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.
In the Tropical Rainforest, a valley is usually in the shape of a 'U' or 'V'. A valley or dale (a broad valley) also provides channels for rivers. Flood Plains form at the base of a valley when a stream or river gets tangled together.