Defining Polysaccharide Antibody Deficiency: Measurement of Anti-Pneumococcal Antibodies and Anti-Salmonella typhi Antibodies in a Cohort of Patients with Recurrent Infections.

BACKGROUND: The correlation between different methods for the detection of pneumococcal polysaccharide vaccine (PPV) responses to diagnose specific polysaccharide antibody deficiency (SAD) is poor and the criteria for defining a normal response lack consensus. We previously proposed fifth percentile (p5) values of PPV responses as a new cutoff for SAD. OBJECTIVE: To analyze the association of SAD (determined by either World Health Organization (WHO)-standardized ELISA or multiplex bead-based assay) with abnormal response to Salmonella (S.) typhi Vi vaccination in a cohort of patients with recurrent infections. METHODS: Ninety-four patients with a clinical history suggestive of antibody deficiency received PPV and S. typhi Vi vaccines. Polysaccharide responses to either 3 or 18 pneumococcal serotypes were measured by either the WHO ELISA or a multiplex in-house bead-based assay. Anti-S. typhi Vi IgG were measured by a commercial ELISA kit. Allohemagglutinins (AHA) were measured by agglutination method. RESULTS: Based on the American Academy of Allergy, Asthma and Immunology (AAAAI) criteria for WHO ELISA, 18/94 patients were diagnosed with SAD and 22/93 based on serotype-specific p5 cutoffs for bead-based assay. The association between the two methods was significant, with 10 subjects showing abnormal response according to both techniques. Abnormal response to S. typhi Vi vaccination was found in 7 patients, 6 of which had SAD. No correlation was found between polysaccharide response and AHA, age, or clinical phenotype. CONCLUSION: The lack of evidence-based gold standards for the diagnosis of SAD represents a challenge in clinical practice. In our cohort, we confirmed the insufficient correlation between different methods of specific PPV response measurement, and showed that the S. typhi Vi response was not contributive. Caution in the interpretation of results is warranted until more reliable diagnostic methods can be validated.

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

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.

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 pneumococcal 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 identify 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.

Inflammatory Bowel Disease Patients Are at Increased Risk of Invasive Pneumococcal Disease: A Nationwide Danish Cohort Study 1977-2013.

OBJECTIVES: Inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC) are chronic diseases characterized by an inappropriate immune response, which may also increase the risk of infections. We investigated the risk of invasive pneumococcal disease (IPD) before and after diagnosis of IBD in a population-based cohort study. METHODS: In a cohort of 74,156 IBD patients and 1,482,363 non-IBD controls included and followed during 1977-2013, hazard rate ratios (HRs) for IPD in IBD patients vs. controls were calculated by Cox regression. Within the IBD group, we also calculated the risk according to ever use of specific IBD medications. Next, using conditional logistic regression, we evaluated the odds of IPD prior to IBD diagnosis. RESULTS: The HRs for IPD within the first 6 months after IBD diagnosis were significantly and more than threefold increased and then decreased to a constant level, which for CD was significantly increased (approximately twofold, HR, 1.99; 95% confidence interval (CI), 1.59-2.49) and for UC non-significantly just above 1. IBD medication use including tumor necrosis factor alpha antagonists had limited impact on the risk of IPD, although having ever used azathioprine increased the risk of IPD in patients with UC (HR, 2.38; 95% CI, 1.00-5.67). Up to 4 years prior to IBD diagnosis, the odds ratio for IPD was significantly increased (UC HR, 1.51, 95% CI, 1.05-2.17; CD HR, 1.79, 95% CI, 1.05-3.03). CONCLUSIONS: The risk of IPD is significantly increased both before and after diagnosis of IBD, with limited impact of IBD medications. This suggests that the risk of IPD in patients with IBD is related to the underlying altered immune response in these patients.

Recurrent severe invasive pneumococcal disease in an adult with previously unknown hyposplenia.

