Publications (19)96.85 Total impact
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Article: Eye-opening approach to norovirus surveillance.
Emerging Infectious Diseases 08/2010; 16(8):1319-21. · 6.79 Impact Factor -
Article: Genetic diversity among food-borne and waterborne norovirus strains causing outbreaks in Sweden.
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ABSTRACT: A total of 101 food-borne and waterborne outbreaks that were caused by norovirus and that resulted in more than 4,100 cases of illness were reported to the Swedish Institute for Infectious Disease Control from January 2002 to December 2006. Sequence and epidemiological data for isolates from 73 outbreaks were analyzed. In contrast to health care-related outbreaks, no clear seasonality could be observed. Sequence analysis showed a high degree of genetic variation among the noroviruses detected. Genogroup II (GII) viruses were detected in 70% of the outbreaks, and of those strains, strains of GII.4 were the most prevalent and were detected in 25% of all outbreaks. The GII.4 variants detected in global outbreaks in health care settings during 2002, 2004, and 2006 were also found in the food-borne outbreaks. GI strains totally dominated as the cause of water-related (drinking and recreational water) outbreaks and were found in 12 of 13 outbreaks. In 14 outbreaks, there were discrepancies among the polymerase and capsid genotype results. In four outbreaks, the polymerase of the recombinant GII.b virus occurred together with the GII.1 or GII.3 capsids, while the GII.7 polymerase occurred together with the GII.6 and GII.7 capsids. Mixed infections were observed in six outbreaks; four of these were due to contaminated water, and two were due to imported frozen berries. Contaminated food and water serve as important reservoirs for noroviruses. The high degree of genetic diversity found among norovirus strains causing food-borne and waterborne infections stresses the importance of the use of broad reaction detection methods when such outbreaks are investigated.Journal of clinical microbiology 07/2009; 47(8):2411-8. · 4.16 Impact Factor -
Article: Norovirus strains belonging to the GII.4 genotype dominate as a cause of nosocomial outbreaks of viral gastroenteritis in Sweden 1997--2005. Arrival of new variants is associated with large nation-wide epidemics.
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ABSTRACT: In recent years an increase of the incidence of nosocomial outbreaks caused by noroviruses has been observed throughout Sweden, with high peaks noted in the winter seasons 2002/2003 and 2004/2005, respectively. To phylogenetically characterize norovirus strains causing nosocomial outbreaks from 1997 to 2005 and estimate the impact of norovirus-like disease on the Swedish health care system during the peak season 2002/2003 when a new variant of norovirus occurred. Stool samples from 115 randomly selected nosocomial outbreaks occurring during 1997--2005 throughout Sweden were studied by RT-PCR and sequencing. In addition, to investigate the impact on the health-care system, a questionnaire was distributed to infection control units (n=90) serving all Swedish hospitals, nursing homes and other health-care institutions during the largest epidemic of nosocomial outbreaks. Sequencing of 279 nucleotides of the norovirus RNA polymerase gene in stools containing norovirus RNA showed that strains belonging to the GII.4 genotype dominated. Each of the two large epidemics was due to a new variant within this cluster. The questionnaire revealed that 30,000-35,000 episodes of nosocomial norovirus-like infections occurred in 80 of 82 major Swedish hospitals affected in 2002/2003. New norovirus variants within the cluster GGII.4 may have a major impact on the health-care system.Journal of Clinical Virology 07/2008; 42(2):129-34. · 3.97 Impact Factor -
Article: Outbreak of Salmonella Thompson infections linked to imported rucola lettuce.
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ABSTRACT: On November 15, 2004, a cluster of three cases of Salmonella Thompson infection was registered by the Norwegian reference laboratory. In the following days further cases occurred, prompting a case-control study among the first 13 cases and 26 matched controls. By December 31, 21 cases had been reported, with the first onset on October 24. Consumption of rucola lettuce (Eruca sativa, also known as rocket salad or arugula) (OR 8,8 [1,2-infinity]) and mixed salad (OR 5,0 [1,0-infinity]) was associated with illness. On November 26, Swedish authorities notified the finding of Salmonella Thompson in rucola lettuce through the EU Rapid Alert System for Food and Feed. Later, several countries reported finding this and other Salmonella serovars and Campylobacter in rucola produced in Italy. In response to our alert through the international Enter-net surveillance network, Sweden and England also reported an increase of cases. Salmonella Thompson isolates from products and patients from several countries showed high similarity by pulsed-field gel electrophoresis, but some isolates showed significant differences. We think that the outbreak in Norway reflected a larger international outbreak caused by rucola imported from one Italian producer. Findings of other pathogens indicate a massive contamination, possibly caused by irrigation with nonpotable water. Rapid international information exchange is invaluable when investigating outbreaks caused by internationally marketed products.Foodborne Pathogens and Disease 05/2008; 5(2):165-73. · 2.26 Impact Factor -
Article: Outbreak of norovirus in Västra Götaland associated with recreational activities at two lakes during August 2004.
