Space-time permutation model applied to the past outbreak data of lumpy skin disease in the Balkan Peninsula from august 2015 to july 2017

Zharko Stojmanovski

doi:10.2298/vetgl171027003s

Abstract

Introduction: In August 2015, lumpy skin disease (LSD) was notified for the first time in mainland European Union when it was observed in cattle in Greece. From August 2015 to July 2017, 1,757 outbreaks were reported in cattle in Greece, Bulgaria, Macedonia, Albania, Serbia, and Montenegro. Materials and Methods: The Kulldorff space-time permutation scan statistic contained in the software package SaTScan v 9.4.4 was used to analyse the epizootic past outbreak data and describe the spread of the disease in the 24 months after the first notification. Results and Conclusions:: Seventy-six space-time disease clusters (62 significant and 14 non-significant) were identified. In 2015, 10 clusters with a monthly peak in October (n=5, 50%) were identified, in 2016, the most (n=57) clusters were detected with monthly peak in July (n=15, 26.3%), and up to July 2017, nine clusters with a monthly peak in May (n=3, 3.3%) were determined. Possible high-risk areas were identified using the presented methodology, and so this technique could guide national veterinary authorities to formulate strategies for mitigating the spread of LSD, allocating resources and for formulating epidemiological preparedness plans in neighbouring, LSD-negative, countries.

Highlights

In August 2015, lumpy skin disease (LSD) was notified for the first time in mainland European Union when it was observed in cattle in Greece
In August 2015, for the first time, LSD reached Greece near the border area with Turkey. This disease spread into Bulgaria, Macedonia, Albania, Serbia and Montenegro (Animal Disease Information Summaries, not dated)
For space-time cluster analysis, several parameters were set: Maximum temporal cluster size was set at up to 50 % of the study period (Kulldorff, 2006); maximum size of the spatial window for a cluster was set at up to a 20 km radius which is the Veterinarski Glasnik 2018, 72 (1), 44-55 maximum distance according to the assumption that most LSD occurs over a relatively small distance, in agreement with the vector-borne pattern of lumpy skin disease virus (LSDV) (EFSA, 2017); significance of the clusters was evaluated with Monte Carlo simulation which was set as the default in section inference with a maximum number of 999 replications, under the null hypothesis of random distribution; the time aggregation period was set at up to a 7-day block

Summary

Introduction

In August 2015, lumpy skin disease (LSD) was notified for the first time in mainland European Union when it was observed in cattle in Greece. From August 2015 to July 2017, 1,757 outbreaks were reported in cattle in Greece, Bulgaria, Macedonia, Albania, Serbia, and Montenegro. Transmission is primarily by biting insects (vector) and to a lesser extent through direct contact between animals (Animal Disease Information Summaries, not dated). LSD is endemic in African countries, but unusually, from 2012, the disease reached the Middle East. In 2013, the disease spread in Turkey, and by May 2015, the disease reached the East Thrace area (European Food Safety Authority (EFSA), 2017). In August 2015, for the first time, LSD reached Greece near the border area with Turkey. This disease spread into Bulgaria, Macedonia, Albania, Serbia and Montenegro (Animal Disease Information Summaries, not dated). The goal of the study was to identified space-time disease clusters in the Balkan Peninsula by applying a permutation model of the space-time scan statistic on the past outbreak data from the first notification for the following 24 months

Objectives

Methods

Results

Discussion

Conclusion