Prevailing effectiveness of the 2009 influenza A(H1N1)pdm09 vaccine during the 2010/11 season in Sweden.

Sixty per cent of the Swedish population received the monovalent AS03-adjuvanted pandemic influenza vaccine in the autumn of 2009. We assessed the age-specific effectiveness of this pandemic vaccine against hospitalisation with laboratory-confirmed influenza A(H1N1)pdm09 during the season 2010/11, in the age group from six months to 64 years in Sweden. The screening method was applied to available surveillance data. Our results suggest a prevailing effectiveness of 72% (95% confidence interval (CI): 63­80%) with the highest effectiveness among children, six months to nine years-old (92%, 95%CI: 80­97%). However, there were limitations in data quality and study design due to the lack of systematic recording of administered vaccinations, which underline the importance of preparing for an evaluation when planning for large public health actions. Despite these limitations, we believe the results reflect true, high prevailing vaccine effectiveness. Indeed, there were fewer deaths caused by influenza and the impact of influenza on intensive care units was less severe during the 2010/11 season in Sweden than in countries with lower pandemic vaccination coverage. The association between the pandemic vaccine and narcolepsy has increased the importance of assessing the risks and benefits of the vaccination; studies on the effectiveness and the duration of protection are needed for this.

Role of the enteric nervous system in the fluid and electrolyte secretion of rotavirus diarrhea.

The mechanism underlying the intestinal fluid loss in rotavirus diarrhea, which often afflicts children in developing countries, is not known. One hypothesis is that the rotavirus evokes intestinal fluid and electrolyte secretion by activation of the nervous system in the intestinal wall, the enteric nervous system (ENS). Four different drugs that inhibit ENS functions were used to obtain experimental evidence for this hypothesis in mice in vitro and in vivo. The involvement of the ENS in rotavirus diarrhea indicates potential sites of action for drugs in the treatment of the disease.

Timing of two versus three doses of quadrivalent HPV vaccine and associated effectiveness against condyloma in Sweden: a nationwide cohort study.

OBJECTIVE: To assess incidence of condyloma after two doses of quadrivalent human papillomavirus (qHPV) vaccine, by time since first vaccine dose, in girls and women initiating vaccination before age 20 years. DESIGN: Register-based nationwide open cohort study. SETTING: Sweden. PARTICIPANTS: Girls and women initiating qHPV vaccination before age 20 years between 2006 and 2012. The study cohort included 264 498 girls, of whom 72 042 had received two doses of qHPV vaccine and 185 456 had received all three doses. MAIN OUTCOME MEASURE: Incidence rate ratios (IRRs) of condyloma estimated by time between first and second doses of qHPV in months (m) and age at vaccination, adjusted for attained age. RESULTS: For girls first vaccinated with two doses before the age of 17 years, the IRR of condyloma for 0-3 months between the first and second doses was 1.96 (95% CI 1.43 to 2.68) as compared with the standard three-dose schedule. The IRRs were 1.27 (95% CI 0.63 to 2.58) and 4.36 (95% CI 2.05 to 9.28) after receipt of two doses with 4-7 months and 8+ months between doses, respectively. For women first vaccinated after the age of 17 years, vaccination with two doses of qHPV vaccine and 0-3 months between doses was associated with an IRR of 2.12 (95% CI 1.62 to 2.77). For an interval of 4-7 months between doses, the IRR did not statistically significantly differ to the standard three-dose schedule (IRR=0.81, 95% CI 0.36 to 1.84). For women with 8+ months between dose 1 and dose 2 the IRR was 3.16 (95% CI 1.40 to 7.14). CONCLUSION: A two-dose schedule for qHPV vaccine with 4-7 months between the first and second doses may be as effective against condyloma in girls and women initiating vaccination under 20 years as a three-dose schedule. Results from this nationwide study support immunogenicity data from clinical trials.

Long-term follow-up of successful hepatitis C virus therapy: waning immune responses and disappearance of liver disease are consistent with cure.

