Cases Of H5N1 Avian Influenza Research Articles

MODELING SEASONALITY IN AVIAN INFLUENZA H5N1

The number of cases of H5N1 avian influenza in birds and humans exhibit seasonality which peaks during the winter months. What causes the seasonality in H5N1 cases is still being investigated. This article addresses the question of modeling the periodicity in cumulative number of human cases of H5N1. Three potential drivers of influenza seasonality are investigated: (1) seasonality in bird-to-bird transmission; (2) seasonality caused by wild bird migration or seasonal fluctuation of avian influenza in wild birds; (3) seasonality caused by environmental transmission. A framework of seven models is composed. The seven models involve these three mechanisms and combinations of the mechanisms. Each of the models in the framework is fitted to the cumulative number of humans cases of H5N1. The corrected akaike information criterion (AICc) is used to compare the models and it is found that the model with periodic bird-to-bird transmission rate best explains the data. The best fitted model with the best fitted parameters gives a reproduction number of highly pathogenic avian influenza [Formula: see text]. The best fitted model is a simple SI epidemic model with periodic transmission rate and disease-induced mortality, however, this model is capable of very complex dynamical behavior such as period doubling and chaos.

Epidemiological and risk analysis of the H7N9 subtype influenza outbreak in China at its early stage.

Dozens of human cases infected with H7N9 subtype avian influenza virus (AIV) have been confirmed in China since March, 2013. Distribution data of sexes, ages, professions and regions of the cases were analyzed in this report. The results showed that the elderly cases, especially the male elderly, were significantly more than expected, which is different from human cases of H5N1 avian influenza and human cases of the pandemic H1N1 influenza. The outbreak was rated as a Grade III (severe) outbreak, and it would evolve into a Grade IV (very severe) outbreak soon, using a method reported previously. The H7N9 AIV will probably circulate in humans, birds and pigs for years. Moreover, with the driving force of natural selection, the virus will probably evolve into highly pathogenic AIV in birds, and into a deadly pandemic influenza virus in humans. Therefore, the H7N9 outbreak has been assumed severe, and it is likely to become very or extremely severe in the future, highlighting the emergent need of forceful scientific measures to eliminate any infected animal flocks. We also described two possible mild scenarios of the future evolution of the outbreak.

The social and political lives of zoonotic disease models: Narratives, science and policy

Zoonotic diseases currently pose both major health threats and complex scientific and policy challenges, to which modelling is increasingly called to respond. In this article we argue that the challenges are best met by combining multiple models and modelling approaches that elucidate the various epidemiological, ecological and social processes at work. These models should not be understood as neutral science informing policy in a linear manner, but as having social and political lives: social, cultural and political norms and values that shape their development and which they carry and project. We develop and illustrate this argument in relation to the cases of H5N1 avian influenza and Ebola, exploring for each the range of modelling approaches deployed and the ways they have been co-constructed with a particular politics of policy. Addressing the complex, uncertain dynamics of zoonotic disease requires such social and political lives to be made explicit in approaches that aim at triangulation rather than integration, and plural and conditional rather than singular forms of policy advice.

Decreased expression of surfactant protein D mRNA in human lungs in fatal cases of H5N1 avian influenza

Microarray analysis of gene expression profile of lungs from two fatal H5N1 influenza cases identified 3,435 genes with higher than twofold changes in mRNA levels as compared to those of normal lung. One thousand nineteen genes and 2,416 genes were up-regulated and down-regulated commonly, respectively. Gene ontology analysis identified several ontology terms with significant association with these genes, most of which are related to cellular metabolism and regulation of cellular process including apoptosis and chemotaxis. Pulmonary surfactant protein D (SP-D) was found to be down-regulated. Quantitative RT-PCR confirmed the levels of SP-D mRNA in the lungs infected with H5N1 to be lower than those of normal lungs and lungs from patients with acute respiratory distress syndrome. SP-D plays multiple roles in respiratory innate defense against various pathogens, regulation of inflammatory responses, and maintenance of alveolar integrity. Reduction of SP-D in H5N1 influenza may play important roles in the pathogenesis of the disease.

