The concept of One Health starts with the idea that human health and animal health are linked to each other and the environment. This holistic view of the necessity of protecting the health of humans and animals as well as the ecosystem is ancient – even Hippocrates considered human health as part of environmental health. One World, One Health is also an approach recommended by the World Health Organization (WHO) for health and well-being.
“One Health refers to human and environmental health as well as that of domesticated and wild animals. Health issues such as microbial drug resistance or zoonoses are global and require global and multidisciplinary solutions,” explain the organisers in charge of the conference, Professor Arja Rautio, Doctor of Arctic Health at the University of Oulu, and Professor Antti Oksanen from the Finnish Food Authority. “Health refers to the physical and mental health and well-being of the individual and the community.”
“The One Arctic, One Health conference featured speakers from all member states of the Arctic Council, which include Russia, Finland, Sweden, Norway, Iceland, Greenland, Canada and the United States. The topics were connected to health-related themes typical of the Arctic region, such as various zoonoses or diseases transmitted from animals to humans, the health of indigenous peoples, food safety, adequacy of clean water resources and the effect of climate change on the spread of disease,” says Professor Rautio.
Over one-half of human infectious diseases are zoonotic, meaning that they spread from animals to humans. At worst, zoonoses also spread from one human to another. An even greater proportion of new, threatening infectious diseases originates in animals, so it was natural for zoonoses to be a key theme of the conference.
The conference was organised in cooperation between the Thule Institute of the University of Oulu, the Finnish Food Authority and the Arctic Council as well as the Ministry for Foreign Affairs, Ministry of Agriculture and Forestry and Ministry of Social Affairs and Health of Finland. The conference was connected to Finland’s chairmanship of the Arctic Council, which has reached its final stretch. In May, Iceland will assume chairmanship of the Council.
Familiar diseases and parasites
Professor emeritus Heikki Henttonen, Doctor of Forest Zoology of Natural Resources Institute Finland gave a talk at the conference on diseases familiar to Finns, such as epidemic nephropathy (‘bank vole virus’), which is spread by the Puumala hantavirus, and tularaemia or rabbit fever, which is caused by the Francisella tularensis bacterium. Tick-borne microbes, such as the Borrelia bacterium and Flavivirus, which causes tick-borne encephalitis, will once again receive a great deal of attention in the media in the spring.
“Zoonoses can spread from animal to human, or they can be vector-borne and carried by, for example, bloodsucking mosquitos or ticks. The pathogen itself can be a virus, bacterium, fungus or parasite,” says Professor Henttonen.
“Zoonoses can also spread from human to human, such as the Ebola virus in Africa. Our domestic epidemic nephropathy only spreads from bank vole to human, not from human to human.”
Professor Henttonen particularly emphasised the fact that the epidemiology of zoonoses varies in different biogeographical areas, or biomes. Fluctuations in the host populations of known pathogens, such as the Puumala virus or tularaemia bacterium, differ between the temperate and boreal zone, which is why we need comparative study between the Arctic, boreal and temperate zone.
“Attempts to apply disease models from, say, the temperate zone directly to Arctic conditions can go badly wrong.”
In recent years, the media have repeatedly covered Echinococcus parasites, which cause concerns among the public; mental images of human livers ravaged by tapeworms is enough to ruin anyone’s appetite. “Scientists are kept busy trying to keep sensationalist reporters’ feet on the ground,” says Professor Henttonen with a laugh.
“Of course, Echinococcus multilocularis is life-threatening as a permanent parasitic infection, but we must keep in mind that, in most cases, the person’s own immune system fights off the parasitic infection. Echinococcus multilocularis is found in Estonia, but not here – yet. It will probably spread to Finland sooner or later carried by either pet dogs or wild canids, such as foxes and raccoon dogs. Canids are the main hosts of Echinococcus multilocularis.” Voles serve as intermediate hosts, which is where the Finnish name of the virus, ‘bank vole echinococcus’, comes from.
