Lumpy skin disease outbreak in commercial cattle farms of Chattogram, Bangladesh

Abstract

Lumpy Skin Disease (LSD) is an important viral disease capable of incurring significant economic loss in commercial livestock production. The disease is of major economic importance due to production losses resulting from severe emaciation, lowered milk production, abortion, secondary mastitis, loss of fertility, extensive damage to hides and a loss of draft from lameness. Moreover, death or culling of sick cattle impose indirect losses due to the cattle movement and trade restriction. In mid-2019, an outbreak of LSD was reported in cattle population from different parts of Bangladesh including Chattogram Division. During this study a cross-sectional survey was undertaken from August to December 2019 to investigate the prevalence and associated risk factors of LSD in cattle in Chattogram district. A total of 3327 cattle from 19 commercial farms were investigated for the LSD associated skin lesions and possible risk factors. A total of 120 skin biopsies were collected from the suspected animal for histopathological examination followed by molecular detection through PCR and DNA sequencing. Partial genome sequencing and phylogenetic analyses were also explored on selected specimens. It was revealed that demonstrated that the overall prevalence of LSD in the study population was 10% (95% confidence interval: 9.4 to 11%) where the highest farm level outbreak frequency was 63.33% and lowest 4.22%. Crossbred (OR=3.56) and female (OR=3.56) cattle showed significantly higher susceptibility to the disease compared to their counterparts. Introduction of new animals in any farms was found to be one of the most significant risk factors (OR=2.34) associated with the transmission of the disease. Notably all suspected skin biopsies were positive for LSD virus (LSDV) infection with granulomatous and pyogranulomatous dermatitis as revealed through histopathology. Phylogenetic analysis based on the inverted terminal repeat region of the LSDV genome suggested that the locally circulating strain was closely related to the strains isolated from Middle East and North African countries.