Shigella species are responsible for 165 million cases annually of severe dysentery. The majority of cases occur in children under the age of 5 years in developing countries. More than one million people are estimated to die from Shigella infection each year. Shigella organisms are transmitted by ingestion of contaminated food or water, or by person-to-person contact.
Four species of Shigella cause dysentery: S. sonnei, S. flexneri, S. boydii, and S. dysenteriae. S. sonnei is most common in industrialized countries. S. flexneri is endemic in developing countries and is the most frequently isolated species worldwide. S. dysenteriae type 1 is the cause of epidemic dysentery. A major obstacle to the control of S. dysenteriae type 1 is its resistance to antimicrobial drugs. Vaccine strategies against Shigella include both killed and live vaccines.
The killed, subunit vaccine approach includes the following:
- Parenteral conjugate vaccines coupled to tetanus toxoids or recombinant Pseudomonas aeruginosa exotoxin A
- Parenteral nuclear protein/ribosomal vaccines
- Nasally administered proteosome vaccines consisting of Shigella LPS linked to micelles of the outer membrane protein of group B Neisseria meningitidis
- Inactivated whole cell vaccines
- Nasally administered LPS-Ipa complexes (Invaplex)
The live oral vaccine approach includes:
- Live bivalent S. flexneri 2a and S. sonnei vaccines
- Live attenuated S. flexneri 2a and S. dysenteriae type 1, carrying mutations in the icsA, iuc, int, and toxA genes
- Live attenuated Shigella vaccine with fimbriae genes from ETEC and progressive deletions of virulence genes (CVD 1203 and CVD 1204)
- S. sonnei vaccine (WRSS1) with a single deletion mutation of the VirG gene
Initiative for Vaccine Research
Division of Foodborne, Bacterial and Mycotic Diseases
Here is a link to information about participating in vaccine studies for Traveler’s Diarrhea at the CIR.