Livestock-dense Area Research Articles

Risk of pneumonia in the vicinity of goat farms: a comparative assessment of temporal variation based on longitudinal health data

BackgroundAlthough the association between living in the vicinity of a goat farm and the occurrence of pneumonia is well-documented, it is unclear whether the higher risk of pneumonia in livestock dense areas is season-specific or not. This study explored the temporal variation of the association between exposure to goat farms and the occurrence of pneumonia.MethodsA large population-based study was conducted in the Netherlands, based on electronic health records from 49 general practices, collected for a period of six consecutive years (2014–2019). Monthly incidence rates of pneumonia in a livestock dense area were compared with those of a control group (areas with low livestock density) both per individual year and cumulatively for the entire six-year period. Using individual estimates of livestock exposure, it was also examined whether incidence of pneumonia differed per month if someone lived within a certain radius from a goat farm, compared to residents who lived further away.ResultsPneumonia was consistently more common in the livestock dense area throughout the year, compared to the control area. Analyses on the association between the individual livestock exposure estimates and monthly pneumonia incidence for the whole six-year period, yielded a generally higher risk for pneumonia among people living within 500 m from a goat farm, compared to those living further away. Significant associations were observed for March (IRR 1.68, 95% CI 1.02–2.78), August (IRR 2.67, 95% CI 1.45–4.90) and September (IRR 2.52, 95% CI 1.47–4.32).ConclusionsThe increased occurrence of pneumonia in the vicinity of goat farms is not season-specific. Instead, pneumonia is more common in livestock dense areas throughout the year, including summer months.

Air pollution from livestock farms and the oropharyngeal microbiome of COPD patients and controls.

Air pollution from livestock farms is known to affect respiratory health of patients with chronic obstructive pulmonary disease (COPD). The mechanisms behind this relationship, however, remain poorly understood. We hypothesise that air pollutants could influence respiratory health through modulation of the airway microbiome. Therefore, we studied associations between air pollution exposure and the oropharyngeal microbiota (OPM) composition of COPD patients and controls in a livestock-dense area. Oropharyngeal swabs were collected from 99 community-based (mostly mild) COPD cases and 184 controls (baseline), and after 6 and 12weeks. Participants were non-smokers or former smokers. Annual average livestock-related outdoor air pollution at the home address was predicted using dispersion modelling. OPM composition was analysed using 16S rRNA-based sequencing in all baseline samples and 6-week and 12-week repeated samples of 20 randomly selected subjects (n=323 samples). A random selection of negative control swabs, taken every sampling day, were also included in the downstream analysis. Both farm-emitted endotoxin and PM10 levels were associated with increased OPM richness in COPD patients (p<0.05) but not in controls. COPD case-control status was not associated with community structure, while correcting for known confounders (multivariate PERMANOVA p>0.05). However, members of the genus Streptococcus were more abundant in COPD patients (Benjamini-Hochberg adjusted p<0.01). Moderate correlation was found between ordinations of 20 subjects analysed at 0, 6, and 12weeks (Procrustes r=0.52 to 0.66; p<0.05; Principal coordinate analysis of Bray-Curtis dissimilarity), indicating that the OPM is relatively stable over a 12week period and that a single sample sufficiently represents the OPM. Air pollution from livestock farms is associated with OPM richness of COPD patients, suggesting that the OPM of COPD patients is susceptible to alterations induced by exposure to air pollutants.

Prevalence of non-specific health symptoms in livestock dense areas: Looking beyond respiratory conditions.