BACKGROUND: The risk of life-threatening and invasive infections with encapsulated bacteria is increased in patients with hyposplenia or asplenia. We report a case of recurrent invasive pneumococcal meningitis in a woman with previous unknown hyposplenia. She was vaccinated after the first episode of meningitis and developed sufficient levels of pneumococcal antibodies. The pneumococcal strains isolated were serotype 7 F and 17 F. To our knowledge, there has been no previously reported case of recurrent invasive pneumococcal disease in a pneumococcal vaccinated adult with hyposplenia and apparently sufficient antibody response. CASE PRESENTATION: We report the course of a 38-year-old Caucasian woman presenting with recurrent episodes of invasive pneumococcal disease (IPD) and previously unknown hyposplenia. Hyposplenia was discovered during the second episode of IPD and no underlying medical condition was found. Despite immunization against S. pneumoniae and measurement of what was interpreted as protective levels of serotype-specific IgG antibodies after vaccination, the patient suffered from a third episode of IPD. CONCLUSIONS: Individuals with predisposing medical conditions or a history of severe infections with encapsulated bacteria should be screened for spleen dysfunction. If splenic function is impaired, prevention against severe invasive infection with encapsulated bacteria are a major priority.

No excess risk of adverse pregnancy outcomes among women with serological markers of previous infection with Coxiella burnetii: evidence from the Danish National Birth Cohort.

BACKGROUND: Q fever caused by Coxiella burnetii is transmitted to humans by inhalation of aerosols from animal birth products. Q fever in pregnancy is suspected to be a potential cause of fetal and maternal morbidity and fetal mortality but the pathogenesis is poorly understood, and even in Q fever endemic areas, the magnitude of a potential association is not established.We aimed to examine if presence of antibodies to C. burnetii during pregnancy or seroconversion were associated with adverse pregnancy outcomes. METHODS: The Danish National Birth Cohort collected blood samples and interview data from 100,418 pregnant women (1996-2002). We sampled 397 pregnant women with occupational or domestic exposure to cattle or sheep and a random sample of 459 women with no animal exposure. Outcome measures were spontaneous abortion, preterm birth, birth weight and Small for Gestational Age (SGA).Blood samples collected in pregnancy were screened for antibodies against C. burnetii by enzyme-linked immunosorbent assay (ELISA). Samples positive for IgG or IgM antibodies in the ELISA were confirmed by immunofluorescence antibody test (IFA). RESULTS: Among the 856 women, 169 (19.7%) women were IFA positive; 147 (87%) of these had occupational or domestic contact with livestock (IFA cutoff > =1:128).Two abortions were IFA positive vs. 6 IFA negative (OR: 1.5; 95%CI: 0.3-7.6). Three preterm births were IFA positive vs. 38 IFA negative (OR: 0.4; 95% CI: 0.1-1.1). There was a significant difference in birth weight of 168 g (95% CI: 70-267 g) with IFA positive being heavier, and the risk of being SGA was not increased in the newborns of IFA positive women (OR: 0.4; 95%CI: 0.8-1.0).Most seropositive women were IgG positive indicating previous exposure. Seroconversion during pregnancy was found in 10 women; they all delivered live babies at term, but two were SGA. CONCLUSION: We found no increased risk of adverse pregnancy outcome in women with verified exposure to C. burnetii.To our knowledge, this is the first population-based seroepidemiologic study evaluating pregnancy outcome in women with serologically verified exposure to C. burnetii against a comparable reference group of seronegative women.

Comparison of two commercially available ELISA antibody test kits for detection of human antibodies against Coxiella burnetii.

BACKGROUND: Q fever is a zoonosis caused by Coxiella burnetii. The disease is emerging in many parts of the world, likely in part due to increased awareness and the availability of better diagnostic tests. The clinical diagnosis of Q fever is difficult, and most confirmed cases rely on serology. METHODS: This study compared the sensitivity, specificity, and performance of 2 commercial enzyme-linked immunosorbent assay (ELISA) kits, with a commercial microimmunofluorescence antibody test (IFA) used as reference. RESULTS: One of the ELISA kits showed a higher sensitivity and a lower cross-reactivity than the other kit. Likewise, the same kit was superior when comparing the area under the receiver operating characteristic curves. CONCLUSIONS: The results support the continued use of IFA as a primary serological test for Q fever; for large numbers of samples, an ELISA kit can be used as a screening tool, if followed by a confirmatory IFA test.

