Isolate-Based Surveillance of Bordetella pertussis, Austria, 2018-2020.

Pertussis is a vaccine-preventable disease, and its recent resurgence might be attributable to the emergence of strains that differ genetically from the vaccine strain. We describe a novel pertussis isolate-based surveillance system and a core genome multilocus sequence typing scheme to assess Bordetella pertussis genetic variability and investigate the increased incidence of pertussis in Austria. During 2018-2020, we obtained 123 B. pertussis isolates and typed them with the new scheme (2,983 targets and preliminary cluster threshold of <6 alleles). B. pertussis isolates in Austria differed genetically from the vaccine strain, both in their core genomes and in their vaccine antigen genes; 31.7% of the isolates were pertactin-deficient. We detected 8 clusters, 1 of them with pertactin-deficient isolates and possibly part of a local outbreak. National expansion of the isolate-based surveillance system is needed to implement pertussis-control strategies.

Antibody kinetics in primary- and secondary-care physicians with mild to moderate SARS-CoV-2 infection.

Three hundred and ninety-seven primary- and secondary-care physicians were tested for the presence of IgG (and IgA) antibodies against SARS-coronavirus-2 with a commercially available ELISA. In 19 of 20 individuals with PCR-proven infection and only mild to moderate symptoms not requiring hospitalization positive IgG levels occurred within two to three weeks. Among the remaining 377 persons without clear-cut evidence of infection, unequivocally positive IgG antibodies were found in only one, showing a surprisingly low prevalence (0.3%, 95% CI: 0.01-1.5) in physicians with likely contacts with infected patients in a region highly affected by the pandemic (Tyrol, Austria).

Multiple Influenza Virus Infections in 4 Consecutive Epidemiological Seasons: A Retrospective Study in Children and Adolescents.

BACKGROUND: Recent observations provide evidence for group-specific immunity toward influenza A infections and raise the question of how often we can get the flu. METHODS: We retrospectively analyzed 2308 cases of children and adolescents with clinically manifested influenza and a positive PCR-test during the last 4 epidemiological seasons (2014-15 through 2017-18). RESULTS: In the 2015-16 epidemiological season, almost 12% of patients had experienced an influenza infection during the previous season; in the 2016-17 season, more than 14% had at least 1 infection during the previous 2 seasons, and in 2017-18 season, over 18% had 1 or more infections during the previous 3 seasons. The majority of these repetitive infections occurred in children between 3-8 years of age. 29 patients experienced 3 or 4 infections during these seasons, whereas 38 children had 2 influenza episodes within the same season. Epidemiological pattern of circulating viral strains changed yearly; however, we identified 5 patients with confirmed influenza B infections during the 2014-15 and 2017-18 seasons, when only subtype Yamagata was circulating in Austria. CONCLUSIONS: Repetitive influenza infections in consecutive epidemiological seasons occurred quite frequently in children and adolescents. Observations like ours contribute to a better understanding of the immunity against influenza virus infections and could have implications for future vaccination strategies.

Consecutive Infections With Influenza A and B Virus in Children During the 2014-2015 Seasonal Influenza Epidemic.

In a retrospective analysis of the test results for 647 patients with laboratory-confirmed influenza, we identified 13 children with influenza A virus infection who were subsequently infected with influenza B virus after a mean interval of 50 days. None of these children were considered immunodeficient or had an increased frequency of infections. Our data provide novel information in showing that consecutive infection with influenza A and B viruses can occur during a regular influenza season in immune-competent children and that a preceding influenza A virus infection may not provide cross-protection against influenza B virus infection.

False-negative serology in patients with acute parvovirus B19 infection.