The aim of this study was to gain more insight in the association between prevalence of diverse acute non-specific symptoms (NSS) and livestock density as a possible risk factor among residents of livestock-dense and non-dense regions, taking into account socio-demographic factors and psychological morbidity. Prevalence of NSS and psychological morbidity were assessed for the year 2017, based on electronic health records from 39 general practices in the Netherlands. The study group consisted of people who lived in rural areas with high numbers of livestock (n=74093), while the control group included people in rural areas with low numbers of livestock (n=50139). For a large portion of the study group, exposure estimates (to livestock) were calculated. Multiple logistic multilevel regression analyses were performed. Two methods were used: 1) area comparisons between study and control areas in relation to health problems, and 2) estimates of livestock exposure (to goats, poultry, pigs, and cattle) within the study area. It was found that prevalence of diarrhea, headache, sleep disturbance, respiratory symptoms, and skin problems were higher in the study group. The data suggest that there may be a protective effect of livestock exposure: in general, there was a lower risk of NSS closer to livestock (within the exposure analyses). The study suggests that the previously identified higher risk of respiratory health problems in livestock dense areas might also apply to the prevalence of various other NSS. Longitudinal research taking into account different or more individual and contextual characteristics could possibly elucidate why prevalence of NSS in closer proximity to livestock is lower compared to people who live further away, whilst a more overarching analysis indicated that living in livestock dense areas was associated with more NSS.

Prolonged carriage of (livestock-associated) MRSA in individuals without professional livestock contact.

To investigate prolonged carriage of MRSA in adults from the general population living in a livestock-dense area, using WGS. A cross-sectional study during 2014-15 among 2492 adults without professional livestock contact identified 14 (0.6%) nasal MRSA carriers, 10 of which carried livestock-associated (LA)-MRSA of multiple-locus variable-number tandem repeat analysis (MLVA) complex (MC) 398. Two years later, 12 MRSA-positive and 88 MRSA-negative participants provided a second nasal swab and filled in a short questionnaire. Isolates from persons who were MRSA positive at both timepoints were compared using MLVA and isolates with the same MLVA type were sequenced. The WGS data were used for core-genome MLST (cgMLST) and resistome analysis, including sequenced isolates from the national MRSA surveillance. All MRSA-negative persons tested negative again, while 6 of the 12 initially MRSA-positive persons tested positive again. MLVA revealed that isolate pairs from five individuals had the same MLVA type, of which three were LA-MRSA. cgMLST showed that the distance between these isolate pairs ranged between 3 and 13 genes, while the minimum distance to unrelated isolates from the national MRSA surveillance was 38 genes. Moreover, the resistome present in the five isolate pairs was identical within each pair. None of the prolonged carriers was hospitalized during the 3 months before the sampling moment and none of them with LA-MRSA had contact with livestock in this period. Prolonged carriage of MRSA, including LA-MRSA, can be demonstrated after more than 30 months in persons without professional livestock contact.

Morbidity Rates in an Area with High Livestock Density: A Registry-Based Study Including Different Groups of Patients with Respiratory Health Problems.

There is continuing debate and public health concern regarding the previously confirmed association between high livestock density and human health. The primary aim of the current study is to assess the prevalence of respiratory and other health problems in a livestock dense area in the Netherlands, based on recent longitudinal health data and a large sample. Analyses are expanded with the investigation of different subgroups of patients with respiratory health problems and the inclusion of various chronic and acute health outcomes, as well as prescribed medication. Prevalence of health symptoms and chronic conditions was assessed for the period 2014–2016, based on electronic health records registered in 26 general practices located in areas with intensive livestock farming in the Netherlands (“livestock dense area”, n = 117,459 unique residents in total). These were compared with corresponding health data from general practices (n = 22) in different rural regions with a low density of livestock farms or other major environmental exposures (“control area”, n = 85,796 unique residents in total). Multilevel regression models showed a significantly higher prevalence of pneumonia in the total sample in the livestock dense area, which was also observed among susceptible subgroups of children, the elderly, and patients with chronic obstructive pulmonary disease (COPD). Lower respiratory tract infections, respiratory symptoms, vertigo, and depression were also more common in the livestock dense area compared to the control area. In general, there were no significant differences in chronic conditions such as asthma, COPD, or lung cancer. Prescription rates for broad-spectrum antibiotics were more common among patients with pneumonia in the livestock dense area. Acute respiratory infections and symptoms, but not chronic conditions, were considerably more common in areas with a high livestock density. Identification of causal pathogens on the basis of serological analyses could further elucidate the underlying mechanisms behind the observed health effects.