Laboratory Diagnostics of Rickettsia 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.

Evaluation of serological tests for the diagnosis of rickettsiosis in Denmark.

Two commercially available immunofluorescence assays (IFA) were compared using historical sera evaluated for rickettsial antibodies by the Weil-Felix test. An IFA test produced by Focus Diagnostics prepared with Rickettsia rickettsii and R. typhi antigens was compared with a custom made kit from Fuller Laboratories with R. rickettsii, R. typhi, R. conorii and R. helvetica as antigens. The serum panel used for the comparison included Weil-Felix-positive and -negative samples. Cross-reactions were analyzed using serum samples from patients with clinical symptoms similar to those of rickettsiosis. When analyzing the data using the manufacturers' cut-off values, 41% of samples from presumably healthy blood donors were found positive for spotted fever group Rickettsia antibodies. This does not correlate to the general picture of rickettsiosis in Denmark. Furthermore, sera with Coxiella burnetii antibodies were found to be cross-reacting in both tests. When applying cut-off values calculated on the 95% percentile on data from blood donor serum samples, there was no significant difference between the two kits. Moreover, when using the newly established cut-off, cross-reactions were eliminated.

Persistence of antibodies to pneumococcal conjugate vaccine compared to polysaccharide vaccine in patients with Crohn's disease - one year follow up.

Background: Patients suffering from Crohn's disease (CD) are at increased risk of infectious diseases, such as pneumococcal infection. The risk increases with immunotherapy. Pneumococcal infection can be prevented by vaccination. Methods: We conducted a randomized trial of the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugated vaccine (PCV13) in groups of CD patients treated with immunosuppressive (IS) drugs in the form of thiopurines (PPV23 n = 28, PCV13 n = 28) alone or in combination with TNF-α antagonists (PPV23 n = 13, PCV13 n = 13) and CD patients not treated with any of these drugs (untreated) (PPV23 n = 30, PCV13 n = 24). In this article, we report the immunogenicity of PPC23 and PCV13 one year after vaccination. Results: No overall differences in vaccine-induced serotype-specific immunoglobulin G (IgG) antibodies or functional antibodies (opsonophagocytic activity (OPA)) were found between the two vaccines. PCV13 induced a higher concentration of IgG antibodies for serotype 9V than PPV23 in untreated patients. In contrast, PPV23 induced higher OPA for serotypes 6B and 19F than PCV13 in IS treated patients. Untreated patients showed generally higher IgG and OPA antibody levels than patients treated with IS and TNF-α antagonists. Conclusions: In conclusion, we found no general differences in the persistence of induced antibodies when comparing PPV23 with PCV13 regardless of treatment and also within treatment groups (IS, IS + TNF-α and untreated). This was demonstrated for both serotype-specific IgG antibodies and as functional antibodies (OPA). Patients treated with thiopurines in combination with TNF-α inhibitors have an impaired immune response against both PPV23 and PCV13, as compared to untreated patients. This study has been registered in the European Clinical Trials Database (EudraCT, record no 2012-002867-86) and ClinicalTrials.gov (record no. NCT01947010).

Multilaboratory Comparison of Pneumococcal Multiplex Immunoassays Used in Immunosurveillance of Streptococcus pneumoniae across Europe.

