outbreaks. As further information becomes available, WHO may decide either to revert to phase 3 or to raise the level of alert further.
The outcome of the Emergency Committee’s meeting included recommendations to countries not to close borders or to restrict international travel. It is considered prudent for people who are ill to delay international travel and for those developing symptoms following international travel to seek medical attention. In addition, WHO will facilitate the process needed to develop a vaccine effective against the A (H1N1) virus.
WHO published interim guidance for the surveillance of human infection with swine influenza A (H1N1) virus, including case definition and requirements for reporting to WHO, on 27 April 2009.
Wednesday, May 20, 2009
Avian Influenza: Current H5N1 Situation
The highly pathogenic avian influenza A (H5N1) epizootic (animal outbreak) in Asia, Europe, the Near East, and Africa is not expected to diminish significantly in the short term. It is likely that H5N1 virus infections among domestic poultry have become endemic in certain areas and that sporadic human infections resulting from direct contact with infected poultry and/or...
wild birds will continue to occur. So far, the spread of H5N1 virus from person-to-person has been very rare, limited and unsustained. However, this epizootic continues to pose an important public health threat.
There is little pre-existing natural immunity to H5N1 virus infection in the human population. If H5N1 viruses gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result, with potentially high rates of illness and death worldwide. No evidence for genetic reassortment between human and avian influenza A virus genes has been found to date, and there is no evidence of any significant changes to circulating H5N1 virus strains to suggest greater transmissibility to or among humans. Genetic sequencing of avian influenza A (H5N1) viruses from human cases in Vietnam, Thailand, and Indonesia shows resistance to the antiviral medications amantadine and rimantadine, two of the medications commonly used for treatment of influenza. This leaves two remaining antiviral medications (oseltamivir and zanamivir) that should still be effective against currently circulating strains of H5N1 viruses. A small number of oseltamivir resistant H5N1 virus infections of humans have been reported. Efforts to produce pre-pandemic vaccine candidates for humans that would be effective against avian influenza A (H5N1) viruses are ongoing. However, no H5N1 vaccines are currently available for human use.
Research suggests that currently circulating strains of H5N1 viruses are becoming more capable of causing disease (pathogenic) in animals than were earlier H5N1 viruses. One study found that ducks infected with H5N1 virus are now shedding more virus for longer periods without showing symptoms of illness. This finding has implications for the role of ducks in transmitting disease to other birds and possibly to humans as well. Additionally, other findings have documented H5N1 virus infection among pigs in China and Vietnam; H5N1 virus infection of cats (experimental infection of housecats in the Netherlands, isolation of H5N1 virus from domestic cats in Germany and Thailand, and detection of H5N1 viral RNA in domestic cats in Iraq and Austria); H5N1 virus infection of dogs (isolation of H5N1 virus from a domestic dog in Thailand); and isolation of H5N1 viruses from tigers and leopards at zoos in Thailand). In addition, H5N1 virus infection in a wild stone marten (a weasel-like mammal) was reported in Germany and in a wild civet cat in Vietnam. Avian influenza A (H5N1) virus strains that emerged in Asia in 2003 continue to evolve and may adapt so that other mammals may be susceptible to infection as well.
Notable findings of epidemiologic investigations of human H5N1 cases include:
* Thailand, 2004: An investigation concluded that probable limited human-to-human spread of influenza A (H5N1) had occurred in a family as a result of prolonged and very close contact between an ill child and her mother in a hospital. Transmission did not continue beyond one person.
* Vietnam, 2004: While the majority of known human H5N1 cases have begun with respiratory symptoms, one atypical fatal H5N1 case in a child in southern Vietnam presented with fever, diarrhea and seizures, and was initially diagnosed as encephalitis. The etiology was identified retrospectively as H5N1 virus through testing of cerebrospinal fluid, fecal matter, and throat and serum samples. Further research is needed to ascertain the implications of such findings.
* Vietnam, 2005: Investigations suggest transmission of H5N1 viruses to two persons through consumption of uncooked duck blood.
* Azerbaijan, 2006: Investigations revealed contact with H5N1-infected wild dead birds (swans) as the most plausible source of infection in several cases in teenagers involved in removing feathers from the birds.
* Indonesia, 2006: WHO reported evidence of limited human-to-human spread of H5N1 virus. In this situation, 8 people in one family were affected, with 7 deaths. H5N1 virus was isolated from 7 cases. The first family member is thought to have become ill through contact with infected poultry. This person then infected six family members. One of those six people (a child) then infected another family member (his father). No further spread outside of the exposed family was documented or suspected.
