IN Six Modern Plagues and How We Are Causing Them, journalist and veterinarian Mark Jerome Walters contends that disease outbreaks are often triggered by the damage we’ve done to the environment.

To build his case, Walters looks at the origins of mad cow disease, HIV/Aids, an antibiotic-resistant strain of salmonella, Lyme disease, hantavirus, and West Nile virus. In each case, he finds evidence that human manipulation of the environment is at least partly responsible for recent outbreaks. The modern epidemic of mad cow disease, for instance, was most likely sparked by the widespread and longstanding practice of “rendering,” or using animal parts in cattle feed. The brisk bush-meat trade in some African markets may have been responsible for passing the HIV virus from apes to humans — and could someday send new, similarly deadly viruses our way as well.

There’s also evidence that modern-day outbreaks of hantavirus pulmonary syndrome, an often-fatal respiratory disease carried by rodents in the US Southwest, are linked to global climate change.

Walters also shows how easily and rapidly such drug-resistant bacteria can spread. In the 1970s, a series of salmonella outbreaks around the world was eventually traced to Peruvian fishmeal. Infected seabirds had defecated on the fish, which had been drying on boat decks; the fishmeal was fed to poultry, the poultry was fed to people, and the people became sick with salmonella.

Six Modern Plagues makes an important and potentially life-saving point — one that’s becoming more and more difficult to ignore. “Preservation of natural ecosystems, along with greater social equity, research, good surveillance, and benefits of modern medicine, can improve the health of not only people but many species,” Walter writes. “Human health does not belong to us alone. Nor, unfortunately, do the plagues we are all now experiencing.”

Walters exposes the root environmental causes of disease outbreaks like salmonella. He chronicles how the livestock and drug industries, despite multiple examples of resistant bacteria, have continued to push for the regular use of antibiotics in large livestock operations. The practice not only allows animals to be raised in close quarters and unsanitary conditions, but also dramatically increases the chances that new, multiple-drug-resistant strains of bacteria will continue to emerge and spread.

In 1995, the US Food and Drug Administration even approved the use of fluoroquinolones in poultry. Just two years later, salmonella bacteria in the United States were showing resistance to the drugs. — Samina Iqbal