Abstract
Lumpy skin disease (LSD) is economically important viral disease of cattle mainly in Africa and Middle East. Mass vaccination is a better strategy to control this disease in endemic countries. However, there is an increasing field report of vaccine failure. Thus, observational study was designed to investigate LSD outbreaks and vaccine effectiveness. Different dairy farms were selected on basis of reports of outbreak occurrence. A total of 191 dairy cattle from 17 smallholder and 1551 from four big dairy farms were included for assessment. Skin biopsies were taken from 31 LSD affected cattle for isolation and molecular characterization. Semi-structured questionnaires were administered to farm owners, animal health personnel and farm managers to gather relevant epidemiological data. Out of 1742 dairy cattle, 213 (12.2%) showed characteristic clinical signs of LSD and 27 cattle (1.5%) were died as the result of the disease. Viruses were isolated from 26 skin samples on Vero cell line and the isolates were confirmed to be LSDV using conventional PCR and real-time PCR. The complete sequence of RPO30 gene of the isolates showed that all isolates substituted at least one nucleotide in respect to vaccine strains. The vaccine effectiveness of annual vaccination was estimated to be 67.1% (95% CI = 57.3 – 74.7) in contrast to vaccination during outbreaks. Conversely, the occurrences of outbreak of LSD infection in vaccinated dairy herds are suggestive of vaccine failure. Thus, it’s the time to direct efforts towards to the development of new effective vaccine. Keywords: Dairy Cattle; Ethiopia; LSD; LSDV; Outbreak; Vaccine Effectiveness DOI : 10.7176/JBAH/9-11-01 Publication date :June 30 th 2019
Highlights
Lumpy skin disease (LSD) is a viral disease of cattle which is characterized by high fever, multiple circumscribed firm skin nodules, enlargement of superficial lymph nodes, nasal discharge and lachrymation; but in severity, clinical signs are highly variable
The resulting Polymerase Chain Reaction (PCR) products of GTPV/LSDV differed in length by 21 nucleotides produced from sheep pox virus (SPPV) genomes
The present outbreak investigated in dairy cattle was caused by LSDV
Summary
Lumpy skin disease (LSD) is a viral disease of cattle which is characterized by high fever, multiple circumscribed firm skin nodules, enlargement of superficial lymph nodes, nasal discharge and lachrymation; but in severity, clinical signs are highly variable. It is caused by Lumpy skin disease virus which is a member of the Capripoxvirus genus in the Poxviridae family. The morbidity and mortality rates of LSD vary considerably, depending on host susceptibility and the abundance of insect vectors involved in transmission. Mortality of 10 to 40% and even higher have been reported on occasion but the lower range of 1 to 5% is more usual (Babiuk et al, 2008)
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