Investigations into the transmission of lumpy skin disease virus in Kazakhstan

Abstract

Lumpy skin disease (LSD) is a transboundary emerging disease of cattle induced by lumpy skin disease virus (LSDV), a member of the capripoxvirus genus of the family Poxviridae. An acute form of LSD is characterised by high fever, formation of firm, eruptive, well-circumscribed skin lesions and necrotic plaques in the mucous membranes of the respiratory and digestive tracks. The state of LSDV during inter-epidemic periods has not been established, and no vector for disease transmission has been determined either in cattle or in wild animals to date. However, rapid transmission of LSD is mainly associated with a high presence of hematophagous insects in hot and wet weather. In early clinical experiments, involvement of insects in the transmission of LSDV was successfully demonstrated by Aedes aegypti mosquitoes. In addition, LSDV has been isolated from Stomoxys calcitrans following feeding on infected animals. However, the role of Stomoxys species in the transmission of LSDV remained uncertain and suspected to be mechanical, which was demonstrated in a transmission study using Aedes aegypti mosquitoes. This thesis aims to investigate the vector competence of three Stomoxys species (Stomoxys calcitrans, Stomoxys sitiens, Stomoxys indica) as well as their role in the epidemiology of LSD. This was demonstrated by testing for retention of LSDV in stable flies and a transmission experiment to recipient animals following an interrupted blood meal. In addition, Stomoxys rearing techniques were examined and modified to obtain a sufficient supply of laboratory-reared flies for transmission studies. This thesis also represents the outcomes of investigations into the epidemiology of LSD in Kazakhstan, with the intention of better understanding the disease by defining the risk factors associated with LSD in Kazakhstan.