appeared in theWestern Hemisphere in 1993, killing several young people in the Southwest. Since then, it has infected people fromCanada to the tip of Argentina, killing more than 500 in the United States alone.

mit a disease to people. This transmis- sion can be direct or through an inter- mediary such as a tick or mosquito. In the case of West Nile, the

strongest carriers tend to be the kinds of perching birds that predominate in disturbed, fragmented and less- diverse habitats. They include com- mon backyard species such as house sparrows, grackles, robins and crows. By contrast, the types of birds that pre- dominate in undisturbed woodlands, wetlands and prairies tend to carry lit- tle West Nile virus in their blood- streams. “As a result, where many bird species exist, very fewmosquitoes get infected, and so we humans are at lower risk,” says biologist Brian Allan ofWashingtonUniversity in St. Louis. Allan’s studies have shown that across

NWF PRIORITY

CONSERVING BIODIVERSITY BEGINNING LONG BEFORE the word was coined, NWF has been at the forefront of pro- tecting what is now called biodiversity. “We tend to think of the biodiversity crisis as something new,” says Bruce Stein, NWF’s associate director for wildlife conservation and global warming. “But this organization was spawned by a previous biodiversity crisis: the 1930s Dust Bowl, when prairie habitats that sustain the nation’s waterfowl (northern pintail, right) were collapsing.” Since then, NWF and its affiliates have campaigned to conserve healthy populations of all native species of fish and wildlife. NWF works to protect wildlife “not only in treasured landscapes like national parks,” says Stein. “We also teach people to appreciate and nurture diversity in their own backyards.” NWF’s current focus on climate change is consistent with this legacy, he adds, because “today climate change is the single greatest threat to biodiversity.” To learn more, go to www.nwf.org/Wildlife/What-We-Do.aspx.

AUGUST/SEPTEMBER 2010 | WWW.NWF.ORG | 27 |

the nation, bird diversity is a signifi- cant buffer against the spread ofWest Nile virus to humans. Taken together, these studies sug-

gest it’s no coincidence that the world is seeing a dramatic rise in newly emerging and reemerging infectious diseases, Ostfeld says. The first Lyme disease outbreaks, for instance, occurred in the 1970s in and around Lyme, Connecticut. The disease is now the most prevalent arthropod- borne infection in North America. (Arthropods include insects, ticks, spi- ders and their relatives.) West Nile first appeared in North America in 1999 in New York City. Since then it has spread across the United States, infecting tens of thousands and killing more than 1,000 people. Hantavirus

THREATS TO RESEARCH For decades, “save the rain forest” campaigns have touted the treasure chest of potential medicines lost when these biodiverse landscapes are razed. The concern is a valid one.Most drugs in common use derive directly or indi- rectly from natural sources. But less than 1 percent of the world’s plants have been analyzed for their medical potential. Meanwhile, plant extinction rates have accelerated to levels hun- dreds of times higher than those seen in preindustrial times. But medicinal plants are far from

the only—or even the most impor- tant—contribution that biodiversity makes to medical research, Chivian argues. He cites several groups of threatened plants and animals with vital importance to medical research. They include: Amphibians: Medical researchers

are racing to study a wide variety of amphibians for the vast array of chem- icals they produce to protect their soft and vulnerable bodies from predators and infections. Of particular interest are natural chemicals called antimi- crobial peptides, or AMPs. Already, biochemists have developed several amphibian AMPs into potent experi- mental antibiotics. Today the need for such drugs is particularly keen, espe-

MASA USHIODA (SEAPICS.COM); ABOVE, MARK STRICKLAND (SEAPICS.COM); RIGHT, ROSEANNE B. SMITH