During hunter-gatherer society - predominant diseases were those with high transmission rates, macro parasitic diseases (didnt require vectors for transmission), and stds. With move to agriculture - conditions favoured the emergence of epidemic diseases. Emergence of cities - urban life; uruk in mesopotamia (3500 bc) Characterized by parasites with long lived transmission stages (e. g. eggs, larva,) Evidence that it dates back to 1900 bc. Thought to rst have appeared in the nile valley of egypt. Agriculture, the inundation of the nile, eventually irrigation created favourable conditions that promoted the spread of the disease. Disease now known as snail fever or blood uke disease/endemic hematuria/schistosomiasis. European invasion of egypt (1799-1801) resulted in the rst european experience with the disease. 430 bc, epidemic started in ethiopia, moved into egypt, and was brought by ship to athens. The plague was blamed for the defeat of the athens by the spartans in a war that started in 431.