Much of the Earth has been altered by humans, affecting natural ecosystems, including disease-carrying insects. For the first time, researchers have investigated when and how environmental changes affect the transmission of insect-borne diseases, providing insights into future disease management.
Vector-borne diseases (VBD) are spread by organisms called vectors. Vectors carry disease-causing agents from person to person or from animal to person. VBD is high in tropical and subtropical regions and disproportionately affects the poor. According to the World Health Organization (WHO), more than 700,000 people die from her VBD every year worldwide.
Mosquitoes are common vectors for diseases such as malaria and viruses, Chikungunya, dengue, and Zika. Another common vector is the sandfly. Leishmaniasis is a parasitic disease that causes sores on the skin (cutaneous leishmaniasis) or affects internal organs, usually the spleen, liver and bone marrow (visceral leishmaniasis).
For the first time, researchers from Griffith University, Stanford University, and the University of California have used cumulative pressure mapping and machine learning to map how environmental changes affect VBD infection.
Cumulative pressures are environmental pressures that can be combined with other past, present, and future pressures to produce additive, concerted, or antagonistic effects. Environmental pressures include climate change, urbanization, land clearing, pollution, tourism and industry.
VBD is highly sensitive to environmental change, and natural ecosystems are affected by both large-scale and small-scale environmental changes. Researchers say they are just beginning to understand the effects of human pressure caused by this kind of change.
“Humans are good at modifying the Earth. Ninety-five percent of the Earth’s surface has been modified in some way by humans,” said Dr. Eloise Skinner, lead author of the study. “We know that modifying the surface of the Earth also changes species communities, including plants, animals and insects.”
Monitoring the impact of environmental changes on VBD is difficult. Given the complex social and ecological factors that influence vector and human disease transmission.
In the current study, researchers used the “Human Footprint Index” as a single metric to capture the multidimensional impact of human-land interactions. Human footprints rely on cumulative pressure mapping to compute a scale of human pressure from 0 to 50.
Certain areas of human footprints are associated with variations in ecological integrity and function. Previous research has confirmed that three or more human footprints is the tipping point at which a species becomes extinct. For comparison, areas with less than four human footprints are considered intact ecosystems containing mostly natural habitats. A Human Footprint greater than 12 indicates high human pressure.
The researchers used Brazil to represent global patterns of human pressure given its ecological and socioeconomic diversity and diverse land use. They investigated his six most common VBDs: dengue, chikungunya, malaria, Zika, cutaneous leishmaniasis, and visceral leishmaniasis.
“As human pressures increase, we can expect different disease outbreaks to change. For example, dengue fever is a highly urban pathogen, and malaria is occurring on the front lines of deforestation,” Skinner said. said. “But how urbanized must an area be for dengue to become a risk? How much forest must be converted before we see an increase in malaria? ?”
Using machine learning to compare human footprints to VBD infections, researchers showed that there are distinct thresholds in human footprints that influence the prevalence of a given VBD.
As human footprints vary from moderate (4 to 7) to high (7 to 12) to severe (>12), VBD outbreaks range from malaria, cutaneous leishmaniasis, visceral leishmaniasis, to dengue fever, Chikungunya fever and Zika fever. Dengue, Chikungunya and Zika are viruses that require specific responses to be effectively treated.
“These are diseases that require distinct responses in vector control, diagnosis, and environmental management,” said Skinner.
This study shows that human pressure on the environment, human footprints, is an important predictor of VBD infection. This deeper understanding can inform our ability to predict future disease outbreaks.
“Biomedical and chemical approaches alone have not been able to sustainably eliminate these VBDs, so managing the socio-ecological environment that facilitates transmission of pathogens is an important frontier for planetary health. is,” said the researcher.
This research natural sustainability.
Source: Griffith University