Surveillance studies are required to estimate the impact of pneumococcal vaccination in both children and the elderly across Europe. The World Health Organization (WHO) recommends use of enzyme immunoassays (EIAs) as standard methods for immune surveillance of pneumococcal antibodies. However, as levels of antibodies to multiple serotypes are monitored in thousands of samples, a need for a less laborious and more flexible method has evolved. Fluorescent-bead-based multiplex immunoassays (MIAs) are suitable for this purpose. An increasing number of public health and diagnostic laboratories use MIAs, although the method is not standardized and no international quality assessment scheme exists. The EU Pneumo Multiplex Assay Consortium was initiated in 2013 to advance harmonization of MIAs and to create an international quality assessment scheme. In a multilaboratory comparison organized by the consortium, agreement among nine laboratories that used their own optimized MIA was assessed on a panel of 15 reference sera for 13 pneumococcal serotypes with the new WHO standard 007sp. Agreement was assessed in terms of assay accuracy, reproducibility, repeatability, precision, and bias. The results indicate that the evaluated MIAs are robust and reproducible for measurement of vaccine-induced antibody responses. However, some serotype-specific variability in the results was observed in comparisons of polysaccharides from different sources and of different conjugation methods, especially for serotype 4. On the basis of the results, the consortium has contributed to the harmonization of MIA protocols to improve reliability of immune surveillance of Streptococcus pneumoniaeIMPORTANCE Serology of Streptococcus pneumoniae is challenging due to existence of multiple clinically relevant serotypes and the introduction of multivalent vaccines in national immunization programs. Multiplex immunoassays (MIAs) are applied as high-throughput cost-effective methods for serosurveillance, and yet laboratories use their own protocols. The aims of this study were to assess the agreement of results generated by MIAs in different laboratories within the EU Pneumo Multiplex Assay Consortium, to analyze factors contributing to differences in outcome, and to create a harmonized protocol. The study demonstrated good agreement of results of MIAs performed by laboratories using controlled assays for determination of levels of vaccine-induced pneumococcal antibodies. The EU Pneumo Multiplex Assay Consortium is open to everyone working in public health services, and it aims to facilitate efforts by participants to run and maintain a cost-effective, reproducible, high-quality MIA platform.

Initial Serological Response after Prime-boost Pneumococcal Vaccination in Rheumatoid Arthritis Patients: Results of a Randomized Controlled Trial.

OBJECTIVE: To evaluate the initial serological responses to pneumococcal vaccination with the 13-valent protein-conjugated pneumococcal vaccine (PCV13) followed by the 23-valent polysaccharide pneumococcal vaccine (PPV23) among patients with rheumatoid arthritis (RA) treated with biological disease-modifying antirheumatic drugs (bDMARD) according to dosing and intervals between immunizations. METHODS: Investigator-initiated clinical trial. Patients with RA receiving bDMARD were randomized (1:1:1) to immunization with single dose PCV13 followed by PPV23 after 16 or 24 weeks, or double dose PCV13 followed by PPV23 after 16 weeks. A comparison group of patients with RA treated with conventional synthetic (cs)DMARD received single dose PCV13 followed by PPV23 16 weeks later. Pneumococcal antibodies were collected before and 4 weeks after each vaccination. The primary endpoint was the proportion of participants responding to ≥ 6/12 pneumococcal serotypes 4 weeks after both vaccinations. RESULTS: Sixty-five participants receiving bDMARD and 35 participants receiving csDMARD were included. After PPV23 vaccination, 87% (95% CI 0.76-0.94) and 94% (95% CI 0.77-0.99), respectively, of participants treated with bDMARD and csDMARD had reached the primary endpoint. There was no significant difference in primary endpoint between the 3 randomization arms. The response for rituximab-treated participants was 25% compared to ≥ 89% in participants treated with bDMARD with other mode of action. CONCLUSION: The early serological response to prime-boost vaccination with PCV13 followed by PPV23 was very similar among participants receiving bDMARD and csDMARD. However, notable differences in response were observed according to individual bDMARD. It is important to consider the RA treatment when planning pneumococcal vaccination in patients with RA.

Fifth Percentile Cutoff Values for Antipneumococcal Polysaccharide and Anti-Salmonella typhi Vi IgG Describe a Normal Polysaccharide Response.

