Danger: Colds Ahead! The cause of man's commonest disease is not yet known. Colds are still a puzzle to doctors. Colds, like other disease, are probably caused by a germ, but that germ has never been found. If there is such a germ, it is so tiny it does not show under the best microscope. Fall is the worst season of the year for colds. Fall is even worse than winter. More people catch cold in October than in any other month, but all months from October to June are "cold" months. خطر: سرماخورد ...