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.
Demographics of Croatia
In addition to demographic losses through significant migrations, the population of Croatia suffered significant losses due to wars and epidemics. In the 20th century alone, there were several such events. The first was World War I, when the loss of the population of Croatia amounted to an estimated 190,000 persons, or about 5.5% of the total population recorded by the 1910 census. The 1918 flu pandemic started to take its toll in Croatia in July 1918, with peaks of the disease occurring in October and November. Available data is scarce, but it is estimated that the pandemic caused at least 15,000–20,000 deaths. During World War II, nearly 195,000 people died in the territory of present-day Croatia. The surrender of the armed forces of the Independent State of Croatia and of the civilians accompanying the troops of the British Army at the end of World War II was followed by repatriation and subsequent events that became known as the Bleiburg tragedy. A substantial number of people were executed, but the exact number is disputed. The claims range from 12,000–15,000 to as many as 80,000 killed in May 1945. Finally, approximately 20,000 were killed or went missing during the 1991–1995 Croatian War of Independence. The figure pertains only to those persons who would have been recorded by the 1991 census as living in Croatia.