Zoonoses – Transmitted between animals and humans

In addition to the direct transmission of pathogens from one living organism to another, there are also indirect transmission routes: infection often occurs via food or through so-called vectors (organisms that transmit pathogens), usually mosquitoes or ticks. These organisms ingest the pathogen when feeding on the blood of an infected animal or human and transmit it to the next living organism when they feed again.

The list of zoonoses is long. The causative agents include bacteria, viruses, parasites, fungi, and prions. Below you will find most of the zoonotic agents found in Central Europe:

Transmission through contact with animals

Transmission can occur through direct contact with animals, but also indirectly via feces, urine, saliva, and other bodily secretions.

Bacteria

• Infections with Bordetella and Chlamydia are part of the feline rhinitis complex (see article on feline rhinitis).
• Glanders (see corresponding article)
• Anthrax (see corresponding article)

Viruses

• Rabies (see corresponding article)
• Leptospirosis (see corresponding article)
• Bornase disease (see corresponding article)
• Hantavirus disease: This is transmitted by inhaling dust from the feces, urine, and saliva of infected rodents, especially bank voles. Dogs, cats, and horses do not fall ill, but can transmit the virus to humans through contact with their fur. The symptoms are similar to those of a flu-like infection. However, there are also severe cases involving kidney failure.
• Avian influenza: Humans and animals can become infected through contact with infected birds. Mild cases occur, but there are also severe cases with flu and respiratory symptoms.
• Swine flu: Humans and animals can become infected through contact with infected pigs. However, dogs and cats usually become infected through contact with infected humans. The disease manifests itself through acute flu and respiratory symptoms.

Parasites

• Flea infestation (see relevant article)
• Mite infestation (see relevant article)
• Toxoplasmosis (see relevant article)
• Giardiasis (see relevant article)
• Echinococcosis: Humans can become infected with the small dog tapeworm and the fox tapeworm through direct contact with fur, smear infection, or contaminated soil. The larvae of the dog tapeworm form cysts in the liver and lungs. The larvae of the fox tapeworm grow in the liver, lungs, and even the brain (see article on meningoencephalitis), resembling tumors and continuing to grow. If detected late, this can cause considerable damage to the organs.
• Toxocariasis: Humans can become infected with roundworm eggs from dogs and cats through direct contact with fur, smear infection, or contaminated soil. The worms cannot develop in the human intestine. However, the larvae penetrate the liver, lungs, heart, brain, and eyes, where they can cause considerable damage.  
• Cryptosporidiosis: These mainly occur in farm animals such as cattle, sheep, and goats and cause diarrhea in young animals. The single-celled intestinal parasites are transmitted via contaminated water or as a smear infection and cause persistent, watery diarrhea in other animals and humans.

Fungi

• Skin fungal diseases (see corresponding articles for dogs, cats, horses and chinchillas)

Transmission through food

Foodborne zoonoses are most common in humans. With the exception of prions, they cause sudden gastrointestinal symptoms such as diarrhea, abdominal pain, and vomiting, as well as fever and aching limbs.

Bacteria

• Listeriosis: via raw milk, raw meat, and vegetables (see article on meningoencephalitis)
• Salmonellosis: often via raw eggs or poultry meat
• Campylobacteriosis: often via poultry meat
• EHEC (=enterohaemorrhagic Escherichia coli): via raw milk or beef

Parasites

• Trichinellosis: via raw meat from pigs, wild boar, or other wild animals (see article on meningoencephalitis)

Prions

• BSE (=bovine spongiform encephalopathy): infected beef can cause variant Creutzfeldt-Jakob disease (vCJD) in humans and FSE (feline spongiform encephalopathy, see article on meningoencephalitis) in cats.

Transmission via vectors

The most important vectors include various species of mosquitoes and ticks.

Bacteria

• Borreliosis (see corresponding articles for dogs and horses), the main carrier is the tick species Ixodes ricinus.

Viruses

• TBE (see relevant article), the main carrier is the tick species Ixodes rizinus.
• Leishmaniasis (see relevant article), the main carrier in Europe is sand flies of the genus Phlebotomus
• West Nile fever (see relevant article), the main carrier is mosquitoes of the genus Culex

Protection against zoonoses primarily consists of good food hygiene, various vaccinations, tick and mosquito protection, and regular deworming of your animals.

Wash your hands thoroughly with soap after contact with animals or working in the garden, and especially before eating. Wash plant-based foods carefully before consumption. Pregnant women, young children, immunocompromised individuals, and the elderly in particular should refrain from consuming raw foods. Raw meat and unwashed vegetables are also a source of infection for animals. This is particularly important to note when feeding your pet a raw diet (see relevant article).

Have your dog vaccinated regularly against rabies and leptospirosis and your cat against cat flu in accordance with the recommendations of StiKo Vet (Standing Vaccination Commission for Veterinary Medicine). There are also protective vaccinations for humans against some viral infectious diseases, such as TBE and rabies.

For dogs and cats, year-round tick prophylaxis is recommended to protect against tick-borne pathogens such as TBE or Lyme disease, which also protects against fleas, mites, and sand flies. It is also important to check your pet's coat daily and remove any ticks quickly.

In mosquito-infested areas, wear long, loose-fitting clothing, use insect repellent, and avoid dusk and dawn when mosquitoes are active, even when walking your dog.

Regular deworming of your dog and cat protects your pet, but also you. Your veterinarian will be happy to advise you on this.

The occurrence of zoonotic agents in food, feed, and live animals is recorded and evaluated in all countries of the European Union as part of the legally required zoonosis monitoring program. In Germany, reports on zoonosis monitoring are published on the website of the Federal Office of Consumer Protection and Food Safety (https://www.bvl.bund.de). You can also find results data on zoonosis monitoring on the interactive online portal ZooNotify (https://zoonotify.bfr.berlin) from the Federal Institute for Risk Assessment.

Various diseases must therefore be reported to the health department (humans) or the veterinary office (animals). The report is made by your doctor or veterinarian.