Description of an outbreak of human trichinellosis in an area of Argentina historically regarded as Trichinella-free: The importance of surveillance studies

Trichinellosis is an important food-borne zoonosis which is not treated as a major public health concern in Argentina. After more than 20 years without reports of infection in an area regarded as Trichinella-free, research studies reported that infection occurred in humans, pigs and game animals, including the recent outbreak of human trichinellosis revealed here. The outbreak, affecting 64 individuals, occurred in July 2010 in the province of Entre Ríos. Epidemiological studies, clinical observations, laboratory analyses and immunoserological specific assays (indirect immunofluorescence, IIF, and ELISA) were performed. Food samples were analyzed by artificial digestion, and Trichinella larvae isolates were identified to the species level by multiplex PCR. The main source of infection, commercially available food, had a parasite load of 1.1 muscle larvae per gram. Larvae were identified as Trichinella spiralis. Patients presented predominantly with oedema, fever and myalgia; and laboratory findings and/or immunoserological tests were positive for trichinellosis. Individuals received outpatient treatment. No deaths or secondary sequelae were recorded. Results suggest that the presence of T. spiralis infection should be suspected in all endemic areas, especially where animal husbandry and official food safety controls are not properly conducted. The lack of the cases reported ought not to be taken as a proof of parasite absence. We highlight the importance of the urgent need to implement interdisciplinary and inter-institutional programs aimed to control infection transmission, to guarantee food safety and to conduct epidemiological surveillance studies.