Incidence and severity of SARS-CoV-2 infection in former Q fever patients as compared to the Dutch population, 2020-2021.

Surveillance data shows a geographical overlap between the early coronavirus disease 2019 (COVID-19) pandemic and the past Q fever epidemic (2007-2010) in the Netherlands. We investigated the relationship between past Q fever and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in 2020/2021, using a retrospective matched cohort study.In January 2021, former Q fever patients received a questionnaire on demographics, SARS-CoV-2 test results and related hospital/intensive care unit (ICU) admissions. SARS-CoV-2 incidence with 95% confidence intervals (CI) in former Q fever patients and standardised incidence ratios (SIR) to compare to the age-standardised SARS-CoV-2 incidence in the general regional population were calculated.Among 890 former Q fever patients (response rate: 68%), 66 had a PCR-confirmed SARS-CoV-2 infection. Of these, nine (14%) were hospitalised and two (3%) were admitted to ICU. From February to June 2020 the SARS-CoV-2 incidence was 1573/100 000 (95% CI 749-2397) in former Q fever patients and 695/100 000 in the general population (SIR 2.26; 95% CI 1.24-3.80). The incidence was not significantly higher from September 2020 to February 2021.We found no sufficient evidence for a difference in SARS-CoV-2 incidence or an increased severity in former Q fever patients vs. the general population during the period with widespread SARS-CoV-2 testing availability (September 2020-February 2021). This indicates that former Q fever patients do not have a higher risk of SARS-CoV-2 infection.

Self-testing for the detection of SARS-CoV-2 infection with rapid antigen tests for people with suspected COVID-19 in the community.

OBJECTIVES: To evaluate the performance of nasal mid-turbinate self-testing using rapid antigen detection tests (RDT) for persons with suspected coronavirus disease 2019 (COVID-19) in the community. Self-testing for COVID-19 infection with lateral flow assay severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RDT, provides rapid results and could enable frequent and extensive testing in the community, thereby improving the control of SARS-CoV-2. METHODS: Participants visiting a municipal SARS-CoV-2 testing centre, received self-testing kits containing either the BD Veritor System (BD-RDT) or Roche SARS-CoV-2 antigen detection test (Roche-RDT). Oro-nasopharyngeal swabs were collected from the participants for quantitative RT-PCR (qRT-PCR) testing. As a proxy for contagiousness, viral culture was performed on a selection of qRT-PCR positive samples to determine the Ct-value at which the chance of a positive culture dropped below 0.5 (Ct-value cut-off). Sensitivity and specificity of self-testing were compared to qRT-PCR with a Ct-value below the Ct value cut-off. Determinants independently associated with a false-negative self-test result were determined. RESULTS: A total of 3201 participants were included (BD-RDT n = 1595; Roche-RDT n = 1606). Sensitivity and specificity of self-testing compared with the qRT-PCR results with a Ct-value below the Ct-value cut-off were 78.4% (95% CI 73.2%-83.5%) and 99.4% (95% CI 99.1%-99.7%), respectively. A higher age was independently associated with a false-negative self-testing result with an odds ratio of 1.024 (95% CI 1.003-1.044). CONCLUSIONS: Self-testing using currently available RDT has a high specificity and relatively high sensitivity to identify individuals with a high probability of contagiousness.

Adaptation, spread and transmission of SARS-CoV-2 in farmed minks and associated humans in the Netherlands.

In the first wave of the COVID-19 pandemic (April 2020), SARS-CoV-2 was detected in farmed minks and genomic sequencing was performed on mink farms and farm personnel. Here, we describe the outbreak and use sequence data with Bayesian phylodynamic methods to explore SARS-CoV-2 transmission in minks and humans on farms. High number of farm infections (68/126) in minks and farm workers (>50% of farms) were detected, with limited community spread. Three of five initial introductions of SARS-CoV-2 led to subsequent spread between mink farms until November 2020. Viruses belonging to the largest cluster acquired an amino acid substitution in the receptor binding domain of the Spike protein (position 486), evolved faster and spread longer and more widely. Movement of people and distance between farms were statistically significant predictors of virus dispersal between farms. Our study provides novel insights into SARS-CoV-2 transmission between mink farms and highlights the importance of combining genetic information with epidemiological information when investigating outbreaks at the animal-human interface.

