The incidence of acute gastrointestinal illness in Sweden.

AIMS: The aim of this study was to estimate the self-reported domestic incidence of acute gastrointestinal illness in the Swedish population irrespective of route of transmission or type of pathogen causing the disease. Previous studies in Sweden have primarily focused on incidence of acute gastrointestinal illness related to consumption of contaminated food and drinking water. METHODS: In May 2009, we sent a questionnaire to 4000 randomly selected persons aged 0-85 years, asking about the number of episodes of stomach disease during the last 12 months. To validate the data on symptoms, we compared the study results with anonymous queries submitted to a Swedish medical website. RESULTS: The response rate was 64%. We estimated that a total number of 2744,778 acute gastrointestinal illness episodes (95% confidence intervals 2475,641-3013,915) occurred between 1 May 2008 and 30 April 2009. Comparing the number of reported episodes with web queries indicated that the low number of episodes during the first 6 months was an effect of seasonality rather than recall bias. Further, the result of the recall bias analysis suggested that the survey captured approximately 65% of the true number of episodes among the respondents. CONCLUSIONS: The estimated number of Swedish acute gastrointestinal illness cases in this study is about five times higher than previous estimates this study provides valuable information on the incidence of gastrointestinal symptoms in Sweden, irrespective of route of transmission, indicating a high burden of acute gastrointestinal illness, especially among children, and large societal costs, primarily due to production losses.

Cost of Illness for Five Major Foodborne Illnesses and Sequelae in Sweden.

OBJECTIVES: The main objective of this study was to derive cost estimates of five major foodborne illnesses (campylobacteriosis, salmonellosis, enterohemorrhagic Escherichia coli (EHEC), yersiniosis and shigellosis) in Sweden. These estimates provide a necessary contribution to perform future cost-benefit analyses aimed at reducing the burden of foodborne disease. A secondary aim was to obtain estimates of the true number of cases that occur in the community, thus providing necessary ground for calculating costs. METHODS: The true number of cases for each foodborne illness was simulated by multiplying the reported number of cases by sequential multipliers, one for each potential source of information loss about a case. This assessment of the true number of cases was then used to estimate the number of cases of sequelae for each illness. An incidence-based analysis was then used to calculate direct medical and non-medical costs, as well as indirect costs. Data for estimating the true number of cases for each illness were primarily based on an expert panel, while the derivation of costs mainly utilized national registries, databases and published literature. RESULTS: The estimated number of cases was between 7- and 11-fold higher than the reported number of cases, indicating the importance of taking information loss into account when calculating costs. By far the most common pathogen of the five was campylobacter, with an estimated 101,719 (90% credibility interval [CI] 59,640-158,025) human cases occurring annually. For salmonella, 19,678 (90% CI 8394-40,456) cases were estimated to occur each year, while the other three pathogens were less common, with a yearly incidence of approximately 2500-5500 cases each. The total cost for the five pathogens (including sequelae) amounted to €142 million annually. Campylobacter was the most costly pathogen, representing 69% of the total costs. Salmonellosis and EHEC constituted 18 and 9% of these costs, respectively, while yersiniosis and shigellosis represented approximately 2% each. Costs for sequelae were significant and accounted for approximately 50% of the total costs. CONCLUSIONS: Our simulations indicated that campylobacter infection was more common and more costly than salmonella, EHEC, yersinia and shigella combined. Estimated costs for all illnesses were highly influenced by (1) considering potential information losses about cases in the population (which increased costs 7- to 11-fold), and (2) taking account of post-infection sequelae (which doubled the costs).

Estimation of the expected change in domestic human salmonella cases in Sweden in 2010, given a hypothetical relaxation of the current salmonella control programme.

The Swedish salmonella control programme has been very successful in reducing the number of salmonella infections in both humans and animals. However, the costs for the control have increased and it has thus been questioned if the control measures could be relaxed and, if so, what effect this would have on human and animal health. The aim of the present study is to evaluate the expected effects on human health of a relaxation of the Swedish control i.e. a substitution of the present programme with a programme similar to the ones present in Denmark or The Netherlands. Data from the year 2010 was used to illustrate this. It was assumed that the domestic exposure to salmonella would then become the same in Sweden as it was in Denmark or the Netherlands in that year. As official statistics on the number of reported salmonella cases are not comparable across European countries, data from five different sources were used to try to obtain comparable estimates of the domestic salmonella exposure in the three countries. The study shows that the number of reported domestic human salmonella cases in Sweden in 2010 would increase by approximately 900 to 2400 cases in the Danish scenarios and 6400 to 8400 in the Dutch scenarios. Although uncertainty exists, it was concluded that the number of reported domestic salmonella cases would increase substantially in Sweden in case of a relaxation of the current control programme.

Economic effects of introducing alternative Salmonella control strategies in Sweden.

The objective of the study was to analyse the economic effects of introducing alternative Salmonella control strategies in Sweden. Current control strategies in Denmark and the Netherlands were used as benchmarks. The true number of human Salmonella cases was estimated by reconstructing the reporting pyramids for the various scenarios. Costs were calculated for expected changes in human morbidity (Salmonella and two of its sequelae), for differences in the control programmes and for changes in cattle morbidity. The net effects (benefits minus costs) were negative in all scenarios (€ -5 to -105 million), implying that it would not be cost-effective to introduce alternative control strategies in Sweden. This result was mainly due to an expected increase in the incidence of Salmonella in humans (6035-57108 reported and unreported new cases/year), with expected additional costs of € 5-55 million. Other increased costs were due to expected higher incidences of sequelae (€ 3-49 million) and a higher cattle morbidity (€ 4-8 million). Benefits in terms of lower control costs amounted to € 4-7 million.

Willingness to pay for compulsory deworming of pets entering Sweden to prevent introduction of Echinoccoccus multilocularis.

To investigate if the Swedish entry rules for pets to prevent the introduction of Echinococcus multilocularis (EM) are proportional (i.e. that their costs do not exceed the value of their benefits), a dichotomous-choice contingent valuation study was conducted. The study was performed before the first case of EM was detected in Sweden in February 2011. About 5000, randomly selected, Swedish citizens were invited to participate and 2192 of them (44%) accepted to do so. Missing information on whether or not one would accept to pay for keeping the rules for 143 respondents resulted in 2049 observations (41%) available for the estimation of willingness to pay (WTP), and missing information on personal characteristics for another 274 respondents reduced the number of observations available for sensitivity analysis to 1775 (36%). Annual expected WTP for keeping the rules ranged between € 54.3 and € 99.0 depending on assumptions about compensations demanded by respondents not willing to pay. The estimates are conservative since only answers from respondents that were absolutely certain they would pay the suggested bid were regarded as yes-responses. That WTP is positive implies that Swedish citizens perceived the benefits of the rules to be larger than their costs.