* Vietnam, 2006: A study reported a correlation between high H5N1 viral concentration and elevated inflammatory cytokine levels in fatal cases. The authors concluded that early antiviral treatment is needed to suppress H5N1 viral replication to prevent the inflammatory response that appears to be implicated in the pathogenesis of H5N1 virus infection.
Human H5N1 Cases
(WHO) has reported human cases of avian influenza A (H5N1) in Asia, Africa, the Pacific, Europe and the Near East. Indonesia and Vietnam have reported the highest number of H5N1 cases to date. Overall mortality in reported H5N1 cases is approximately 60%. The majority of cases have occurred among children and adults aged less than 40 years old. Mortality was highest in cases aged 10-19 years old. Studies have documented the most significant risk factors for human H5N1 infection to be direct contact with sick or dead poultry or wild birds, or visiting a live poultry market. Most human H5N1 cases have been hospitalized late in their illness with severe respiratory disease. A small number of clinically mild H5N1 cases have been reported. The current cumulative number of confirmed human cases of avian influenza A/(H5N1) is available on the WHO Avian Influenza website. Despite the high mortality, human cases of H5N1 remain rare to date.
Clusters of Human H5N1 Cases
Clusters of human H5N1 cases ranging from 2-8 cases per cluster have been identified in most countries that have reported H5N1 cases. Nearly all of the cluster cases have occurred among blood-related family members living in the same household. Whether such clusters are related to genetic or other factors is currently unknown. While most people in these clusters have been infected with H5N1 virus through direct contact with sick or dead poultry or wild birds, limited human-to-human transmission of H5N1 virus cannot be excluded in some clusters.
Animal H5N1 Cases
Since December 2003, avian influenza A (H5N1) virus infections in animals have been reported in Asia, Africa, the Pacific, Europe and the Near East. View the update on avian influenza in animals from the World Organization for Animal Health Web site.
Bird Import Ban
There is currently a ban on the importation of birds and bird products from H5N1-affected countries. The regulation states that no person may import or attempt to import any birds (Class Aves), whether dead or alive, or any products derived from birds (including hatching eggs), from the specified countries. For more information, see Embargo of Birds from Specified Countries.
Travel
Updated Information for Travelers about Avian Influenza A(H5N1) is available at the CDC Travelers’ Health Web site. Also see Guidelines and Recommendations - Interim Guidance about Avian Influenza A (H5N1) for U.S. Citizens Living Abroad.
CDC Response
CDC is working with WHO and other international partners to monitor the situation closely. In addition, CDC continues to work with WHO and the National Institutes of Health (NIH) on development of a vaccine for influenza A (H5N1). For more information view CDC's Response to Avian Influenza.
* Also see Updated Interim Guidance for Laboratory Testing of Persons with Suspected Infection with Avian Influenza A (H5N1) Virus in the United States for CDC’s domestic H5N1 surveillance recommendations.
The World Health Organization has additional resources and information on avian influenza A H5N1, including
* Recommendations and laboratory procedures for detection of avian influenza A(H5N1) virus in specimens from suspected human cases (pdf 165K, 28 pages)
* WHO guidelines for investigation of human cases of avian influenza A(H5N1) (pdf 115K, 18 pages)
* Collecting, preserving and shipping specimens for the diagnosis of avian influenza A(H5N1) virus infection Guide for field operations (pdf 2.36M, 83 pages)
Background on the Current Outbreaks
Highly pathogenic avian influenza A (H5N1) virus is an influenza A virus subtype that occurs mainly in birds and is highly contagious among birds, causing high mortality among domestic poultry. Outbreaks of highly pathogenic H5N1 among poultry and wild birds are ongoing in a number of countries. Currently, there are two different groups (or clades) of H5N1 viruses circulating among poultry (clade 1, and clade 2 viruses). At least three subgroups or subclades of clade 2 H5N1 viruses have infected humans to date: subclades 2.1, 2.2, and 2.3 viruses. H5N1 virus infections of humans are rare and most cases have been associated with direct poultry contact during poultry outbreaks. While the H5N1 virus does not now infect people easily, infection in humans is very serious when it occurs; so far, more than half of people reported infected have died. Rare cases of limited human-to-human spread of H5N1 virus may have occurred, but there is no evidence of sustained human-to-human transmission.
