In this study comprising isolates from 2001 to 2003, resistance was considerably more widespread among Campylobacter jejuni from humans infected abroad than infected within Norway. The discrepancy was particularly notable for fluoroquinolone resistance (67.4% vs. 6.5%). This is probably a reflection of a low resistance prevalence in Norwegian broiler isolates (1.2% fluoroquinolone resistant).
Plasmid profile analysis, restriction endonuclease analysis, and multilocus enzyme electrophoresis were used in conjunction with serotyping, bacteriophage typing, and biochemical fingerprinting to trace epidemiologically related isolates of Salmonella typhimurium from an outbreak caused by contaminated chocolate products in Norway and Finland. To evaluate the efficiency of the epidemiological marker methods, isolates from the outbreak were compared with five groups of control isolates not known to be associated with the outbreak. Both plasmid profile analysis and phage typing provided further discrimination over that produced by serotyping and biochemical fingerprinting. Plasmid profile analysis and phage typing were equally reliable in differentiating the outbreak isolates from the epidemiologically unrelated controls and were significantly more effective than multilocus enzyme electrophoresis and restriction enzyme analysis of total DNA. The greatest differentiation was achieved when plasmid profile analysis and phage typing were combined to complement serotyping and biochemical fingerprinting. However, none of the methods employed, including restriction enzyme analysis of plasmid DNA, were able to distinguish the outbreak isolates from five isolates recovered in Norway and Finland over a period of years from dead passerine birds and a calf.
In 1987, a nationwide outbreak of Salmonella typhimurium O:4-12 infection traced to contaminated chocolate bars occurred in Norway. In the 5 years after the outbreak, elevated numbers of sporadic cases caused by the epidemic strain of Salmonella were detected, followed by a decline in subsequent years. To characterize the epidemiology of this infection, the authors analyzed information concerning all sporadic cases reported in Norway from 1966 to 1996. Of the 153 patients infected by the outbreak strain, 43% were less than 5 years of age, and only three persons had acquired the infection abroad. In contrast, 46% of the cases attributable to other S. typhimurium O:4-12 variants and 90% of the total number of Salmonella infections were related to foreign travel. A distinct seasonality was observed: 76% of the cases appeared between January and April. At the same time of year, the epidemic strain was regularly encountered as the etiologic agent of fatal salmonellosis among wild passerine birds, suggesting an epidemiologic link between the avian and human cases. The strain was rarely isolated from other sources. From 1990 to 1992, the authors conducted a prospective case-control study of sporadic indigenous infections to identify risk factors and obtain guidance for preventive efforts. Forty-one case-patients, each matched by age, sex, and geographic area with two population controls, were enrolled. In conditional logistic regression analysis, the following environmental factors were independently related to an increased risk of infection: drinking untreated water, having direct contact with wild birds or their droppings, and eating snow, sand, or soil. Cases were also more likely than controls to report having antecedent or concurrent medical disorders. Forty-six percent of the study patients were hospitalized for their salmonellosis.
Over the last 20 years, Salmonella infections in humans have increased considerably in the industrialized world, including Norway. The situation has been characterized as a serious problem, with considerable economic, political and public health implications. In contrast to the situation in most other countries, a large majority of the Norwegian patients have contracted the infection abroad. The endemic level of salmonellosis in Norway is low, and the prevalence of Salmonella in Norwegian food products is negligible. Appropriate intersectorial actions are required to maintain Norway's favourable status. Such actions include: preventing import of infected food, feed, and live animals; ensuring good hygienic practices at all stages of production, processing, and preparation of food; maintaining the present good health status of meat producing animals; providing consumers with drinking water of adequate hygienic quality; and intensifying national and international collaboration to prevent and control salmonellosis.
In the year 2100 a global mean temperature increase of 2 degrees C, and a 50 cm rise in sea level are expected. An escalation in the intensity and duration of heat waves will increase mortality, whilst higher temperatures in cold regions may reduce it. On a global scale, vector-borne diseases such as malaria, dengue, yellow fever and some types of viral encephalitis are likely to increase. 50 to 80 million more cases of malaria could occur annually. Elevated temperatures and more frequent floods could cause an increase in salmonellosis, cholera and giardiasis. Indirectly, shortages of freshwater and foods may cause serious health problems. The world may see more environmental refugees. For Norway a temperature increase of 3-4 degrees C during winter and 2 degrees C in summer is expected, with more precipitation, especially in western parts. The possibility of the Gulf Stream turning at 40 degrees N and causing a temperature decrease of 10 degrees C, is not very likely. Malaria could reestablish itself in Europe, but hardly in Norway. The most harmful arthropod vector in Norway, the tick Ixodes ricinus, might extend its range into the most populated parts of the country. Marine algal blooms might increase the risk of cholera. Health problems caused by greater floods, poisonous algae and certain freshwater cercaria might increase.
