Pathogenesis
The pathogenesis of BPF is not well established but it is thought that patients become pharyngeal or conjunctival carriers of H. aegyptius, which is followed by spreading to the bloodstream. This hypothesis is supported by the isolation of from both the conjunctiva and oropharynx of documented BPF cases with H. aegyptius bacteremia. Possible virulence factors of H. aegyptius include lipooligosaccharides (LOS), capsular polysaccharides, pilus proteins (mediates adhesion to mucosal membrane), immunoglobulin A1 (IgA1), membrane associated proteins, and extracellular proteins. In a study conducted by Barbosa et al., a 60 kilodalton hemagglutinating extracellular product was suggested to be the major pathogenic factor linked to the hemorrhagic manifestations of BPF. This molecule was found to be absorbable by human O-type erythrocytes. After the molecule had been injected into rabbits, they showed reactions similar to that of BPF patients. Further research is being conducted to determine the mechanisms involved with the other virulence factors of H. aegyptius. The overall pathogenesis of BPF probably involves multiple steps and a number of bacterial factors.
Read more about this topic: Brazilian Purpuric Fever