Children are most commonly infected. Estimated prevalence rates among children in various world regions are 4â28%. Ascariasis: Ascaris, or roundworm, infection is the common helminthic infection in humans, with an estimated worldwide prevalence of 1 billion. The causative organism, A lumbricoides, is cosmopolitan in distribution, being most abundant in tropical countries.
Definition of hollow. 1  1 : an unfilled space : cavity, hole in the hollow of a tree. 2  2 : a depressed or low part of a surface; especially : a small valley or basin.
Unlike a canyon, a valley is broad, with a large area of floor, rather than a narrow profile. Valleys are generally easy to navigate, and they tend to have a different climate than the surrounding area. It is also common for them to have rich deposits of alluvial mud, making these areas ideal for agriculture.