BACKGROUND: A sustained viral response (SVR) after interferon-based therapy of chronic hepatitis C virus (HCV) infection is regarded to represent a cure. Previous studies have used different markers to clarify whether an SVR truly represents a cure, but no study has combined a clinical work-up with highly sensitive HCV RNA detection, and the determination of immune responses. AIM: To determine clinical, histological, virological and immunological markers 5-20 years after SVR. METHODS: In 54 patients, liver biochemistry, histology and elastography were evaluated. Liver biopsies, plasma and peripheral blood mononuclear cells (PBMCs) were tested for minute amounts of HCV RNA. HCV-specific T-cell responses were monitored by ELISpot and pentamer staining, and humoral responses by measuring HCV nonstructural (NS)3-specific antibodies and virus neutralisation. RESULTS: Liver disease regressed significantly in all patients, and 51 were HCV RNA-negative in all tissues tested. There was an inverse association between liver disease, HCV-specific T-cell responses and HCV antibody levels with time from SVR, supporting that the virus had been cleared. The three patients, who all lacked signs of liver disease, had HCV RNA in PBMCs 5-9 years after SVR. All three had HCV-specific T cells and NS3 antibodies, but no cross-neutralising antibodies. CONCLUSIONS: Our combined data confirm that a SVR corresponds to a long-term clinical cure. The waning immune responses support the disappearance of the antigenic stimulus. Transient HCV RNA traces may be detected in some patients up to 9 years after SVR, but no marker associates this with an increased risk for liver disease.

Encapsulation of rotavirus into poly(lactide-co-glycolide) microspheres.

Two small-scale double emulsion techniques for incorporation of formaldehyde-inactivated rotavirus particles (FRRV) into poly(lactide-co-glycolide) (PLG) microspheres were developed and optimised. The effects of high-speed homogenisation versus vortex mixing on the double emulsion stability, microsphere size, entrapment efficiency and in vitro release of FRRV in the second emulsification step were studied. A stable double emulsion was verified only when using vortex mixing in this step. Slow removal of the organic phase allowed measurement of the size of the emulsion droplets and subsequent prediction of the size of the resulting microspheres. Microspheres in the size range of 1-10 microm were prepared using both techniques. The homogenisation technique was sensitive to changes in the operating time, the emulsification energy and the volume of the outer aqueous phase, while the vortex technique was more robust. Rotavirus was released in vitro in a triphasic manner with both techniques. The more robust vortex technique was selected for preparation of PLG microspheres containing rotavirus for in vivo studies. After immunisation of mice with a single intramuscular injection, the PLG-FRRV microspheres elicited an IgG antibody response in serum detected by ELISA equally high as that elicited with FRRV alone. These results indicate that the antigenicity of FFRV was retained after incorporation into PLG microspheres using the vortex technique.

Aetiology and epidemiology of acute gastro-enteritis in Swedish children.

In a prospective 1-year study, 144 children attending or admitted to hospital and 272 children outside hospital with acute gastro-enteritis and 200 controls were investigated by a broad panel of diagnostic methods for enteropathogenic agents in the faeces and for related antibody responses. Enteropathogens were identified in 77% of the inpatients, 63% of the outpatients and 8% of the controls. Rotavirus and Yersinia enterocolitica were detected significantly more often among inpatients. Altogether, viral, bacterial and parasitic agents were found in 58%, 14% and 1% of diarrhoeal patients, respectively. The isolation of more than one pathogenic agent was uncommon (6.5%). Rotavirus (45%) and enteric adenoviruses 40 and 41 (7.9%) predominated among the viruses, while Campylobacter jejuni (4.8%) was most common among the bacteria. Clostridium difficile and/or its cytotoxin, which were found in 14% of the children with gastroenteritis and in 15% of the controls, were significantly associated with antibiotic therapy but not with gastro-intestinal illness. Diarrhoeal infections of unknown aetiology exhibited a seasonal peak in the autumn. The duration of excretion of enteropathogens was investigated. Rotavirus particles were detectable by solid-phase immune electron microscopy for 14-25 days after the diarrhoea had ceased. Transmission of rotavirus and bacterial pathogens within families was studied also.

Incidence and estimates of the disease burden of rotavirus in Sweden.

Laboratory and hospitalization data from two children's hospitals with large primary catchment areas and national laboratory and hospitalization data for children under 4 y of age with acute diarrhoea were compiled to estimate the number of hospitalizations and the cost burden associated with rotavirus diarrhoea in Sweden. According to our estimates 1500-1700 rotavirus-associated hospitalizations occur annually in Sweden in children under 4 y of age (3.7 hospitalizations/1000 children/y). This number represents 2.3% of admissions for all diagnoses in children of this age group. The cost of these hospitalizations is 13.5-15 million Swedish crowns (US$1.8-2 million). Serotyping by PCR for two years revealed that serotype 1 (G1) was the most common (49% and 58%, respectively) identified. Serotypes 2-4 were identified in the following proportions G2 (23% and 5%), G3 (21% and 0%) and G4 (7% and 16%). The national laboratory report data for 1993-96 show that as much as 7-13% of rotavirus infections occur in elderly people.

[The first rotavirus vaccine approved in the USA and Europe]. / Första rotavirusvaccinet godkänt i USA och Europa.