BACKGROUND: Serotype-specific antibody responses to unconjugated pneumococcal polysaccharide vaccine (PPV) evaluated by a World Health Organization (WHO)-standardized enzyme-linked immunosorbent assay (ELISA) are the gold standard for diagnosis of specific polysaccharide antibody deficiency (SAD). The American Academy of Allergy, Asthma and Immunology (AAAAI) has proposed guidelines to interpret the PPV response measured by ELISA, but these are based on limited evidence. Additionally, ELISA is costly and labor-intensive. Measurement of antibody response to Salmonella typhi (S. typhi) Vi vaccine and serum allohemagglutinins (AHA) have been suggested as alternatives. However, there are no large cohort studies and cutoff values are lacking. OBJECTIVE: To establish cutoff values for antipneumococcal polysaccharide antibody response, anti-S. typhi Vi antibody, and AHA. METHODS: One hundred healthy subjects (10-55 years) were vaccinated with PPV and S. typhi Vi vaccine. Blood samples were obtained prior to and 3-4 weeks after vaccination. Polysaccharide responses to 3 serotypes were measured by WHO ELISA and to 12 serotypes by an in-house bead-based multiplex assay. Anti-S. typhi Vi IgG were measured with a commercial ELISA kit. AHA were measured by agglutination method. RESULTS: Applying AAAAI criteria, 30% of healthy subjects had a SAD. Using serotype-specific fifth percentile (p5) cutoff values for postvaccination IgG and fold increase pre- over postvaccination, only 4% of subjects had SAD. One-sided 95% prediction intervals for anti-S. typhi Vi postvaccination IgG (≥11.2 U/ml) and fold increase (≥2) were established. Eight percent had a response to S. typhi Vi vaccine below these cutoffs. AHA titer p5 cutoffs were ½ for anti-B and » for anti-A. CONCLUSION: We establish reference cutoff values for interpretation of PPV response measured by bead-based assay, cutoff values for S. typhi Vi vaccine responses, and normal values for AHA. For the first time, the intraindividual consistency of all three methods is studied in a large cohort.

Recurrent Invasive Pneumococcal Disease Serotype 12F in a Vaccinated Splenectomized Patient.

This is the first case report of recurrent invasive pneumococcal disease (IPD), specifically, due to serotype 12F. The patient described here was vaccinated with the 23-valent pneumococcal polysaccharide vaccine (PPV23) due to previous splenectomy, and an anti-pneumococcal IgG test concluded that she had responded sufficiently to vaccination. Still, she had a fulminate recurrent infection with PPV23 serotype 12F. We investigated the anti-pneumococcal IgG test, and it turned out that it is based on the geometric mean value of only 12 of the serotypes included in PPV23; 12F is none of them. The reason is that there are no titer cut-offs available for 11 of the PPV23 serotypes, including 12F, neither nationally nor internationally. Yet, this is not specified in the answer to the clinicians. This case illustrates the need for titer cut-offs for the remaining pneumococcal serotypes in available vaccines, in order to get a more accurate estimation of the vaccination coverage for the individual patient. Therefore, more research on this area is warranted, along with a discussion of whether the laboratory answers to the clinicians should be more detailed.

Immunosuppressive drugs impairs antibody response of the polysaccharide and conjugated pneumococcal vaccines in patients with Crohn's disease.

BACKGROUND: Patients with Crohn's disease (CD) have a higher risk of infectious diseases including pneumococcal infections, and the risk increases with immunotherapy. The primary endpoint of this study was to investigate the specific antibody response to two pneumococcal vaccines in CD patients with and without immunosuppressive treatment four weeks post vaccination. METHODS: In a randomized trial of the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugated vaccine (PCV13), a group of CD patients treated with immunosuppressive drugs (IS) alone or in combination with TNF-α antagonists were compared to a group of CD patients not treated with any of these drugs (untreated). Specific pneumococcal antibody concentrations were measured against 12 serotypes common to the two vaccines before and 4 week after vaccination. RESULTS: PCV13 induced a significantly higher antibody response for one serotype (23F) in IS treated patients and for two serotypes (9V and 23F) in untreated patients compared to CD patients vaccinated with PPV23. Untreated PPV23 recipients had higher responses for serotypes 9V and 18C compared to IS+TNF-α treated PPV23 recipients. Comparison between treatment groups showed that immunosuppressive treatment impaired the antibody response to both vaccines and that TNF-a treatment further conveyed additional impairment of the response. CONCLUSION: PCV13 induces higher antibody response for some serotypes compared to PPV23. In addition, CD patients treated with immunosuppressive drugs alone or in combination with TNF-α antagonists had an impaired antibody response to both PPV23 and PCV13 compared to patients not receiving any of these treatments. The study has been registered in the European Clinical Trials Database (EudraCT, record no 2012-002867-86) and ClinicalTrials.gov (record no. NCT01947010).

