The association that we found between PTX3 levels in serum and specific symptoms or signs of more severe disease (high fever accompanied by bloody or numerous diarrheal stools) is consistent with shigellosis being an inflammatory infection of the colon mucosa that induces the corresponding innate response involving recruitment of neutrophils, macrophages, and dendritic cells to the site of infection which rapidly secrete PTX3 to fight the invading bacteria. This evidence concerns the gene PTX3 and infection.