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ABSTRACT: A large community outbreak of norovirus (NV) gastrointestinal infection occurred in Västra Götaland County, Sweden in August 2004, following attendance at recreational lakes. A frequency age-matched case control study was undertaken of persons who had attended these lakes to identify risk factors. 163 cases and 329 controls were included. Analysis indicates that having water in the mouth while swimming (OR=4.7; 95% CI 1.1-20.2), attendance at the main swimming area at Delsjön Lake (OR=25.5; 95% CI 2.5-263.8), taking water home from a fresh water spring near Delsjön lake (OR=17.3; 95% CI 2.7-110.7) and swimming less than 20 m from shore (OR=13.4; 95% CI 2.0-90.2) were significant risk factors. The probable vehicle was local contamination of the lake water (especially at the main swimming area). The source of contamination could not be determined.Scandinavian Journal of Infectious Diseases 02/2007; 39(4):323-31. · 1.72 Impact Factor -
Article: The epidemiology of travel-associated shigellosis--regional risks, seasonality and serogroups.
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ABSTRACT: To give a detailed risk estimate of contracting travel-associated shigellosis in various regions of the world. Data on notifications of travel-associated shigellosis in Sweden 1997-2003 were compared with information on recent travel abroad from a comprehensive database based on telephone interviews with more than 160,000 Swedish travellers. From the national notification database 2678 patients with travel-associated shigellosis were retrieved. The highest risk of being notified with shigellosis was seen in returning travellers from India and neighbouring countries (318/100,000 travellers), East Africa (219/100,000), West Africa (120/100,000), and North Africa (76/100,000). Data on serogroup was available for 2529 isolates. Shigella sonnei was the most common serogroup (67%), followed by Shigella flexneri (26%), Shigella boydii (5%), and Shigella dysenteriae (3%). A higher risk was seen in children below the age of six, compared to older children and adults and in women compared to men. A distinct seasonal pattern was noted with the highest risk of shigellosis in July-October and the lowest in May. Denominator based data on reported travel-associated infections are well suited to give risk estimates per region of infection, that could be used to target high-risk groups for pre-travel advice.The Journal of infection 11/2005; 51(3):222-9. · 4.13 Impact Factor -
Article: Imported giardiasis: impact of international travel, immigration, and adoption.
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ABSTRACT: From the Swedish national database, regarding notified Giardia cases, we could for the period 1997-2003 identify 3,697 cases of travel-associated giardiasis, 4,151 cases in newly arrived immigrants and refugees, and 455 cases in internationally adopted children. These were compared with data sets on the number of international travelers, immigrants/refugees, and adopted children. The overall risk of being notified with giardiasis in returning travelers was 5.3 of 100,000, with the highest incidences in travelers from the Indian Subcontinent (628 of 100,000), East Africa (358 of 100,000), and West Africa (169 of 100,000). A large proportion of the travel-related cases were seen in persons with family roots in the country of infection-a risk group deserving special attention. The overall risk in immigrants and refugees was 1,180/100,000 with the highest risk in persons from Afghanistan (3,800 of 100,000) and Iraq (2,990 of 100,000). The incidence was highest among internationally adopted children (8,110 of 100,000), with geographical risks not entirely correlating to those in travelers and immigrants.The American journal of tropical medicine and hygiene 07/2005; 72(6):825-30. · 2.59 Impact Factor -
Article: Effect of regulation and education on reptile-associated salmonellosis.