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.

The immunological effects of oral polio vaccine provided with BCG vaccine at birth: a randomised trial.

BACKGROUND: Vaccines may have non-specific effects. An observational study from Guinea-Bissau suggested that oral polio vaccine at birth (OPV0) provided with Bacillus Calmette-Guérin (BCG) vaccine was associated with down-regulation of the immune response to BCG vaccine 6 weeks later. Based on the previous finding, we wanted to test our a priori hypothesis that OPV would dampen the immune response to BCG, and secondarily to test immune responses to other antigens. METHODS: The study was conducted at the Bandim Health Project in Guinea-Bissau in 2009-2010. Infants were randomised to OPV0+BCG versus BCG alone at birth, and subsequently randomised to have a blood sample taken at 2, 4 or 6 weeks post-randomisation. Excreted levels of cytokines (IL-2, IL-5, IL-10, TNF-α and IFN-γ) were measured from whole blood in vitro stimulations with a panel of recall vaccine antigens (BCG, PPD, OPV), mitogen (PHA) or innate agonists (LPS, Pam3cys, PolyI:C). Additionally, we measured the local reaction to BCG, white blood cell distribution, C-reactive protein (CRP) and retinol-binding protein (RBP). Cytokine production was analysed as the prevalence ratios of responders above the median. RESULTS: Blood samples from 430 infants (209 OPV0+BCG; 221 BCG alone) were analysed. There were no strong differences in effects 2, 4 and 6 weeks post-randomisation and subsequent analyses were performed on the pooled data. As hypothesised, receiving OPV0+BCG versus BCG alone was associated with significantly lower prevalence of IFN-γ responses to PPD (prevalence ratio (PR): 0.84 (0.72-0.98)) and reduced IL-5 to PPD (PR: 0.78 (0.64-0.96)). No effects were observed for CPR, RBP, white blood cell distribution, or BCG scar prevalence. CONCLUSION: The results corroborate that OPV attenuates the immune response to co-administered BCG at birth.

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.

Evaluation of serotype-specific pneumococcal IgG measurement using two different polysaccharides from ATCC and SSI Diagnostica.

Streptococcus pneumoniae (pneumococcus) is a major cause of morbidity and mortality especially in infants and elderly people. Pneumococcus capsular polysaccharide has been characterised and more than 90 different serotypes have been identified. Serotype-specific antibodies against the capsular polysaccharide are produced during infection. At present, many countries follow the WHO pneumococcal ELISA IgG measurement protocol, in which polysaccharides from ATCC are used as antigens. In recent years, serotype specific polysaccharides from different producers have been tested in pneumococcal antibody assay's. In this project, purified serotype specific pneumococcal antigens from SSI Diagnostica and from ATCC were compared. In general, the data showed that both types of polysaccharide could be used as antigens. Furthermore, the effect of adsorption using different combinations of adsorption procedures was tested, showing similar results using CWPSmulti or CWPS+22F.

Seasonal and habitat variation in the prevalence of Rickettsia helvetica in Ixodes ricinus ticks from Denmark.

A total of 704 unfed ticks of the species Ixodes ricinus collected in Denmark were screened for Rickettsia DNA by a genus-specific real-time PCR. Of the nymphs, 4.7% (31/662) were positive for rickettsial DNA. Among the positive ticks, we observed a seasonal and habitat variation. The infection rate was highest in May as compared to July, August, and October. Ecotone (high tick density) showed an elevated prevalence as compared to spruce or beech forests. Sequencing revealed only DNA from R. helvetica.