Geostatistical visualisation and spatial statistics for evaluation of the dispersion of epidemic highly pathogenic avian influenza subtype H5N1

Ward, Michael P.; Maftei, Daniel; Apostu, Cristian; Suru, Andrian

doi:10.1051/vetres:2007063

Cited by 52 publications

(48 citation statements)

References 32 publications

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“…Then the local indicator of spatial autocorrelation (LISA) statistic was estimated (Spatial Analyst, ArcGIS TM 9.3. ESRI Inc., Redland CA) to detect any clusters of model residuals (Anselin, 2005;Ward et al, 2008b), and LISA analysis identified significant (P<0.05) clusters of residuals in the east and southwest of Bhutan. However, no significant (P=0.068) spatial autocorrelation (I=0.042) was detected in the model standardized residuals when the spatial relationship between sub-districts were defined using the second order rook contiguity weight matrix.…”

Section: Resultsmentioning

confidence: 99%

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan

Tenzin

Dhand

Ward

2012

Preventive Veterinary Medicine

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Preventive Veterinary Medicine, (2012); 107:21 -26. Available online at: http://www.sciencedirect.com/science/article/pii/S0167587712001420 AbstractAnthropogenic and environmental factors were assessed as predictors of sub-districts in Bhutan that reported rabies in domestic animals during the period 1996−2009. Rabies surveillance data were retrieved from the Veterinary Information System database. Anthropogenic and environmental information were obtained from public data sources. Using the total number of rabies cases reported in domestic animals, the 205 sub-districts of Bhutan were categorized as those sub-districts that reported rabies and those that did not report rabies (n=146). Logistic regression models were fit to the data and odds ratios and 95% confidence intervals were estimated. Sub-districts that share a border with India (OR 10.43; 95% CI: 4.42-24.64; P<0.001); sub-districts connected by major roads (OR 3.09; 95% CI: 1.24-7.68; P=0.015); and greater human population density (OR 3.26; P=0.003) were significantly associated with a sub-district reporting animal rabies in Bhutan during 1996−2009. Results suggest that human population characteristics play an important role in rabies occurrence.

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Section: Resultsmentioning

confidence: 99%

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan

Tenzin

Dhand

Ward

2012

Preventive Veterinary Medicine

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“…Phylogenetic analyses of the lineage relationship were executed on the virus strains isolated in eastern Asia , South Korea (Lee et al, 2008), Nigeria (Ducatez et al, 2006) and western Africa (Ducatez et al, 2007). Local level space-time cluster analyses of H5N1 outbreaks over short time periods have been carried out in China (Oyana et al, 2006), Vietnam (Pfeiffer et al, 2007) and Romania (Ward et al, 2008). The purpose of these studies was to identify spatio-temporal patterns of the spread of the disease and to ascertain possible underlying mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…If H5N1 is spread by wild birds, either over long or over short distances, this might be deduced from spatial-temporal patterns of the disease outbreaks (Onozuka and Hagihara, 2008;Ward et al, 2008). Wild birds utilize large number of over-staging sites along the flyways to forage during the migration, and settle in breeding and wintering sites during the non-migration seasons.…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal dynamics of global H5N1 outbreaks match bird migration patterns

et al. 2009

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Abstract. The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant pandemic threat and a serious public health risk. An efficient surveillance and disease control system relies on the understanding of the dispersion patterns and spreading mechanisms of the virus. A space-time cluster analysis of H5N1 outbreaks was used to identify spatio-temporal patterns at a global scale and over an extended period of time. Potential mechanisms explaining the spread of the H5N1 virus, and the role of wild birds, were analyzed. Between December 2003 and December 2006, three global epidemic phases of H5N1 influenza were identified. These H5N1 outbreaks showed a clear seasonal pattern, with a high density of outbreaks in winter and early spring (i.e., October to March). In phase I and II only the East Asia Australian flyway was affected. During phase III, the H5N1 viruses started to appear in four other flyways: the Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and the East Africa West Asian flyway. Six disease cluster patterns along these flyways were found to be associated with the seasonal migration of wild birds. The spread of the H5N1 virus, as demonstrated by the space-time clusters, was associated with the patterns of migration of wild birds. Wild birds may therefore play an important role in the spread of H5N1 over long distances. Disease clusters were also detected at sites where wild birds are known to overwinter and at times when migratory birds were present. This leads to the suggestion that wild birds may also be involved in spreading the H5N1 virus over short distances.

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“…Techniques for the detection of spatial and spatiotemporal clusters described elsewhere (Carpenter 2001) have been commonly applied as a useful tool in other highly infectious disease epidemics, such as foot-and-mouth disease (FMD) or avian influenza (AI) (Perez et al 2004, Ward et al 2008.…”

Section: Introductionmentioning

confidence: 99%

Epidemiologic investigation of the re-emergence of infectious salmon anemia virus in Chile

Mardones¹,

Pérez²,

Carpenter³

2009

Dis. Aquat. Org.

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Reports from surveillance activities were analyzed to determine the epidemiology of the re-emergence of infectious salmon anemia virus (ISAV) in Atlantic salmon farms in Chile. The epidemic and spatial and spatiotemporal patterns were described, taking into account commercial compartmentalization of the farms. During the 64 wk study period, 76 ISAV-infected salmon farms, representing 17 companies, were reported in 65% of the management geographic zones of the 10th region in southern Chile. Approximately 20% of the farms at risk became infected, with the incidence rate increasing slightly over time. Results from epidemic analyses and observed spatial and spatiotemporal patterns suggested an initial dispersal and subsequent clustering of cases around the index case (IC) in a propagated epidemic mode. Results suggested that delayed depopulation may have been a key factor in the spread and persistence of ISAV. Clustering of cases supported the assumption that passive transmission in seawater from ISAV-infected farms (proximity) is a critical factor in controlling disease. The re-emergence of ISAV in Chile has resulted in one of the largest ISAV epidemics reported in the world and this study generates new hypotheses and provides useful information for spatial disease control planning in salmon farming areas.

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Geostatistical visualisation and spatial statistics for evaluation of the dispersion of epidemic highly pathogenic avian influenza subtype H5N1

Cited by 52 publications

References 32 publications

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan

Spatio-temporal dynamics of global H5N1 outbreaks match bird migration patterns

Epidemiologic investigation of the re-emergence of infectious salmon anemia virus in Chile

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