Morbidity rates in livestock dense areas

TPS 751: Farms, antibiotics, infections, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: There is ongoing debate and public concern regarding the possible effects of livestock density on human health. Two studies were performed based on longitudinal health data, to investigate the prevalence of infections/symptoms, chronic illnesses and medication among residents of livestock dense areas. Methods: In the first study prevalence of health outcomes was assessed for seven consecutive years (2010-2016), based on a sample of ±100000 individuals. Data were obtained from electronic health records registered in 26 general practices located in areas with intensive livestock farming in the Netherlands (provinces of North-Brabant and Limburg) (“study area”). These were compared with data from 22 general practices in rural regions with a low density of livestock farms or other major environmental exposures (“control area”). In the second study, a different “study area” was used (Gelderland, Overijssel and Utrecht) and analyses were repeated for the period 2014-2017 based on a sample of ±70000 residents. Results: The first study suggested a significantly higher prevalence of pneumonia, which was consistent over the years (2013: OR=1.5, 99% CI 1.03 – 2.17; 2014: OR=1.45, 99% CI 1.00 – 2.1; 2015: OR=1.58, 99% CI 1.09 – 2.3; 2016: OR=1.6, 99% CI 1.13 – 2.28). Lower respiratory tract infections, respiratory symptoms and vertigo were also consistently more common compared to the control area. Significant results were also observed for subgroups with respiratory conditions, children and the elderly. The second study verified the previous findings on respiratory outcomes, showing a consistently higher prevalence of pneumonia and acute respiratory symptoms in other livestock dense area(s). Both studies showed no significant differences in chronic conditions such as asthma and COPD. Conclusions: Respiratory infections and symptoms are more common in livestock dense areas. Assessment of temporal associations including individual exposure estimates and identification of causal pathogens based on serological analyses may shed further light.

Prevalence of non-specific symptoms in livestock dense areas

OPS 07: Farm animals, antibiotics, infections and the microbiome, Room 110, Floor 1, August 27, 2019, 10:30 AM - 12:00 PM Background: A large body of studies showed that prevalence of respiratory health problems is higher when people live closer to livestock farms, compared to people who live further away. Acute somatic and mental health symptoms such as headache, sleep problems and anxiety can also be directly or indirectly associated with environmental exposures, especially in the light of recent zoonoses with a severe impact on human health. The present study aims to gain more insight in possible differences between residents of livestock dense and non-dense regions, in the prevalence of diverse acute non-specific symptoms (NSS), taking into account socio-demographic factors and psychiatric morbidity. Methods: Prevalence of diverse acute health symptoms as well as anxiety and depression was assessed for the year 2017, based on electronic health records registered in 39 general practices in the Netherlands. Data were obtained from the Primary Care Database (PCD) of Nivel. The “study group” included people who lived in rural areas with high livestock density (n=74093) and was compared to a “control group” (people in other rural areas with low livestock density) (n=50139). Multiple logistic multilevel regression analyses were performed. Results: Prevalence of anxiety was significantly higher among people living in livestock dense regions, while there was no significant difference in depression. There was a significantly higher chance that people in the study group had acute health symptoms such as abdominal complaints, diarrhea, headache, dizziness, sleep disturbance, coughing, and skin symptoms, compared to the control group. Conclusions: The study suggests that the previously identified higher risk of respiratory health problems in livestock dense areas also applies to the prevalence of various NSS. The results need to be verified while considering individual livestock exposure estimates and other relevant individual and environmental factors over a broader time period.

