Risk factors and potential preventive measures for nephropatia epidemica in Sweden 2011-2012: a case-control study.

INTRODUCTION: Nephropatia epidemica (NE), a relatively mild form of hemorrhagic fever with renal syndrome caused by the Puumala virus (PUUV), is endemic in northern Sweden. We aim to study the risk factors associated with NE in this region. METHODS: We conducted a matched case-control study between June 2011 and July 2012. We compared confirmed NE cases with randomly selected controls, matched by age, sex, and place of infection or residence. We analyzed the association between NE and several occupational, environmental, and behavioral exposures using conditional logistic regression. RESULTS: We included in the final analysis 114 cases and 300 controls, forming 246 case-control pairs. Living in a house with an open space beneath, making house repairs, living less than 50 m from the forest, seeing rodents, and smoking were significantly associated with NE. CONCLUSION: Our results could orient public health policies targeting these risk factors and subsequently reduce the NE burden in the region.

Improved partner notification for genital chlamydia can be achieved by centralisation of the duty to a specially trained team.

Partner notification is mandatory for Chlamydia trachomatis infections in Sweden. A significant quality improvement of partner notification for genital chlamydia was achieved by increasing the skills and reducing the number of individuals conducting partner notifications. By centralisation of the partner notification to a specially trained team of nurses, an additional 12% of genital chlamydia cases were found. Routine partner notification achieved a score of 3.3 notified partners per index case, and shows how important this activity is for detection of asymptomatic chlamydia infections in the community.

Occurrence of genetic variants of Listeria monocytogenes strains.

Isolates of Listeria monocytogenes saved from outbreaks of listeriosis, cases of sporadic listeriosis, and similar events do not always belong to a solitary genetic variant. Variants of the same strain may have evolved from a unique clone, and plasmid loss or gain and phage-mediated genetic changes are suggested as the main mechanism. Some of these reports are summarized in this short communication.

Prevalence trends of the new variant of Chlamydia trachomatis in four counties of Sweden in 2007-2011.

A new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden in 2006, and it could not be detected by diagnostic systems from Abbott and Roche, whereas the third system used, from Becton Dickinson (BD), detects nvCT. We analyzed 3648 samples from 2 counties that used Roche and 2 counties that used BD methods from 2007 to 2011. After implementation of a Roche method that detects nvCT, its proportion has decreased and converged in the 4 counties but are still at different levels in Roche and BD counties. Future studies are needed to see if nvCT will decline further.

Pharyngeal Chlamydia trachomatis is not uncommon any more.

BACKGROUND: The significance of Chlamydia trachomatis (Ct) infection in the pharynx, and possible symptoms, are under discussion. Most studies have involved only homo/bisexual men. We report findings of pharyngeal Ct (PhCt) infections in patients with long-lasting throat discomfort and the prevalence of PhCt in genitally Ct-infected young people in a Swedish primary care setting. METHOD: Sub-study 1 (SS1) included 48 persons aged 15-35 y, with pharyngeal discomfort for more than 14 days. Sub-study 2 (SS2) included 150 persons, aged 15-35 y, with genital Ct. Questionnaires concerning symptoms, sexual behaviour and sexual identity were completed for both groups. Samples for Ct testing were taken from the pharynx, and in SS1, samples were also collected to ascertain genital Ct. RESULTS: In SS1, 2 of 48 persons (4%) with pharyngeal discomfort had PhCt. In all, 35 of the 48 persons (73%) included in SS1 reported unprotected oral sex during the previous year. In SS2, 11 of 92 women (12%) and 4 of 58 men (7%) tested positive for PhCt. More women (94%) than men (83%) had given unprotected oral sex. Persons with PhCt had more symptoms from the upper respiratory tract (p = 0.04). CONCLUSIONS: Some primary care patients with long-lasting throat discomfort have a PhCt infection. PhCt infection is not uncommon in genitally infected sexually active people. More heterosexual women than heterosexual men had given unprotected oral sex and were infected by Ct in the pharynx. Thus, research on PhCt should not focus on homo/bisexual men only. Information about Ct should include the risk of contracting a PhCt infection as well as a gender perspective.

