Karl Ekdahl

Duration of Nasopharyngeal Carriage of Penicillin-Resistant Streptococcus pneumoniae: Experiences from the South Swedish Pneumococcal Intervention Project

As a part of an intervention project, all detected carriers of penicillin-resistant pneumococci (PRP) (MIC, > or = 0.5 mg/L) in Malmöhus County, southern Sweden, were followed by means of weekly nasopharyngeal cultures. The median duration of carriage in 678 individuals was 19 days (range, 3-267 days). The duration of carriage was longest in children < 1 year old (median, 30 days) and shortest in adults > 18 years old (median, 14 days). Index cases, whose cultures were performed during an acute infection, were carriers for a mean of 10 days longer than asymptomatic contact cases (P < .05). The PRP spontaneously disappeared from the nasopharynx within 4 weeks in 68%, within 8 weeks in 87%, and within 12 weeks in 94% of the individuals. Other significant risk factors for prolonged carriage were the occurrence of > 6 episodes of acute otitis media (AOM) or first episode of AOM before the age of 1 year (P < .01), the carriage of PRP by other family members (P < .05), and the obtainment of a first positive culture during the winter months (P < .05).

Non‐Hodgkin's lymphoma and other nonhepatic malignancies in Swedish patients with hepatitis C virus infection

The aim of this study was to evaluate the association between hepatitis C virus (HCV) infection and non‐Hodgkins lymphoma (NHL), multiple myeloma (MM), thyroid cancer (TC), chronic lymphatic leukemia (CLL), acute lymphatic leukemia (ALL), and Hodgkins lymphoma (HL). A Swedish cohort of 27,150 HCV‐infected persons notified during 1990‐2000 was included in the study. The database was linked to other national registers to calculate the observation time, expressed as person‐years, and to identify all incident malignancies in the cohort. The patients were stratified according to assumed time of previous HCV infection. The relative risk of malignancy was expressed as a standardized incidence ratio (SIR)—the observed number compared to the expected number. During 1990‐2000 there were 50 NHL, 15 MM, 14 ALL, 8 TC, 6 CLL, and 4 HL diagnoses in the cohort. Altogether, 20 NHL, 7 MM, 5 TC, 4 CLL, 1 ALL, and 1 HL patient fulfilled the criteria to be included in the statistical analysis. The observation time was 122,272 person‐years. The risk of NHL and MM was significantly increased in the stratum with more than 15 years of infection (SIR 1.89 [95% CI, 1.10‐3.03] and 2.54 [95% CI, 1.11‐5.69], respectively). The association was not significant in TC or CLL. In conclusion, we report the incidence of several malignancies in a nationwide cohort of HCV‐infected persons. Although the delayed diagnosis of HCV probably has resulted in an underestimation of the risk, this study showed a significantly increased risk of NHL and MM. (HEPATOLOGY 2005;41:652–659.)

Short- and Long-term Effects of Bacterial Gastrointestinal Infections

Bacterial gastrointestinal infections are associated with short- and long-term complications from several organ systems.

Age- and Serogroup-Related Differences in Observed Durations of Nasopharyngeal Carriage of Penicillin-Resistant Pneumococci

ABSTRACT Using data from an ongoing Swedish intervention project, the observed durations of nasopharyngeal carriage of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) (MIC of penicillin G of ≥0.5 μg/ml) stratified by both pneumococcal serogroup and age of the carrier were compared. The means and 95% confidence intervals (CIs) were estimated by fitting a gamma distribution to the observed duration of carriage for each age and serogroup stratum. The mean observed duration of carriage for all cases was 37 days (95% CI, 35 to 38 days). Children below the age of 5 years carried PNSP for significantly longer periods (43 days; 95% CI, 41 to 45 days) compared with older individuals (25 days; 95% CI, 24 to 27 days). There were also differences within the group of cases below the age of 5 years, as the duration of carriage became significantly shorter for each increasing age step: <1, 1 to 2, and 3 to 4 years. In addition, patients <5 years of age carried serogroups 9 and 14 for significantly shorter periods than groups 6 and 23. Serogroup 9 was also carried for significantly shorter periods than group 19. For patients aged 5 years or older, no significant difference in carriage duration for different ages or serogroups could be noted. As young children have the longest duration of PNSP carriage, interventions aiming to reduce the prevalence in this group are of great importance. The results highlight the importance of taking both serogroup and age of the carriers into account when studying the dynamics of pneumococcal transmission in young children.

Frequency of penicillin-resistant pneumococci in children is correlated to community utilization of antibiotics.

