MEDLINE Abstracts: Incidence of Avian Influenza
MEDLINE Abstracts: Incidence of Avian Influenza
What's new in the literature concerning incidence of avian influenza? Find out in this easy-to-navigate collection of recent MEDLINE abstracts compiled by the editors at Medscape Pulmonary Medicine.
Morb Mortal Wkly Rep. 2004;53:100-103
Since mid-December 2003, 8 Asian countries (Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam) have reported an epizootic of highly pathogenic avian influenza in poultry and various other birds caused by influenza A (H5N1). As of February 9, 2004, a total of 23 laboratory-confirmed human cases of influenza A (H5N1) had been reported in Thailand and Vietnam. In 18 (78%) of these cases, the patients died. Clinical experience with avian H5N1 disease in humans is limited. The human H5N1 viruses identified in Asia in 2004 are antigenically and genetically distinguishable from the 1997 and February 2003 viruses. To aid surveillance and clinical activities, this report provides a preliminary clinical description of the initial 5 confirmed cases in Thailand.
Morb Mortal Wkly Rep. 2004;53:97-100
During December 2003 to February 2004, outbreaks of highly pathogenic avian influenza A (H5N1) among poultry were reported in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam. As of February 9, 2004, a total of 23 cases of laboratory-confirmed influenza A (H5N1) virus infections in humans, resulting in 18 deaths, had been reported in Thailand and Vietnam. In addition, approximately 100 suspected cases in humans are under investigation by national health authorities in Thailand and Vietnam. The Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and national health authorities in Asian countries are working to assess and monitor the situation, provide epidemiologic and laboratory support, and assist with control efforts. This report summarizes information about the human infections and avian outbreaks in Asia and provides recommendations to guide influenza A (H5N1) surveillance, diagnosis, and testing in the United States.
Fouchier RA, Schneeberger PM, Rozendaal FW, et al
Proc Natl Acad Sci USA. 2004;101:1356-1361
Highly pathogenic avian influenza A viruses of subtypes H5 and H7 are the causative agents of fowl plague in poultry. Influenza A viruses of subtype H5N1 also caused severe respiratory disease in humans in Hong Kong in 1997 and 2003, including at least 7 fatal cases, posing a serious human pandemic threat. Between the end of February and the end of May 2003, a fowl plague outbreak occurred in The Netherlands. A highly pathogenic avian influenza A virus of subtype H7N7, closely related to low pathogenic virus isolates obtained from wild ducks, was isolated from chickens. The same virus was detected subsequently in 86 humans who handled affected poultry and in 3 of their family members. Of these 89 patients, 78 presented with conjunctivitis, 5 presented with conjunctivitis and influenza-like illness, 2 presented with influenza-like illness, and 4 did not fit the case definitions. Influenza-like illnesses were generally mild, but a fatal case of pneumonia in combination with acute respiratory distress syndrome occurred also. Most virus isolates obtained from humans, including probable secondary cases, had not accumulated significant mutations. However, the virus isolated from the fatal case displayed 14 amino acid substitutions, some of which may be associated with enhanced disease in this case. Because H7N7 viruses have caused disease in mammals, including horses, seals, and humans, on several occasions in the past, they may be unusual in their zoonotic potential and, thus, form a pandemic threat to humans.
Capua I, Alexander DJ
Eur J Clin Microbiol Infect Dis. 2004;23:1-6
Among avian influenza viruses and avian paramyxoviruses (APMV) are the aetiological agents of two of the most devastating diseases of the animal kingdom: (i). the highly pathogenic form of avian influenza, caused by some viruses of the H5 and H7 subtypes, and (ii). Newcastle disease, caused by virulent strains of APMV type 1. Mortality rates due to these agents can exceed 50% in naive bird populations, and, for some strains of AI, nearly 100%. These viruses may also be responsible for clinical conditions in humans. The virus responsible for Newcastle disease has been known to cause conjunctivitis in humans since the 1940s. The conjunctivitis is self-limiting and does not have any permanent consequences. Until 1997, reports of human infection with avian influenza viruses were sporadic and frequently associated with conjunctivitis. Recently, however, avian influenza virus infections have been associated with fatalities in human beings. These casualties have highlighted the potential risk that this type of infection poses to public health. In particular, the pathogenetic mechanisms of highly pathogenic avian influenza viruses in birds and the possibility of reassortment between avian and human viruses in the human host represent serious threats to human health. For this reason, any suspected case should be investigated thoroughly.
