All-time high tularaemia incidence in Norway in 2011: report from the national surveillance.

Tularaemia has mainly been a sporadic disease in Norway. In 2011, 180 persons (3.7 per 100,000 population) were diagnosed with tularaemia. This article describes the epidemiological and clinical features of tularaemia cases during a year with exceptionally high tularaemia incidence. Data from the national reference laboratory for tularaemia combined with epidemiological data from the Norwegian Surveillance System for Communicable Diseases (MSIS) were used. The incidence of tularaemia varied greatly between counties, but almost every county was involved. The majority (77.8 %) of the cases were diagnosed during the autumn and winter months. The geographic distribution also showed seasonal patterns. Overall, oropharyngeal tularaemia (41.1 %) was the most common clinical presentation, followed by glandular (14.4 %), typhoidal (14.4 %), respiratory (13.3 %) and ulceroglandular (12.8 %) tularaemia. From January to April, oropharyngeal tularaemia dominated, from May to September, ulceroglandular tularaemia was most common, whereas from October to December, there was an almost even distribution between several clinical forms of tularaemia. Eighty-five (47.2 %) of all tularaemia cases were admitted to, or seen as outpatients in, hospitals. An unexpectedly high number (3.9 %) of the patients had positive blood culture with Francisella tularensis. The clinical manifestations of tularaemia in Norway in 2011 were diverse, and changing throughout the year. Classification was sometimes difficult due to uncharacteristic symptoms and unknown mode of transmission. In rodent years, tularaemia is an important differential diagnosis to keep in mind at all times of the year for a variety of clinical symptoms.

Gastrointestinal disease outbreaks in cycling events: are preventive measures effective?

In 2009, following a bike race, a gastrointestinal illness outbreak affected many participants. A cohort study showed an attack rate of 16·3% with the main risk factor being mud splashes to the face. Considering these findings, in 2010 recommendations to participants in the bike race were issued and environmental control measures were implemented. In 2010, a retrospective cohort study using web-based questionnaires was conducted to measure the use of preventive measures and to assess risk factors associated with gastrointestinal illness. A 69% response rate was achieved and 11721 records analysed, with 572 (attack rate 4·9%) matching the case definition, i.e. participants reporting diarrhoea within 10 days of race. There was a clear increase in the use of mudguards (96·7% reported access to/receiving information on preventive measures) and a significant decrease in gastrointestinal illness. This may indicate that the measures have been effective and should be considered, both in terms of environmental control measures as well as individual measures.

Outbreak of tularaemia in central Norway, January to March 2011.

From January to March 2011, 39 cases of tularaemia were diagnosed in three counties in central Norway: 21 cases of oropharyngeal type, 10 cases of glandular/ulceroglandular type, two of respiratory and two of typhoid type. Three cases were asymptomatic and clinical information was unavailable for one case. The mean age was 40.3 years (range 2-89 years). Thirty-four reported use of drinking water from private wells. An increased rodent (lemming) population and snow melting may have led to contamination of the wells with infected rodents or rodent excreta.

Outbreak of Shigella sonnei infection in Norway linked to consumption of fresh basil, October 2011.

We report a Shigella sonnei outbreak of 46 cases that occurred in Norway during October 2011. Two municipalities were involved. A large cluster (42 cases)was concentrated in north Norway, while a smallcluster (4 cases) occurred in the south-east region.Epidemiological evidence and trace back investigations have linked the outbreak to the consumption of imported fresh basil. The product has been withdrawn from the market. No further cases have been reported since 25 October.

Shigella sonnei infections in Norway associated with sugar peas, May-June 2009.

In May 2009, the Norwegian Institute of Public Health (NIPH) identified a possible outbreak of Shigella sonnei infection involving four cases. Additionally, five suspected cases in two separate households were reported. Inspectors from the Norwegian Food Safety Authority (NFSA) visited the two households and found an unopened package of sugar peas imported from Kenya in one of the households. One sample from the sugar peas was positive for Shigella sonnei by two PCR methods. Based on this result and information from patient interviews, the NFSA prohibited all sales of sugar peas imported from Kenya.

Risk factors associated with the presence of Campylobacter species in Norwegian broiler flocks.

A case-control study was conducted in 2005 to identify risk factors for the presence of Campylobacter spp. in Norwegian broiler flocks. A total of 131 broiler farms (44 cases and 87 controls) were included in the study, and 1 flock from each farm was included in the statistical analyses. Data on farm and flock level were collected by means of a questionnaire designed for the present study. The relationship and strength of association between the presence of Campylobacter spp. in the broiler flocks and several factors were investigated by unconditional logistic regression. The following factors were found to be associated with an increased risk of testing positive for Campylobacter spp.: water from a private water source, swine holdings closer than 2 km, a specific slaughterhouse, a hired animal caretaker, transport personnel passing through the hygiene barrier when delivering day-old chickens, less than 9 d between depopulation and restocking, and multiple broiler houses on the farm.

