Scientific Opinion on lumpy skin disease

Abstract

Lumpy skin disease (LSD) is a viral disease of cattle characterised by severe losses, especially in naive animals. LSD is endemic in many African and Asian countries, and it is rapidly spreading throughout the Middle East, including Turkey. LSD is transmitted by mechanical vectors, but direct/indirect transmission may occur. The disease would mainly be transferred to infection-free areas by transport of infected animals and vectors. In the EU, it could only happen through illegal transport of animals. The risk for that depends on the prevalence in the country of origin and the number of animals illegally moved. Based on a model to simulate LSD spread between farms, culling animals with generalised clinical signs seems to be sufficient to contain 90 % of epidemics around the initial site of incursion, but the remaining 10 % of simulated epidemics can spread up to 400 km from the site of introduction by six months after incursion. Whole-herd culling of infected farms substantially reduces the spread of LSD virus, and the more rapidly farms are detected and culled, the greater the magnitude of the reduction is. Only live attenuated vaccines against LSD are available. Homologous vaccines are more effective than sheep pox strain vaccines. The safety of the vaccines should be improved and the development of vaccines for differentiating between infected and vaccinated animals is recommended. Epidemics are not self-limiting when effective vaccination or culling are not applied. Active surveillance, rapid detection and prompt culling of infected herds are effective measures for LSD control. The role of vectors for LSD transmission should be further investigated in both controlled environments and the field. Awareness-raising campaigns for farmers and veterinary staff to promote recognition of LSD should be considered. The cooperation of the EU with neighbouring countries should be encouraged to prevent transboundary disease spread.

Urgent advice on lumpy skin disease

“…The assessment methodologies included a mathematical model similar to the one used in the previous opinion by EFSA (EFSA AHAW Panel, 2015) for simulating the between-farm LSDV spread according to different control measures applied, in particular different combinations of stamping out (no stamping out, partial stamping out of clinical cases, total stamping out of the affected herds) and vaccination (no vaccination, vaccination after detection of infection in a region, vaccination of the whole country or region leading to fully immunised population by the time of disease incursion). Furthermore, a survival analysis was conducted for the estimation of the effectiveness of vaccination as applied in Greece in 2016.…”

“…The methodologies included a mathematical model similar to the one used in the previous opinion by EFSA (EFSA AHAW Panel, 2015) for simulating LSDV spread according to different control measures applied and an estimation of the effectiveness of vaccination at the farm level using survival analysis in order to confirm the suitability of transmission parameters derived from published data from Israel (Ben-Gera et al, 2015) as used in the model.…”

“…The effect of a partial stamping-out policy was already assessed for non-vaccinated herds in the EFSA scientific opinion on LSD (EFSA AHAW Panel, 2015), where stamping out of animals showing generalised clinical signs 2 in herds infected with LSD virus (LSDV) was considered. In that assessment, a simulation of a possible LSDV incursion in Greece showed that by applying a partial stamping-out policy, approximately 90% of outbreaks remained confined to the region around the initial site of incursion, but 10% of simulated outbreaks spread up to approximately 300-400 km from the site of introduction by 6 months after the incursion.…”

“…Transmission between farms was described using a kernel-based approach (see Appendix A), as presented in detail in the EFSA opinion on LSD (EFSA AHAW Panel, 2015). The model was adapted to include vaccination by replacing herd sizes with the number of unprotected animals in each herd.…”

“…With vaccination effectiveness being the proportion of vaccinated animals eventually protected from infection, herd size multiplied by 1 minus vaccination effectiveness gives the number of susceptible animals in a vaccinated herd (Anderson and May, 1983). 4 The force of infection and outbreak duration were estimated from data on the location and time of infection for reported cases of LSD from the epidemic in Israel during 2012 and 2013, as in the previous opinion (EFSA AHAW Panel, 2015). These data were chosen to model the force of infection, because they are the only ones available for LSDV spread in a situation without vaccination and no stamping out of infected farms, this being the closest scenario to the 'natural' spread of the disease.…”