Nonetheless, because all influenza viruses have the ability to change, scientists are concerned that H5N1 viruses one day could be able to infect humans more easily and spread easily from one person to another. Because H5N1 viruses have not infected many humans worldwide, there is little or no immune protection against them in the human population and an influenza pandemic (worldwide outbreak of disease) could begin if sustained H5N1 virus transmission occurred. Experts from around the world are watching the H5N1 situation very closely and are preparing for the possibility that H5N1 viruses may begin to spread more easily from person to person.
wild birds will continue to occur. So far, the spread of H5N1 virus from person-to-person has been very rare, limited and unsustained. However, this epizootic continues to pose an important public health threat.
There is little pre-existing natural immunity to H5N1 virus infection in the human population. If H5N1 viruses gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result, with potentially high rates of illness and death worldwide. No evidence for genetic reassortment between human and avian influenza A virus genes has been found to date, and there is no evidence of any significant changes to circulating H5N1 virus strains to suggest greater transmissibility to or among humans. Genetic sequencing of avian influenza A (H5N1) viruses from human cases in Vietnam, Thailand, and Indonesia shows resistance to the antiviral medications amantadine and rimantadine, two of the medications commonly used for treatment of influenza. This leaves two remaining antiviral medications (oseltamivir and zanamivir) that should still be effective against currently circulating strains of H5N1 viruses. A small number of oseltamivir resistant H5N1 virus infections of humans have been reported. Efforts to produce pre-pandemic vaccine candidates for humans that would be effective against avian influenza A (H5N1) viruses are ongoing. However, no H5N1 vaccines are currently available for human use.
Research suggests that currently circulating strains of H5N1 viruses are becoming more capable of causing disease (pathogenic) in animals than were earlier H5N1 viruses. One study found that ducks infected with H5N1 virus are now shedding more virus for longer periods without showing symptoms of illness. This finding has implications for the role of ducks in transmitting disease to other birds and possibly to humans as well. Additionally, other findings have documented H5N1 virus infection among pigs in China and Vietnam; H5N1 virus infection of cats (experimental infection of housecats in the Netherlands, isolation of H5N1 virus from domestic cats in Germany and Thailand, and detection of H5N1 viral RNA in domestic cats in Iraq and Austria); H5N1 virus infection of dogs (isolation of H5N1 virus from a domestic dog in Thailand); and isolation of H5N1 viruses from tigers and leopards at zoos in Thailand). In addition, H5N1 virus infection in a wild stone marten (a weasel-like mammal) was reported in Germany and in a wild civet cat in Vietnam. Avian influenza A (H5N1) virus strains that emerged in Asia in 2003 continue to evolve and may adapt so that other mammals may be susceptible to infection as well.
Notable findings of epidemiologic investigations of human H5N1 cases include:
* Thailand, 2004: An investigation concluded that probable limited human-to-human spread of influenza A (H5N1) had occurred in a family as a result of prolonged and very close contact between an ill child and her mother in a hospital. Transmission did not continue beyond one person.
* Vietnam, 2004: While the majority of known human H5N1 cases have begun with respiratory symptoms, one atypical fatal H5N1 case in a child in southern Vietnam presented with fever, diarrhea and seizures, and was initially diagnosed as encephalitis. The etiology was identified retrospectively as H5N1 virus through testing of cerebrospinal fluid, fecal matter, and throat and serum samples. Further research is needed to ascertain the implications of such findings.
* Vietnam, 2005: Investigations suggest transmission of H5N1 viruses to two persons through consumption of uncooked duck blood.
* Azerbaijan, 2006: Investigations revealed contact with H5N1-infected wild dead birds (swans) as the most plausible source of infection in several cases in teenagers involved in removing feathers from the birds.
* Indonesia, 2006: WHO reported evidence of limited human-to-human spread of H5N1 virus. In this situation, 8 people in one family were affected, with 7 deaths. H5N1 virus was isolated from 7 cases. The first family member is thought to have become ill through contact with infected poultry. This person then infected six family members. One of those six people (a child) then infected another family member (his father). No further spread outside of the exposed family was documented or suspected.
* Vietnam, 2006: A study reported a correlation between high H5N1 viral concentration and elevated inflammatory cytokine levels in fatal cases. The authors concluded that early antiviral treatment is needed to suppress H5N1 viral replication to prevent the inflammatory response that appears to be implicated in the pathogenesis of H5N1 virus infection.
