On-Farm Vaccination Programme Needed to Reduce Lumpy Skin Disease Outbreaks23 August 2016
A programme of on-farm vaccination should be carried out to reduce the number of outbreaks of lumpy skin disease in high risk regions, according to a new report by the European Food Safety Authority Panel on Animal Health and Welfare (AHAW) carried out for the European Commission, writes Chris Harris.
The report also calls for farmers and veterinarians to be trained in the clinical identification of lumpy skin disease in order to reduce underreporting.
Lumpy skin disease background
Lumpy skin disease (LSD or LSDV) is an infectious, eruptive, disease of cattle, which is occasionally fatal. It is characterised by nodules on the skin and other parts of the body and a secondary bacterial infection often aggravates the condition. Its causal virus is related to the sheep and goat pox virus. It is usually found in southern and eastern Africa, but has spread to sub-Saharan west Africa and has also been found in the Middle East.
In 2013, it was confirmed in Turkey and in the last year it has been recorded in Eastern Europe and Bulgaria.
The publication of the AHAW study comes shortly after an appeal by the Austrian delegation to the European Commission’s agricultural council in July for EU-wide action to be taken on Lumpy Skin Disease.
The delegation briefed the Council on the threat posed by lumpy skin disease to the European animal health sector and urged the Commission to take appropriate measures such as reviewing the current legal framework and procedures to facilitate vaccination and establishing as a matter of the highest priority a legal framework to allow preventive vaccination in countries or regions at risk, as well as clarifying the list of safe commodities and trade restrictions of vaccinated animals and their product.
The Austrians also called on the European Commission to take a leading role at EU level, including common purchase and distribution of vaccines by the European Commission.
European Commission meeting on lumpy skin disease
In the council meeting, the Commission stressed the importance of good preparedness and encouraged EU countries to follow the Commission’s advice more consistently and to work on regional cooperation. The Commission also said that it was willing to help facilitate a vaccination programme.
The AHAW Panel report followed a request from the European Commission for an assessment of the implications of the spread of the disease and its persistence following the implementation of a stamping out (culling) policy on affected animals in regions where the disease had been confirmed, compared to a policy of stamping out and vaccination.
The study looked at data from Greece and Bulgaria, two countries currently affected by Lumpy Skin Disease. It investigated the size of the herds that were infected, their locations and information about vaccination and the type of virus – whether it was field or vaccine strain.
The investigation also looked at the effectiveness of vaccination that has been carried out in Greece this year.
The panel compared the effectiveness of using a partial stamping out policy with total stamping out and also the timing of vaccination and its effectiveness after the disease was reported.
It found that the highest protection came 21 days after vaccination.
“It can be concluded that, according to the model for the transmission of LSDV between farms, vaccination has a greater impact in reducing LSDV spread than any stamping-out policy, even when low vaccination effectiveness is considered (40 per cent),” said the study.
“When vaccination is evenly applied so that 95 per cent of the farms are vaccinated with 75 per cent of vaccinated animals effectively protected, then total stamping out and partial stamping out result in a similar probability of eradicating the infection.
“Nevertheless, when no vaccination is applied or when assuming a low vaccination effectiveness (e.g. 40 per cent), the probability of eradication is higher when total stamping out is performed as compared to partial stamping out.
“Partial stamping out results in a limited increase of the number of farms affected as compared to total stamping out.”
The report adds that vaccination measures were most effective in reducing LSDV spread if protection had already been developed at the time of virus entry, followed by increasing the number of protected herds after virus entry.
“No vaccination is the least effective option in reducing LSDV spread,” it says.
The AHAW panel recommends that if the objective is to minimise the number of outbreaks of LSD in regions at risk for LSDV introduction or where LSDV has been already introduced, vaccination should be implemented.
There should be high vaccination coverage both within the farm and between farms to achieve the best coverage, and the vaccination needs to be applied uniformly across the animal population to avoid areas where there could be high densities of unvaccinated farms.
The report adds that vaccination could be accompanied with partial stamping out instead of total stamping out if a small increase in the number of affected farms or a reduction in the probability of eliminating the outbreaks are considered acceptable.
However, it adds that the effectiveness of partial stamping out should be evaluated under field conditions.
It calls for farmers and veterinarians to be trained in the clinical identification of LSD in order to reduce underreporting.
In 2015, an EFSA Scientific Opinion on LSD reported that epidemics are not self-limiting when effective vaccination or culling are not applied.
Vaccination options for lumpy skin disease
The report said that only live attenuated vaccines against LSD are available and it found that homologous vaccines are more effective than sheep pox strain vaccines.
It called for the safety of the vaccines to be improved and for the development of vaccines that could differentiate between infected and vaccinated animals.
The World Organisation for Animal Health (OIE) sets out sanitary measures including stamping out and quarantine controls during and outbreak and it outlines the implications of the two vaccination possibilities.
Homologous live attenuated virus vaccine – Neethling strain – offers potential immunity for up to three years but the Heterologous live attenuated virus vaccine – sheep or goat pox vaccine – may cause local, sometimes severe, reactions. Its use is not advised in countries free from sheep and goat pox.
Dr F. Glyn Davies is head of the ODA Virology Project, Veterinary Research Laboratories in Kenya. In a study for the Food and Agriculture Organisation of the United Nations on “Lumpy skin disease of cattle: A growing problem in Africa and the Near East”, she says that while there is no specific antiviral treatment available for LSD-infected cattle, the two vaccines, Neethling and Kenya sheep and goat pox virus, have been used widely in Africa with success.
Chris Harris is a freelance agriculture and food journalist and former editor in chief with 5m Publishing. He has been reporting on the meat and livestock sectors for nearly 30 years. @AgEdChrisHarris