Spatio-temporal dynamics and risk cluster analysis of highly pathogenic avian influenza (H5N1) in poultry: Advancing outbreak management through customized regional strategies in Egypt

Abstract

Background: Highly pathogenic avian influenza (HPAI) (H5N1) has been endemic in Egypt for almost two decades, profoundly impacting both the poultry industry and public health. Egypt stands as a prominent epicenter for HPAI H5N1 outbreaks in Africa, marked by the highest number of positive human cases. Despite continuous governmental efforts, prior research underscored the inadequacy of strategies in controlling the virus spread.

Aim: This study identified spatiotemporal patterns and high-risk clusters of HPAI H5N1 outbreaks at the subdistrict level.

Methods: This study involved trial tracking of HPAI H5N1 endemicity dynamics, enabling tailored interventions at a regional level based on robust epidemiological investigations to address the persistent challenge of HPAI H5N1 in Egypt. This study illuminated spatiotemporal outbreak dynamics, with specific attention on Menofia governorate.

Results: Despite the region's early poultry impacts, initial outbreaks did not originate from Menofia in studied epidemic waves (EWs). Outbreak risk spatial distribution displayed an escalating pattern at the northern border, followed by risk reduction through the sixth EW. The predominant hot spot region was localized within rural districts, particularly villages, while urbanization coincided with lower outbreak density. Observed smoothed densities revealed epidemic propagation within urban centers, preceding its transition to new areas and establishing direct connections with neighboring cities. Primary cluster prognostication was plausible, occurring in regions previously hosting elevated relative risk clusters during preceding EWs. Identification of enduring pinpoint clusters, persistent for extended durations, indicated close contact dynamics and localized viral circulation within populations.

Conclusion: This study highlights the significance of customized regional interventions based on the rigorous epidemiological framework. This approach is pivotal in the profound comprehension of endemicity dynamics, efficiently limits geographical infection spread, and contains outbreaks within delineated areas.

Keywords: Endemicity dynamics; Highly pathogenic avian influenza; Risk clusters; Spatiotemporal dynamics; Tailored intervention strategies.

Fig. 1.. Epidemic curves of outbreaks of highly pathogenic avian influenza subtype H5N1 in Menofia governorate from January 2006 to December 2016, illustrating A) daily, B) weekly, and C) monthly frequency of outbreaks as a function of time. Vertical lines delineate the six EWs.

Fig. 2.. (A) Spatial Distribution of HPAI H5N1 outbreaks in Menofia governorate in the period from 2006 to 2016 (B, C, D, E, F, and G are representing the six epidemic waves). Vertical axis represents the cities, while horizontal axis represents the total no. of outbreaks.

Fig. 3.. Spatial distribution of HPAI H5N1 outbreaks in Menofia governorate were divided into corresponding subsets according to the EWs and depicted in the village-based map for visual comparison using ARCGIS 10.5 software (ESRI, Redlands, CA, USA).

Fig. 4.. Raster risk map showing interpolated spatial prediction surface of HPAIH5N1 outbreak risk, based on ordinary kriging with ArcMap version 10.1 (ESRI, Redlands, CA, USA). Daily outbreaks of highly pathogenic avian influenza subtype H5N1 over six EWs were represented by light green dots and outbreak Relative risk from spatial analysis highlighted in monochromatic red (the higher the risk, the darker the color).

Fig. 5.. Spatial patterns and spatio-temporal clusters of daily, weekly, and monthly based outbreaks of highly pathogenic avian influenza subtype H5N1 over six EW in Menofia governorate. Outbreaks represented by light green dots and outbreak density from adaptive kernel density estimation highlighted in monochromatic grey (the higher the density, the darker the color). Significant spatio-temporal clusters detected from the space–time permutation scan statistics are illustrated by the most likely cluster (red circle) and by a secondary cluster (blue-dashed circles).