Human H5N1 Cases
(WHO) has reported human cases of avian influenza A (H5N1) in Asia, Africa, the Pacific, Europe and the Near East. Indonesia and Vietnam have reported the highest number of H5N1 cases to date. Overall mortality in reported H5N1 cases is approximately 60%. The majority of cases have occurred among children and adults aged less than 40 years old. Mortality was highest in cases aged 10-19 years old. Studies have documented the most significant risk factors for human H5N1 infection to be direct contact with sick or dead poultry or wild birds, or visiting a live poultry market. Most human H5N1 cases have been hospitalized late in their illness with severe respiratory disease. A small number of clinically mild H5N1 cases have been reported. The current cumulative number of confirmed human cases of avian influenza A/(H5N1) is available on the WHO Avian Influenza website. Despite the high mortality, human cases of H5N1 remain rare to date.
Clusters of Human H5N1 Cases
Clusters of human H5N1 cases ranging from 2-8 cases per cluster have been identified in most countries that have reported H5N1 cases. Nearly all of the cluster cases have occurred among blood-related family members living in the same household. Whether such clusters are related to genetic or other factors is currently unknown. While most people in these clusters have been infected with H5N1 virus through direct contact with sick or dead poultry or wild birds, limited human-to-human transmission of H5N1 virus cannot be excluded in some clusters.
Animal H5N1 Cases
Since December 2003, avian influenza A (H5N1) virus infections in animals have been reported in Asia, Africa, the Pacific, Europe and the Near East. View the update on avian influenza in animals from the World Organization for Animal Health Web site.
Bird Import Ban
There is currently a ban on the importation of birds and bird products from H5N1-affected countries. The regulation states that no person may import or attempt to import any birds (Class Aves), whether dead or alive, or any products derived from birds (including hatching eggs), from the specified countries. For more information, see Embargo of Birds from Specified Countries.
Travel
Updated Information for Travelers about Avian Influenza A(H5N1) is available at the CDC Travelers’ Health Web site. Also see Guidelines and Recommendations - Interim Guidance about Avian Influenza A (H5N1) for U.S. Citizens Living Abroad.
CDC Response
CDC is working with WHO and other international partners to monitor the situation closely. In addition, CDC continues to work with WHO and the National Institutes of Health (NIH) on development of a vaccine for influenza A (H5N1). For more information view CDC's Response to Avian Influenza.
* Also see Updated Interim Guidance for Laboratory Testing of Persons with Suspected Infection with Avian Influenza A (H5N1) Virus in the United States for CDC’s domestic H5N1 surveillance recommendations.
The World Health Organization has additional resources and information on avian influenza A H5N1, including
* Recommendations and laboratory procedures for detection of avian influenza A(H5N1) virus in specimens from suspected human cases (pdf 165K, 28 pages)
* WHO guidelines for investigation of human cases of avian influenza A(H5N1) (pdf 115K, 18 pages)
* Collecting, preserving and shipping specimens for the diagnosis of avian influenza A(H5N1) virus infection Guide for field operations (pdf 2.36M, 83 pages)
Background on the Current Outbreaks
Highly pathogenic avian influenza A (H5N1) virus is an influenza A virus subtype that occurs mainly in birds and is highly contagious among birds, causing high mortality among domestic poultry. Outbreaks of highly pathogenic H5N1 among poultry and wild birds are ongoing in a number of countries. Currently, there are two different groups (or clades) of H5N1 viruses circulating among poultry (clade 1, and clade 2 viruses). At least three subgroups or subclades of clade 2 H5N1 viruses have infected humans to date: subclades 2.1, 2.2, and 2.3 viruses. H5N1 virus infections of humans are rare and most cases have been associated with direct poultry contact during poultry outbreaks. While the H5N1 virus does not now infect people easily, infection in humans is very serious when it occurs; so far, more than half of people reported infected have died. Rare cases of limited human-to-human spread of H5N1 virus may have occurred, but there is no evidence of sustained human-to-human transmission.
Nonetheless, because all influenza viruses have the ability to change, scientists are concerned that H5N1 viruses one day could be able to infect humans more easily and spread easily from one person to another. Because H5N1 viruses have not infected many humans worldwide, there is little or no immune protection against them in the human population and an influenza pandemic (worldwide outbreak of disease) could begin if sustained H5N1 virus transmission occurred. Experts from around the world are watching the H5N1 situation very closely and are preparing for the possibility that H5N1 viruses may begin to spread more easily from person to person.
