One world, one health. This idea reflects that we live in a globalized world, in which humans, wildlife and domestic animals share the same environment, including pathogens and diseases. And where changes in this environment affect us, sooner or later, all of us. In the last 100 years, great advances have been made in food, health and the economy that have favored well-being and the increase of the human population. But, ironically, these improvements have also brought with them the appearance of new infectious diseases, or the resurgence of others that we considered controlled. Why has this paradox occurred?
Given the growing demand of the population, there has been deforestation of forests, the introduction of invasive species and changes in land use. All of these human-caused factors have led to new encounters with pathogens at the human-wildlife interface, and have facilitated the emergence of more than 300 new and re-emerging infectious disease cases worldwide. Ebola, chikungunya, malaria, Chagas disease, and now the defiant Zika virus are some examples of these infectious diseases.
In this context, why are wildlife studies so important? Mainly, because 60% of these diseases in humans are caused by pathogens that spread from animals . Research on these pathogens in fauna is therefore essential to understand the origin and causes of these diseases, and to successfully develop strategies to mitigate and control these threats. Mosquitoes, bed bugs, ticks and many other arthropods are responsible for the transmission of viruses – such as Dengue, Chikungunya and West Nile virus – of protozoa – malaria and Chagas disease – and of bacteria – the case of the disease of Lyme – infecting billions of people each year. And the alteration of the environment can favor the proliferation of these vectors and the diseases they transmit.
Why is the study of malaria in wild birds important?
Since ancient times, man has observed birds to decipher their future. Today, the scientific study of birds provides us with very valuable information, free of any social or economic condition, on the health of our world. Our research group studies avian malaria because it is one of the main indicators of environmental quality in a region. In addition, it provides reliable information on the consequences of global change on the planet. In many cases, emerging infectious diseases have their origin in the destruction of the natural habitat . Analyzing the malaria infection in birds of the Amazon, the main natural reserve on the planet, we have detected that the incidence of this disease in birds in deforested areas of the Amazon is three times higher than in closely preserved forest areas. This result shows us the importance of preserving forests as a means of caring for our health.
We have also been able to verify another alarming result: the presence of an invasive malaria species in 8 species of Neotropic birds, which indicates changes in the environment that favor the colonization of exotic species. This presence implies serious health problems for all organisms in the environment, including people . It is Plasmodium relictum , responsible for bird extinctions worldwide and present in 39% of the infections analyzed on the border with the Peruvian Amazon.
Finally, I would like to draw your attention to the fact that most infectious disease surveillance and research takes place in Europe, North America and Australia. However, the predicted areas of greatest risk for these zoonotic wildlife diseases are in Tropical Africa, Latin America, and Asia . Therefore, surveillance and monitoring studies on wildlife parasites in these places are urgently needed. I also recommend promoting the creation of international networks with a multidisciplinary perspective , involving scientists, educators, policy makers and professionals, in the study of emerging diseases as a valuable strategy for their prevention in the 21st century.
Alfonso Marzal Reynolds is a professor in the Department of Zoology at the University of Extremadura and a member of the Evolutionary Biology and Ethology research group. His main line of research is the study of avian malaria. He is part of the international team Avian Malaria Project and Research Coordination Network Malaria. This article has been written in collaboration with the UEx Scientific Culture Diffusion Service.