Van Eijk M, White MR, Batenburg JJ, et al
Am J Respir Cell Mol Biol. 2003 Dec 12 [Epub ahead of print]
Pigs can be infected with both human and avian influenza A virus (IAV) strains and are, therefore, considered to be important intermediates in the emergence of new IAV strains due to mixing of viral genes derived from human, avian, or porcine influenza viruses. These reassortant strains may have potential to cause pandemic influenza outbreaks in humans. The innate immune response against IAV plays a significant role in containment of IAV in the airways. We studied the interactions of IAV with porcine surfactant protein D (pSP-D), an important component of this first line defense system. Hemagglutination inhibition analysis shows that the distinct interactions of pSP-D with IAV mediated by the N-linked carbohydrate moiety in the carbohydrate recognition domain of pSP-D, depend on the terminal sialic acids (SAs) present on this carbohydrate. Analysis by both lectin staining and by cleavage with linkage-specific sialidases shows that the carbohydrate of pSP-D is exclusively sialylated with alpha (2,6)-linked SAs, in contrast to surfactant protein A which contains both alpha (2,3)- and alpha (2,6)-linked SAs on its N-linked carbohydrate. Enzymatic modification of the SA-linkages present on pSP-D demonstrates that the type of SA-linkage is important for its hemagglutination inhibitory activity, and correlates with receptor-binding specificity of the IAV strains. The SAs present on pSP-D appear especially important for interactions with poorly glycosylated IAV strains. It remains to be elucidated to what extent the unique sialylation profile of pSP-D is involved in host range control of IAV in pigs and, whether it facilitates adaptation of avian or human IAV strains that can contribute to the production of reassortant strains in pigs.
Webby RJ, Webster RG
Science. 2003;302:1519-1522
During the past year, the public has become keenly aware of the threat of emerging infectious diseases with the global spread of severe acute respiratory syndrome (SARS), the continuing threat of bioterrorism, the proliferation of West Nile virus, and the discovery of human cases of monkeypox in the United States. At the same time, an old foe has again raised its head, reminding us that our worst nightmare may not be a new one. In 2003, highly pathogenic strains of avian influenza virus, including the H5N1 and H7N7 subtypes, again crossed from birds to humans and caused fatal disease. Direct avian-to-human influenza transmission was unknown before 1997. Have we responded to these threats by better preparing for emerging disease agents, or are we continuing to act only as crises arise? Here we consider progress to date in preparedness for an influenza pandemic and review what remains to be done. We conclude by prioritizing the remaining needs and exploring the reasons for our current lack of preparedness for an influenza pandemic.
Tanaka H, Park CH, Ninomiya A, et al
Vet Microbiol. 2003;95:1-13
The direct transmission of H5N1 influenza A viruses from chickens to humans in Hong Kong in 1997 emphasized the need to have information on the pathogenesis of avian influenza virus infection in mammals. H5N1 influenza viruses isolated from patients during the incident killed experimentally infected mice. The principal lesions of the mice were broncho-interstitial pneumonia and nonsuppurative encephalitis. Infectious viruses and/or viral antigens were detected in the brain as well as in the trigeminal and vagal ganglia, but not in the blood of the mice. These findings suggest that the virus reached the brain through the vagus and/or trigeminal nerves following replication in the respiratory mucosa. The results imply that neurotropism of the H5N1 virus in mice is a novel characteristic in the pathogenesis of infection by human influenza virus isolates.
Katz JM
Avian Dis. 2003;47(3 suppl):914-920
In the late 1990s, H5N1 and H9N2 avian influenza viruses caused respiratory infections in humans in Hong Kong. Exposure to domestic poultry in live-bird markets was significantly associated with human H5N1 disease. Seroepidemiologic studies conducted among contacts of H5N1-infected persons determined that human-to-human transmission of the avian H5N1 viruses occurred but was rare. The relatively high rates of H5 and H9 antibody seroprevalence among Hong Kong poultry workers in 1997 highlight the potential for avian viruses to transmit to humans, particularly those with occupational exposure. Such transmission increases the likelihood of reassortment between a currently circulating human virus and an avian virus and thus the creation of a strain with pandemic potential.