Potential number of human cases of H5N1 avian influenza in Egypt

H5N1 is one of the avian influenza virus subtypes that has the potential to evolve into a global pandemic that could cause millions of human deaths and great economic losses. Cases involving humans have occurred in 15 countries. Costly interventions have been used by governments and health organisations. Thus, a challenging question arises regarding how many cases of the disease may actually have been prevented as a result of such interventions. This paper answers such a question by applying a statistical model to the 2006-January 2009 outbreak in Egypt. Egypt was chosen as it had the highest number of human avian influenza cases outside Asia, and the second highest number in that period worldwide. Brookmeyer and Blades' statistical model was applied. The sensitivities of the estimated number of human cases and exposure dates to the assumed incubation period, the delay in intervention and the coverage/effectiveness of the intervention were investigated. In the absence of intervention, it appears that the outbreak could have been approximately 1.5 times as large, but it is unlikely it would have exceeded 150 cases. The results underscore the importance of early detection of an outbreak and intervention, together with effective public health control measures.

Live poultry exposure, Guangzhou, China, 2006

BackgroundLive poultry in wet markets and backyard husbandry comprise potentially major exposure sources for human cases of H5N1 avian influenza. In China the magnitude of risk from this exposure is unknown. We estimated exposure based on self-reported behavior. MethodsIn January–March 2006, 1550 face-to-face interviews derived from stratified cluster and randomized within-household sampling provided data on live poultry exposure in Guangzhou, China based on self-reported buying and touching patterns. Standardized exposures were calculated and after adjustment extrapolated to the urban population. ResultsThe results, adjusted for gender, showed that 1,248/1,550 (80%, 95% Confidence Limits 78–82%) respondents reported an average of 20.5 live chicken purchases/household annually. Of those buying poultry 33% touched poultry before buying while 20% of households raised live poultry. Total exposures from wet market and backyard husbandry in Guangzhou greatly exceed those of adjacent Hong Kong (15,280,000 e/year vs. 1,110,900 e/year). Backyard exposure frequency likely exceeds that from live poultry retail, but purchases were more prevalent and hence comprise a significant risk source. ConclusionThe Guangzhou population faces risks from the high prevalence of exposures during purchase and poultry rearing. Better management for raising and selling poultry in Guangzhou is needed.

A spatiotemporal statistical model of the risk factors of human cases of H5N1 avian influenza in South-east Asian countries and China

This article aims to quantify the risk factors associated with the human cases of H5N1 avian influenza in South-east Asian countries and China; a dangerous region for this disease that has the potential for a pandemic outbreak. A statistical model with time and spatial dimensions was built to capture the international spread patterns of this disease. The grid search method was used to fit the model with 2004-2006 data. The grid search approach is a simple procedure that allows the fit of any function to data. This study found that: (1) when the number of domestic H5N1 human cases increases by one person in a certain time period, the chance that the country will have a human case in the next period increases by 22.10%; (2) when the number of human cases in a neighbouring country increases by one person in a certain time period, the chance that the country will have a human case in the next period increases by 1.62%; (3) when the number of avian cases in a neighbouring country increases by one, the chance that the country will have a human case increases by 0.02%; (4) as the human population increases by one unit, the chance that the country will have a human case increases by 0.10%; (5) when the quantity of imported poultry increases by 1000 metric tons, the chance that the country will have a human case increases by 0.03%; (6) when the outbreak of the disease among domestic birds increases by one, the chance that the country will have a human case increases by 0.19%; and finally (7) when the number of birds destroyed increases by 1000, the chance that the country will have a human case decreases by 0.30%. These findings shed new light on the spatiotemporal characteristics of the epidemic, and thus need to be taken into consideration in interdisciplinary and scientific discussion of the disease.