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ABSTRACT: Reptiles have become increasingly common as domestic pets, and with them reptile-associated Salmonella infections in humans. From 1990 to 2000, a total of 339 reptile-associated Salmonella cases were reported in Sweden. In 1996, as part of its efforts to adapt its import regulations to those of the European Union, Sweden no longer required certificates stating that imported animals were free of Salmonella. A subsequent increase was noted in the incidence of reptile-associated cases from 0.15/100,000 in the period 1990-1994 to 0.79/100,000 in 1996 and 1997. After a public education campaign was begun through the news media, the incidence dropped to 0.46/100,000. Children were the most affected age group among patients (incidence 1.3/100,000). Salmonella enterica serotype Enteritidis was the most frequent serotype (24% of isolates), followed by S. Typhimurium (9% of isolates). Import restrictions and public information campaigns are effective public health measures against reptile-associated salmonellosis.Emerging infectious diseases 04/2005; 11(3):398-403. · 6.17 Impact Factor -
Article: International outbreak of Salmonella Oranienburg due to German chocolate.
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ABSTRACT: This report describes a large international chocolate-associated Salmonella outbreak originating from Germany. We conducted epidemiologic investigations including a case-control study, and food safety investigations. Salmonella (S.) Oranienburg isolates were subtyped by the use of pulsed-field gel electrophoresis (PFGE). From 1 October 2001 through 24 March 2002, an estimated excess of 439 S. Oranienburg notifications was registered in Germany. Simultaneously, an increase in S. Oranienburg infections was noted in other European countries in the Enter-net surveillance network. In a multistate matched case-control study in Germany, daily consumption of chocolate (matched odds ratio [MOR]: 4.8; 95% confidence interval [CI]: 1.3-26.5), having shopped at a large chain of discount grocery stores (MOR: 4.2; CI: 1.2-23.0), and consumption of chocolate purchased there (MOR: 5.0; CI: 1.1-47.0) were associated with illness. Subsequently, two brands from the same company, one exclusively produced for that chain, tested positive for S. Oranienburg. In two other European countries and in Canada chocolate from company A was ascertained that also contained S. Oranienburg. Isolates from humans and from chocolates had indistinguishable PFGE profiles. No source or point of contamination was identified. Epidemiological identification of chocolate as a vehicle of infections required two months, and was facilitated by proxy measures. Despite the use of improved production technologies, the chocolate industry continues to carry a small risk of manufacturing Salmonella-containing products. Particularly in diffuse outbreak-settings, clear associations with surrogates of exposure should suffice to trigger public health action. Networks such as Enter-net have become invaluable for facilitating rapid and appropriate management of international outbreaks.BMC Infectious Diseases 03/2005; 5:7. · 3.12 Impact Factor -
Article: Could flies explain the elusive epidemiology of campylobacteriosis?
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ABSTRACT: Unlike salmonellosis with well-known routes of transmission, the epidemiology of campylobacteriosis is still largely unclear. Known risk factors such as ingestion of contaminated food and water, direct contact with infected animals and outdoor swimming could at most only explain half the recorded cases. We put forward the hypothesis that flies play a more important role in the transmission of the bacteria, than has previously been recognized. Factors supporting this hypothesis are: 1) the low infective dose of Campylobacter; 2) the ability of flies to function as mechanical vectors; 3) a ubiquitous presence of the bacteria in the environment; 4) a seasonality of the disease with summer peaks in temperate regions and a more evenly distribution over the year in the tropics; 5) an age pattern for campylobacteriosis in western travellers to the tropics suggesting other routes of transmission than food or water; and finally 6) very few family clusters. All the evidence in favour of the fly hypothesis is circumstantial and there may be alternative explanations to each of the findings supporting the hypothesis. However, in the absence of alternative explanations that could give better clues to the evasive epidemiology of Campylobacter infection, we believe it would be unwise to rule out flies as important mechanical vectors also of this disease.BMC Infectious Diseases 02/2005; 5:11. · 3.12 Impact Factor -
Article: Risk factors for domestic sporadic campylobacteriosis among young children in Sweden.
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ABSTRACT: A case-control study was conducted in Sweden to study risk factors for domestically acquired Campylobacter jejuni/coli infections among children aged less than 6 y. A total of 126 cases, reported to the national surveillance system were recruited over 1 y. Controls, selected from the population register, were matched to the cases by age, gender, place of residence and time of infection of the case. Information was gathered by posted questionnaires. Two separate conditional regression models were developed including and excluding 'protective' factors. Two of the factors significantly associated with Campylobacter infection were water-related: having a well in the household (OR=2.6) and drinking water from a lake/river (OR=7.4; 6.0). Other exposures associated with increased risk were: having a dog (OR=8.4; 3.8) and eating grilled meat (OR=5.5; 2.1). Drinking unpasteurized milk was borderline significant in 1 model (OR=3.7). Eating sausage was protective (OR=0.05). Eating chicken was not a significant risk. Exposures such as eating grilled meat and drinking water from a lake or a river were more common in the warm months, a factor that may partly explain the observed seasonality. The authors suggest that differences between risk factors across studies may reflect geographical and age-specific differences in the sources of infection.Scandinavian Journal of Infectious Diseases 02/2005; 37(2):101-10. · 1.72 Impact Factor -
Article: Regional risks and seasonality in travel-associated campylobacteriosis.