A new live oral rotavirus vaccine (Rotashield) has now been approved both in the USA and Europe. In large multicentre trials involving over 10,000 children, the vaccine has been shown to have a manifest protective effect, first and foremost against severe rotavirus-induced diarrhoea, but to be associated with certain side effects. The Advisory Committee on Immunisation Practices and the American Academy of Paediatrics are now recommending that Rotashield be included in the child vaccination programme. Use of the vaccine in Europe is likely to vary from one country to another. The issue of general recommendations for its use in Sweden should await the results of cost-benefit analysis and review of experience of the vaccine's use in the USA. In addition, a more comprehensive identification of rotavirus serotypes occurring in Sweden is a prerequisite for adequate assessment of the vaccine's necessity in this country.

Clinical and epidemiological features of acute infantile gastroenteritis associated with human rotavirus subgroups 1 and 2.

During a prospective 1-year study rotavirus isolates from 169 children with gastroenteritis were investigated by polyacrylamide gel electrophoresis. A total of 118 (70%) of the strains analyzed contained sufficient viral nucleic acid to give visible electrophoretic patterns; 36% were identified as strains belonging to subgroup 1 (short patterns), and 64% were identified as strains belonging to subgroup 2 (long patterns). The two subgroups cocirculated at equal frequencies during the first 7 months of the year, after which subgroup 1 rotavirus completely disappeared. Subgroup 2 rotavirus occurred throughout the year. No significant differences between the subgroups in relation to age or sex distribution were observed. Fever and temperatures exceeding 39 degrees C were significantly more frequent in children who shed rotavirus subgroup 1. Diarrhea and vomiting occurred at similar rates in both groups of patients, but were more pronounced in children who shed rotavirus subgroup 2. One of three dominant electropherotypic variants of subgroup 2 rotavirus was found to be associated with more intense symptoms, higher rates of hospitalization, and a significantly higher frequency of respiratory symptoms; the clinical picture may indicate that this rotavirus electropherotype has higher virulence.

Enteric adenoviruses.

Human adenoviruses are classified into 47 serotypes and six subgenera (A-F) with different tropisms. In recent years adenovirus type 40 (Ad40) and 41 (Ad41) of subgenus F have been shown to be causative agents in enteric infections, which is second in importance only to rotaviruses as a cause of infantile gastroenteritis. Infection with EAds occurs worldwide and has been associated with 4-17% of cases of diarrhoea in children. AD40 and Ad41 primarily affect young children less than 2 years of age and occur throughout the year. The clinical characteristics include watery diarrhoea accompanied by vomiting, low grade fever and mild dehydration. A distinct feature of EAds infection is the protracted diarrhoea (mean 8.6 and 12.2 days for Ad40 and Ad41, respectively). Respiratory symptoms are infrequent. Serotypes Ad40 and Ad41 differ from all other (established) adenoviruses by being unable to replicate in conventional cell cultures. These fastidious viruses only grow in selected cell lines, 293 cells being the most commonly used. In spite of the difficulty of isolating Ad40 and Ad41, they can be directly identified and typed by ELISA and solid-phase immune electron microscopy. The amount of viral DNA in stool specimens is sufficient for identification by DNA restriction and dot-blot assays. The recent development of highly sensitive and specific monoclonal antibody-based ELISAs enable accurate diagnosis of adenovirus gastroenteritis in routine work and make possible the evaluation of the role of the enteric adenoviruses in diarrhoeal disease in the developing countries.

Molecular epidemiology of rotavirus infections in Uppsala, Sweden, 1981: disappearance of a predominant electropherotype.

The molecular epidemiology of rotavirus infections was studied in children with acute gastroenteritis in Uppsala, Sweden, during 1981. Altogether 118 virus strains were investigated by analysis of the RNA migration pattern in silver-stained polyacrylamide gels. Six different electropherotypes were seen: two with "short" and four with "long" RNA migration patterns. Forty-two strains (36%) exhibited "short" patterns. The seasonal distribution showed that strains with "long" and "short" RNA patterns cocirculated in equal frequency during the first seven months of the year, until the predominant "short" RNA electropherotype suddenly disappeared. More than 11 RNA segments were seen in two stool specimens. A complete correlation was found between the electrophoretic migration of segments 10 and 11 and the serological defined subgroup specificity.

Clinical features of acute gastroenteritis associated with rotavirus, enteric adenoviruses, and bacteria.

