What diseases are relevant for the wolf?
Wolves can fall sick with the same diseases and be infested with the same parasites like dogs. Equally, some diseases are dangerous for humans (rabies and fox tapeworm Echinococcus multilocularis) and some are not.
Rabies: Germany has been considered rabies-free since 2008. Therefore, this disease does not pose a threat at the moment. Despite this, wildlife like wolves and foxes, but also raccoons and raccoon dogs are further monitored in order to identify and fight a potential re-introduction.
Fox tapeworm: The fox tapeworm is an endoparasite for which the fox can be the final host. Through infected scats, the tapeworm can be passed on to humans. Humans are false intermittent hosts and can become diseased with alveolar Echinoccoccosis, which can be life-threatening under certain circumstances. However, the number of infections in humans are very low. The main area of distribution of fox tapeworms are the Swabian Alps, the Alb-Donau region and the Allgäu. In these areas, the infection rate of foxes is 50 to 100%. North of this region, less than 5% are infected with E. multilocularis.
Sarcoptic mange, canine distemper, parvovirosis and Aujeszky’s disease (pseudorabies) are not dangerous for humans.
Sarcoptic mange: Sarcoptic mange is an ectoparasitosis caused by scabies mites. The disease is usually passed on through direct body contact. Strong itching that goes along with inflammatory reactions and secondary bacterial infections of the skin cause loss of hair and skin sloughing. The fur condition of infested animals is bad, as the continuous scratching causes bald patches in different body regions, such as back and tail. In the advances stage, infested animals can show a slower flight behaviour, but they are not aggressive towards humans. Sarcoptic mange is highly infectious for other carnivores. Sarcoptic mange outbreaks can lead to significantly higher mortality rates in a wolf population, especially among the pups. Animals with a strong immune system can heal up the disease completely, even when their infestation is massive. Sarcoptic mange is very frequent in foxes and raccoon dogs and is also passed on to other species by them. Infection of domestic animals is possible, but can be cured easily. In rare cases, humans can catch the disease, which leads to a pseudo form of sarcoptic mange that generally heals up without any medical treatment.
Canine distemper: The canine distemper virus is mainly carried by dogs and is rare in wolves. The disease is usually passed on through direct body contact, secretions and excrements. High fever and fatigue are typical symptoms. Depending on the infected organ system, diarrhoea and vomiting or airway symptoms can occur. At later stages, brain damage and malfunction of the central nervous system are possible. As most dogs in Germany are vaccinated against canine distemper, passing on of the disease from dogs to wolves is unlikely. However, canine distemper epidemics like the ones that can be observed in fox populations, are dangerous for infected animals, especially for young ones. According to surveys in the Yellowstone National Park, canine distemper epidemics can cause pup mortality rates of up to 68%. Humans are not susceptible for canine distemper infections.
Parvovirosis: The canine parvovirus is distributed through excrements of infected animals and can be passed on from these through insects as well. In the cause of the disease, strong vomiting and diarrhoea through to lethal dehydration can occur, depending on the age and condition of the infected animal. A canine parvovirus infection that was imported through dogs to Isle Royale (U.S.A.) in the early 1990ies caused a collapse of the local wolf population. Most dogs in Germany are vaccinated against the parvovirus. Like with the canine distemper, passing on of the disease from dogs to wolves is unlikely. The virus cannot be passed on to humans.
Pseudorabies: The pseudorabies or Aujeszky’s disease is a virus infection, and the pathogen belongs to the herpes family. The infection is lethal in almost all mammals. Humans, other primates and horses are not susceptible for pseudorabies. Infection occurs through the contact with wild boars or domestic pigs, which carry the virus for the rest of their lives after infection. There is no risk of infection through other carnivores like wolves, as these animals do not excrete the pathogen. Therefore, passing on of the disease is not possible from wolf to wolf or from wolf to dog. Quickly after infection, brain and medulla inflammations occur along with malfunction of the central nervous system. In cattle and dogs, strong itching is additionally found. The infection then leads to the death of the animal. It is an animal disease that has to be reported to the authorities. Germany has been pseudorabies-free since 2003 in domestic pigs, however, the disease rate is increasing in wild boars again. This trend is the same in other European countries. Infected wolves and dogs die quickly after occurrence of the symptoms (1-2 days).