Sunday, May 17, 2009
Welcome to the Influenza Virus Tracking System (interim)
The World Health Organization (WHO) is developing an electronic system to track influenza A(H5) and other sub-type viruses potential of a pandemic that have been shared by Member States with WHO through the Global Influenza Surveillance Network (GISN). This is in ...
response to the request from the inter-governmental meeting (IGM) on sharing of influenza viruses and access to vaccines and other benefits.
The tracking system, currently available as an interim version, tracks the A(H5) and other potential pandemic sub-type viruses and clinical specimens that have been shared with WHO since 24 November 2007, as well as all A(H5N1) viruses that have been developed into candidate vaccine viruses and these candidate vaccine viruses since 2004.
The current interim tracking system indicated the following details:
* What A(H5N1) viruses/specimens have been shared with WHO
* Where these viruses/specimens are located
* What progeny materials have been generated
* Analyses that have been conducted on the viruses/specimens progeny materials
* Development of reassortant viruses as candidate vaccine viruses
* Distribution of viruses/specimens, progeny materials and candidate vaccine viruses
Improvement of the interim system is ongoing and it is anticipated that this system will be upgraded in the future.
Currently, data entry is conducted by WHOCollaborating Centers on influenza, WHO H5 Reference Laboratories, and Essential Regulatory Laboratories which are involved in the WHO A(H5N1) vaccine virus selection and development process. These are designated WHO laboratories.
response to the request from the inter-governmental meeting (IGM) on sharing of influenza viruses and access to vaccines and other benefits.
The tracking system, currently available as an interim version, tracks the A(H5) and other potential pandemic sub-type viruses and clinical specimens that have been shared with WHO since 24 November 2007, as well as all A(H5N1) viruses that have been developed into candidate vaccine viruses and these candidate vaccine viruses since 2004.
The current interim tracking system indicated the following details:
* What A(H5N1) viruses/specimens have been shared with WHO
* Where these viruses/specimens are located
* What progeny materials have been generated
* Analyses that have been conducted on the viruses/specimens progeny materials
* Development of reassortant viruses as candidate vaccine viruses
* Distribution of viruses/specimens, progeny materials and candidate vaccine viruses
Improvement of the interim system is ongoing and it is anticipated that this system will be upgraded in the future.
Currently, data entry is conducted by WHOCollaborating Centers on influenza, WHO H5 Reference Laboratories, and Essential Regulatory Laboratories which are involved in the WHO A(H5N1) vaccine virus selection and development process. These are designated WHO laboratories.
World-Influenza A(H1N1)
28 April 2009 -- Several countries have confirmed cases of influenza A(H1N1). General information on the influenza A(H1N1) have been posted on the WHO website.
WHO does not recommend...
restricting international travel. As usual it is considered prudent for people who are ill to delay international travel and for people developing symptoms following international travel to seek medical attention.
Regarding the risk of being infected by an influenza virus, travellers are advised, whenever possible, to avoid crowded enclosed spaces and close contact with people suffering from acute respiratory infections. Hand-washing after direct contact with ill persons or their environment may reduce the risk of illness. Ill persons should be encouraged to practice cough etiquette (maintain distance, cover coughs and sneezes with disposable tissues or clothing, wash hands).
Regarding specific measures related to protection against influenza A(H1N1), information is presently insufficient to make recommendation on the use of antivirals. For the use of antivirals in treatment of influenza A(H1N1) virus infection, the clinicians have to make decisions based on the clinical and epidemiological assessment and harms and benefit of the treatment for the patient.
WHO does not recommend...
restricting international travel. As usual it is considered prudent for people who are ill to delay international travel and for people developing symptoms following international travel to seek medical attention.
Regarding the risk of being infected by an influenza virus, travellers are advised, whenever possible, to avoid crowded enclosed spaces and close contact with people suffering from acute respiratory infections. Hand-washing after direct contact with ill persons or their environment may reduce the risk of illness. Ill persons should be encouraged to practice cough etiquette (maintain distance, cover coughs and sneezes with disposable tissues or clothing, wash hands).
Regarding specific measures related to protection against influenza A(H1N1), information is presently insufficient to make recommendation on the use of antivirals. For the use of antivirals in treatment of influenza A(H1N1) virus infection, the clinicians have to make decisions based on the clinical and epidemiological assessment and harms and benefit of the treatment for the patient.
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