First reported foodborne outbreak associated with microsporidia, Sweden, October 2009

Abstract

SUMMARYMicrosporidia are spore-forming intracellular parasites that infrequently cause disease in immunocompetent persons. This study describes the first report of a foodborne microsporidiosis outbreak which affected persons visiting a hotel in Sweden. Enterocytozoon bieneusi was identified in stool samples from 7/11 case-patients, all six sequenced samples were genotype C. To confirm that this was not a chance finding, 19 stool samples submitted by healthy persons from a comparable group who did not visit the hotel on that day were tested; all were negative for microsporidia. A retrospective cohort study identified 135 case-patients (attack rate 30%). The median incubation period was 9 days. Consumption of cheese sandwiches [relative risk (RR) 4·1, 95% confidence interval (CI) 1·4–12·2] and salad (RR 2·1, 95% CI 1·1–4) were associated with illness. Both items contained pre-washed, ready-to-eat cucumber slices. Microsporidia may be an under-reported cause of gastrointestinal outbreaks; we recommend that microsporidia be explored as potential causative agents in food- and waterborne outbreaks, especially when no other organisms are identified.

A New and Highly Divergent Enterocytozoon bieneusi Genotype Isolated from a Renal Transplant Recipient

“…are the major species infecting humans, with E. bieneusi being the most prevalent (10,15). Transmission occurs mainly through fecal-oral routes, with sources of infection including other infected humans and animals, contaminated water, and, as illustrated recently, food (1,4). Microsporidia have emerged as an important cause of opportunistic infection in patients with AIDS, being predominantly associated with wasting and diarrhea.…”

Microsporidia

“…The distribution of case-patients over time indicates a point-source outbreak but is broad, reflecting a wide range of incubation periods. The median incubation time between the date of the conference and illness onset in case-patients was 9 days for all case-patients (range 0 -21 days) and 7 days (range 3 -15 days) for the four microbiologically confirmed casepatients, with the latter (3 -15 days) more reliable and comparable to other protozoan parasites such as Cryptosporidium (1 -12 days) and Giardia (3 -25 days) (Decraene et al, 2012). …”

“…In Poland, Sweden, Costa Rica, and Egypt, various vegetables and fruits such as lettuce, celery, cilantro, mung beans, strawberries, and raspberries purchased from local markets were identified containing human-pathogenic microsporidia species (Decraene et al, 2012;Jedrzejewski et al, 2007;Calvo et al, 2004;Mossallam, 2010). In 2009, an outbreak of microsporidiosis was found associated with contaminated food served at conference in a hotel in Sweden (Decraene et al, 2012).…”

“…Only one cohort study in Sweden describing a foodborne outbreak in 2009 (in a conference in a hotel) associated with E. bieneusi, has documented incubation periods for cases of microsporidiosis (Decraene et al, 2012). The distribution of case-patients over time indicates a point-source outbreak but is broad, reflecting a wide range of incubation periods.…”

Extraintestinal Microsporidiosis

“…The species known to infect humans have been isolated from a large variety of birds, fish, insects, and other animals, as well as from food and water sources (3,5,6). Modes of transmission are thought to include ingestion, inhalation, direct trauma to skin or mucous membrane, sexual contact, and transplacental (mother to child) (2).…”