Syndemic
The worst of the 20th century influenza pandemics was the 1918 pandemic, where between 20-40 percent of the world’s population became ill between 40-100 million people died. More people died of the so-called Spanish flu (caused by the H1N1 viral strain) pandemic in the single year of 1918 than during all four-years of the Black Death. The pandemic had devastating effects as disease spread along trade and shipping routes and other corridors of human movement until it had circled the globe. InIndia, the mortality rate reached 50 per 1,000 population. Arriving during the closing phase of the World War I, the pandemic impacted mobilized national armies. Half of U.S. soldiers who died in the "Great War," for example, were victims of influenza. It is estimated that almost ¾ of a million Americans died during the pandemic. In part, the death toll during the pandemic was caused by viral pneumonia characterized by extensive bleeding in the lungs resulting in suffocation. Many victims died within 48 hours of the appearance of the first symptom. It was not uncommon for people who appeared to be quite healthy in the morning to have died by sunset. Among those who survived the first several days, however, many died of secondary bacterial pneumonia. It has been argued that countless numbers of those who expired quickly from the disease were co-infected with tuberculosis, which would explain the notable plummet in TB cases after 1918.
Serbian Campaign of World War I
The Serb sources claim that the Kingdom of Serbia lost 1,100,000 inhabitants during the war. Of 4.5 million people, there were 275,000 military deaths and 450,000 among the ordinary citizenry. The civilian deaths were attributable mainly to food shortages and the effects of epidemics such as Spanish flu. In the addition to the military deaths, there were 133,148 wounded. According to the Yugoslav government in 1924, Serbia lost 365,164 soldiers, or 26% of all mobilized personnel, while France suffered 16.8%, Germany 15.4%, Russia 11.5%, and Italy 10.3%.