Field Trial of Attenuated Salmonella Typhi Live Oral Vaccine TY21A in Liquid and Enteric-Coated Formulations and Epidemiological Survey for Incidence of Diarrhea due to Shigella Species
Abstract
In October, 1986, a randomized, controlled field trial was initiated in Area Sur Oriente and Area Norte, Santiago, Chile, to compare the relative and absolute efficacy of three doses of Ty21a vaccine given in enteric-coated capsule or liquid formulation. Intensive clinical and bacteriologic surveillance is being maintained. Preliminary data show that the liquid formulation is associated with a significantly lower attack rate for typhoid fever than the enteric-coated capsule formulation. Surveillance for this trial continues. Epidemiologic and microbiologic surveillance was initiated in three populations of children in the Santa Julia neighborhood of Area Oriente, Santiago with the broad objective of preparing a field area where the efficacy of vaccines against Shigella, enterotoxigenic E. coli and other diarrheal pathogens can be evaluated. In the first years of surveillance diarrhea in young children showed a prominent seasonality with approximately twice as many episodes occuring in the warm season. Similarly, isolation of Shigella was maximal during the warm months. An impressive portion of the episodes of diarrhea in Santa Julia children, particularly during summer, are due to Shigella and E. coli pathogens. During the summer months in Santa Julia it is likely that Shigella is readily transmitted from child to child by direct contact involving small inocula. Such transmission, which is dependent on personal hygiene practices, is apparently little affected by the widespread availability of potable water in the population.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1989
- Accession Number
- ADA248309
Entities
People
- Catterine Ferreccio
- Myron M. Levine
- Valeria Prado
Organizations
- University of Maryland School of Medicine