Multidrug-Resistant Shigella dysenteriae Type 1: Forerunners of a New Epidemic Strain in Eastern India?

zoonosis in the very first phase but later has spread in the human population as a typical anthroponosis and caused the present pandemic. Similarly, pandemic strains of influenza developed through an antigenic shift from avian influenza A viruses. For some etiologic agents or their genotypes, both animals and humans are concurrent reservoirs (hepatitis virus E, Norwalk-like calicivirus, enteropathogenic Escherichia coli, Pneumocystis, Cryptosporidium, Giardia, and Cyclospora); these diseases might conditionally be called anthropozoonoses. Other difficulties can occur with classifying diseases caused by sporulating bacteria (Clostridium and Bacillus): Their infective spores survive in the soil or in other substrata for very long periods, though they are usually produced after a vegetative growth in the abiotic environment, which can include animal carcasses. These diseases should therefore be called sapronoses. For some other etiologic agents, both animals and abiotic environment can be the reservoir (Listeria, Erysipelothrix, Yersinia pseudotuberculosis, Burkholderia pseudomallei, and Rhodococcus equi), and the diseases might be, in fact, called saprozoonosis (not sensu 9 ) in that their source can be either an animal or an abiotic substrate. For a concise list of anthropo-, zoo-, and sapronoses, see the online appendix available from: URL: http://www. cdc.gov/ncidod/EID/vol9no3/02-0208app.htm.