Rabies is just one example of a life-threatening disease that can be transmitted from animals to humans. Zoonoses of this type could increase in Africa. To stop this, researchers are using an approach that considers the health of animals and humans together.
Monkeypox, plague, Marburg fever: Numerous diseases are transmitted from animals to humans. Rabies is another well-known example of a so-called zoonoses. The bite of an infected stray dog on holiday is enough to transmit the disease.
"Almost everything we humans carry around with us comes from animals. Measles, for example, spread from cattle to humans around 300 BC," says veterinarian Fabian Leendertz from the Helmholtz Center for Infection Research in Greifswald.
According to the assumptions of many researchers, the Sars-CoV-2 coronavirus is also very likely to have passed from animals to humans. However, conclusive proof of this is still pending. According to the Robert Koch Institute RKI, the Ebola virus can be transmitted to humans through contact with certain animals or animal products.
The World Health Organization (WHO) warned in July that Africa could become a hotspot for zoonoses. In the past ten years, the number of outbreaks of zoonoses there has increased by 63 percent compared to the previous decade (2001-2011), according to the WHO.
"In Africa, a lot of risky human behavior can be observed that can promote zoonoses: for example, massive interventions in ecosystems, including the deforestation of primary forests. Hunting and the consumption of wild animals also pose a high risk," explains Sascha Knauf from the Friedrich- Loeffler Institute FLI, the Federal Research Institute for Animal Health in Greifswald.
Another factor that plays a role in the spread of zoonoses in African countries is the increasing mobility of people, adds zoonoses researcher Leendertz. The result: "This also makes pandemics more likely. You can't completely prevent them, but you can be better prepared."
This includes a better health infrastructure, especially in poorer countries, but also monitoring the causes of animal deaths. In Africa in particular, there should be well-trained staff in the rural areas in the villages who can quickly stop zoonoses before they spread further.
"In the case of epidemics, vaccinations make sense for risk groups or around affected areas, like a kind of ring," says Leendertz. Better and comprehensive global prevention is one of the lessons learned from the corona pandemic. The 194 WHO member countries have decided to draw up a framework agreement for this.
In order to curb pandemics, research is now pursuing a holistic concept called "One Health", which looks at animals and humans as living beings. Even before the One Health approach became popular in research, it had already been shown to what extent keeping animals healthy also benefits people: A successful example of how a holistic approach can achieve good results for animals and people is the de facto eradication of rabies in Germany, says researcher Knauf from the FLI. According to the RKI, Germany has been practically rabies-free since 2008; primarily through the systematic immunization of foxes.
"People's health cannot be seen in isolation. We live with animals, we eat animals. The environment, in turn, influences the animal world, for example climate change. You have to think across disciplines," says Leendertz, who works at the Helmholtz Center at the Institute for One Health works.
However, the WHO forecast for Africa as a zoonoses hotspot should also be questioned, says veterinarian Knauf from the FLI: "It is difficult to say whether there is an actual increase in zoonoses - or whether one simply finds more because one looks more intensively the search goes.
At the end of the day, however, the consequence remains the same: we all have to change our risky behavior. Because it is the people who create the problem, not the animals. The next pandemic could just as easily start in Europe or Asia." Man-made climate change could also favor zoonoses. "If the temperatures in Germany rise, pathogens from tropical areas can settle here more easily. An example is the West Nile fever virus."
According to Knauf, who researches at the Institute for International Animal Health/One Health of the FLI, one thing is certain: Germany can still learn a lot from Africa. "For example, we don't have a national One Health strategy, many African countries do." About Nigeria. In 2019, the continent’s most populous country, with more than 200 million people, published a multi-year national one-health strategy. Among other things, zoonoses such as bird flu and Lassa fever are to be monitored particularly closely in the West African country.
According to the FLI, at the beginning of February only a few individuals contracted the virus during the course of the world's largest wave of bird flu ever documented. Human-to-human transmission is not known. However, many researchers are concerned about a viral mutation in the bird flu outbreak on a mink farm in Spain, which the FLI says could represent an adaptation to mammals.