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ABSTRACT: The epidemiology of travel-associated campylobacteriosis is still largely unclear, and various known risk factors could only explain limited proportions of the recorded cases. Using data from 28,704 notifications of travel-associated campylobacteriosis in Sweden 1997 to 2003 and travel patterns of 16,255 Swedish residents with overnight travel abroad in the same years, we analysed risks for travel-associated campylobacteriosis in 19 regions of the world, and looked into the seasonality of the disease in each of these regions. The highest risk was seen in returning travellers from the Indian subcontinent (1,253/100,000 travellers), and the lowest in travellers from the other Nordic countries (3/100,000 travellers). In Africa, large differences in risk between regions were noted, with 502 /100,000 in travellers from East Africa, compared to 76/100,00 from West Africa and 50/100,000 from Central Africa. A distinct seasonal pattern was seen in all temperate regions with peaks in the summer, while no or less distinct seasonality was seen in tropical regions. In travellers to the tropics, the highest risk was seen in children below the age of six. Data on infections in returning travellers together with good denominator data could provide comparable data on travel risks in various regions of the world.BMC Infectious Diseases 12/2004; 4(1):54. · 3.12 Impact Factor -
Article: Emergence of new Salmonella Enteritidis phage types in Europe? Surveillance of infections in returning travellers.
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ABSTRACT: Among human Salmonella Enteritidis infections, phage type 4 has been the dominant phage type in most countries in Western Europe during the last years. This is reflected in Salmonella infections among Swedish travellers returning from abroad. However, there are differences in phage type distribution between the countries, and this has also changed over time. We used data from the Swedish infectious disease register and the national reference laboratory to describe phage type distribution of Salmonella Enteritidis infections in Swedish travellers from 1997 to 2002, and have compared this with national studies conducted in the countries visited. Infections among Swedish travellers correlate well with national studies conducted in the countries visited. In 2001 a change in phage type distribution in S. Enteritidis infections among Swedish travellers returning from some countries in southern Europe was observed, and a previously rare phage type (PT 14b) became one of the most commonly diagnosed that year, continuing into 2002 and 2003. Surveillance of infections among returning travellers can be helpful in detecting emerging infections and outbreaks in tourist destinations. The information needs to be communicated rapidly to all affected countries in order to expedite the implementation of appropriate investigations and preventive measures.BMC Medicine 10/2004; 2:32. · 6.03 Impact Factor -
Article: Emerging genotype (GGIIb) of norovirus in drinking water, Sweden.
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ABSTRACT: From May through June 2001, an outbreak of acute gastroenteritis that affected at least 200 persons occurred in a combined activity camp and conference center in Stockholm County. The source of illness was contaminated drinking water obtained from private wells. The outbreak appears to have started with sewage pipeline problems near the kitchen, which caused overflow of the sewage system and contaminated the environment. While no pathogenic bacteria were found in water or stools specimens, norovirus was detected in 8 of 11 stool specimens and 2 of 3 water samples by polymerase chain reaction. Nucleotide sequencing of amplicons from two patients and two water samples identified an emerging genotype designated GGIIb, which was circulating throughout several European countries during 2000 and 2001. This investigation documents the first waterborne outbreak of viral gastroenteritis in Sweden, where nucleotide sequencing showed a direct link between contaminated water and illness.Emerging infectious diseases 01/2004; 9(12):1548-52. · 6.17 Impact Factor -
Article: Emergence of new Salmonella Enteritidis phage types in Europe? Surveillance of infections in returning travellers
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ABSTRACT: Abstract Background Among human Salmonella Enteritidis infections, phage type 4 has been the dominant phage type in most countries in Western Europe during the last years. This is reflected in Salmonella infections among Swedish travellers returning from abroad. However, there are differences in phage type distribution between the countries, and this has also changed over time. Methods We used data from the Swedish infectious disease register and the national reference laboratory to describe phage type distribution of Salmonella Enteritidis infections in Swedish travellers from 1997 to 2002, and have compared this with national studies conducted in the countries visited. Results Infections among Swedish travellers correlate well with national studies conducted in the countries visited. In 2001 a change in phage type distribution in S. Enteritidis infections among Swedish travellers returning from some countries in southern Europe was observed, and a previously rare phage type (PT 14b) became one of the most commonly diagnosed that year, continuing into 2002 and 2003. Conclusions Surveillance of infections among returning travellers can be helpful in detecting emerging infections and outbreaks in tourist destinations. The information needs to be communicated rapidly to all affected countries in order to expedite the implementation of appropriate investigations and preventive measures.BMC Medicine. 01/2004; -
Article: Detection of a previously uncommon salmonella phage in tourists returning from Europe.
