“Rabies elimination should be a long-term national commitment” – Dr. Florence Cliquet, OIE expert

Why are rabies oral vaccination campaigns important in Europe?

F.C.: Wildlife is the main reservoir and vector of rabies in Europe, mainly foxes. They can transmit the disease to domestic animals, pets and humans. It was therefore important to find an efficient way to immunize fox populations with vaccines. Oral vaccination by aircraft and helicopter became the solution. The method is based on the distribution of baits with vaccines in capsules, blisters or plastic sachet from the air, which are then consumed by animals.

The vaccination is performed in spring and autumn, and no interruption should occur before rabies elimination is achieved to maintain a sufficient vaccination coverage of fox populations. Therefore, as soon as the programme starts, budgets should be allocated each year for vaccination and also for disease surveillance.

This is a unique way of animal vaccination on large areas and rabies is, so far, the only disease to have such a method of control. Oral vaccination was implemented on a large scale in the last 30 years in western, central and northern Europe, as well as in southeast European countries. This strategy has become a very efficient way to eliminate rabies.

How was the method of rabies oral vaccination developed?

F.C.: The method, as well as the first oral vaccine baits, were developed in the 1970’s by a team led by Dr. Franz Steck and Dr. Alexander I. Wandeler* – researchers from the Swiss Rabies Centre. The first oral vaccination campaign started in 1978 in Switzerland on a very small territory to test the feasibility of the method. Later, European countries, such as Germany, Luxemburg, Belgium, Italy and France followed the Swiss example.

In the beginning, these countries tested the method in very limited areas. Then, they extended vaccination areas progressively. Most of these states have declared themselves to be free of rabies at the beginning of the 21^st century. They were progressively followed by northern and central European member states. The network of experts on rabies is currently supporting eastern European countries to reach zero cases of humans dying of rabies by 2030. I truly believe this is an achievable goal for this subregion.

Today, the oral vaccination strategy is well standardized due to the efforts and knowledge from other countries. Let’s say – they had a lot of problems. While we knew that challenges could occur, the method could still easily be used on a large scale because it is well developed and clearly written.

But I recommend countries to start slowly, by testing the feasibility under local conditions.

* Dr Alexander I. Wandeler is one of the authors of the book “Historical Perspective of Rabies in Europe and the Mediterranean Basin,” published by the World Organisation for Animal Health (OIE), in conjunction with the World Health Organisation (WHO) and the Veterinary Laboratories Agencies (UK).

What are the important elements of oral vaccination campaigns?

F.C.: The elimination of rabies should be a political decision, strongly supported by national authorities. Once a country starts to implement a rabies eradication programme, it should continue until the elimination of the disease, without interruptions. If there are interruptions, all the previous efforts could become useless. Considering the cost of the method, the budget should be allocated for a long-term period, 5-6 years minimum.

There are also some specific recommendations to consider during the implementation of the vaccination campaigns:

• First define the area to be vaccinated: There is no standard recipe or protocol for this. But in general, the selected area should be at least 5,000 square kilometres. When possible, it is better to select an area close to the sea or bordering with a rabies-free area of another country or region. This will decrease the possibility of reinfection.

For example, rabies is endemic to the wildlife in Ukraine. Vaccinating the entire surface would be an enormous task, so the first step could be to define an adequate area. The country has started vaccination campaigns in the western regions – close to the Polish border. This has turned out to be beneficial for both countries, since the possibility of reinfection on both sides of the border has decreases.

• Ensure the efficiency of the vaccine. It should consistently work under local climatic conditions and effectively immunize at least 70% of fox population.
• Follow the recommendations for perfect aerial distribution, depending on the pilot’s performance, since baits will be dropped on the ground from the air. Flight routes should be parallel and fairly short – providing a sufficient density of the dropped baits on the ground. We estimate that the density should be 20-25 baits per square kilometre. Otherwise, the fox population will be insufficiently vaccinated.
• Consider the climate and geographical conditions of the country. Vaccinating at high temperatures is not recommended, since it could decrease the effectiveness of the vaccine. Therefore, vaccination campaigns should be performed in autumn and spring. Also, vaccinating in regions located at more than 2,500 metres elevation is not efficient due to a very low fox population density at this attitude.
• Improve rabies passive surveillance – a key pillar of the control programme. This involves the collection of samples from any suspected wild or domestic animal, as well as from dead animals for laboratory testing. It should be implemented in parallel to the vaccination campaigns.
• Consider manual distribution of vaccine baits in places that are inaccessible by aircraft. Note that this technique should not be used for large scale distribution.
• Any other measures, such as mandatory pet vaccinations, population awareness and interests of all the stakeholders involved in the programme should be also considered. The general public is the main concern of the programme in the detection of rabies symptoms, and it should be well aware of the risks.

How much time would pass between the start of the programme and the first results?

F.C.: Ideally, if a country implements vaccination campaigns of wild animals twice per year in all infected areas, with no interruption in the programme, and follows the above-mentioned recommendations, rabies could be eliminated within 5 or 6 years. The first results, such as a decrease in rabies incidence, can be observed after two or three vaccination campaigns. However, this timing depends on certain local geographical conditions.

Which vaccine types are applied for oral vaccination of foxes in the European Union?

F.C.: Two vaccines are currently used in Europe, both are live vaccines. The oldest one is a classic live attenuated vaccine. The other one is a recombinant vaccine, a GMO vaccine where the strain of the virus has three directed mutations.

How does your laboratory support the national efforts against rabies?

F.C.: Our laboratory, the Nancy Laboratory for Rabies and Wildlife, belongs to ANSES, the French Agency for Food, Environmental and Occupational Health & Safety. It is the Reference Laboratory for Rabies for the OIE, the WHO and the EU. It was founded in 1971, three years after the notification of rabies in foxes in France. Therefore, we are the national reference laboratory, working on rabies in animals and dealing with diagnostics, serology, molecular biology and virology.

We work closely with OIE experts on reviewing and updating the Manual of Diagnostic Tests and Vaccines for Terrestrial Animals for the Rabies chapter. We are also part of OIE working groups and projects, for example, the recent OIE Reference Laboratories network (RABLAB).

We work closely with the bordering non-EU countries in geographical Europe and with northern African countries. We provide them technical support particularly for rabies diagnosis, and we are also involved in the OIE twinning projects for rabies control in Asia and Africa.

Why have you decided to pursue rabies research?

F.C.: I have been working on rabies since 1992. The first position I applied for was a veterinarian, even though I am an immunologist. However, the head of the laboratory accepted my candidature to work with rabies. I was very motivated and decided to continue within this research area because rabies is a very interesting disease.

It is a challenge for me – to make my small contribution to rabies control, notably in countries where the situation is difficult and rabies continues to kill, in particular children. Dying of rabies today is not normal – we have all the means to eliminate this disease; we have vaccines.

I am inspired by the fact that I can personally help and contribute – with OIE, as well as other international organisations – to achieve zero human deaths from dog-mediated rabies by 2030. It will be difficult, but if we all work together – we can succeed.