Transmission of SARS-CoV-2 on mink farms between humans and mink and back to humans.

Animal experiments have shown that nonhuman primates, cats, ferrets, hamsters, rabbits, and bats can be infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition, SARS-CoV-2 RNA has been detected in felids, mink, and dogs in the field. Here, we describe an in-depth investigation using whole-genome sequencing of outbreaks on 16 mink farms and the humans living or working on these farms. We conclude that the virus was initially introduced by humans and has since evolved, most likely reflecting widespread circulation among mink in the beginning of the infection period, several weeks before detection. Despite enhanced biosecurity, early warning surveillance, and immediate culling of animals in affected farms, transmission occurred between mink farms in three large transmission clusters with unknown modes of transmission. Of the tested mink farm residents, employees, and/or individuals with whom they had been in contact, 68% had evidence of SARS-CoV-2 infection. Individuals for which whole genomes were available were shown to have been infected with strains with an animal sequence signature, providing evidence of animal-to-human transmission of SARS-CoV-2 within mink farms.

Two Community Clusters of Legionnaires' Disease Directly Linked to a Biologic Wastewater Treatment Plant, the Netherlands.

A biologic wastewater treatment plant was identified as a common source for 2 consecutive Legionnaires' disease clusters in the Netherlands in 2016 and 2017. Sequence typing and transmission modeling indicated direct and long-distance transmission of Legionella, indicating this source type should also be investigated in sporadic Legionnaires' disease cases.

Estimation of acute and chronic Q fever incidence in children during a three-year outbreak in the Netherlands and a comparison with international literature.

BACKGROUND: In the Dutch 2007-2009 Q fever outbreak Coxiella burnetii was transmitted aerogenically from dairy goat farms to those living in the surrounding areas. Relatively few children were reported. The true number of pediatric infections is unknown. In this study, we estimate the expected number of acute and chronic childhood infections. METHODS: As Coxiella was transmitted aerogenic to those living near infected dairy goat farms, we could use adult seroprevalence data to estimate infection risk for inhabitants, children and adults alike. Using Statistics Netherlands data we estimated the number of children at (high) risk for developing chronic Q fever. Literature was reviewed for childhood (0-15 years) Q fever reports and disease rates. We compared this with Dutch reported and our estimated data for 2007-2009. RESULTS: In The Netherlands epidemic, 44 children were reported (1.2 % of total notifications). The childhood incidence was 0.15 compared to 2.6 per 10,000 inhabitants for adults. No complications were reported. Based on the expected similarity in childhood and adult exposure we assume that 9.8 % of children in the high-risk area had Q fever infection, resulting in 1562 acute infections during the Q fever epidemic interval. Based on the prevalence of congenital heart disease, at least 13 children are at high risk for developing chronic Q fever. In medical literature, 42 case reports described 140 childhood Q fever cases with a serious outcome (four deaths). In chronic Q fever, cardiac infections were predominant. Four outbreaks were reported involving children, describing 11 childhood cases. 36 National and/or regional studies reported seroprevalences varying between 0 and 70 %. CONCLUSION: In the 3-year Dutch epidemic, few childhood cases were reported, with pulmonary symptoms leading, and none with a serious presentation. With an estimated 13 high-risk children for chronic infection in the high exposure area, and probably forty in the whole country, we may expect several chronic Q fever complications in the coming years in paediatric practice.

Long-Term Serological Follow-Up of Acute Q-Fever Patients after a Large Epidemic.