In a prospective one year study, comprising children with acute gastroenteritis admitted to hospital or treated as outpatients, the clinical and laboratory features of rotavirus diarrhoea (168 cases) were compared with those of enteric adenovirus (32 cases), bacterial (42), mixed (16), and non-specific (135) infections. The rotavirus disease was remarkably consistent, with a sudden onset of vomiting, a high frequency of fever and dehydration, and a mean duration of diarrhoea of 5.9 days. Outpatients excreting rotavirus had a similar but milder illness, mainly on account of less pronounced vomiting. The predominant symptom of enteric adenoviruses was long lasting diarrhoea (mean 10.8 days). Abdominal pain, bloody stools, prolonged diarrhoea (mean 14.1 days), leucocytosis, and a raised erythrocyte sedimentation rate strongly suggested a bacterial aetiology. Mixed infections caused longer lasting diarrhoea (mean 8.0 days) than rotavirus alone, but the severity of the illness was not increased. The clinical features of infection with unidentified pathogens most resembled those of bacterial infections. Respiratory symptoms were not significantly associated with any particular pathogen. Hypernatraemia and complications were uncommon. This study showed that the clinical features of gastroenteritis with rotavirus, enteric adenoviruses, and bacteria each exhibited patterns that could guide the experienced clinician to a presumptive diagnosis.

Latex agglutination test for adenovirus diagnosis in diarrheal disease.

A commercial latex agglutination test for diagnosis of adenovirus in diarrheal disease (Adenolex, Orion Diagnostica, Finland) was evaluated by comparison with the results obtained by ELISA, electron microscopy (EM), and virus isolation. Fifty specimens originated from the diagnostic routine, and 50 were selected from a previous epidemiological study on the etiology of diarrheal disease in children. Thirteen of the 100 specimens reacted with the latex control, impairing interpretation of the results. Although the ELISA detected adenovirus antigen in 10(2) higher dilutions than the latex agglutination test, a total agreement was obtained between results by the two tests for 87 specimens including 42 positives. The two additional positives found by EM and virus isolation could not be diagnosed by the latex agglutination test. Of 37 specimens containing enteric adenoviruses (types 40 and 41), the agglutination test diagnosed all but 4 specimens containing type 41 virus. These four specimens were negative also by ELISA and adenovirus had been detected by virus isolation on the 293 cell line. The latex agglutination test gave positive results with nine specimens containing adenovirus types other than the enteric types 40 and 41. The latex agglutination test was found to be a rapid and simple method for the detection of adenovirus in diarrheal disease. Compared to ELISA and EM, the sensitivity was 100% and 95% respectively, and the specificity 100%.

First documented case of human babesiosis in Sweden.

A 34-year-old splenectomized man presented with fever, myalgia and dysuria. His condition rapidly deteriorated, he became anuric and developed severe haemolytic anaemia, thrombocytopenia and fibrinolysis. Peripheral blood smears revealed intra-erythrocytic parasites consistent with Babesia divergens in 40% of the erythrocytes. The diagnosis was confirmed by gerbil inoculation and by a significant rise in antibody titer. Blood exchange transfusion reduced the number of babesia infected erythrocytes to 1%. Parenteral therapy with a combination of quinine and clindamycin eradicated parasitaemia after 10 days of treatment and the patient rapidly improved. Renal failure necessitated haemodialysis for one month, whereafter the patient made a full recovery. Human babesiosis is a rare disease, but with a potential fatal outcome and should be considered as a diagnostic alternative in splenectomized and otherwise immunocompromised individuals with severe febrile illnesses.

Importance of enteric adenoviruses 40 and 41 in acute gastroenteritis in infants and young children.

In a prospective 1-year study of acute infantile gastroenteritis, adenoviruses were detected in the stools or by seroconversions, or both, in 56 of 416 (13.5%) ill children. By use of DNA restriction enzyme analysis, enzyme immunoassay, and culture techniques, 33 of 56 (59%) adenovirus specimens were identified as enteric adenoviruses 40 and 41 (Ad40 and Ad41). They were found as the sole recognizable cause of diarrhea in 30 of 416 (7.2%) ill children and in 0 of 200 controls. Three additional ill children had enteric adenoviruses as a part of a dual infection. Evidence for established adenoviruses (Ad1 through Ad39) in gastroenteritis was found in 15 of 416 (3.6%) ill children but also in 3 of 200 (1.5%) controls. Eight adenovirus specimens remained untyped. Seroconversions were demonstrated in 17 of 18 (94%) paired serum samples from patients shedding enteric adenoviruses. The predominant symptom of infections with enteric adenoviruses was diarrhea, with a mean duration of 8.6 days (Ad40) and 12.2 days (Ad41). One-third of the children with Ad41 infections had prolonged symptoms (greater than or equal to 14 days). The frequency of respiratory symptoms was low (21%). The established adenoviruses presented a different clinical picture, characterized by diarrhea of shorter duration, higher fever, and significantly increased occurrence of respiratory symptoms (79%). In conclusion, enteric adenoviruses appear to be an important cause of acute infantile gastroenteritis, second only to rotaviruses in this study.