Wigglesworthia glossinidia is a Gram-negative bacterium in the family Enterobacteriaceae, related to E. coli, which lives in the gut of the tsetse fly. The bacterium was described by Serap Aksoy and bears the name of the British entomologist Sir Vincent Brian Wigglesworth, who died the year prior to its description. Wigglesworthia has symbiotically coevolved with the tsetse fly for millions of years, and is a textbook example of a bacterial endosymbiont. Because of this relationship, Wigglesworthia has lost a large part of its genome and has one of the smallest known genomes of any living organism, consisting of a single chromosome of 700,000 bp and a plasmid of 5,200. Together with Buchnera aphidicola, Wigglesworthia has been the subject of genetic research into the minimal genome necessary for any living organism. Wigglesworthia also synthesizes key B-complex vitamins which the tsetse fly does not get from its diet of blood. Without the vitamins Wigglesworthia produces, the tsetse fly has greatly reduced growth and reproduction. Since the tsetse fly spreads African sleeping sickness, it has been suggested that Wigglesworthia may one day be used to control the spread of this disease.