Risk factors for Marek's disease and mortality in white Leghorns in Norway.

A prospective longitudinal field study was conducted in the period from January 1994 to January 1996 to analyse the relationship between some selected risk factors in the growing and laying periods and (1) the flock-level occurrence of Marek's disease (MD) during the period from 16 to 32 weeks of age and (2) the cumulative mortality during the same period. A total of 171 layer flocks in 102 egg-production farms were included in the statistical analyses.A logistic regression (with strain of layer and vaccination program against MD as fixed effects) of flock-level MD-status during the first 16weeks of the laying period was conducted. Of the risk factors investigated, "multi-age management" and "housing system" were significantly associated at the rearing farm, and "number of hens in each cage" at the egg-production farm. Flocks kept in single-age facilities had a lower risk of MD than flocks housed in farms with multi-age management. The odds of MD were larger for flocks housed on a litter floor in the rearing farms compared to flocks housed in battery cages. At the egg-production stage, flocks kept in battery cages housing more than three hens were at greater risk of MD than those held in cages for three hens or less.A weighted least-squares regression (with strain of layer and flock-level MD-status as fixed effects) of cumulative mortality during the period from 16 to 32weeks of age was also run. The same risk factors (with the same directions of effects) and "size of the rearing farm" were included in the final model of mortality. Chicks reared in medium-sized farms were at higher risk of dying than those coming from either small or large rearing farms. Our results confirm the importance of preventing chicks from being exposed to MD-virus during the rearing period, to reduce the risk of MD-outbreaks (and thereby, mortality losses) during the early stage of the egg-laying period.

Factors associated with mortality in Norwegian broiler flocks.

Our aim in this longitudinal study (covering years from 1996 to 1999) was to use data regularly recorded in a production database, to identify farm- and flock-level factors associated with cumulative mortality in broiler flocks during: (a) the 1st week after housing and (b) the rest of the growout (2nd to 5th week). A total of 1664 broiler flocks kept in 132 broiler farms were included. The average weekly cumulative mortality was 1.54% (95% CI: 1.46, 1.62%) during the 1st week and 0.48% (95% CI: 0.47, 0.49%) during the rest of the growout. The final least-squares regression model of cumulative mortality during the 1st week identified the following significant factors: study year, flock size, stocking density, use of paper underlay for feeding during the 1st week, and the interaction terms between type of ventilation, drinking system and floor insulation. The final model for the 2nd to 5th week demonstrated that the factors age of the broiler house, heating system and control system for the air intake were associated with cumulative mortality, but the effects of the two latter variables were significantly modified by age of the broiler house. A significant difference in mortality between flocks delivered from various hatcheries was found in both analyses. Our results suggest that changes in several housing factors and management routines might reduce the mortality losses, but the relationship depends on the stage of production.

A longitudinal field study of mortality and Marek's disease in Norwegian and imported white Leghorns.

High mortality during the first part of the laying period was observed in Norwegian White Leghorns during the period 1988-1992. A longitudinal field study with repeated measurement of cumulative mortality was undertaken in the period from January 1994 to January 1996 to investigate (1) the mortality and susceptibility to Marek's disease (MD) in the Norwegian strain (NB41) compared to two imported layers, (2) the effect of MD on the total cumulative mortality in the period from 16 to 32 weeks of age in White Leghorn flocks, and (3) the effect of MD as judged by repeated measurement of cumulative mortality in the same period. All five layer hatcheries and 67% of the pullet-rearing farms in Norway participated in the field study. The egg-production farms were sampled by convenience. Recordings for the whole period were completed for 169 flocks in 101 farms. The statistical analyses were performed using both a general fixed-effects linear model and a mixed model with repeated measurements, with total flock-level cumulative mortality and flock-level cumulative mortality in four-week intervals as outcome variables, respectively. The overall cumulative flock-level incidence of MD was 12% (24% and 8% in NB41 and Lohmann White, respectively). MD was not recorded in any of the Shaver White flocks. A significant difference (p < 0.001) was found in (1) total cumulative mortality: 8.2% in the NB41 and 5.0% in the imported layers, and (2) 'interval-specific' cumulative mortality: 0.36% in the NB41 and 0.15% in the imported birds. A strong relationship was also demonstrated between MD and repeated measurements of 'interval-specific' cumulative mortality (p < 0.001) but not when cumulative mortality was used as an overall measure for the whole laying period (p = 0.11). The results from the repeated-measures analysis also indicated a stronger effect of MD on flock-level 'interval-specific' cumulative mortality in the NB41 than in the imported hens. The different cumulative mortality and susceptibility to MD observed in the NB41, compared to the imported hens, shows that the farmers will be able to reduce their losses by replacing the NB41 strain with one of the imported strains.

A field study of naturally occurring specific antibodies against Clostridium perfringens alpha toxin in Norwegian broiler flocks.