The Lancet 08/2002; 360(9327):175. · 38.28 Impact Factor -
Article: [Giardiasis as differential diagnosis in diarrhea outbreaks in child day centers. Written hygienic guidelines and adequate testing can reduce the transmission].
Lakartidningen 104(7):500-3. -
Article: Risk of travel-associated typhoid and paratyphoid fevers in various regions.
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ABSTRACT: Although enteric fever (typhoid and paratyphoid fevers) is a major global public health problem, comparable data on the risks of contracting travel-associated enteric fever in various regions of the world are scarce. From the Swedish database on notifiable communicable diseases, we retrieved all case records from 1997 to 2003 on typhoid and paratyphoid fevers. The data set was compared with data on travel patterns obtained from a comprehensive travel database with information from interviews with more than 16,000 Swedish residents with recent overnight travel outside Sweden. The overall risk of being notified with enteric fever after travel was 0.42 in 100,000 travelers. The highest risk for typhoid fever was seen in travelers from India and neighboring countries (41.7 in 100,000), the Middle East (5.91 in 100,000), and Central Africa (3.33 in 100,000), whereas the risk was comparatively low in East Asia (0.24 in 100,000). Almost the same risk areas stood out for paratyphoid fever: India and neighbors (37.5 in 100,000), the Middle East (3.64 in 100,000), and East Africa (3.33 in 100,000). The epidemiology of paratyphoid fever was considerably affected by a large outbreak of paratyphoid B in a Turkish tourist resort in 1999. The youngest children were at highest risk for typhoid fever (odds ratio 44.2), whereas youths ages 7 to 18 years were at highest risk for paratyphoid fever (odds ratio 9.7). Detailed risk data for enteric fever after travel could form the basis for travel advice. Vaccination against typhoid fever should always be considered for travelers to the Indian subcontinent, the Middle East, and Africa but should not routinely be given to travelers to the Malay Peninsula.Journal of Travel Medicine 12(4):197-204. · 1.75 Impact Factor -
Article: Hepatitis A risk in travelers.
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ABSTRACT: Traveling to highly endemic areas for hepatitis A is increasing while the immunization level in travelers has been shown to be low in the countries studied. In this population-based study, we have estimated the incidence rate of travel-related hepatitis A during 1997 to 2005 by use of the Swedish notification system of communicable diseases and an ongoing national database on travel patterns. We have also acquired airport-based immunization data from 2007. During the study period, 636 cases of travel-related hepatitis A were notified. Traveling to East Africa was associated with the highest incidence rate (14.1 cases/100,000 person months), followed by the Middle East (5.8/100,000 person months), and India with neighboring countries (5.6/100,000 person months). Visiting Friends and Relatives (VFR) travelers represented 83, 91, and 70% of the cases to these three regions. By age-group, the highest incidence was found in children 0 to 14 years (3.1/100,000 travelers) where 88% of the cases were VFR travelers. Incidence rate in unprotected travelers to East Asia, North Africa, and the Middle East was 2, 12, and 18 cases/100,000 person months, respectively. In 2007, 79% of the travelers were immunized against hepatitis A. We conclude that travelers, and especially children, who are VFR in endemic areas constitute a high-risk group for acquiring hepatitis A infection, while the risk for unprotected tourists to East Asia is low.Journal of Travel Medicine 16(4):233-8. · 1.75 Impact Factor
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Institutions
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2004–2005
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Swedish Institute for Communicable Disease Control
Stockholm, Stockholm, Sweden
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