In Europe, the number of reported sporadic human cases of Salmonella Livingstone infection is low, and outbreaks are rare. We report the largest S. Livingstone outbreak described in the literature having an identified source of infection. In February 2001, an increased incidence of infection caused by S. Livingstone was observed in Norway and Sweden. By July 2001, 44 cases were notified in Norway and 16 in Sweden. The median age was 63 years, and 40 were women. There were three deaths, and 22 patients were hospitalized. Based on standardized questionnaires and retrospective studies of S. Livingstone strains in Norway and Sweden, food items with egg powder were suspected, and S. Livingstone was subsequently recovered from a processed fish product at the retail level. Analysis by pulsed-field gel electrophoresis documented that isolates from the fish product belonged to the same clone as the outbreak strain.
IgG antibody activity to Yersinia enterocolitica serogroup O:3 was detected in sera from 56 (7.4%) of 755 Norwegian military recruits, using an enzyme-linked immunosorbent assay. The highest prevalence was found among recruits from Oslo city (12/56, 21.4%). The recruits answered a questionnaire which covered demographic data, specific exposures, and clinical information. The following risk factors were found to be independently associated with IgG activity in logistic regression analysis: receiving drinking water from a private well (odds ratio (OR) = 3.40; p = 0.004), being a resident of Oslo city (OR = 2.99; p = 0.006), and living in eastern Norway (OR = 2.25; p = 0.015). By univariate analysis, living in an urban area was associated with IgG activity, but this factor did not independently affect risk. Present or previous contact with animals, including pigs, and travels abroad were not associated with an increased risk. Yersinia enterocolitica O:3 seropositive recruits were more likely to report previous surgery for suspected appendicitis than seronegative individuals (OR = 4.26; p = 0.0024). Among recruits with previous appendectomy, mesenteric lymphadenitis as the sole peroperative finding was more common in patients with IgG activity to Y. enterocolitica O:3 (4/7) than in seronegative patients (1/19) (p = 0.01). Recurrent diarrhea, steatorrhea or joint complaints were not associated with antibody activity.
In 1989 and 1990, a case-control study designed to identify risk factors for sporadic infections with thermotolerant Campylobacter bacteria was conducted in three counties in southeastern Norway. The investigation was confined to infections which were acquired in Norway. A total of 52 bacteriologically confirmed cases and 103 controls matched by age, sex, and geographic region were interviewed. The following risk factors were found to be independently associated with illness in conditional logistic regression analysis: consumption of sausages at a barbecue (odds ratio [OR] = 7.64; P = 0.005), daily contact with a dog (OR = 4.26; P = 0.024), and eating of poultry which was brought into the house raw (frozen or refrigerated) (OR = 3.20; P = 0.024). The risk associated with consumption of sausages at a barbecue could not be attributed to cross-contamination from poultry products. By univariate analysis, consumption of poultry which was brought raw and frozen was associated with illness (OR = 2.42; P = 0.042), even though freezing substantially reduces the number of viable campylobacters. When poultry consumption was examined by country of origin, eating of poultry produced in Denmark or Sweden was strongly associated with illness (OR = 13.66; P = 0.014), whereas consumption of poultry produced in Norway was not (OR = 1.33; P = 0.41).
Yersinia enterocolitica is a recognized cause of gastroenteritis in northern Europe. During October 1988-January 1990, a prospective case-control study was performed to address risk factors associated with sporadic Y. enterocolitica infections in southeastern Norway. Sixty-seven case-patients (mean age 23.4 years, range 8 months-88 years) and 132 age-, sex- and geographically-matched controls were enrolled in the study. Multivariate analysis of the data showed that persons with Y. enterocolitica infection reported having eaten significantly more pork items (3.79 v. 2.30 meals, P = 0.02) and sausage (2.84 v. 2.20 meals, P = 0.03) in the 2 weeks before illness onset than their matched controls; only one patient had eaten raw pork. Patients were also more likely than controls to report a preference for eating meat prepared raw or rare (47 v. 27%, P = 0.01), and to report drinking untreated water (39 v. 25%, P = 0.01) in the 2 weeks before illness onset. Each of these factors was independently associated with disease, suggesting a link between yersiniosis and consumption of undercooked pork and sausage products and untreated water. Efforts should be directed towards developing techniques to reduce Y. enterocolitica contamination of pork and educating consumers about (1) proper handling and preparation of pork items and (2) the hazards of drinking untreated water.