A Virulent Enemy

It was nature's own bioterror attack. The year was 1898, during the Spanish-American War, and the United States was losing more soldiers to yellow fever than to combat. In the disease's final, hideous stages, patients turned yellow with jaundice and vomited digested blood. They suffered bone-crushing pain and fevers that spiked to 104 degrees and above. One doctor who examined corpses described the victims' blood as steaming--their organs seeming to have been immersed in boiling water.

Today we've largely forgotten yellow fever, but a gripping new book, "The American Plague" by Molly Caldwell Crosby, could help remedy that. In an account that's highly readable (if short on scientific detail), Crosby chronicles the history of the disease, which still afflicts an estimated 200,000 people around the world and is viewed by U.S. officials as a potential bioterror threat.

Crosby dwells on two epi- sodes--the 1878 epidemic that crippled Memphis and the efforts of Walter Reed, the famed U.S. Army surgeon, to uncover the cause in the wake of the Spanish-American War (infected mosquitoes, as it turned out). In Memphis in 1878, society collapsed. Newspapers and businesses shut down as half the population fled, often leaving doors wide open and dinner tables set with silver. Nuns and doctors dared to deliver aid, but many clergy simply blamed the epidemic on the city's decadence, especially its Mardi Gras celebrations, which rivaled New Orleans's. In Crosby's telling, the city never fully recovered. Federal officials promised help, but delivered little. Businessmen decided they were better off elsewhere and did not return.

Could it happen again? Mosquito eradication banished the disease from the United States in the early 1900s, and a vaccine made further inroads worldwide. But the disease is making a comeback in South America and especially Africa, due to the interruption of vaccination campaigns and reinfestations of mosquitoes. And there's another nagging worry. Yellow fever is listed as a Category C bioterror agent. "It can infect people by aerosols, if you have the right droplet size," says Scott Weaver, a tropical-disease expert at the University of Texas. "It's not Category A because there's a vaccine." But in a population with no immunity--like ours today--it could still kill.