How does climate change affect zoonoses that already occur in or are spreading to the North?
“That is a multifaceted question. Global warming, shorter snow cover durations and the general increase in base production increase the diversity of biotic communities, and this may diversify and stabilise predator communities, which might level out fluctuations in rodent populations. This could then reduce the incidence of epidemic nephropathy, for example. On the other hand, the increase in base production increases predator numbers, and diseases spread by predators, such as Echinococcus multilocularis spread by foxes, may become more common.”
“With global warming, ticks will spread north and bring diseases. The diseases spread by the mosquito, black fly and biting midges will benefit from climate change,” analyses Professor Henttonen.
Most topical zoonoses of Arctic America
Dr Emily Jenkins, Associate Professor of Veterinary Microbiology at the University of Saskatchewan in Canada gave a presentation at the conference on the growing disease hazards in North America. The three topical diseases are chronic wasting disease (CWD), echinococcosis and toxoplasmosis.
CDW, which is commonly known as zombie deer disease, is caused by structurally abnormal prion proteins. Mad cow disease from a few decades back was also a prion disease.
“CDW has been occurring in captive cervids in Canada and the United States for a long time now. It has spread from captive to wild cervids. The CWD prion spreads through cervid stool and saliva as well as dead carcasses and can survive in the environment for long periods of time,” says Professor Jenkins. Once it has contaminated the environment, it is very difficult to get rid of.
The meat of contaminated animals is inedible because the abnormal prion cannot be destroyed by boiling or freezing. The CWD prion is not yet known to infect humans, but it has been known to infect macaques, which is considered alarming.
“Caribou meat is an important food product for the indigenous peoples in Canada. The spreading of CWD to the north would be disastrous for indigenous peoples.
For a long time, CWD remained a North American disease, but in 2016 it was discovered in wild mountain reindeer in Norway. The latest studies show that the CWD in Norway is not identical to the North American pathogen. Prions are known to mutate easily, and the Norwegian CWD may be a variant born in a sheep or deer in Norway.
Northern cervid echinococcus (Echinococcus canadensis) is a parasite that has spread widely in North America. However, it is not as dangerous as Echinococcus multilocularis. In recent years, there have also been findings of pet dogs and humans infected with Echinococcus multilocularis.
“According to studies, this Echinococcus strain is of European origin and has probably been carried between continents by dogs, in spite of the deworming treatment requirements,” says Professor Jenkins.
The third zoonosis mentioned by Professor Jenkins is toxoplasmosis, an infection caused by a single-celled parasite called Toxoplasma gondii, which multiplies in cat intestine. The parasite’s oocysts, egg-like environmentally resistant forms, spread widely in the wild. Toxoplasmosis is estimated to be the most significant parasitic infection in Arctic North America. Humans most often catch it from environments contaminated by cat faeces and raw meat.
Most toxoplasmosis infections pass unnoticed or with mild symptoms. However, in a pregnant woman, a toxoplasmosis infection causes a serious risk of miscarriage or a permanent disability for the baby.
“A significant portion of North American indigenous peoples have been infected with toxoplasmosis. They catch the infection from contaminated domestic water or undercooked or uncooked meat, poultry or sea mammals. Toxoplasmosis has been found in belugas or white whales and, in principle, it can be transmitted by any undercooked meat,” says Professor Jenkins.
Toxoplasma cysts remain in muscles and the central nervous system as tissue cysts and may rupture during cancer treatments, for example.
Next year in Alaska
At the end of the conference, a brainstorming meeting was held on how the cooperation should be continued and developed. The importance of communications, or how research knowledge reaches the wider public and political decision-makers, was brought up. It was also emphasised that the voice of women and indigenous peoples should be heard better. The sharing of research knowledge and data between researchers was considered extremely important.
In 2020, the One Health, One Future conference will be held in Fairbanks, Alaska on 11–14 March.
Author: Satu Räsänen
Last updated: 22.3.2019