Diffusion and physiological responses to the influenza pandemic of 1918-19 in Nigeria. 
Although virologists are not in agreement on the origins of the 1918-19 influenza pandemic, it has long been associated with the virulent type A virus.  At least 21 million people died from the disease over a 12-month period, becoming one of the world's worst short-term demographic disasters.  The disease was introduced into Nigeria by passengers and crews who arrived via ship from overseas.  Thus, coastal ports were the primary focus of the diffusion of the disease.  Its spread to the hinterland was facilitated by improvements in transportation technology.  Neither maritime quarantine, nor the isolation of patients checked the spread of the disease.  About 500,000 Nigerians, out of a population of 18 million, died in less than 6 months, and between 50 and 80% of the population was stricken.  The over-crowded urban centers were the hardest hit and, even though pandemic declined almost as suddenly as it began, morbidity, mortality, and panic adversely affected the productive capacity of the country.  Since the 1930s, virologists have gained much knowledge about the agents responsible for influenza diffusion, but the disease remains one of the few plagues to be eradicated.  This is partly because of the exceptional adaptability of influenza viruses, and partly because artificially and naturally-acquired immunity to influenza are temporary in duration, making reinfection possible even by the same type or subtype of influenza.