UTILITY OF A POLYMERASE CHAIN-REACTION DIAGNOSTIC SYSTEM IN A STUDY OF THE EPIDEMIOLOGY OF SHIGELLOSIS AMONG DYSENTERY PATIENTS, FAMILY CONTACTS, AND WELL CONTROLS LIVING IN A SHIGELLOSIS-ENDEMIC AREA

Polymerase chain reaction (PCR) diagnostic methods have rarely been us ed in epidemiologic studies of Shigella and enteroinvasive Escherichia coil (EIEC) infections. In this study, amplification of the invasion plasmid antigen H (ipaH) gene by PCR and standard culture methods was used to identify Shigella species or EIEC among 154 patients with dyse ntery, 154 age-matched controls, and family contacts in Thailand. The ipaH PCR system increased the detection of Shigella species and EIEC f rom 58% to 79% among patients with dysentery and from 6% to 22% among 527 family contacts; 75% of infections in family members were asymptom atic. Detection of the ipaH gene was statistically associated with dys entery. Household contacts of patients with shigellosis diagnosed only by PCR had significantly higher rates of shigellosis than household c ontacts of patients who did not have Shigella or EIEC infections. Dete ction of the ipaH gene by PCR is far more sensitive than detection by standard culture and is highly correlated with evidence of Shigella tr ansmission among family contacts.