MEMPHIS, Tenn.—Before 1878, this city was a "Casablanca on the Mississippi," a rough river town of 50,000, two-and-a-half miles long and one mile wide, densely populated with immigrants from Ireland, Germany, and Italy, Jews from Central and Eastern Europe, white cotton traders, scalawags and carpetbaggers, and former slaves up from the plantations farther south.

It was a city of sharp contrasts—bars and brothels from its waterfront to its eastern edge, "a dangerous, dirty place" with pigs roaming the streets, but also churches, opera, French cuisine at the finer restaurants and the ever-present Peabody Hotel.

Then came the 1878 yellow-fever epidemic. More than half the population fled. Of the 20,000 who remained, 17,000 got sick, and 5,000 died. It was a plague of biblical dimensions, and it exposed an even deeper dissonance in the city—the bravery and selflessness of those who stayed to fight, and the corrupt and cowardly leaders who fled after long refusing to fund the basic city services that might have lessened suffering.

Memphis in 1878 became a city of the dead—people hiding behind shuttered windows and locked doors, the clickety-clack of wagons carrying the corpses to waiting gravediggers.

This is the story that unfolds in Jeanette Keith's new book "Fever Season: The Story of a Terrifying Epidemic and the People Who Saved the City" (Bloomsbury Press, 2012, $30). A historian who teaches at Bloomsburg University in Bloomsburg, Pa., Keith offers an amazing tale that hits close to home, not only to Mississippians and Louisianians who remember all too well a different disaster, Hurricane Katrina, but also to the East Coast, still reeling from Superstorm Sandy.

It's a human tale of untold suffering and courage that makes you question whether we've really progressed much in our understanding of public and private life, the role of government, and the limits of charity.

"Yellow Jack," as the fever was known, is a horrific disease. The victim's temperature tops 105, delirium sets in, and the destruction of the body's organs produces the telltale "black vomit" and the stink of impending death. Infected mosquitoes cause the sickness—mosquitoes that originally came from Africa on slave ships—but people wouldn't know this until Major Walter Reed and others made that determination decades later in Havana, Cuba.

The 1878 epidemic wreaked havoc in Mississippi, too. Some 3,000 died. Towns were decimated, some losing half their population. A skinflint Mississippi government created a Board of Health that helped fight the fever, according to historians James W. Loewen and Charles Sallis.

In Memphis, people looking for causes pointed to the city's filth and squalor. Cotton traders in Memphis grew rich but, as a municipality, the city "was a failure," Keith writes. Only the well-to-do had any kind of water or sewage system. Garbage went uncollected, streets turned to mud after heavy rains, and crime ran rampant while political leaders enjoyed mint juleps with cotton traders at the Peabody.

Of course, people blamed the poor, particularly Irish workers who populated the teeming warren of shanties along the levees.

Race complicated things. Memphis largely escaped the ravages of the Civil War. White bitterness after the "Lost Cause," however, led to one of the nation's worst race riots there in 1866. Newly enfranchised black voters aligned with the city's Irish and Italian immigrants in the mid-1870s and put a half-dozen blacks on the City Council and an Irishman in the mayor's office. Reconstruction ended in 1877, however, and white rule soon reasserted itself—with a vengeance.

As horrible as it was, the 1878 epidemic provided an opportunity for a major southern city to point the way to a truly "New South" where all people could work together. Among the heroes who stayed to fight the scourge were Catholic priests and nuns, Episcopalian nuns, the brothel madam Annie Cook, doctors, nurses, journalists, and a host of former slaves who, as soldiers, police officers, relief workers and nurses, used their newfound freedom to help others.

They were celebrated for a while, but then attitudes on race and class hardened. Banquets held after the plague excluded not only blacks but also working-class Irish and women. "The very fact that white Memphians (and white Memphis) would not have survived without the aid of blacks was something that whites had to deny and hide," Keith says.

Memphis was a changed city after 1878, even losing its charter for a while. From a city of European immigrants, it became a city of poor southern black and white immigrants. Modern Memphis is a city of 650,000, famed for the music that those poor southerners made its legacy, and poverty and crime are still a plague. It is—like the South as a whole—working even today on those old issues of race and class that seem never to go away completely.

A veteran journalist who teaches at the University of Mississippi, Joe Atkins is author of "Covering for the Bosses: Labor and the Southern Press." His blog is laborsouth.blogspot.com.