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Published on 26/05/2014

Work on rabies by Nancy laboratory for rabies and wildlife

Last update: 20 November 2014

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Organising, coordinating, implementing and monitoring oral fox vaccination campaigns against rabies

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In the 1970s, the laboratory extensively participated to scientific research work for developing oral vaccine baits.

A number of experimental trials were undertaken to check efficacy and safety of vaccines before their marketing. In 1986, the laboratory tested the first available methods of oral vaccination with baits (chicken head baits) deposited in the field by foot distribution. From 1990, the overall organisation of the oral vaccination campaigns has been centralised: the Anses-Nancy Laboratory for rabies and wildlife was requested by the national competent authority to organize and plan the oral vaccination of foxes and, in close cooperation with its delegates, to implement and evaluate the programmes.

From 1988 to 1998, year of the last recorded case of vulpine rabies, the laboratory planned the strategy and performed oral vaccination campaigns in infected areas twice a year using helicopters. These campaigns were then prolonged until 2003 along Northern and Eastern borders and were performed once again in 2005.

Several field trials have been conducted to improve the efficiency of oral vaccination programme, particularly to promote cubs' coming into contact with baits and also to counterbalance the increase in the fox population.

 

Rabies surveillance and vaccination monitoring

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Rabies surveillance is the key element of rabies control and prevention programmes. It is based on laboratory investigations on samples taken from susceptible animals to collect sufficient spatial and temporal descriptive data used to build the control programme.

The national network for animal rabies surveillance is centralised at ANSES-Nancy laboratory for rabies and wildlife. The incidence of rabies in animals is currently assessed throughout all the country by undertaking diagnosis on suspect animals using the OIE and WHO reference tests, i.e. the fluorescent antibody test, the cell and the mouse inoculation tests (WHO, 2013; OIE, 2013). The positive cases are systematically investigated by sequencing to characterise the virus strains of isolated lyssaviruses, and also to study the circulating field isolates in the country.

The monitoring of the efficacy of oral vaccination programmes was conducted in vaccinated areas by:..

  • Assessing bait uptake by testing the target species (foxes) in vaccinated areas for biomarker (tetracycline) occurrence and assessing age categories of foxes marked by tetracycline.
  • Assessing rabies antibodies in target species in vaccinated areas: the laboratory has developed a reliable ELISA test which is recommended by OIE and in 2004 organised an international training workshop.
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Technical competences in rabies

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The laboratory is experienced in the validation and standardisation of laboratory techniques, mainly for diagnosis and serology, and regularly organises international workshops and inter laboratory tests.

The laboratory has developed the straw sampling technique to facilitate sampling on dead animals for diagnostic analysis. The laboratory has developed and validated a rapid, safe and inexpensive method for collecting brain samples from the field using filter paper (FTA technology) for further analyses by molecular techniques.

Two different techniques have been developed which are currently recommended by WHO and OIE:

  • An ELISA adapted to rabies antibody titration from wildlife field sera, 
  • The FAVN test which is an adaptation of the RFFIT for specific detection of rabies neutralising antibodies in domestic and wild carnivores.

A simple procedure has been recently developed by the laboratory allowing simple sampling of blood from foxes and raccoon dogs in field conditions coupled with the use of a reliable ELISA for rabies antibody titration.

For more than 20 years, the laboratory has been in charge of the control of potency of all batches of inactivated rabies vaccines for parenteral use produced or imported in France, by using the NIH test as well as the European Pharmacopoeia test. The laboratory is part of the OMCL (Official Medicine Control Laboratory) network and is involved in OCABR (Official Control Authority Batch Release) of veterinary oral and inactivated rabies vaccines.

The laboratory is also involved in the control of equine immunoglobines intended for post-exposure treatment, adaptation of rabies isolates on cell cultures or mouse and viral titrations in cells and mice.

For several years, molecular tools have been developed (RT-PCR with universal and specific primers, heminested PCR, real time PCR, Southern Blot, nucleotide pyrosequensing, NGS sequencing and phylogenetic analyses) to characterise rabies viruses and to trace spill-over transmissions from reservoir to non-reservoir animals and humans, to possibly detect the emergence of rabies virus variants in new species and geographical areas.

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Research activities on rabies

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The research work of the laboratory is mainly intended to increase knowledge on the pathogenicity of certain rabies viruses (those that infect European bats), to develop experimental models and to investigate the transmission of bat lyssaviruses to other bats and to non flying animals.

The main current programmes, in close cooperation with other national rabies laboratories, are the following:..

  • Programme for surveillance and research on rabies in bats,
  • Experimental studies on captive animals to investigate the pathogenicity of several field isolates.
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