Spatial bridges and the spread of Chlamydia: the case of a county in Sweden.

OBJECTIVES: The so-called small-world effect can have a great impact on efforts to control the incidence and prevalence of sexually transmitted infections. This is because a small number of so-called spatial bridgers (individuals who, through sexual contacts, interconnect geographically distant areas) can drastically lower the average path length in the sexual network and, as a result, make locally based intervention programs much less effective. The objectives of this study were to analyze the sociodemographic characteristics of these bridgers and to compare the result with the remaining study population. The purpose was to determine whether it is possible to identify them for targeted intervention programs. STUDY DESIGN: During 2001, contact tracing was performed in approximately 98% of all cases with positive test results in Värmland County. The sexual networks obtained constituted a study population of 851 individuals. Statistical analysis was used to characterize individuals engaged in spatial bridging behavior. RESULTS: Approximately 8% of the study population was characterized as spatial bridgers. Using multivariate analysis, we found almost no significant differences between these individuals and the rest of the study population when it came to sociodemographic variables, including education, economy, and ethnicity. CONCLUSION: The number of spatial bridgers is high enough to create a small-world network with links that can fuel the endemic chlamydia in Värmland County. Sociodemographic information could not be used to characterize spatial bridgers. In interventions against chlamydia, spatial bridgers shall be considered as potentially important for sustaining the disease.

Improved contact tracing of Chlamydia trachomatis in a Swedish county--is genotyping worthwhile?

The vast majority of genital Chlamydia trachomatis infections are non-symptomatic or mildly symptomatic. Efficient contact tracing and screening programmes are the most effective means to reveal these infections. We conducted a prospective study on the effects of contact tracing performed by specially trained midwives in a centralized municipality-based organization during one year. In order to improve the efficiency of the contact tracing, all C. trachomatis-positive isolates in the county during one year were typed by sequencing the ompA gene. Contact tracing in two municipalities the year prior to the study revealed 1.6 partners for each index case (n = 110). The corresponding figure for the whole county during the study period was 2.1 partners per index case (n = 2065). Genotyping added valuable information in mapping individual sexual networks, but was not essential for achieving satisfactory contact tracing results.

Characterization of ompA genotypes by sequence analysis of DNA from all detected cases of Chlamydia trachomatis infections during 1 year of contact tracing in a Swedish County.

In this study we aimed to characterize the ompA gene by sequencing DNA from all detected cases of Chlamydia trachomatis infection in a Swedish county during 2001, in order to improve the efficiency of contact tracing. Approximately 990 bp of the ompA gene was amplified, and sequence analysis was achieved in 678 (94%) of 725 C. trachomatis-positive cases in this unselected population. The most prevalent genotype was serotype E (39%), followed by F (21%), G (11%), D (9%), K (9%), J (7%), H (2%), B (1%), and Ia (1%). Serotype E was found in five genotype variants, with the reference sequence comprising 96% of all E cases. Serotype D was the most variable, and of seven sequence variants, three were identified as recombinants with serotype E. Altogether 29 genetic variants were detected, and mutations and recombination events are discussed. Clinical manifestations were not associated with genotypes. Sequence variation was linked to sexual networks identified by contact tracing and improved epidemiological knowledge but was of limited benefit.

Antibiotic resistance among Campylobacter jejuni/coli strains acquired in Sweden and abroad: a longitudinal study.

Antibiotic resistance was compared in 844 Campylobacter jejuni/coli strains acquired outside Sweden and 575 acquired in Sweden during 1990-2002. There was a clear gradual increase in ciprofloxacin and tetracycline resistance among C. jejuni/coli strains acquired outside Sweden during the 13 y period. This trend was not seen for erythromycin or in domestically acquired strains for any of the 3 antibiotics tested.

Intrafamilial spread of highly virulent staphylococcus aureus strains carrying the gene for Panton-Valentine leukocidin.

Necrotizing pneumonia caused by Staphylococcus aureus carrying the gene for Panton-Valentine leukocidin is a newly described disease entity. We report 2 cases with intrafamilial spread.