A survey of human cases of H5N1 avian influenza reported by the WHO before June 2006 for infection control

H5N1 avian influenza has been widely spreading in fowl in the Eastern Hemisphere and has caused hundreds of severe human cases. Here, information regarding the 224 human cases of H5N1 avian influenza reported by the World Health Organization (WHO) before June 2006 were surveyed and analyzed. The results suggested that human infections escalated in the past 3 years and that control of animal H5N1 influenza, avoidance of high-risk behaviors, and proper disposal of diseased or dead fowl are vital for the prevention of human infections. Age distribution of the human cases demonstrated that older people are more immune to the infection, possibly because of the cross protectivity induced by their previous infection with human influenza A viruses. This survey also suggested that live vaccines against human influenza may be of utility in the prevention of avian influenza virus infection in humans and that new preventive measures should be considered for the control of animal H5N1 influenza epidemics, which are likely more numerous than indicated by official reports.

A rationale for using steroids in the treatment of severe cases of H5N1 avian influenza

Acute hypercytokinaemia represents an imbalance of pro-inflammatory and anti-inflammatory cytokines, and is believed to be responsible for the development of acute respiratory distress syndrome and multiple organ failure in severe cases of avian (H5N1) influenza. Although neuraminidase inhibitors are effective in treating avian influenza, especially if given within 48 h of infection, it is harder to prevent the resultant hypercytokinaemia from developing if the patient does not seek timely medical assistance. Steroids have been used for many decades in a wide variety of inflammatory conditions in which hypercytokinaemia plays a role, such as sepsis and viral infections, including severe acquired respiratory syndromes and avian influenza. However, to date, the results have been mixed. Part of the reason for the discrepancies might be the lack of understanding that low doses are required to prevent mortality in cases of adrenal insufficiency. Adrenal insufficiency, as defined in the sepsis/shock literature, is a plasma cortisol rise of at least 9 microg dl(-1) following a 250 microg dose of adrenocorticotropin hormone (ACTH), or reaching a plasma cortisol concentration of >25 microg dl(-1) following a 1-2 microg dose of ACTH. In addition, in the case of hypercytokinaemia induced by potent viruses, such as H5N1, systemic inflammation-induced, acquired glucocorticoid resistance is likely to be present. Adrenal insufficiency can be overcome, however, with prolonged (7-10 or more days) supraphysiological steroid treatment at a sufficiently high dose to address the excess activation of NF-kappaB, but low enough to avoid immune suppression. This is a much lower dose than has been typically used to treat avian influenza patients. Although steroids cannot be used as a monotherapy in the treatment of avian influenza, there might be a potential role for their use as an adjunct treatment to antiviral therapy if appropriate dosages can be determined. In this paper, likely mechanisms of adrenal insufficiency are discussed, drawing from a broad background of literature sources.

A survey of human cases of H5N1 avian influenza reported by the WHO before June 2006 for infection control

H5N1 avian influenza has been widely spreading in fowls in the Eastern Hemisphere and caused hundreds of severe human cases. Here, the information of the 224 human cases of H5N1 avian influenza reported by the World Health Organization before June 2006 were surveyed and analyzed. The results suggested that human infections escalated in the past 3 years, and control of animal H5N1 influenza, avoidance of high-risk behaviors, and proper disposal of diseased or dead fowls are vital for the prevention of the human infections. Age distribution of the human cases demonstrated that older people are more immune to the infection, possibly because of the cross protectivity induced by their previous infections with human influenza A viruses. This survey also suggested that live vaccines against human influenza may be of utility in the prevention of the avian influenza virus infections in humans, and new preventive measures should be considered for the control of animal H5N1 influenza epidemics, which are likely more serious than indicated by official reports.

Pandemic Influenza and Pregnancy

With the emerging infectious disease threat of pandemic avian influenza, obstetricians should be aware of the disproportionate morbidity and mortality documented among gravidas in the twentieth century pandemics. To date the majority of fatal cases of H5N1 avian influenza have been recorded in young previously healthy adults, reminiscent of the epidemiology of the 1918 "Spanish flu" pandemic. All providers of obstetric services and all facilities providing obstetric care have a key role in terms of pandemic planning for our potentially disproportionately affected, vulnerable patient population. This article summarizes the relevant data and frames the current threat to obstetric providers and facilities posed by H5N1 avian influenza in terms of pandemic potential. In addition, suggestions for basic pandemic planning efforts are reviewed.

Avian Influenza Risk Communication, Thailand

Avian Influenza Risk Communication, Thailand