Necrotic enteritis (NE), a disease associated with high numbers of the intestinal bacterium Clostridium perfringens, is common in intensive broiler production. Antimicrobial feed additives may control the disease, but their use is now being questioned in many countries. A field study was undertaken at the end of 1997 to study the level of naturally occurring specific humoral immunity against phospholipase C (PLC; C perfringens alpha toxin) in Norwegian broiler flocks. Blood samples were collected at hatch from 61 study flocks, and the sampling was repeated for 56 of the same flocks at processing. The level of specific antibodies against PLC was analyzed in an enzyme-linked immunosorbent assay (ELISA) test. Data on production performance and weekly mortality were recorded. The relationship between the age of the hens and the level of specific maternal antibodies in the progenies was studied. The association between the level of the maternal antibodies and the production performance, including mortality, was analyzed. The level of specific antibodies against PLC in day-old broiler flocks was relatively high and varied considerably compared with the levels in the broilers at processing. The progenies from the oldest hens had significantly higher levels of specific antibodies than the chicks from younger hens. No outbreak of NE occurred during the study period, making it impossible to analyze the association between naturally occurring specific immunity against PLC and the occurrence of the disease. However, the results showed that the flocks with high titers of specific maternal antibodies against PLC had lower mortality during the production period than flocks with low titers.

An epidemiological study of the hatchability in broiler breeder flocks.

The aim of the present retrospective longitudinal study was to identify factors that significantly influenced the hatchability observed during the period from 1996 to 1998. Data from 112 Ross 208 breeder flocks in 39 breeding farms were included in a repeated-measures analysis with the flock-level "interval-specific" hatchability of the eggs as outcome variable. The overall mean of interval-specific hatchability in the study was 75.9% (95% confidence interal: 75.3 to 76.6%). The hatchability was influenced by the storage time from lay until incubation and whether the farmers delivered floor eggs for hatching. The method used for disinfecting the hatching eggs and the flock average slaughter weight were significantly associated with the hatchability. A significant effect of time (production year) and flock size were also found on the hatching results. The results showed that several factors may influence the hatchability, the most detrimental being long egg storage time. With an optimization of the capacity and administration of the hatcheries, it would be possible to improve the hatching results.

Trends in Campylobacter incidence in broilers and humans in six European countries, 1997-2007.

The objective of this study was to examine incidences of Campylobacter in broilers and humans, and to describe seasonal variation and long-term trends by comparing longitudinal surveillance data in six Northern European countries (Denmark, Finland, Iceland, Norway, Sweden and the Netherlands). Due to high degree of seasonality and autocorrelation, seasonally adjusted (de-seasonalized) and trend adjusted data (de-trended) were used for comparing incidences within and between the six countries. De-seasonalized time series were obtained by fitting the incidence time series to mean monthly temperature and then removing this effect from the data. Long-term trends were fitted to the de-seasonalized time series. The incidence of Campylobacter colonization in broiler flocks and incidence of campylobacteriosis in humans showed a concordant seasonality for all the countries. There was a strong association between the incidence in both broilers and humans in a given month and the mean temperature of the northern hemisphere in the same month, as well as the preceding month, as shown by the cross-correlations and the chosen Generalized Additive Model. Denmark and Sweden showed a steadily decreasing trend for Campylobacter in broilers and human campylobacteriosis in the period 2001-2007. In Iceland, there was a decreasing trend for campylobacteriosis in humans from 1999 to 2007, whilst the broiler trend for Campylobacter was stable from 2001 to 2004, then falling thereafter. In Norway, the human campylobacteriosis trend showed a steady increase throughout the period. On the other hand, the Norwegian broiler trend for Campylobacter showed a decrease from 2001 until 2004, but was thereafter stable. There was no significant decrease or increase in incidence for human campylobacteriosis in the Netherlands, and the trend for Campylobacter in broilers was close to stable. The seasonality seen in broiler and human closely follows the temperature, and was probably caused, at least partly, by temperature related factors.

Occurrence of moulds in drinking water.

AIMS: In order to determine the occurrence of filamentous fungi in public drinking water systems in Norway, water from 14 water supply networks from all over the country was sampled and analysed. Networks with both ground and surface water sources were included in this study. METHODS AND RESULTS: During a one-year period, 273 water samples were collected. Frequencies of fungi in samples from raw water, treated water and from home and hospital installations were determined on the basis of incubation of 100 ml membrane-filtered samples on dichloran 18% glycerol agar media. Filamentous fungi were recovered from 62% of all samples. In ground water 42.3% of the samples were positive for mould growth, while surface waters yielded 69.7% positive samples. CONCLUSIONS: The risk to recover moulds from surface water is three times higher compared with ground water. It is more likely to detect moulds in cold waters and showers than in hot waters. SIGNIFICANCE AND IMPACT OF THE STUDY: By analysing the water reaching the consumers, the results reported in present study indicate that filamentous fungi in drinking water is not negligible, and that moulds should be considered as part of the microbiological analysis parameters in drinking water.