Companion Animals as a Source of Viruses for Human Beings and Food Production Animals.

Companion animals comprise a wide variety of species, including dogs, cats, horses, ferrets, guinea pigs, reptiles, birds and ornamental fish, as well as food production animal species, such as domestic pigs, kept as companion animals. Despite their prominent place in human society, little is known about the role of companion animals as sources of viruses for people and food production animals. Therefore, we reviewed the literature for accounts of infections of companion animals by zoonotic viruses and viruses of food production animals, and prioritized these viruses in terms of human health and economic importance. In total, 138 virus species reportedly capable of infecting companion animals were of concern for human and food production animal health: 59 of these viruses were infectious for human beings, 135 were infectious for food production mammals and birds, and 22 were infectious for food production fishes. Viruses of highest concern for human health included hantaviruses, Tahyna virus, rabies virus, West Nile virus, tick-borne encephalitis virus, Crimean-Congo haemorrhagic fever virus, Aichi virus, European bat lyssavirus, hepatitis E virus, cowpox virus, G5 rotavirus, influenza A virus and lymphocytic choriomeningitis virus. Viruses of highest concern for food production mammals and birds included bluetongue virus, African swine fever virus, foot-and-mouth disease virus, lumpy skin disease virus, Rift Valley fever virus, porcine circovirus, classical swine fever virus, equine herpesvirus 9, peste des petits ruminants virus and equine infectious anaemia virus. Viruses of highest concern for food production fishes included cyprinid herpesvirus 3 (koi herpesvirus), viral haemorrhagic septicaemia virus and infectious pancreatic necrosis virus. Of particular concern as sources of zoonotic or food production animal viruses were domestic carnivores, rodents and food production animals kept as companion animals. The current list of viruses provides an objective basis for more in-depth analysis of the risk of companion animals as sources of viruses for human and food production animal health.

Avian influenza viruses in mammals.

Highly pathogenic avian influenza viruses of subtype H5N1 are remarkable because of their expanding non-avian host range and wide tissue tropism. They have caused severe or fatal respiratory and extra-respiratory disease in seven naturally infected species of carnivore. However, they are not unique in their ability to cross the species barrier, to cause clinical disease and mortality, or to replicate in extra-respiratory organs. Low pathogenic avian influenza viruses have crossed from birds to swine, horses, harbour seals, whales and mink; have resulted in severe respiratory disease and mortality; and may have spread beyond the respiratory tract in some of these species. They are also transmitted from mammal to mammal in most species, and have become endemic in swine and horse populations, demonstrating their ability to adapt to and become sustained in mammals. Until now, highly pathogenic avian influenza viruses H5N1 have not acquired this ability, but there are concerns that they may adapt to mammalian species and, thus, could spark an influenza pandemic in humans.

Rodents as shared indicators for zoonotic parasites of carnivores in urban environments.

Rodents are shared intermediate or paratenic hosts for Echinococcus multilocularis, Toxocara spp. and Toxoplasma gondii, and may serve as valuable indicators for assessing the occurrence and the level of environmental contamination and infection pressure with free-living stages of these zoonotic parasites. We investigated 658 non-commensal rodents for parasite infections in the canton of Geneva, Switzerland. The prevalence of infection with E. multilocularis was highest in Arvicola terrestris captured in the north-western area (16.5%, CI: 10.1%-24.8%), possibly reflecting a higher red fox density due to the low incidence of sarcoptic mange in this part of the canton. The exposure rate to Toxocara spp. was highest in the urban area (13.2%, CI: 7.9%-20.3%), and may account for higher densities of domestic carnivore and red fox definitive hosts within the city. Exposure to T. gondii was widespread (5.0%, CI: 3.2-7.4%), indicating a ubiquitous distribution of infected cat definitive hosts. Interestingly, a widespread distribution of Taenia taeniaeformis, a parasite mainly transmitted by cats, was similarly evidenced in A. terrestris. Distinct spatial patterns for the different zoonotic parasites likely reflected differences in distribution, abundance, and habitat use of the respective definitive hosts. These results highlight the potential value of rodents as shared indicators for these pathogens.

Echinococcus multlocularis infections of rural, residential and urban foxes (Vulpes vulpes) in the canton of Geneva, Switzerland.

We examined 267 red foxes (Vulpes vulpes) from the canton of Geneva, Switzerland, for intestinal infections with Echinococcus multilocularis. This region is situated in the core area of the endemic range of this zoonotic cestode in Central Europe. Several factors were taken into account and urbanisation level appeared to be the most explicative to describe observed differences. The prevalence decreased significantly from rural and residential areas (prevalence of 52%, CI 43-62%, and 49%, CI 38-59 %, respectively) to the urban area (prevalence of 31%, CI 19-42%). A few juvenile foxes harboured very high burdens up to more than 120,000 worms and were significantly more heavily infected than adults. The intensity of infection decreased from rural and residential areas to the city, suggesting a lower contamination of the urban environment.