Zoonosis

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Zoonoses (from ancient Greek ζῶον zōon "animal" and νόσος nósos "disease") are infectious diseases that can be transmitted from animal to person and from person to animal and occur naturally in vertebrates . The definition of the World Health Organization ( WHO ) from 1959 states that zoonoses are infectious diseases that can be transmitted naturally between humans and other vertebrates.

Originally, zoonoses were only understood to mean animal diseases. During the century before last, there was a change in the meaning of the name. In addition to the actual animal diseases, in the mid-19th century, zoonoses were now also understood to include diseases that could be transmitted from animals to humans. When the term zoonosis is used today, no distinction is made with regard to the transmission route. Zoonoses can therefore be transmitted from humans to animals ( anthropozoonosis ) or from animals to humans ( zooanthroponosis ).

There are currently about 200 diseases known that occur in both animals and humans and can be transmitted in both directions. The actual pathogens can be prions , viruses , bacteria , fungi , protozoa , helminths or arthropods .

Concept history

The word zoonosis was first used in 1876 by Ernst Wagner in his Handbuch der Allgemeine Pathologie .

Classification of zoonoses

According to the direction of infection

The different zoonoses can be divided into different groups based on the reservoir .

  • Zooanthroponoses : The infection is only transmitted from animals to humans. An example is infection with Toxocara canis .
  • Anthropozoonoses : The infection is transmitted almost exclusively from humans to animals. An example is infection with Entamoeba histolytica .
  • Amphixenoses : The infection occurs in both humans and animals and is transmitted in both directions. An example is infection with Taenia saginata .

Life cycle

A classification based on the life cycle is also possible.

  • Direct (ortho) zoonosis : Zoonosis is transmitted from one vertebrate to another through direct contact or a mechanical vector . One example is scabies or mange
  • Cyclozoonosis : In cyclozoonosis, the pathogen has to switch between different hosts. Both intermediate and final hosts are vertebrates. This form of zoonosis is only observed in parasitic pathogens that have a heteroxic cycle.
  • Metazoonosis : In a metazoonosis, the pathogen has to switch between different hosts. The intermediate host is an invertebrate .
  • Saprozoonosis : Saprozoonoses have a reservoir outside of the animal kingdom. Examples of reservoirs include plants, soil, and water. Examples of pathogens that fall under this class are Giardia intestinalis , Ancylostoma and Toxocara canis .
  • Latent zoonosis : Transmission of zoonosis through meat, for example . The pathogen does not cause any symptoms in the intermediate host .

Occurrence

The incidence and prevalence of most zoonoses is difficult to estimate. On the one hand, many zoonoses remain undiagnosed; on the other hand, most zoonoses are not required to be reported .

In general, however, the risk of becoming infected with a zoonosis, the greater the more frequent and the more direct contact with animals.

Eating habits can influence the spread of zoonoses. The prevalence of toxoplasmosis in England is lower than in France because English people eat less raw or seared meat. Cysticercosis , an infestation of humans with larvae of the pork tapeworm , does not occur in Jewish or Islamic population groups because they do not eat pork.

The destruction of pristine forests through deforestation , mining, road building through remote locations, rapid urbanization and population growth puts people in contact with wild animal species from which pathogens can spread to human communities.

hazards

The salmonellosis is mainly through food ( eggs , dairy products transferred, poultry meat). It is the most commonly reported zoonosis. High temperatures increase the risk of Salmonella multiplying in food.

In 2005 there were several deaths from rabies in Germany . A patient was infected with rabies in India. The symptoms of the disease were then ascribed to the patient's drug use and so after the patient's death, infections developed in several organ transplant recipients who received organs from the patient.

Immune-incompetent people (people with an immune system that is already severely weakened or even completely inoperable due to another disease ), such as AIDS patients in an advanced stage or people who are undergoing chemotherapy , immuno-weak people, such as old people or children, are also included exposed to the risk of becoming infected with pathogens that do not normally lead to patent infections in humans (the phase of a parasitic infection of an organism from the time the invaders have completed development into adult, egg-laying parasites and the first appearance of their reproductive products in the body excretions of the host ).

There is a special danger for pregnant women. Some zoonoses can cause harm to the fetus . Even newborns still have a relatively weak immune system and can be at great risk from otherwise harmless infections. Children who are not breastfed are particularly at greater risk, as the mother's defenses are also transferred to the infant through breast milk.

Certain professional groups, such as veterinarians or farmers , have an increased risk of infection because they often come into contact with vectors.

Prevention

Anyone who comes into contact with animals or their products can be exposed to an infection. It is irrelevant whether humans hunt animals or domesticate them as farm animals or pets. Infections from animals to humans are avoided by the same measures as interpersonal infections. In animal husbandry, hygiene (clean stables and enclosures, cleaning hands, disinfection , e.g. by cooking and ironing textiles ) is the most important preventive measure . Excessive contact between animals and humans can also provoke transmission of infection.

The eradication of dangerous zoonoses, such as tuberculosis , or the control of pathogens through regular treatments such as vaccinations or deworming , helps to reduce the general risk of infection.

Animals that appear healthy can also be a source of infections that can be fatal. An example of this is the transmission of herpes viruses from monkeys to humans.

Risk of epidemic

There is also a risk of epidemic occurrence with some zoonoses. An example of such a plague is the plague . Many other zoonoses are rather limited in their epidemic potential because they require contact between the host or vector and humans.

