Epidemiology and clinical aspects of enteric fever in Israel.

Enteric fever decreased in Israel in the last 50 years, but its current epidemiology is unknown. In a nationwide study, we evaluated all cases of enteric fever from 1995 to 2003. On hundred thirty-six cases met the case definition. During the period studied, the incidence of enteric fever decreased from 0.42 to 0.23/100,000. A total of 57.4% of the cases were acquired abroad. The incidence of endemic enteric fever was 2.7 times higher in Arabs than in Jews. In Arabs, Salmonella Typhi was the causative agent in all cases, and almost all cases were endemic. In Jews, most cases were imported, with a decrease in imported S. typhi, cases and an increase in imported S. Paratyphi A cases. Salmonella Paratyphi B was endemic, and restricted to the Jewish population. The reasons for the difference in causative agents along ethnic lines need further evaluation. A more efficient vaccine for travelers that includes S. Paratyphi A is needed.

Enteric fever in Israeli travelers: a nationwide study.

BACKGROUND: Enteric fever (EF) has become a travel-related disease in industrialized countries. The possible effects of vaccination on typhoid epidemiology in travelers are unknown. We compared the incidence and clinical and microbiologic findings in travelers returning with EF, according to pretravel vaccination status and vaccine type. METHODS: We performed a nationwide descriptive analysis of EF incidence in Israeli travelers; EF is a notified disease in Israel. Data from 1995 through 2003 were evaluated; all cases of EF acquired during recent travel (6 wk) were included. From 1995 to 1999, the Ty21a oral vaccine was used exclusively in Israel. It was replaced with the Vi vaccine from 2000 to 2003. Patients with pretravel typhoid vaccination were compared with unvaccinated patients, and according to vaccine type. RESULTS: Seventy-eight cases met our criteria. The causative agents were Salmonella typhi in 79.5% and Salmonella paratyphi A in 20.5%; 74.4% were acquired by travelers to the Indian Subcontinent. S. paratyphi A accounted for 10.5% of cases among Ty21a vaccinees as compared with 47.4% among Vi vaccinees (p = .02). For the Indian Subcontinent, the general attack rate of S. typhi and S. paratyphi A during the period of vaccination with Ty21a was 2.37 in 10,000 and 0.26 in 10,000 travelers, respectively, whereas during the period of vaccination with Vi, the attack rate was 1.40 in 10,000 and 0.79 in 10,000. There were no deaths; however, more complications and relapses occurred in the S. paratyphi A group. CONCLUSIONS: Among Israeli travelers S. typhi infection is declining whereas S. paratyphi A is increasing, with most cases occurring in vaccinated travelers. Prior typhoid vaccination did not modify the course of the disease. S. paratyphi A infection in travelers is not milder than S. typhi infection. Although this is not a prospective, controlled, randomized trial, it appears that the Ty21a vaccine may be less effective for S. typhi but may offer some protection against S. paratyphi A. Sequential vaccination with the available oral and Vi vaccine may merit consideration. A more effective vaccine for S. typhi and S. paratyphi A is urgently needed.