Zoonoses represent a growing threat to human health. How to explain it? And what exactly do we mean by the term “zoonosis”?
The term “zoonosis” comes from ancient Greek: zôon meaning “animal” and ours “disease“. It refers to infectious and parasitic diseases that are transmitted between animals and humans.
This concept has evolved over time with distinctions based on the mode of transmission or the animals involved, but these differences become less relevant in the “One Health” perspective, where it is recognized that animal and human health are interconnected.
Examples of zoonoses still present in the world are rabies, transmitted by the bite of infected dogs, which causes nearly 60,000 deaths per year, or brucellosis transmitted by contact with infected animals or by the consumption of unpasteurized dairy products. which causes feverjoint pain and can cause serious complications if left untreated.
Lyme disease is another example. This disease is transmitted to humans through the bite of infected ticks. These ticks acquire the bacteria by feeding on certain animals, such as rodents or deer, which serve as natural reservoirs for the bacteria. pathogenic. In this case, the first symptoms that may appear include fatigue and skin rashes. But if left untreated, it can also lead to neurological or heart problems.
Multiple and complex causes
The threat posed by zoonoses is on the rise. While approximately 60% of human infectious diseases are of zoonotic origin, 75% of emerging diseases come from animals.
Among the latter, we find recent examples leading to pandemics such as SARS (SARS-CoV), Ebola, and Covid-19 (SARS-CoV-2), which highlight light the vulnerability increasing human populations in an interconnected world. Avian influenza (H5N1 influenza virus) is another example of a zoonosis that can cause health crisis majeure.
The underlying causes of the increase in zoonoses are multiple and complex. Among the main factors, we find the loss of biodiversity which increases the probability of contact between wild species and the human population, and climate change, which modifies the habitats and behavior of animal species, in particular vectors (mosquitoes, midges, ticks ) of diseases.
However, these phenomena are not exclusively biological: they are also influenced by socio-economic factors, such as lifestyle, poverty, cultural practices or beliefs, but also international travel or travel.
Intensive breeding of domestic animals, certain hunting practices, breeding of wildlife and live animal markets could also increase the risks of transmission, particularly in regions where health regulations are weak.
How to prevent zoonoses?
Global efforts are in place to monitor and prevent these zoonoses. The “One Health” approach, which integrates various disciplines (human and veterinary medicine, epidemiology, human and social sciences, ecology, microbiology), has become essential in this fight. However, response capacities vary by region. Some at-risk areas, particularly in the Global South, lack resources for surveillance and prevention.
To overcome this, international initiatives like PREZODE (Prevention of Zoonotic Disease Emergence) seek to anticipate and manage future risks by strengthening surveillance networks and mobilizing local communities.
This initiative relies in particular on regional research platforms such as the system for managing emerging risks in South-East Asia (GREASE). In fact, the Greater region Mekongrich in biodiversity, is a hotspot for the emergence of new zoonoses due to theinteraction close relationship between human and animal populations and the degradation ofenvironment.
To respond to this growing threat, it is imperative to emphasize prevention, as well as strengthening surveillance, research and response capacities. The One Health approach provides an integrated framework for understanding and countering these threats. It combines the efforts of scientists, local authorities and rural communities to prevent new global health crises.
The challenges remain numerous. But by strengthening international cooperation and integrating solutions based on the preservation of biodiversity and the management of ecosystems, we can hope to reduce the impact of zoonoses on human populations.
Auteurs:
François Roger – Regional Director for South-East Asia, veterinarian and epidemiologist, CIRAD
Flavie Luce Goutard – Epidemiologist, CIRAD
Marisa Peyre – Deputy head of ASTRE research unit, epidemiologist, Cirad
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