Molecular detection and isolation of Lumpy Skin Disease Virus from outbreak cases in Ilubabor Zone, Oromia, Ethiopia

Lumpy Skin Disease (LSD) is a viral disease caused by Lumpy Skin Disease Virus (LSDV), a member of the genus Capripoxvirus within the family Poxviridae. It is a notifiable, economically important disease of cattle that causes significant production losses in affected areas.

A descriptive outbreak investigation was conducted from October 2021 to August 2022 in Darimu, Bacho, and Yayo districts of Ilubabor Zone, Western Oromia, Ethiopia. The study aimed to detect and isolate LSDV from clinically affected cattle. A total of 79 samples were collected from 22 clinically affected cattle, including skin nodule biopsies (n = 17), skin scrapings (n = 7), whole blood (n = 17), and swabs (ocular n = 14, nasal n = 12, and lesion swabs n = 12). Viral DNA was extracted using the QIAGEN kit and detected by real-time polymerase chain reaction (qPCR). Virus isolation was attempted in lamb kidney cell culture from 17 skin nodule biopsies.

Out of 1,080 cattle at risk, 146 were affected, and 7 died. Overall, morbidity, mortality, and case fatality rates were 13.5%, 0.65%, and 4.8%, respectively. All 79 samples (100%) tested positive by real-time qPCR. Seventeen skin nodule biopsies were selected for virus isolation and inoculated into lamb kidney cell culture. Ct values varied by sample type: skin nodules (mean Ct 19.96), lesion swabs (21.95), and skin scrapes (21.31) had the lowest Ct values (indicating higher viral load), while blood had the highest (31.69). Cytopathic effects were observed in 4 of the 17 (23.5%) cultures. The changes included cell rounding, aggregation of degenerating cells, and monolayer detachment.

Lumpy Skin Disease Virus was confirmed as the cause of the investigated outbreak, resulting in economic losses for farmers in the study area. Regular annual vaccination and further studies on field viruses and vaccine strain compatibility (matching) are recommended to support disease control and improve eradication strategies.