Healthcare (Commonwealth Union) – The impact of various environmental factors on our health and many living organisms has long been observed by scientists. As a result of extensive research for long periods of time together with improved technology, the results of such research have improved in recent years.
A new study in Nature reports that authors have identified a distinct “anthropogenic fingerprint” in the global distribution of emerging infectious diseases of humans. The research also shows that the factors contributing to outbreaks can vary considerably depending on the disease at the same time.
Scientists from around the world have carried out the most comprehensive data-driven analysis to date of the environmental drivers of emerging infectious diseases. Researchers examined 58,318 outbreaks of 32 diseases in 169 countries. They looked at diseases transmitted directly from animals to humans, known as zoonotic diseases, such as coronaviruses, Ebola and mpox, and those transmitted by vectors such as mosquitoes, ticks and fleas, including dengue, Lyme disease and malaria.
The analysis demonstrated that the probability of outbreaks was generally higher in locations where people and livestock are situated in close proximity to highly fragmented, forested environments. This includes fragmented forests that have been broken up by settlements, agriculture or other forms of human development. Another possibility is that species that can survive in these changed environments are more likely to carry pathogens, giving more opportunities for contact between wildlife, livestock and people.
The impact of human-induced environmental change was particularly evident in the case of vector-borne diseases. Fragmented ecosystems and areas with long-term drops in rainfall linked to climate change are associated with higher risks of outbreaks of diseases including dengue and Zika, researchers have found.
But for zoonotic diseases – those that jump from animals to humans and include many of the potential pandemic threats – the researchers found no environmental factor that reliably predicted where outbreaks would emerge. Factors such as deforestation, rising temperature and expanding agricultural activity had varying influence from disease to disease. The researchers therefore stress that disease- and region-specific data are needed to identify and monitor potential outbreak risks.
The findings challenge the idea that there is a single, consistent set of environmental drivers responsible for the emergence of infectious diseases worldwide.
The study also emphasises the significance of healthcare access in determining where outbreaks are identified and recorded. On average, each additional hour of travel to the nearest health-care facility reduced the likelihood of reporting an emerging disease outbreak by 32%. Thus, apparent disease “hotspots” may mostly reflect areas with better healthcare and surveillance systems, rather than necessarily being places where infections are most widespread.
“The researchers are calling for a more proactive and comprehensive strategy to prevent epidemics and pandemics. Such an approach would mean stronger health systems, internationally coordinated disease surveillance and measures based on the ecosystem approach to address diseases of particular importance.
Lead author Dr Rory Gibb, from UCL’s People and Nature Lab, said: “Our results suggest there is no one recipe from the atmosphere that can predict where emerging infectious disease outbreaks will happen. He also noted that disease spillover from animals to humans is common in human-modified habitats around the world, but the specific human activities that trigger outbreaks vary between diseases.
“This means that improving people’s access to healthcare and strengthening disease monitoring systems is critically important, to help make sure that outbreaks of any disease can be detected early and stopped before they become epidemics or pandemics.”
The Co-author of the study, Professor Sadie Ryan of the University of Florida indicated that spillover disease outbreaks have various factors, molded by the socioecological system and it puts a spotlight on the need for a single Health integrated approach to monitor and engage as there is no particular intervention strategy.
