Pandemic influenza is distributed equally in all climates, seasons, continents, and seas. Endemic epidemics are more common in the colder season.
Strictly limited to the tropical zone and adjacent districts, occurring particularly in the hot months of the year. Shows special preference for the coasts and shores of rivers, and rarely reaching the interior.
Rapid geographic distribution in all directions.
Slow geographic distribution.
Equally and rapidly distributed over all parts of the affected town.
Often limited to unhygienic quarters.
Acute simultaneous general infection the rule.
Infectious from person to person. Eminently contagious, perhaps transmitted partly through the air.
Miasmatic contagious (endogenous exogenous); epidemics dependent upon season and locality.
Duration of pandemic influenza, six to eight weeks; of endemic influenza, often several months.
Duration of epidemic, two to five months.
Independent of race, nationality, social condition, occupation, and sex.
Relative immunity of early childhood.
Immunity generally acquired by an attack.
Probably no acquired immunity.
Enormous morbidity with very slight relative mortality.
Absolute mortality very considerable. Increase in the general mortality figure by deaths from "acute affections of the respiratory organs" and "pulmonary tuberculosis."
Absolute mortality very slight.
Period of incubation very short- one to a few days.
Sudden onset without prodromal symptoms, with chill and usually high temperature.
Average duration of the fever but a few days.
Three day fever.
Great prostration. Intense pain in the head, loin, back, and extremities.
Neuralgic joint pains frequent. Inflammation of joints extremely rare.
Extraordinarily intense joint pains, especially of the knee joints, combined with lightning like, absolute immobility, often accompanied by inflammatory swelling of the articulations.
Ambulatory form common.
Ambulatory cases rare. Cases compelled to take to bed, the rule.
Catarrhal inflammatory phenomena of the respiratory mucous membrane, coryza, and conjunctivitis, laryngobron chitis, and tracheobronchitis with paroxysmal cough, the rule.
Generally entirely absent.
Gastric phenomena not prominent, often absent.
Gastric phenomena-complete anorexia and heavily coated tongue are pathognomonic and prominent symptoms.
Enteritis hemorrhagica, dysenteric diarrhea combined with vomiting; bloody flux occasionally.
Spleen often enlarged.
Spleen never enlarged (?).
Cardiac asthenia, syncope, angina pectoris, etc., occasionally.
Phlebitis, arterial thrombosis, hemorrhages of all kinds, abortion occasionally.
At the acme of influenza a vasomotor, sometimes macular, reddening of the skin, especially of , the face. Genuine eruptions, especially as sequelae, are very rare.
In the stage of fever a fleeting erythema. On the third to fourth day, a pathognomonic measly scarlatiniform erysipelatous eruption, with subsequent desquamation and severe pruritus.
Herpes not rare.
Conjunctivitis, keratitis, neuroret initis, tenonitis, glaucoma, etc., paralysis of the muscles of the eye, accommodation, etc., repeatedly noted.
Convalescence in the majority of cases prompt and of brief duration; occasionally, however, protracted.
Convalescence usually very protracted.