Investigation of increased listeriosis revealed two fishery production plants with persistent Listeria contamination in Finland in 2010.

In 2010, a marked increase in listeriosis incidence was observed in Finland. Listeria monocytogenes PFGE profile 96 was responsible for one-fifth of the reported cases and a cluster of PFGE profile 62 was also detected. Investigations revealed two fishery production plants with persistent Listeria contamination. It appears likely that the plants were at least partly responsible for the increase of listeriosis. Epidemiological investigation revealed that 57% (31/54) of cases with underlying immunosuppressive condition or medication reported eating gravad or cold-smoked fish. Two public notices were issued by THL and Evira informing which groups were most at risk from the effects of listeriosis and should therefore be cautious in consuming certain products. Systematic sampling of foods and adequate epidemiological investigation methods are required to identify the sources of Listeria infections. Continuous control measures at fishery production plants producing risk products are essential.

Population-based surveillance study of Campylobacter infections in Finland.

The annual incidence in 14,361 campylobacteriosis cases reported in Finland in 2002-2005 varied between 61 and 76/100,000 population. The mean incidence was highest (148/100,000) in the 25-29 years age group and lowest (range 21-24/100,000) in children aged 5-14 years and patients aged ≥75 years. The number of domestic cases was low in winter and peaked in summer. A total of 622 strains isolated from domestic infections and 785 foreign travel-related strains were serotyped. Serotypes Pen 3 and Pen 37 had the strongest association with travel-related infections (96%, P<0·001), and Pen 6,7, Pen 12 and Pen 27 were significantly associated with domestic infections (>70% domestic within each serotype, P<0·001). Pen 2 and Pen 1,44 were less common in older than in younger patients. Of domestic strains, a higher proportion of Pen 2 strains was isolated in winter (18%) compared to the other serotypes (0-10%).

Correct identification and discrimination between Campylobacter jejuni and C. coli by a standardized hippurate test and species-specific polymerase chain reaction.

Hippurate hydrolysis test results of 240 Campylobacter strains were compared with those of two multiplex polymerase chain reaction (PCR) assays. Of the 152 strains identified in Finnish clinical microbiology routine laboratories as C. coli (hippurate-negative), 11% were C. jejuni (hippurate-positive) by standardized hippurate test and 39% by PCR in the reference laboratory. Two of the 81 hippurate-positive strains were identified as C. coli. Standardizing the hippurate test by determining minimum and maximum turbidity limits (McFarland 6 and McFarland 10, OD(450) values 0.8 and 1.4, respectively) for the bacterial cell suspension eliminated the false-positive results, but 32% of the 145 hippurate-negative strains were still identified as C. jejuni by PCR. The species identification of Campylobacter isolates in Finland could be improved by using a standardized hippurate hydrolysis test to identify hippurate-positive C. jejuni and testing hippurate-negative strains by molecular methods. This would also improve the epidemiological data on this important zoonotic pathogen.

Surveillance of listeriosis in Finland during 1995-2004.

We analysed the surveillance data from listeriosis cases notified to the Finnish National Infectious Diseases Register between 1995 and 2004 and describe our recent experience in investigating clusters of listeriosis cases. The number of annual cases varied between 18 and 53 but no trends in incidence were identified (average annual incidence was 7 cases per million inhabitants). Only a few cases affected pregnant women or newborns. Most of the patients were elderly people with non-malignant underlying illnesses; 25% of them died from their infections. By routine sero- and genotyping of the listeria isolates, we detected several clusters; the vehicle for infection was only identified for two outbreaks. At least one quarter of listeriosis cases (78/315) was caused by a certain sero-genotype or closely related genotypes, which have also been found from vacuum-packed cold-smoked or cold-salted fish products. During 2000-2003, Finnish consumers were repeatedly informed about food precautions for risk groups. The information was also given to attending physicians and prenatal clinics.

Molecular and phenotypic profiling of sorbitol-fermenting Escherichia coli O157:H- human isolates from Finland.

This study investigated the occurrence of virulence-associated genes, including stx1, stx2, stx2c, stx2d, stx2e, eae and its subtypes (alpha, beta, gamma, epsilon), efa1, cdt-V cluster, enterohaemorrhagic Escherichia coli (EHEC)-hlyA, katP, espP, etpD, sfpA and the flagellar fliC gene, in nine sorbitol-fermenting (SF), beta-glucuronidase-positive E. coli O157:H- (non-motile) isolates obtained from humans in Finland between 1997 and 2001. In addition, the production of Shiga toxin (Stx), cytolethal distending toxin (CDT)-V and EHEC haemolysin (EHEC-Hly) was studied, and the phage type (PT) and pulsed-field gel electrophoresis (PFGE) types were determined. All nine isolates carried eae-gamma, efa1, EHEC-hlyA, etpD, sfpA and fliC; eight also harboured the cdt-V gene cluster and five were positive for stx2. None of the isolates harboured stx1, stx2c, stx2d, stx2e, katP or espP. All isolates harbouring the corresponding genes also produced Stx2 and CDT-V in titres ranging from 1:32 to 1:128 and from 1:2 to 1:4, respectively. None of the isolates expressed EHEC-Hly on enterohaemolysin agar. Seven isolates belonged to PT88 and two had a PT88 variant pattern. Seven isolates showed a close genetic relationship, with a PFGE similarity index (SI) of 92-98%. Two isolates, temporally the first and last, obtained 5 years apart, were the most divergent (SI of 71% and 85%, respectively). The study demonstrated that SF E. coli O157:H- isolates from Finland are closely related and show a close relationship with SF E. coli O157 strains isolated in Germany. This finding suggests a clonality of SF E. coli O157:H- isolates from different geographical regions.

Surveillance of listeriosis in Finland during 1995-2004.

We analysed the surveillance data from listeriosis cases notified to the Finnish National Infectious Diseases Register between 1995 and 2004 and describe our recent experience in investigating clusters of listeriosis cases. The number of annual cases varied between 18 and 53 but no trends in incidence were identified (average annual incidence was 7 cases per million inhabitants).

Multiple outbreaks of Yersinia pseudotuberculosis infections in Finland.

During 2001, 89 culture-confirmed cases of Yersinia pseudotuberculosis were reported in Finland; 55 (62%) were serotype O:1, and 34 (38%) were serotype O:3. Four major pulsed-field gel electrophoresis profiles were identified. A case-control study of 25 case patients and 71 healthy controls identified eating outside the home as a risk factor for infection.