The Great Plague by John Barry Part IV It Begins

Camp Funston military emergency hospital 1918.

It Begins Part IV.It is difficult to know for certain just where the 1918 influenza originated. Circumstantial evidence suggests that several people probably carried the influenza virus from Haskell County, Kansas to Camp Funston around late February or early March, 1918. Within days the first cases of influenza began appearing and within three weeks, 1100 men were hospitalized from Funston. The virus was found in military camps in Georgia and then in other camps as well as cities located adjacent to military camps. From there it is likely the virus spread to Brest, France where American troops disembarked on their way to the bloody fields of Europe. The disease spread to Chaumont and then to Paris, to Spain where it picked up the infamous name, "the Spanish flu" and onward throughout Europe, the United Kingdom as well as Asia and the Orient. Most cases were mild and there were doubts that it was in fact influenza. But there were some cases that were serious with victims dying within hours of getting sick. Then, it seemed to disappear. But as Barry writes,
"For the virus had not disappeared. It had only gone underground, like a forest fire burning in the roots, swarming and mutating, adapting, honing itself, watching and waiting, waiting to burst into flame."

In hindsight, it is easy to see now that the 1918 pandemic came in waves. The first spring wave, as mentioned above was mild, but the second wave was much more lethal.  Barry writes that a phenomena known as "passage" can cause a virus to increase in potency. It does so by passing from one animal to the next, each time adapting better to its host environment and becoming more efficient at infection.  So the first wave may have been mild due to the virus beginning to adapt to its new host (man). Then as it gained proficiency at infecting each new person, it became more lethal. Researchers believe this is the explanation for why an outbreak of mild influenza in February, 1918 in the US gradually developed into a virulent form of influenza later in the year.

By late spring, early summer of 1918, people began to die of influenzal pneumonia. The second wave began gradually with separate outbreaks of increasing severity occuring throughout America and Europe. Increasingly there were reports of ships pulling into port with sick sailors who spread the virus to dock workers, troops and others. In this manner, the virus was spread around the world.  But the worst was to come and it began at Camp Devens, a military cantonment thirty-five miles northwest of Boston. Built to hold a maximum of 36,000 men, by September 6, 1918 it was severely overcrowded with over 45,000 men. Gradually, from late August into early September, medical personnel began to see more and more men with pneumonia and influenza like illness. Staff did nothing to quarantine the sick soldiers and they were unprepared for what happened next - an explosion of illness unlike anything they had ever seen.

Suddenly hundreds of soldiers became ill with a severe form of pneumonia. There were so many sick men, that the hospital was completely overwhelmed by September 26. Not only were soldiers dying, but also the doctors and nurses treating them. The pattern was the same for most: influenza illness that rapidly progressed to pneumonia which led to cyanosis and death in a matter of hours. The men getting sick and dying were young and in the prime of their life.

When Welch, Cole, Russell and Vaughan, all top researchers and medical men, saw the dead and dying, viewed the autopsies they were "puzzled and felt an edge of fear."
The outbreak was not confined to Devens though because soldiers had transferred out of Devens immediately before the outbreak and taken the virus with them along the eastern coast of the US, into the midwest, down to Mexico and throughout the world.
Barry states that two parallel struggles emerged: that of society which now struggled to cope with the sick and the dying and that of the medical community which raced to find the cause and the cure.