What's new in the literature concerning incidence of avian influenza? Find out in this easy-to-navigate collection of recent MEDLINE abstracts compiled by the editors at Medscape Pulmonary Medicine.
Morb Mortal Wkly Rep. 2004;53:100-103
Since mid-December 2003, 8 Asian countries (Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam) have reported an epizootic of highly pathogenic avian influenza in poultry and various other birds caused by influenza A (H5N1). As of February 9, 2004, a total of 23 laboratory-confirmed human cases of influenza A (H5N1) had been reported in Thailand and Vietnam. In 18 (78%) of these cases, the patients died. Clinical experience with avian H5N1 disease in humans is limited. The human H5N1 viruses identified in Asia in 2004 are antigenically and genetically distinguishable from the 1997 and February 2003 viruses. To aid surveillance and clinical activities, this report provides a preliminary clinical description of the initial 5 confirmed cases in Thailand.
Morb Mortal Wkly Rep. 2004;53:97-100
During December 2003 to February 2004, outbreaks of highly pathogenic avian influenza A (H5N1) among poultry were reported in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam. As of February 9, 2004, a total of 23 cases of laboratory-confirmed influenza A (H5N1) virus infections in humans, resulting in 18 deaths, had been reported in Thailand and Vietnam. In addition, approximately 100 suspected cases in humans are under investigation by national health authorities in Thailand and Vietnam. The Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and national health authorities in Asian countries are working to assess and monitor the situation, provide epidemiologic and laboratory support, and assist with control efforts. This report summarizes information about the human infections and avian outbreaks in Asia and provides recommendations to guide influenza A (H5N1) surveillance, diagnosis, and testing in the United States.
Fouchier RA, Schneeberger PM, Rozendaal FW, et al
Proc Natl Acad Sci USA. 2004;101:1356-1361
Highly pathogenic avian influenza A viruses of subtypes H5 and H7 are the causative agents of fowl plague in poultry. Influenza A viruses of subtype H5N1 also caused severe respiratory disease in humans in Hong Kong in 1997 and 2003, including at least 7 fatal cases, posing a serious human pandemic threat. Between the end of February and the end of May 2003, a fowl plague outbreak occurred in The Netherlands. A highly pathogenic avian influenza A virus of subtype H7N7, closely related to low pathogenic virus isolates obtained from wild ducks, was isolated from chickens. The same virus was detected subsequently in 86 humans who handled affected poultry and in 3 of their family members. Of these 89 patients, 78 presented with conjunctivitis, 5 presented with conjunctivitis and influenza-like illness, 2 presented with influenza-like illness, and 4 did not fit the case definitions. Influenza-like illnesses were generally mild, but a fatal case of pneumonia in combination with acute respiratory distress syndrome occurred also. Most virus isolates obtained from humans, including probable secondary cases, had not accumulated significant mutations. However, the virus isolated from the fatal case displayed 14 amino acid substitutions, some of which may be associated with enhanced disease in this case. Because H7N7 viruses have caused disease in mammals, including horses, seals, and humans, on several occasions in the past, they may be unusual in their zoonotic potential and, thus, form a pandemic threat to humans.
Capua I, Alexander DJ
Eur J Clin Microbiol Infect Dis. 2004;23:1-6
Among avian influenza viruses and avian paramyxoviruses (APMV) are the aetiological agents of two of the most devastating diseases of the animal kingdom: (i). the highly pathogenic form of avian influenza, caused by some viruses of the H5 and H7 subtypes, and (ii). Newcastle disease, caused by virulent strains of APMV type 1. Mortality rates due to these agents can exceed 50% in naive bird populations, and, for some strains of AI, nearly 100%. These viruses may also be responsible for clinical conditions in humans. The virus responsible for Newcastle disease has been known to cause conjunctivitis in humans since the 1940s. The conjunctivitis is self-limiting and does not have any permanent consequences. Until 1997, reports of human infection with avian influenza viruses were sporadic and frequently associated with conjunctivitis. Recently, however, avian influenza virus infections have been associated with fatalities in human beings. These casualties have highlighted the potential risk that this type of infection poses to public health. In particular, the pathogenetic mechanisms of highly pathogenic avian influenza viruses in birds and the possibility of reassortment between avian and human viruses in the human host represent serious threats to human health. For this reason, any suspected case should be investigated thoroughly.
