Epidemiology and control of an outbreak of typhoid in a psychiatric institution

Abstract

An outbreak of typhoid caused by Salmonella typhi of the same Vi-phage type (D1) and of the same antibiogram was reported in a large psychiatric institution in Singapore. A total of 95 (4.8%) of the 1965 inmates were infected, 47 with symptoms and 48 asymptomatic. Transmission was through close person-to-person contact and not through contaminated food or water. The source of infection could not be established. The outbreak was brought under control by maintaining a high standard of environmental sanitation, active search for fever and diarrhoeal cases, identification of asymptomatic cases by rectal swabbing, and isolation of those found to be infected. Mass immunization with two doses of heat-phenol inactivated typhoid vaccine was also carried out concurrently. The vaccine was found to have an efficacy of 65.8% in preventing clinical illness.

Fever in a returned traveller

“…He could have contracted typhoid when he had visited PNG 10 months previously and become a S. typhi carrier. Although his father did not recall any illness consistent with S. typhi infection, epidemiological studies during typhoid outbreaks have shown that up to half of S. typhi infections may be asymptomatic 9 . However, S. typhi was not present in the father's stools when tested shortly after the patient's discharge (although there is the remote possibility that he had spontaneously cleared carriage after transmitting the bacteria to his son).…”

Reviving the “Moore Swab”: a Classic Environmental Surveillance Tool Involving Filtration of Flowing Surface Water and Sewage Water To Recover Typhoidal Salmonella Bacteria

“…Sears et al (92) may have underestimated the sensitivity, since the period of sampling may not have in fact coincided with deposition of S. Typhi into the sewer by the carrier, particularly if shedding was intermittent or if the carrier did not use the connected toilet during the sampling period. In cases of institutional sewage surveillance (e.g., hospitals and prisons), disinfectants may diminish sensitivity of the culture-based bacteriology (93).…”

Infections in Psychiatric Facilities, with an Emphasis on Outbreaks

“…Outbreaks of Salmonella enteritis in psychiatry units have been reported from several countries ( ). [29][30][31][32][33] Outbreaks occurred through close person-to-person contact [29,32,33] or because of contamination of food. [29,30] Management Recommendations.The identification of the asymptomatic reservoir of Salmonella by rectal swabbing is a major approach in controlling outbreaks.…”