Complex sentence: Dengue fever, also known as breakbone fever, is a mosquito borne infectious tropical disease caused by the dengue virus primarily in the equatorial regions of Africa, the Americas, South-East Asia and the Western Pacific.
Split into simpler sentences: Dengue fever, also known as breakbone fever, is a mosquito--borne infectious tropical disease caused by the dengue virus. This disease occurs primarily in the equatorial regions of Africa, the Americas, South-East Asia and the Western Pacific.