BACKGROUND: Acute parvovirus B19 (B19V) infection is characterized by high-level viremia. Antibodies against the capsid proteins VP1 and VP2 may complex with B19V-particles thereby becoming undetectable in diagnostic tests. OBJECTIVES: We intended to obtain data on the frequency of false-negative serology in acute B19V-infection. STUDY DESIGN: 129 plasma or serum samples of healthy blood donors and of patients with suspected B19V-infection were analyzed for B19V-DNA by qPCR and VP1/VP2-specific IgG and IgM by ELISA. Eleven of these samples were derived from four pregnant women with previous contact to B19V-infected individuals. Using acidic conditions virus/antibody-complexes were disrupted and detected by WesternLine and ELISA. RESULTS: 83/118 samples were derived from acutely infected individuals displaying viremia (10(3)-10(12)geq/mL). In 24/83 viremic samples (28.9%) VP1/VP2-specific IgM and IgG were undetectable in ELISA, but could be demonstrated to be complexed with B19V-particles. Each 7/83 (8.4%) was IgM-positive/IgG-negative and IgM-negative/IgG-positive, in 45/83 samples (54.2%) IgG and IgM could be detected. 35 samples did not contain B19V-DNA; five of these were from seronegative persons. Analyzing consecutive sera derived from four pregnant women, B19V-DNA was demonstrated in 10/11 samples, B19V-specific IgG- and IgM-antibodies were detectable in 10/11 and 4/11 samples, respectively. In 2/4 women seroconversion was observed, but IgM was not detected in 50% of the samples. B19V-specific IgG but not IgM was detectable in 2/4 women. CONCLUSION: Acute B19V-infection cannot be diagnosed by exclusive analysis of B19V-specific antibodies. Only the combination of assays for detection of B19V-DNA and antibodies enables correct serodiagnosis.

Pathways for the regulation of interferon-gamma-inducible genes by iron in human monocytic cells.

To elucidate iron-regulated interferon-gamma (IFN-gamma) effector functions, we investigated three IFN-gamma-inducible genes [intercellular adhesion molecule-1 (ICAM-1), human leukocyte antigen (HLA)-DR, guanosine 5'-triphosphate-cyclohydrolase I (GTP-CH)] in primary human monocytes and the cell line THP-1. IFN-gamma increased the surface expression of ICAM-1 and HLA-DR and stimulated GTP-CH activity. Addition of iron before cytokine stimulation resulted in a dose-dependent reduction of these pathways, and iron restriction by desferrioxamine (DFO) enhanced ICAM-1, HLA-DR, and GTP-CH expression. Iron neither affected IFN-gamma binding to its receptor nor IFN-gamma receptor surface expression. IFN-gamma-inducible mRNA expression of ICAM-1, HLA-DR, and GTP-CH was reduced by iron and increased by DFO by a transcriptional mechanism. Moreover, ICAM-1 and to a lesser extent, GTP-CH and HLA-DR mRNA expression were regulated post-transcriptionally, as iron pretreatment resulted in shortening the mRNA half-life compared with cells treated with IFN-gamma alone. Thus, iron perturbations regulate IFN-gamma effector pathways by transcriptional and post-transcriptional mechanisms, indicating that iron rather interferes with IFN-gamma signal-transduction processes.

Fully vaccinated children are rare: immunization coverage and seroprevalence in Austrian school children.

Vaccination coverage for vaccine-preventable diseases in Austria as well as in many Central European countries has been reported to be too low to eradicate such diseases and prevent further outbreaks. Austria lacks an adequate surveillance system to monitor prevalence of the diseases, the vaccination coverage and seroconversion. School children aged 10-14 years (n = 1077) were recruited in all four schools in the city of Schwaz, Austria, to present their vaccination documents and to give blood for serological testing (diphtheria, pertussis, measles, mumps, rubella, varicella). All participants received a report with a personal guideline for (re-) vaccination. Overall vaccination coverage was 86.4% for measles, 85.5% for mumps and 35.0% for rubella. Tetanus vaccination coverage was 98.4% for the first, 97.8% for the second and 96.7% for the third dose, while 55.4% of the study subjects received the recommended two booster injections. For diphtheria the corresponding vaccination coverage was found to be almost identical. Pertussis coverage was lower in general (first dose: 90.9%; second dose: 89.0%; third dose: 86.5%). Oral poliomyelitis vaccination showed a coverage of 98.6, 96.5, 95.3%, with 78.7% receiving the fourth dose. Overall 38.7% were classified as fully vaccinated. Seropositivity for measles was found in 90.4%, for mumps in 61.8%, for rubella in 82.3%, for diphtheria in 65.8%, for pertussis in 35.6% and for varicella in 95.0%. In summary, fully vaccinated children are rare and intensive public health efforts will be necessary to reach higher levels of immunity and prevent further outbreaks.