Respiratory health effects and atopic sensitization in non-farming residents associated with particulate matter and endotoxin emitted by livestock farms

OPS 08: Biological contaminants and respiratory health, Room 117, Floor 1, August 26, 2019, 4:30 PM - 5:30 PM Background: Living in livestock-dense areas has been associated with health effects, suggesting airborne exposures to livestock farm emissions to be relevant for public health. Livestock farm emissions involve complex mixtures of various gases and particles. Endotoxin, a pro-inflammatory agent of microbial origin, is a constituent of livestock farm emitted particulate matter (PM) that is potentially related to the observed health effects. Quantification of livestock associated endotoxin exposure at residential addresses has not been performed earlier. We aimed to assess exposure-response relations for a range of respiratory endpoints and atopic sensitization in relation to modelled livestock farm emitted PM10 and endotoxin. Methods: Self-reported respiratory symptoms and health information of 12,117 persons participating in a population based cross-sectional study was used. For 2,494 persons, also data on lung function (spirometry) and serologically assessed atopic sensitization was available. Annual-average PM10 and endotoxin concentrations at home addresses were predicted by dispersion modelling and land-use regression (LUR) modelling. Exposure-response relations were analysed with generalized additive models. Results: Health outcomes were generally more strongly associated with exposure to livestock farm emitted endotoxin compared to PM10. An inverse association was observed for dispersion modelled exposure with atopic sensitization (endotoxin: p=.004, PM10: p=.07) and asthma (endotoxin: p=.029, PM10: p=.022). Prevalence of respiratory symptoms decreased with increasing endotoxin concentration at the lower range, at the higher range prevalence increased with increasing concentration (p<.05). Associations between lung function parameters with exposure to PM10 and endotoxin were not statistically significant (p>.05). Conclusions: Exposure to livestock farm emitted particulate matter is associated with respiratory health effects and atopic sensitization in non-farming residents. Results indicate endotoxin to be a potentially plausible etiologic agent, suggesting non-infectious aspects of microbial emissions from livestock farms to be important with respect to public health.

Evaluation of Methicillin-Resistant Staphylococcus aureus Carriage and High Livestock Production Areas in North Carolina through Active Case Finding at a Tertiary Care Hospital

Recent reports from the Netherlands document the emergence of novel multilocus sequence typing (MLST) types (e.g., ST-398) of methicillin-resistant Staphylococcus aureus (MRSA) in livestock, particularly swine. In Eastern North Carolina (NC), one of the densest pig farming areas in the United States, as many as 14% of MRSA isolates from active case finding in our medical center have no matches in a repetitive sequence-based polymerase chain reaction (rep-PCR) library. The current study was designed to determine if these non-matched MRSA (NM-MRSA) were geographically associated with exposure to pig farming in Eastern NC. While residential proximity to farm waste lagoons lacked association with NM-MRSA in a logistic regression model, a spatial cluster was identified in the county with highest pig density. Using MLST, we found a heterogeneous distribution of strain types comprising the NM-MRSA isolates from the most pig dense regions, including ST-5 and ST-398. Our study raises the warning that patients in Eastern NC harbor livestock associated MRSA strains are not easily identifiable by rep-PCR. Future MRSA studies in livestock dense areas in the U.S. should investigate further the role of pig–human interactions.

Endotoxin and particulate matter emitted by livestock farms and respiratory health effects in neighboring residents

BackgroundLiving in livestock-dense areas has been associated with health effects, suggesting airborne exposures to livestock farm emissions to be relevant for public health. Livestock farm emissions involve complex mixtures of various gases and particles. Endotoxin, a pro-inflammatory agent of microbial origin, is a constituent of livestock farm emitted particulate matter (PM) that is potentially related to the observed health effects. Quantification of livestock associated endotoxin exposure at residential addresses in relation to health outcomes has not been performed earlier. ObjectivesWe aimed to assess exposure-response relations for a range of respiratory endpoints and atopic sensitization in relation to livestock farm associated PM10 and endotoxin levels. MethodsSelf-reported respiratory symptoms of 12,117 persons participating in a population-based cross-sectional study were analyzed. For 2494 persons, data on lung function (spirometry) and serologically assessed atopic sensitization was additionally available. Annual-average PM10 and endotoxin concentrations at home addresses were predicted by dispersion modelling and land-use regression (LUR) modelling. Exposure-response relations were analyzed with generalized additive models. ResultsHealth outcomes were generally more strongly associated with exposure to livestock farm emitted endotoxin compared to PM10. An inverse association was observed for dispersion modelled exposure with atopic sensitization (endotoxin: p = .004, PM10: p = .07) and asthma (endotoxin: p = .029, PM10: p = .022). Prevalence of respiratory symptoms decreased with increasing endotoxin concentration at the lower range, while at the higher range prevalence increased with increasing concentration (p < .05). Associations between lung function parameters with exposure to PM10 and endotoxin were not statistically significant (p > .05). ConclusionsExposure to livestock farm emitted particulate matter is associated with respiratory health effects and atopic sensitization in non-farming residents. Results indicate endotoxin to be a potentially plausible etiologic agent, suggesting non-infectious aspects of microbial emissions from livestock farms to be important with respect to public health.

