Rapide et précoce diagnosticde l’influenza aviaire
24 mai 2010 – Influenza A, including avian influenza, is a major public health threat in developed and developing countries. Early, rapid and accurate detection is a key component of strategies to contain, halt or mitigate disease transmission. In the context of highly pathogenic avian influenza (HPAI), the efficient diagnosis of this and other emerging and transboundary diseases is essential to protect animal and human health in the event of a major outbreak.
In a recent scientific consultation on influenza and other emerging infectious diseases at the human-animal interface held in Verona, Italy, it was concluded that there is an urgent need to gain a deeper understanding of host and susceptible population dynamics, along with a firmer grasp of the active and multifaceted interplay between domestic animals and wildlife in diverse agro-ecological systems.
In recent years, experts, scholars and practitioners have highlighted the benefits of using science-based laboratory applications to further elucidate the environmental characteristics used by actual and potential animal hosts in their natural settings. This can be done, for instance, by using stable isotope analysis (SIA), which is a technique that aids in identification of isotopic signatures, the distribution of certain light stable isotopes (for example, Hydrogen-2, Carbon-13, Nitrogen-15, Oxygen-18 and Sulfur-34), and specific chemical elements within complex chemical compounds. This technique, or variations thereof, such as isotope ratio mass spectrometry (IRMS), are utilised to trace food webs and track the origins of target animal species. Some of the substrates for these applications are feather, blood, faecal, hair and aqueous samples collected from animals and the environment.
These techniques are now used - and hopefully can be broadly adopted - to produce the tangible evidence needed to support anecdotal reports that resident animal species are picking up viral diseases from visiting species after they move out (for example, asymptomatic mallard ducks during their sojourn in Siberia shed HPAI in the environment) and also to generate data on the ecology of avian influenzas in key bird species worldwide. In fact, several research institutes around the world have been trying to gather evidence and generate data through careful and systematic tracking of migratory birds along their flyways by collecting and analysing samples from wintering and nesting sites to build up reliable isotopic profiles and comparing them to local profiles from where viral disease outbreaks are reported.
In addition to isotope tracing, classical molecular techniques such as Polymerase Chain Reaction (PCR) are being further refined to enhance detection of influenza viruses. In particular, given that HPAI is oftentimes reported in fairly inaccessible rural settings, field PCR tests are now being designed and tested to assess its applicability and usefulness. The advent of new applications and the differing diagnostic capacities of infected locations call for cross-validation of PCR technique between countries experiencing recurrent disease flare-ups.
Given that early and rapid pathogen detection has been posited as a pillar of comprehensive animal disease risk management programmes, the Joint International Atomic Energy Agency (IAEA)/Food and Agriculture Organization of the United Nations (FAO) Division, held the Final Research Coordination Meeting of the Coordinated Research Project (CRP) on "Early and Rapid Diagnosis of Emerging and Transboundary Animal Diseases" on 10-14 May 2010, in Rome, Italy, in which seasoned veterinary laboratory practitioners and diagnostic experts share their knowledge and expertise as the scientific and technical basis for developing or modifying the early and rapid diagnosis of avian influenzas.
The rapid molecular technology platforms developed and fine-tuned by the CRP has allowed improved turnaround time: early, rapid, and confirmed diagnosis has moved from weeks to a day or two, which has in turn improved field cooperation with surveillance programs. This has been critical to rapid and effective avian influenza control in a country with a confirmed incursion of avian influenza H5N1 (e.g. Nigeria). The infrastructure developed with the avian influenza CRP has allowed future development and growth of other laboratory services (the capability is generic in nature and can be utilized laterally). The avian influenza technology has been shared with public health laboratories where possible, and this has allowed new cooperation and collaboration between the public health and veterinary diagnostic community.
The associated molecular diagnostic training has also allowed improvements to laboratory capability and capacity-building. The sharing of information between the CRP members has assisted in the development of a better understanding of avian influenza diagnosis through molecular techniques including an increased knowledge about the disease's epidemiology, transmission and risks. The project has improved the profile of surveillance programs, including wildlife surveillance, and the capability of the laboratory to carry out the diagnostic components of surveillance efforts.
Additionally, as a complement to ongoing research initiatives and capacity-building efforts, the FAO/IAEA Agriculture and Biotechnology Laboratory, located in Vienna, specializes in research, development and transfer of nuclear methods in animal production and health, among other areas. The laboratory provides a broad range of specialized services and training of scientists, as well as guidance on the introduction of analytical quality control and assurance into counterpart laboratories, and training in the maintenance of laboratory equipment and instruments.