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.
World War II casualties
Compiling or estimating the numbers of deaths and wounded caused during wars and other violent conflicts is a controversial subject. Historians often put forward many different estimates of the numbers killed and wounded during World War II. The authors of the "Oxford Companion to World War II" maintain that "casualty statistics are notoriously unreliable." The table below gives data on the number of dead and military wounded for each country, along with population information to show the relative impact of losses. When scholarly sources differ on the number of deaths in a country, a range of war losses is given, in order to inform readers that the death toll is disputed. Since casualty statistics are sometimes disputed the footnotes to this article present the different estimates by official governmental sources as well as historians. Military figures include battle deaths (KIA) and personnel missing in action (MIA), as well as fatalities due to accidents, disease and deaths of prisoners of war in captivity. Civilian casualties include deaths caused by strategic bombing, Holocaust victims, German war crimes, Japanese war crimes, population transfers in the Soviet Union, Allied war crimes, and deaths due to war related famine and disease.