Lumpy skin disease: I. Data collection and analysis

Abstract

An epidemiological analysis of the temporal and spatial patterns of LSD epidemics and of the risk factors for LSD spread in south-eastern Europe was performed, based on the data collected from affected and at risk countries. Since 2015, the extent of the LSD epidemics in south-eastern Europe was over 7,600 LSD outbreaks with 12,800 affected animals, with most outbreaks occurring between May and August. Most LSD spread occurs over a relatively small distance, approximately between 10 and 20 km, and the speed of propagation was estimated to be mostly up 2 km/day, in agreement with the vector-borne pattern of LSD. Proximity to affected farms, warm temperatures and related vector abundance were among the main risk factors for LSD spread. Within a few months' at least 90% of the animal population had been vaccinated with live homologous vaccine against LSD in south-eastern Europe. Where almost total vaccination coverage was achieved, no further outbreaks were reported. The vaccination effectiveness in Albania was estimated to be around 70% at farm level and 77% at animal level. Possible adverse effects to live homologous vaccine, including fever, decreased milk production and oedema at injection site were reported in Croatia (a LSD-free country) mostly within 2 weeks after vaccination, in 0.09% of the vaccinated animals. Unique farm identifiers should be always used across all databases, so to allow further analysis especially on improving the mathematical models for more robust estimates of transmission parameters applicable to the region, and for better estimation of vaccination effectiveness. All suspected clinical cases in vaccinated animals should be confirmed by differentiating field virus from vaccine strain. Trapping surveys for estimation of vector abundance can be carried out by targeting some sentinel farms, to be followed up during the whole LSD season, while long-term studies can give more accurate information about species composition and seasonality of potential LSD vectors.

Keywords: lumpy skin disease; spread.