OBJECTIVE To study the impact of the utilization of antibiotics in children at the population level on the frequency of penicillin-nonsusceptible pneumococci (PNSP). DESIGN Children ages 0 to 6 years with a nasopharyngeal culture of PNSP were registered on place of residency in the 20 municipalities of the former Malmöhus County (since 1998 a part of Skåne County). Where possible the total number of nasopharyngeal cultures with growth of pneumococci was registered as well. All antibiotic prescriptions for 0- to 6-year-old children were analyzed in the 20 municipalities. MAIN OUTCOME MEASURES Correlation between the utilization of antibiotics and the frequency of PNSP in children at the municipality level. RESULTS The proportion of PNSP among all isolates of pneumococci from nasopharyngeal cultures varied between 0 and 49.5%. The antibiotic utilization in children varied among the 20 neighboring municipalities from 8.5 to 19.7 defined daily doses per 1000 children per day. The municipalities with high total utilization also had more frequent use of macrolides and broad spectrum antibiotics. The was a significant correlation between antibiotic use and the proportion of PNSP (correlation coefficient, 0.96; P = 0.002), and the correlation coefficients for trimethoprim-sulfamethoxazole, amoxicillins, macrolides and cephalosporins were significant at the 0.001 level. There was no significant correlation between the use of penicillin V and the frequency of PNSP. CONCLUSIONS. There was a significant correlation between the frequency of PNSP and the utilization of antibiotics in children at the population level.

Malaria risk in travelers.

Malaria risk around the world was assessed by using Swedish surveillance data from 1997 to 2003 with an extensive travel database as denominator.

Is the Increase in Notifications of Chlamydia trachomatis Infections in Sweden the Result of Changes in Prevalence, Sampling Frequency or Diagnostic Methods?

Based on clinical and laboratory surveillance data, trends in the incidence rates of genital Chlamydia trachomatis infections in Sweden between 1991 and 1999 were analysed according to age group and sex. The influence of changes in laboratory methods on the reported infections was assessed. After a decrease in the incidence rate of infection of 36% between 1991 and 1994, followed by a period of stability, a 20% increase was observed between 1997 and 1999 (from 157 to 189/100,000). Between 1991 and 1999 the female:male ratio decreased from 1.7 to 1.4. Incidence rates started to increase in 1994 in the 15-19 y age group for both sexes. Crude Chlamydia positivity increased from 4.1% (352,050 people tested) in 1994 to 5.4% (305,946 people tested) in 1999. This increase in Chlamydia positivity was seen both in laboratories that had changed to more sensitive methods and in those that had not. Changes in laboratory methods can therefore only partially explain the increase in notified cases. Increased screening of men may have contributed to the increase, but rising incidence rates in all young age groups of both sexes suggest a true increase in prevalence.

Clinical Spectrum and Transmission Characteristics of Infection with Norwalk-Like Virus: Findings from a Large Community Outbreak in Sweden

A large foodborne outbreak caused by Norwalk-like virus (NLV) among children and staff at 30 day care centers provided an opportunity to study symptomatology and attack rates among patients in different age groups, as well as secondary transmission rates in centers and households. A retrospective cohort study of 775 subjects from 13 randomly chosen centers was performed. Diarrhea was more common in adults than in children (P=.001), whereas the reverse was noted with regard to vomiting (P=.003). The primary attack rate was 27% (142 of 524 subjects): 54% of adults versus 19% of children (P<.001). The mean incubation time for foodborne cases of infection was 34 hours. The secondary attack rate was 17%. Risk factors for spread into households were the primary case being a child (relative risk [RR], 3.8; 95% confidence interval [CI], 1.9-7.6) and vomiting (RR, 2.4; 95% CI, 1.0-5.5). The incubation time for person-to-person transmission was approximated by a mean serial interval of 52 hours. This is the first reported outbreak of NLV infection in which secondary transmission into households by individuals has been studied.

A Meta-Analysis on the Effects of Antibiotic Treatment on Duration of Symptoms Caused by Infection with Campylobacter Species

Eleven randomized, controlled trials of antibiotic treatment versus placebo in patients with Campylobacter species infection were pooled in a meta-analysis. Antibiotic treatment shortened the duration of intestinal symptoms by 1.32 days (95% confidence interval, 0.64-1.99; P<.0001). Because of problems with drug resistance, a restrictive attitude towards the administration of antibiotics in uncomplicated cases is advised.

Dengue Fever in Travelers to the Tropics, 1998 and 1999

Dengue fever (DF) has become common in western travelers to the tropics. To improve the basis for travel advice, risk factors and dengue manifestations were assessed in 107 Swedish patients for whom DF was diagnosed after return from travel in 1998 and 1999. Patient data were compared with data on a sample of all Swedish travelers to dengue-endemic countries in the same years. Only three of the patients had received pretravel advice concerning DF from their physicians. Hemorrhagic manifestations were common (21 of 74 patients) but caused no deaths. Risk factors for a DF diagnosis were travel to the Malay Peninsula (odds ratio [OR] 4.95; confidence interval [CI] 2.92 to 8.46), age 15–29 years (OR 3.03; CI 1.87 to 4.92), and travel duration >25 days (OR 8.75; CI 4.79 to 16.06). Pretravel advice should be given to all travelers to DF-endemic areas, but young persons traveling to southern and Southeast Asia for >3 weeks (who constituted 31% of the patients in our study) may be more likely to benefit by adhering to it.