Van Eijk M, White MR, Batenburg JJ, et al
Am J Respir Cell Mol Biol. 2003 Dec 12 [Epub ahead of print]
Pigs can be infected with both human and avian influenza A virus (IAV) strains and are, therefore, considered to be important intermediates in the emergence of new IAV strains due to mixing of viral genes derived from human, avian, or porcine influenza viruses. These reassortant strains may have potential to cause pandemic influenza outbreaks in humans. The innate immune response against IAV plays a significant role in containment of IAV in the airways. We studied the interactions of IAV with porcine surfactant protein D (pSP-D), an important component of this first line defense system. Hemagglutination inhibition analysis shows that the distinct interactions of pSP-D with IAV mediated by the N-linked carbohydrate moiety in the carbohydrate recognition domain of pSP-D, depend on the terminal sialic acids (SAs) present on this carbohydrate. Analysis by both lectin staining and by cleavage with linkage-specific sialidases shows that the carbohydrate of pSP-D is exclusively sialylated with alpha (2,6)-linked SAs, in contrast to surfactant protein A which contains both alpha (2,3)- and alpha (2,6)-linked SAs on its N-linked carbohydrate. Enzymatic modification of the SA-linkages present on pSP-D demonstrates that the type of SA-linkage is important for its hemagglutination inhibitory activity, and correlates with receptor-binding specificity of the IAV strains. The SAs present on pSP-D appear especially important for interactions with poorly glycosylated IAV strains. It remains to be elucidated to what extent the unique sialylation profile of pSP-D is involved in host range control of IAV in pigs and, whether it facilitates adaptation of avian or human IAV strains that can contribute to the production of reassortant strains in pigs.
Webby RJ, Webster RG
Science. 2003;302:1519-1522
During the past year, the public has become keenly aware of the threat of emerging infectious diseases with the global spread of severe acute respiratory syndrome (SARS), the continuing threat of bioterrorism, the proliferation of West Nile virus, and the discovery of human cases of monkeypox in the United States. At the same time, an old foe has again raised its head, reminding us that our worst nightmare may not be a new one. In 2003, highly pathogenic strains of avian influenza virus, including the H5N1 and H7N7 subtypes, again crossed from birds to humans and caused fatal disease. Direct avian-to-human influenza transmission was unknown before 1997. Have we responded to these threats by better preparing for emerging disease agents, or are we continuing to act only as crises arise? Here we consider progress to date in preparedness for an influenza pandemic and review what remains to be done. We conclude by prioritizing the remaining needs and exploring the reasons for our current lack of preparedness for an influenza pandemic.
Tanaka H, Park CH, Ninomiya A, et al
Vet Microbiol. 2003;95:1-13
The direct transmission of H5N1 influenza A viruses from chickens to humans in Hong Kong in 1997 emphasized the need to have information on the pathogenesis of avian influenza virus infection in mammals. H5N1 influenza viruses isolated from patients during the incident killed experimentally infected mice. The principal lesions of the mice were broncho-interstitial pneumonia and nonsuppurative encephalitis. Infectious viruses and/or viral antigens were detected in the brain as well as in the trigeminal and vagal ganglia, but not in the blood of the mice. These findings suggest that the virus reached the brain through the vagus and/or trigeminal nerves following replication in the respiratory mucosa. The results imply that neurotropism of the H5N1 virus in mice is a novel characteristic in the pathogenesis of infection by human influenza virus isolates.
Katz JM
Avian Dis. 2003;47(3 suppl):914-920
In the late 1990s, H5N1 and H9N2 avian influenza viruses caused respiratory infections in humans in Hong Kong. Exposure to domestic poultry in live-bird markets was significantly associated with human H5N1 disease. Seroepidemiologic studies conducted among contacts of H5N1-infected persons determined that human-to-human transmission of the avian H5N1 viruses occurred but was rare. The relatively high rates of H5 and H9 antibody seroprevalence among Hong Kong poultry workers in 1997 highlight the potential for avian viruses to transmit to humans, particularly those with occupational exposure. Such transmission increases the likelihood of reassortment between a currently circulating human virus and an avian virus and thus the creation of a strain with pandemic potential.