Biodiversity Plays Key Role in Disease Prevention

The health of an environment plays a big role in mitigating the spread of some of the world's most dangerous diseases, cites a new paper published in the journal PLOS Biology. And the research brings new information to the discussion about whether or not controversial medicines and vaccines are the best avenue for defense against the spread of these diseases

A recent NPR story (written by Eliza Barclay), says the researchers found that the health of the local ecology plays a big role in whether or not pathogens will thrive and threaten human lives with diseases, including dengue fever, West Nile encephalitis, and malaria.

The paper used a statistical model that was able to predict what would happen to those countries that lose the most biodiversity. And it showed that they would also have higher risks for the spread of deadly vector-borne and parasitic diseases as their natural biodiversity declined.

Matthew Bonds , a researcher at Harvard Medical School and the lead author of the paper, was quoted by NPR: "The general logic is that the more organisms you have out there, the more things there are that can interrupt the life cycle of disease, and the less concentration you'll have of any vector."

The loss of biodiversity may even be the cause for the spike in cases of Lyme disease throughout the Northeast U.S., writes Barclay, "A 2002 paper in the Proceedings of the National Academy of Sciences found that if you have a rich community of tick hosts, like squirrels, mice and other small mammals, the disease is diluted among them. But if the habitat is degraded, and ticks carrying Lyme have only white-footed mice as hosts, the disease risk to humans can rise dramatically."

The planet is already losing a number of its species—as many as 200 per day. According to the United Nations, one-third of the planet's existing species are facing extinction situations. Best efforts to reduce the numbers of species lost takes considerable efforts, some of which can be too little too late. With greenhouse gases and global warming causing major damage to air and water quality along with the sprawl of cities and industry, some species have no chance of bouncing back and thriving.

Bonds looked at the causal relationship between biodiversity and 12 common diseases and found that if countries with high levels of biodiversity (think Brazil's Amazon) were to lose 15 percent of their species, the potential burden for disease could increase by as much as 30 percent. "I think what this shows is that the burden of disease is really important, and it's not just driven by health care," he says. "These diseases spend so much of their life-cycles outside of humans, so they're part of the physical environment."

Putting an emphasis on salvaging ecosystems could be a healthy alternative to drug therapies. With many of these diseases prevalent in the developing world, there's often a lack of understanding about drugs used to treat and prevent some of the illnesses.

Genetically modified mosquitoes developed by the British biotech firm, Oxitec have also created controversy. They've been released in the Cayman Islands, Brazil, and in Malaysia to combat dengue fever, but environmentalists have huge concerns over the risks to other species.