Restaurant-associated outbreak of typhoid fever in Maryland: identification of carrier facilitated by measurement of serum Vi antibodies

Abstract

in the vicinity of Silver Spring, Md. Shrimp salad served in a fast-food restaurant was implicated as the source of infection. Stool cultures were obtained from 104 employees, and serum Vi antibodies were assayed in 97 of the employees. Salmonella typhi was isolated from stool cultures of an 18-year-old asymptomatic female employee, who was a food handler. A high level of Vi antibodies (79.0 Fg/ml), measured by radioimmunoassay, was found in her serum. She had emigrated from an endemic area at the age of 14 years and had visited that endemic area 2 years previously. The causal relation between the carrier and the 10 cases of typhoid fever was confirmed by a common bacteriophage type, denoted "degraded Vi resembling O," in the S. typhi isolates. This phage type is rare in the western hemisphere but common in the endemic area from which the carrier had emigrated. The high level of Vi antibody in the asymptomatic carrier, in contrast to the lower levels in the convalescentand postimmunization-phase sera, facilitated the identification of the source infection in this outbreak. This radioimmunoassay offers a rapid and standardized method for identifying carriers of S. typhi.

Prevention of food worker transmission of foodborne pathogens: risk assessment and evaluation of effective hygiene intervention strategies

“…Twenty percent (49) of outbreaks were attributed to food workers deboning, slicing, chopping or transferring meats, most of which were in a ready‐to‐eat form (R‐T‐E) requiring no further cooking or heating steps prior to consumption (see Table 2). Adding garnishes, such as placing boiled shrimp on top of a tossed salad, putting parsley into cooked food and picking fresh basil, are examples of how even small operations can transmit pathogens to cause outbreaks (Lin et al . 1988; Lew et al .…”

Epidemiology of typhoid fever in Singapore

“…Only one carrier was identified in 12 outbreaks where food handlers were implicated. Combining multiple faecal cultures with some of the reportedly more sensitive methods such as bile sampling with a string capsule device [22] and various Vi antibody serological tests [23][24][25][26][27][28] could well improve the carrier detection rate.…”

Outbreaks Where Food Workers Have Been Implicated in the Spread of Foodborne Disease. Part 6. Transmission and Survival of Pathogens in the Food Processing and Preparation Environment

“…Even minimal hand contact with moist surfaces such as tomato and pineapple slices, cut melon, lettuce, and mashed potatoes can result in significant pathogen transmission (40,87,100,138). Garnishing food by placing boiled shrimp on top of a tossed salad, putting parsley into cooked food, and picking fresh basil demonstrate how even small operations can transmit pathogens and cause outbreaks (108,112). Other actions less frequently thought of as hazardous but associated with outbreaks include handling of baked goods such as buns and cooked pasta products, preparing frosting for cakes, dipping donuts in glaze, mixing milk from powder, reconstituting orange juice from concentrate, using whipping cream and mousse ingredients for desserts, and using water and ice for beverages (66,202,203).…”