A particular danger, which, however, no longer counts as a zoonosis, is a change of host. If there is a change of host, for example from birds or cats to humans, this can trigger pandemics . In the recent past, such a switch between cats and humans has taken place in Asia. A coronavirus responsible for the lung disease SARS , the SARS coronavirus , mutated and could suddenly be transmitted to humans by its natural host (a type of cat), where it can reproduce and be further transmitted by humans.

A case at the beginning of the 2009 influenza pandemic in Canada showed that influenza viruses of the subtype H1N1 can potentially be transmitted naturally from person to animal . In May 2009 the Canadian Food Inspection Agency classified the transmission of the virus from humans to pigs as highly likely. In such cases of zoonosis, there is a risk that viruses will recombine in the pathogen reservoir and form pathogens that are more dangerous for humans, for example.

Monitoring and research efforts

AIDS , SARS and the resulting memories of the Spanish flu have increased interest in research into zoonoses. The European Union initiated a Europe-wide network called Med-Vet-Net of 300 researchers, which is dedicated to the prevention and control of zoonoses. One focus of the network are campylobacterioses, infections of the digestive tract such. B. of Campylobacter jejuni , of which 100 bacterial strains have been identified so far. In 2003 the European Council and the European Parliament defined List A of eight zoonoses that are continuously monitored. These include diseases caused by bacterial strains from the Campylobacter , Listeria , Salmonella families , certain types of Escherichia coli or Mycobacterium bovis , as well as trichinellosis and echinococcosis caused by parasites . List B defines zoonoses for which monitoring begins as soon as a case is identified. These include rabies , West Nile fever, and bird flu .

Examples of zoonoses and zoonotic agents

Figure 3- Examples of Zoonotic Diseases and Their Affected Populations (6323431516) .jpg

Viral zoonoses and their pathogens

Among the hantaviruses are viruses with pulmonary symptoms such as the Sin-Nombre virus, the Black Creek Canal virus, the Muleshoe virus, the Bayouvirus, the Andes virus, the Bermejovirus, the Choclovirus, the Araraquaravirus, the juquitiba virus, the Maciel virus and the Castelo dos Sonhos virus as well as hantaviruses with renal symptoms such as the Hantaan virus, the Dobrava virus , the Puumala virus and the Seoul virus .

Prion-induced zoonoses

Bacterial zoonoses

Zoonotic mycoses

Parasitic zoonoses

Unicellular organisms

worms

Arthropods

literature

  • Pedro N. Acha, Boris Szyfres: Zoonoses and Communicable Diseases Common to Man and Animals. Volume 1: Bacterioses and Mycoses . 3rd ed., 2nd print. PAHO Pan American Health Organization, Washington DC 2003, ISBN 92-75-11580-X
  • Pedro N. Acha, Boris Szyfres: Zoonoses and Communicable Diseases Common to Man and Animals. Volume 2: Chlamydioses, Rickettsioses, and Viroses . 3rd ed.PAHO Pan American Health Organization, Washington DC 2003, ISBN 92-75-11992-9
  • Pedro N. Acha, Boris Szyfres: Zoonoses and Communicable Diseases Common to Man and Animals. Volume 3: Parasitoses . 3rd ed.PAHO Pan American Health Organization, Washington DC 2003, ISBN 92-75-11993-7
  • P. Kimmig, T. Schwarz, HG Schiefer, W. Slenczka, H. Zahner: Zoonoses. Infectious diseases that can be transmitted from animal to human . With CD-ROM. Ed .: Rolf Bauerfeind. 4th edition. Deutscher Ärzte-Verlag, Cologne 2013, ISBN 978-3-7691-1293-1 .
  • Carolin Anna Maria Bumann: Detection of bacterial zoonotic pathogens relevant to food hygiene in small ruminants from Switzerland . LMU, Munich 2010, DNB  1007628111 (202 p., Full text [PDF; 1000 kB ] Dissertation, University of Munich, 2010).
  • Michael R. Conover & Rosanna M. Vail: Human Diseases from Wildlife. CRC Press, 2015. ISBN 978-1-4665-6214-1 (print), ISBN 978-1-4665-6215-8 (eBook)
  • Józef Parnas: Human infectious diseases of animal origin for doctors and veterinarians. 3 volumes, Copenhagen 1975.
  • Manfred Vasold: Zoonoses. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , pp. 1532-1534.

Web links

Commons : Zoonoses  - Collection of images, videos and audio files
Wiktionary: Zoonosis  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ a b Mikhail Stein: Fragile Barrier Between Species , in research eu , special edition October 2008, page 34.
  2. ↑ Kai Niebert: When the market penetrates the virus habitats. Climate reporter, March 27, 2020, accessed on March 28, 2020 (German).
  3. ↑ Compare e.g. B. Publication of recommendations for hygienic requirements for keeping ruminants of July 7, 2014 ( BAnz AT 08/01/2014 B1 ).
  4. ↑ To Alberta Swine Herd Investigated for H1N1 Flu Virus. (No longer available online.) The Canadian Food Inspection Agency, archived from the original September 27, 2011 ; Retrieved May 2, 2009 .
  5. ↑ a b Influenza transmission from humans to pigs - top veterinarian calls for hygiene in the barn , Tagesschau from May 4, 2009.
  6. ↑ Zoonoses as a global problem: "The virus that comes after Covid-19 could hit us even worse". April 14, 2020, accessed April 15, 2020 .