Discussion on a Selection of Key Scientific Articles

By John Atkinson,
Associate Director, Intergovernmental Veterinary Health
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Neethling vaccine proved highly effective in controlling lumpy skin disease epidemics in the Balkans.
Eyal Klement, Alessandro Broglia, Sotiria-Eleni Antoniou, Vangelis Tsiamadis, E. Plevraki, Tamaš Petrović, Vladimir Polaček, Zoran Debeljak, Aleksandra Miteva, Tsviatko Alexandrov, Drago Marojevic, Ledi Pite, Vanja Kondratenko, Zoran Atanasov, Simon Gubbins, Arjan Stegeman and Josè Cortiñas Abrahantes
Preventive Veterinary Medicine (2018), doi.org/10.1016/j.prevetmed.2018.12.001

Key Thoughts:

Diseases (such as lumpy skin disease [LSD]) that have been confined to a region and then suddenly spread to other regions pose a particular threat because there may be a lack of evidence to support decision making regarding disease control. It is therefore important that data is collected and analyzed to enable resources to be directed towards the most effective disease control methods. LSD is a great example of where sound evidence has been gathered and published, supporting not only vaccination as the control method of choice for the disease, but also the type of vaccine to be used.

Article Summary:

Vaccination is important for controlling lumpy skin disease (LSD). There are 3 main groups of (attenuated) vaccines against LSD:

  1. Homologous (LSD virus-based), eg, Neethling,
  2. Heterologous (goat pox-based) eg, Kedong strain,
  3. Heterologous (sheep pox-based)

While the relative efficacy of Neethling vaccine compared to sheep pox vaccine has previously been studied, this study assessed the field effectiveness of Neethling vaccine following its widespread use in Southeast Europe. Other risk factors for LSD were also included in this study.

This study focused on 6 countries in the region (Bulgaria, Serbia, Albania, Greece, FYROM, and Montenegro) and the national veterinary services in each country provided data regarding cattle populations. Vaccination was carried out by field veterinary officers and private veterinarians (under supervision of the authorities) using only 2 permitted vaccines (both Neethling-type vaccines). All animals on a farm were vaccinated, and a farm was considered immunized at 21 days post-vaccination.

Vaccination took place at the same time as epidemic spread, so farms could change their vaccination status during the study, which was accounted for by a survival analysis approach using left truncation and right censoring. Various analyses were undertaken, and a p-value of 0.05 (Wald test) indicated statistical significance.

The Neethling vaccines used were highly effective in protecting against LSD in field across different herd types and different outbreak settings. The overall average vaccine effectiveness across all countries was 79.8% (95% CI: 73.2-84.7), with the highest vaccine effectiveness being 97.3% in Bulgaria and 97.1% in Serbia, and the lowest being 62.5% in Albania. Immunity developed quickly during the first 14 days after vaccination. There was no significant association between the risk of LSD and herd size in this study, and grazing herds were at 5.7 times higher risk compared to non-grazing herds. However, vaccinated farms provided indirect protection due to herd immunity.

These results showing vaccination as being highly effective can only be applied to this Neethling group of vaccines. Further work should be undertaken to identify the vector for LSD in Europe.

Lumpy skin disease: workshop on risk assessment and data collection for epidemiology, control and surveillance
EFSA (European Food Safety Assessment)
EFSA Supporting Publication (2018), doi:10.2903/sp.efsa.2018.EN-1520

Key Thoughts:

While vaccination with Neethling vaccine has been the key tool, it has been the combined effort of multiple countries and stakeholders that has enabled this tool to be used to such dramatic effect in successfully controlling lumpy skin disease epidemics in Europe. It is reassuring to see such coordinated approaches continuing and the publication of agreed data models, which will help future activities.

Article Summary:

The workshop brought together members of the EFSA standing working group on lumpy skin disease (LSD) and representatives of countries affected by and at risk of LSD. The aim was to share knowledge, explain, and apply EFSA analyses, update data models, and assist countries in how to undertake surveys relating to vaccination and disease detection.

Each country presented an update of their LSD control and surveillance activities. No outbreaks have been reported in the Balkan region in 2018, vaccination coverage varied between countries and between years, and some countries are considering different approaches for continuing vaccination.

Various presentations were given, including a mathematical model that has been used to study how vaccination might lead to LSD elimination as well as an analysis of vaccination effectiveness, which is about 80% overall for the region. Diagnostic tools, LSD surveillance, harmonization of data collection, survey design, and the results of the European Union (EU) Survey questionnaire were also discussed.

Data models were agreed upon that specify the type of data to be collected for cattle populations, vaccination (ideally animal level, but farm level if that is not possible), surveillance, estimation of milk drop after vaccination, and serological surveys.

Further meetings will follow with each of the representatives of each country.

 

 

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