BACKGROUND: Serological follow-up of acute Q-fever patients is important for detection of chronic infection but there is no consensus on its frequency and duration. The 2007-2009 Q-fever epidemic in the Netherlands allowed for long-term follow-up of a large cohort of acute Q-fever patients. The aim of this study was to validate the current follow-up strategy targeted to identify patients with chronic Q-fever. METHODS: A cohort of adult acute Q-fever patients, diagnosed between 2007 and 2009, for whom a twelve-month follow-up sample was available, was invited to complete a questionnaire and provide a blood sample, four years after the acute episode. Antibody profiles, determined by immunofluorescence assay in serum, were investigated with a special focus on high titres of IgG antibodies against phase I of Coxiella burnetii, as these are considered indicative for possible chronic Q-fever. RESULTS: Of the invited 1,907 patients fulfilling inclusion criteria, 1,289 (67.6%) were included in the analysis. At any time during the four-year follow-up period, 58 (4.5%) patients were classified as possible, probable, or proven chronic Q-fever according to the Dutch Q-fever Consensus Group criteria (which uses IgG phase I ≥1:1,024 to as serologic criterion for chronic Q-fever). Fifty-two (89.7%) of these were identified within the first year after the acute episode. Of the six patients that were detected for the first time at four-year follow-up, five had an IgG phase I titre of 1:512 at twelve months. CONCLUSIONS: A twelve-month follow-up check after acute Q-fever is recommended as it adequately detects chronic Q-fever in patients without known risk factors. Additional serological and clinical follow-up is recommended for patients with IgG phase I ≥1:512, as they showed the highest risk to progress to chronic Q-fever.

Ongoing transmission of hepatitis B virus in rural parts of the Netherlands, 2009-2013.

BACKGROUND: Reported acute hepatitis B incidence in the Netherlands reached its nadir in 2013. However, regional signals about increased number of hepatitis B cases raised the question how hepatitis B incidence was distributed over the country. In this study, regional differences in hepatitis B epidemiology were investigated using epidemiological and molecular data. METHODS: Acute hepatitis B virus (HBV) infections, reported between 2009-2013, were included. If serum was available, a fragment of S and C gene of the HBV was amplified and sequenced. Regional differences in incidence were studied by geographical mapping of cases and cluster analysis. Regional differences in transmission were studied by constructing regional maximum parsimony trees based on the C gene to assess genetic clustering of cases. RESULTS: Between 2009 and 2013, 881 cases were notified, of which respectively 431 and 400 cases had serum available for S and C gene sequencing. Geographical mapping of notified cases revealed that incidences in rural border areas of the Netherlands were highest. Cluster analysis identified two significant clusters (p<0.000) in the South-western and North-eastern regions. Genetic cluster analysis showed that rural border areas had relatively large clusters of cases with indistinguishable sequences, while other regions showed more single introductions. CONCLUSION: This study showed that regional differences in HBV epidemiology were present in the Netherlands. Rural border regions showed higher incidences and more ongoing transmission, mainly among MSM, than the more urban inland areas. Therefore, preventive measures should be enhanced in these regions.

The use of typing methods and infection prevention measures to control a bullous impetigo outbreak on a neonatal ward.

BACKGROUND: We describe an outbreak of Bullous Impetigo (BI), caused by a (methicillin susceptible, fusidic acid resistant) Staphylococcus aureus (SA) strain, spa-type t408, at the neonatal and gynaecology ward of the Jeroen Bosch hospital in the Netherlands, from March-November 2011. METHODS: We performed an outbreak investigation with revision of the hygienic protocols, MSSA colonization surveillance and environmental sampling for MSSA including detailed typing of SA isolates. Spa typing was performed to discriminate between the SA isolates. In addition, Raman-typing was performed on all t408 isolates. RESULTS: Nineteen cases of BI were confirmed by SA positive cultures. A cluster of nine neonates and three health care workers (HCW) with SA t408 was detected. These strains were MecA-, PVL-, Exfoliative Toxin (ET)A-, ETB+, ETAD-, fusidic acid-resistant and methicillin susceptible. Eight out of nine neonates and two out of three HCW t408 strains yielded a similar Raman type. Positive t408 HCW were treated and infection control procedures were reinforced. These measures stopped the outbreak. CONCLUSIONS: We conclude that treatment of patients and HCW carrying a predominant SA t408, and re-implementing and emphasising hygienic measures were effective to control the outbreak of SA t408 among neonates.

The 2007­2010 Q fever epidemic in The Netherlands: characteristics of notified acute Q fever patients and the association with dairy goat farming.

