Laboratory Diagnostics of <i>Rickettsia</i> Infections in Denmark 2008–2015

Rickettsiosis is a vector-borne disease caused by bacterial species in the genus Rickettsia. Ticks in Scandinavia are reported to be infected with Rickettsia, yet only a few Scandinavian human cases are described, and rickettsiosis is poorly understood. The aim of this study was to determine the prevalence of rickettsiosis in Denmark based on laboratory findings. We found that in the Danish individuals who tested positive for Rickettsia by serology, the majority (86%; 484/561) of the infections belonged to the spotted fever group. In contrast, we could confirm 13 of 41 (32%) PCR-positive individuals by sequencing and identified all of these as R. africae, indicating infections after travel exposure. These 13 samples were collected from wound/skin material. In Denmark, approximately 85 individuals test positive for Rickettsia spp. annually, giving an estimated 26% (561/2147) annual prevalence among those suspected of rickettsiosis after tick bites. However, without clinical data and a history of travel exposure, a true estimation of rickettsiosis acquired endemically by tick bites cannot be made. Therefore, we recommend that both clinical data and specific travel exposure be included in a surveillance system of Rickettsia infections

Presence of Antibodies Against Coxiella burnetii and Risk of Spontaneous Abortion: A Nested Case-Control Study

BACKGROUND AND AIMS: Q fever is a bacterial zoonosis caused by infection with Coxiella burnetii. It is well established that Q fever causes fetal loss in small ruminants. The suspicion has been raised that pregnant women may also experience adverse pregnancy outcome when the infection is acquired or reactivated during pregnancy. The purpose of this study was to assess the potential association between serologic markers of infection with C. burnetii and spontaneous abortion. METHODS: A nested case-control study within the Danish National Birth Cohort, a cohort of 100,418 pregnancies recruited from 1996-2002. Women were recruited in first trimester of pregnancy and followed prospectively. Median gestational age at enrolment was 8 weeks (25 and 75 percentiles: 7 weeks; 10 weeks). During pregnancy, a blood sample was collected at gestational week 6-12 and stored in a bio bank. For this study, a case sample of 218 pregnancies was drawn randomly among the pregnancies in the cohort which ended with a miscarriage before 22 gestational weeks, and a reference group of 482 pregnancies was selected in a random fashion among all pregnancies in the cohort. From these pregnancies, serum samples were screened for antibodies against C. burnetii in a commercial enzyme-linked immunosorbent assay (ELISA). Samples that proved IgG or IgM antibody positive were subsequently confirmatory tested by an immunofluorescence (IFA) test. RESULTS: Among cases, 11 (5%) were C. burnetii positive in ELISA of which one was confirmed in the IFA assay compared to 29 (6%) ELISA positive and 3 IFA confirmed in the random sample. CONCLUSIONS: We found no evidence of a higher prevalence of C. burnetii antibodies in serum samples from women who later miscarried and the present study does not indicate a major association between Q fever infection and spontaneous abortion in humans. Very early first trimester abortions were, however, not included in the study

Antibody Response is More Likely to Pneumococcal Proteins Than to Polysaccharide After HIV-associated Invasive Pneumococcal Disease

Background. Human immunodeficiency virus (HIV)–infected individuals are at increased risk of invasive pneu-mococcal disease (IPD). In order to assess the immunogenicity of pneumococcal proteins and polysaccharide, we investigated protein and serotype-specific antibody responses after HIV-associated IPD. Methods. Specific antipneumococcal immunoglobulin G to 27 pneumococcal protein antigens and 30 serotype polysaccharides was measured in plasma before and after IPD in HIV-infected individuals and compared to HIV-infected individuals without IPD. Results. Over time, 81 % of IPD cases responded to at least 1 protein compared to 51 % of non-IPD controls. HIV IPD cases responded to more proteins than non-IPD controls (8.6 ± 8.4 vs 4.2 ± 7.6 proteins; P =.01), and had a significantly higher probability of yielding an antibody response to the proteins PiaA, PsaA, and PcpA. Twenty-two percent of HIV-infected individuals with IPD had a serotype-specific antibody response. Younger age at the time of IPD was the only predictor of a serotype-specific pneumococcal antibody response, whereas we did not iden-tify predictors of a protein-specific antibody response. Conclusions. Antibody responses occurred more frequently to pneumococcal proteins than to polysaccharide, and protein antibodies persisted for longer than polysaccharide-specific antibodies. PcpA, PiaA, and PsaA were the most immunogenic proteins

Serologic response to pneumococcal vaccination in children experiencing recurrent invasive pneumococcal disease

Abstract Background Some children are prone to recurrent invasive pneumococcal disease (rIPD) and of these, some respond insufficiently to standard pneumococcal vaccination. Little is known about how to handle these children and if they benefit from additional vaccination. Here, we present results from a nationwide study of pediatric rIPD including data on serotype-specific vaccination response to pneumococcal polysaccharide vaccination (PPV23) and pneumococcal conjugate vaccination (PCV7/13). Methods A retrospective, population-based study was conducted using The National Streptococcus pneumoniae Registry, which contains laboratory-confirmed data from all cases of IPD in Denmark. From January 1980–June 2013 all children aged 0–15 years with rIPD were identified. Clinical data and data on serotype-specific pneumococcal antibody response were collected. Over the years quantification of pneumococcal antibodies varied from being presented in arbitrary units (ELISA), in μg/ml (WHO ELISA) and lately in μg/ml based on Luminex technology. Results 2482 children were diagnosed with IPD and 75 episodes of rIPD were documented in 59 children. An underlying disease was documented in 45 (76%) children. Vaccination data were available for 26 children; 11 were vaccinated solely with PPV23, 8 with a combination of PPV23 + PCV7, 5 with PCV7 and 2 with PCV13. In total, nine responded to PPV23 vaccination and ten were PPV23 non-responders. Of the 15 PCV vaccinated children, two children responded subnormal to PCV7. Among PPV23 non-responders, five responded to subsequent PCV vaccination. Conclusions In our population-based study of children with rIPD 53% of the children responded insufficiently to PPV23 vaccination. PPV23 non-responders benefitted from PCV vaccination

Campylobacter, Salmonella, and Yersinia antibodies and pregnancy outcome in Danish women with occupational exposure to animals

Background: The aim of this study was to determine antibody titres against Campylobacter, Salmonella, and Yersinia in a population-based cohort of pregnant women in Denmark in order to evaluate adverse pregnancy outcomes (miscarriage, preterm birth, and small for gestational age) in relation to occupational exposure to animals in women exposed to food producing animals. Methods: We used data and blood samples from the Danish National Birth Cohort. Serum samples collected during the first trimester from 192 pregnant women who were occupationally exposed to domestic animals and 188 randomly selected unexposed pregnant women were analysed for IgG, IgM, and IgA antibodies against Campylobacter, Salmonella, and Yersinia. Pregnancy outcomes of interest were identified through the Danish National Patient Register. Results: Women with occupational exposure to animals had significantly higher IgG antibody concentrations against Campylobacter, Salmonella, and Yersinia, whereas they had lower concentrations of IgM and IgA antibodies. Conclusions: Serological markers were not identified as risk factors for adverse pregnancy outcomes, with the exception of elevated concentrations of Salmonella antibodies, which were found to be associated with an increased risk of preterm birth