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Topic for Research : Zoonosis

Zoonosis

Infections that pass from animals to humans have always been an important issue for veterinary medicine, and hence for CODA-CERVA as well.

Food-producing farm animals, house-pets and feral animals can become sources of infection in humans. Humans get infected by direct contact with infected animals or through animal products (excreta, post-parturition, wool, etc), or transmission of bacteria, viruses or parasites into the food-chain.


Very often the animal itself is not clinically ill, and the infection goes undetected. In humans, however, the symptoms may well be serious or even fatal.


For this reason, it is essential that there should suitable regulations relating to the hygiene and bio-safety for animal feeds, the animal itself, carcasses, meat, eggs and the like, also for the consumer (distribution of foodstuffs, preparation of food in the kitchen).

As far as the approach towards zoonoses in primary production is concerned, (in the living animal, which comes within CODA-CERVA's purview), it falls into three areas:

  • devising appropriate monitoring of animals that do not necessarily display any clinical symptoms,
  • swift and sensitive detection both in the field and in diagnostic laboratories, and
  • the prevention and treatment of infected animals.


Scientific research at CODA-CERVA as the national reference laboratory focuses primarily on the epidemiology of zoonoses, the study of host-germ interactions, perfecting accurate diagnostic techniques, developing potential preventive measures and the search for efficient combat methods.
A major European initiative became available with the zoonosis guidelines (92/117/EEG and 2003/99/EG), establishing the measures required to guard against certain animal zoonoses and animal products.

Zoonosis

There still remain considerable challenges for zoonoses that require attention: newly-emerging diseases , climate change, the mass international movements of people, animals and animal products, and the ease with which bacteria, viruses and parasites are able to pass from animals to humans: "One world, one health".

Moreover, even if international attention to this has faded, the use of zoonotic agents as a weapon in bioterrorism remains an area of research.

As far as bacterial infections are concerned, the closest attention is being paid at CODA-CERVA to brucellosis, leptospirosis, bovine tuberculosis, salmonella, paratuberculosis, Q fever and zoonotic E. coli infections, also germs that could be used for terrorist attacks, glanders, melioidosis, tularæmia, anthrax and plague.


Viral zoonoses
are most frequently caused by a virus that is pathogenic for animals and which can accidently infect humans.

Emerging zoonoses regularly appear which are due to either seemingly new agents or to micro¬organisms that are already known but which appear in places or species where the disease was thus far unknown.

Zoonosis

The virus is sometimes passed on through contact such as via the oral or respiratory route (e.g.: hantavirus infections, influenza) but more frequently via a wound (e.g.: rabies) or a bite (e.g.: arbovirus infections) and raises the importance of reservoirs and vectors that should be identified in order to control the disease.

In particular, arbovirus infections (Arthropod Borne Virus) are viral affections passed on by haematophagous arthropods (biting insects, mosquitoes or anopheles or even ticks).

The viruses involved belong to one of three 3 families = Toga, Bunya & Flavivirus. Arboviruses include several hundred viruses of which around fifty affect humans.

Arboviruses multiply both in vertebrates (and possibly in humans) and in arthropods. Insects become infected by sucking in the blood of these vertebrates. The virus multiplies in the digestive tract of the insect, spreads and reaches the saliva glands, where the virus multiplies reaching very high concentrations.

Insects which do not in any way suffer from this proliferation pass on the virus in their saliva to the next vertebrates that they bite.

Vertebrates are the reservoir for the virus and they are nearly always wild animals. In most cases, if humans are infected by being bitten by the vector, this is only an accidental phenomenon, and constitutes an impasse, because humans do not usually pass on the infection.

Cases include the West Nile Virus, the Rift Valley Fever and the Crimean Congo Fever and do not exist in Belgium, but they may emerge to varying degrees at any time.

Setting up alert systems for arbovirus infections is the aim of the European network of excellence, ARBOZOONET, with which CODA-CERVA is involved.