We describe the Q fever epidemic in the Netherlands with emphasis on the epidemiological characteristics of acute Q fever patients and the association with veterinary factors. Data from 3264 notifications for acute Q fever in the period from 2007 through 2009 were analysed. The patients most affected were men, smokers and persons aged 40­60 years. Pneumonia was the most common clinical presentation (62% in 2007 and 2008). Only 3.2% of the patients were working in the agriculture sector and 0.5% in the meat-processing industry including abattoirs. Dairy goat farms with Coxiella burnetii-induced abortion waves were mainly located in the same area where human cases occurred. Airborne transmission of contaminated dust particles from commercial dairy goat farms in densely populated areas has probably caused this epidemic. In 2010, there was a sharp decline in the number of notified cases following the implementation of control measures on dairy goat and sheep farms such as vaccination, hygiene measures and culling of pregnant animals on infected farms. In combination with a rise in the human population with antibodies against C. burnetii, these have most likely ended the outbreak. Development of chronic Q fever in infected patients remains an important problem for years to come.

Proximity to goat farms and Coxiella burnetii seroprevalence among pregnant women.

During 2007-2009, we tested serum samples from 2,004 pregnant women living in an area of high Q fever incidence in the Netherlands. Results confirmed that presence of antibodies against Coxiella burnetii is related to proximity to infected dairy goat farms. Pregnant women and patients with certain cardiovascular conditions should avoid these farms.

Cost-effectiveness of a screening strategy for Q fever among pregnant women in risk areas: a clustered randomized controlled trial.

BACKGROUND: In The Netherlands the largest human Q fever outbreak ever reported in the literature is currently ongoing with more than 2300 notified cases in 2009. Pregnant women are particularly at risk as Q fever during pregnancy may cause maternal and obstetric complications. Since the majority of infected pregnant women are asymptomatic, a screening strategy might be of great value to reduce Q fever related complications. We designed a trial to assess the (cost-)effectiveness of a screening program for Q fever in pregnant women living in risks areas in The Netherlands. METHODS/DESIGN: We will conduct a clustered randomized controlled trial in which primary care midwife centres in Q fever risk areas are randomized to recruit pregnant women for either the control group or the intervention group. In both groups a blood sample is taken around 20 weeks postmenstrual age. In the intervention group, this sample is immediately analyzed by indirect immunofluorescence assay for detection of IgG and IgM antibodies using a sensitive cut-off level of 1:32. In case of an active Q fever infection, antibiotic treatment is recommended and serological follow up is performed. In the control group, serum is frozen for analysis after delivery. The primary endpoint is a maternal (chronic Q fever or reactivation) or obstetric complication (low birth weight, preterm delivery or fetal death) in Q fever positive women. Secondary aims pertain to the course of infection in pregnant women, diagnostic accuracy of laboratory tests used for screening, histo-pathological abnormalities of the placenta of Q fever positive women, side effects of therapy, and costs. The analysis will be according to the intention-to-screen principle, and cost-effectiveness analysis will be performed by comparing the direct and indirect costs between the intervention and control group. DISCUSSION: With this study we aim to provide insight into the balance of risks of undetected and detected Q fever during pregnancy. TRIAL REGISTRATION: ClinicalTrials.gov, protocol record NL30340.042.09.

[Three years of Q fever in the Netherlands: faster diagnosis]. / Drie jaar Q-koorts in Nederland: snellere diagnose.

OBJECTIVE: To assess if more rapid diagnosis and treatment is possible and to assess if this could be improved, since the first outbreak of Q fever in 2007. DESIGN: Retrospective study of secondary data. METHODS: Analysis of surveillance data regarding Q fever over the period 2007 to 2009 and additional information on some patients from 2007 and 2008 obtained from general practitioners. RESULTS: Diagnostic delay fell sharply between 2007 and 2009 and to a lesser extent, so did therapeutic delay from 2007 to 2008. In high incidence areas, diagnosis and treatment was faster with a lower proportion of patients admitted to hospital than in low incidence areas. CONCLUSION: It appears that familiarity with the condition leads to faster diagnosis coupled with a lower percentage of hospital admissions. In order to react quickly it is necessary that doctor and patient should be aware of Q fever, especially in areas of low incidence. Polymerase chain reaction diagnostic techniques should also be available.