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Influenza A H5N1 immigration is filtered out at some international borders.

ABSTRACT: Geographic spread of highly pathogenic influenza A H5N1, the bird flu strain, appears a necessary condition for accelerating the evolution of a related human-to-human infection. As H5N1 spreads the virus diversifies in response to the variety of socioecological environments encountered, increasing the chance a human infection emerges. Genetic phylogenies have for the most part provided only qualitative evidence that localities differ in H5N1 diversity. For the first time H5N1 variation is quantified across geographic space.We constructed a statistical phylogeography of 481 H5N1 hemagglutinin genetic sequences from samples collected across 28 Eurasian and African localities through 2006. The MigraPhyla protocol showed southern China was a source of multiple H5N1 strains. Nested clade analysis indicated H5N1 was widely dispersed across southern China by both limited dispersal and long distance colonization. The UniFrac metric, a measure of shared phylogenetic history, grouped H5N1 from Indonesia, Japan, Thailand and Vietnam with those from southeastern Chinese provinces engaged in intensive international trade. Finally, H5N1's accumulative phylogenetic diversity was greatest in southern China and declined beyond. The gradient was interrupted by areas of greater and lesser phylogenetic dispersion, indicating H5N1 migration was restricted at some geopolitical borders. Thailand and Vietnam, just south of China, showed significant phylogenetic clustering, suggesting newly invasive H5N1 strains have been repeatedly filtered out at their northern borders even as both countries suffered recurring outbreaks of endemic strains. In contrast, Japan, while successful in controlling outbreaks, has been subjected to multiple introductions of the virus.The analysis demonstrates phylogenies can provide local health officials with more than hypotheses about relatedness. Pathogen dispersal, the functional relationships among disease ecologies across localities, and the efficacy of control efforts can also be inferred, all from viral genetic sequences alone.

SUBMITTER: Wallace RG

PROVIDER: S-EPMC2244808 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature

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Influenza A H5N1 immigration is filtered out at some international borders.

Wallace Robert G RG Fitch Walter M WM

PloS one 20080227 2

<h4>Background</h4>Geographic spread of highly pathogenic influenza A H5N1, the bird flu strain, appears a necessary condition for accelerating the evolution of a related human-to-human infection. As H5N1 spreads the virus diversifies in response to the variety of socioecological environments encountered, increasing the chance a human infection emerges. Genetic phylogenies have for the most part provided only qualitative evidence that localities differ in H5N1 diversity. For the first time H5N1 ...[more]

PMID: 18301773

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Project description:With the COVID-19 vaccination widely implemented in most countries, propelled by the need to revive the tourism economy, there is a growing prospect for relieving the social distancing regulation and reopening borders in tourism-oriented countries and regions. This need incentivizes stakeholders to develop border control strategies that fully evaluate health risks if mandatory quarantines are lifted. In this study, we have employed a computational approach to investigate the contact tracing integrated policy in different border-reopening scenarios in Hong Kong, China. Explicitly, by reconstructing the COVID-19 transmission from historical data, specific scenarios with joint effects of digital contact tracing and other concurrent measures (i.e., controlling arrival population and community nonpharmacological interventions) are applied to forecast the future development of the pandemic. Built on a modified SEIR epidemic model with a 30% vaccination coverage, the results suggest that scenarios with digital contact tracing and quick isolation intervention can reduce the infectious population by 92.11% compared to those without contact tracing. By further restricting the inbound population with a 10,000 daily quota and applying moderate-to-strong community nonpharmacological interventions (NPIs), the average daily confirmed cases in the forecast period of 60 days can be well controlled at around 9 per day (95% CI: 7-12). Two main policy recommendations are drawn from the study. First, digital contact tracing would be an effective countermeasure for reducing local virus spread, especially when it is applied along with a moderate level of vaccination coverage. Second, implementing a daily quota on inbound travelers and restrictive community NPIs would further keep the local infection under control. This study offers scientific evidence and prospective guidance for developing and instituting plans to lift mandatory border control policies in preparing for the global economic recovery.

Project description:Objectiveto map scientific evidence on the extent of tuberculosis in migrants from the international borders between Brazil and the countries of South America.DesignScoping review of quantitative, qualitative and mixed studies. The research was conducted between February and April 2021. The terms "migrants", "tuberculosis", "Brazil", "Uruguay", "Paraguay", "Bolivia", "Peru", "British Guiana" "English Guiana", "French Guiana", "Suriname", "Venezuela", "Argentina", "Colombia" combined with Boolean operators "AND" and "OR" to identified relevant documents. Studies addressing tuberculosis on migrants from international borders of Brazil were included. Pubmed Central (PMC), LILACS (Scientific and technical literature of Latin America and the Caribbean/BVS), Scopus (Elsevier), Scielo (Scientific Electronic Library Online) and gray literature CAPES thesis database were searched. The study was carried out in three stages where the data was selected and extracted by two independent reviewers for full reading.ResultsA total of 705 articles were extracted from the databases chosen for the search, 04 master's dissertations and 01 doctoral thesis. Of these 456 were excluded because they did not meet at least one of the eligibility criteria for this SR and 4 were further excluded because they were duplicates who had not been previously identified. A total of 58 documents were, thus, selected for assessment of the full text. Of these, 40 were further excluded for not meeting at least one of the eligibility criteria. A total of 18 studies were included for data collection: 15 articles, 2 master's dissertations and 1 doctoral thesis, produced between 2002 and 2021.ConclusionThis scoping review mapped the existing evidence on tuberculosis at the international borders of Brazil and on access of immigrants with tuberculosis to health services in Brazil.Descriptorstuberculosis; immigrants; public health surveillance; epidemiological surveillance; sanitary control of borders; health services accessibility.

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Influenza A H5N1 immigration is filtered out at some international borders.

Publications

Influenza A H5N1 immigration is filtered out at some international borders.

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