Insights into Livestock-Related Microbial Concentrations in Air at Residential Level in a Livestock Dense Area.

Microbial air pollution from livestock farms has raised concerns regarding public health. Little is known about airborne livestock-related microbial levels in residential areas. We aimed to increase insights into this issue. Air measurements were performed in 2014 and 2015 at 61 residential sites in The Netherlands. Quantitative-PCR was used to assess DNA concentrations of selected bacteria (commensals: Escherichia coli and Staphylococcus spp.; a zoonotic pathogen: Campylobacter jejuni) and antimicrobial resistance (AMR) genes (tetW, mecA) in airborne dust. Mixed models were used to explore spatial associations (temporal adjusted) with livestock-related characteristics of the surroundings. DNA from commensals and AMR genes was detectable even at sites furthest away from farms (1200 m), albeit at lower levels. Concentrations, distinctly different between sites, were strongly associated with the density of farms in the surroundings especially with poultry and pigs. C. jejuni DNA was less prevalent (42% of samples positive). Presence of C. jejuni was solely associated with poultry (OR: 4.7 (95% CI: 1.7–14), high versus low poultry density). Residential exposure to livestock-related bacteria and AMR genes was demonstrated. Identified associations suggest contribution of livestock farms to microbial air pollution in general and attribution differences between farm types. This supports the plausibility of recent studies showing health effects in relation to residential proximity to farms.

Associations between pneumonia and residential distance to livestock farms over a five-year period in a large population-based study.

In a recent study of electronic health records (EHR) of general practitioners in a livestock-dense area in The Netherlands in 2009, associations were found between residential distance to poultry farms and the occurrence of community-acquired pneumonia (CAP). In addition, in a recent cross-sectional study in 2494 adults in 2014/2015 an association between CAP and proximity to goat farms was observed. Here, we extended the 2009 EHR analyses across a wider period of time (2009–2013), a wider set of health effects, and a wider set of farm types as potential risk sources. A spatial (transmission) kernel model was used to investigate associations between proximity to farms and CAP diagnosis for the period from 2009 to 2013, obtained from EHR of in total 140,059 GP patients. Also, associations between proximity to farms and upper respiratory infections, inflammatory bowel disease, and (as a control disease) lower back pain were analysed. Farm types included as potential risk sources in these analyses were cattle, (dairy) goats, mink, poultry, sheep, and swine. The previously found association between CAP occurrence and proximity to poultry farms was confirmed across the full 5-year study period. In addition, we found an association between increased risk for pneumonia and proximity to (dairy) goat farms, again consistently across all years from 2009 to 2013. No consistent associations were found for any of the other farm types (cattle, mink, sheep and swine), nor for the other health effects considered. On average, the proximity to poultry farms corresponds to approximately 119 extra patients with CAP each year per 100,000 people in the research area, which accounts for approximately 7.2% extra cases. The population attributable risk percentage of CAP cases in the research area attributable to proximity to goat farms is approximately 5.4% over the years 2009–2013. The most probable explanation for the association of CAP with proximity to poultry farms is thought to be that particulate matter and its components are making people more susceptible to respiratory infections. The causes of the association with proximity to goat farms is still unclear. Although the 2007–2010 Q-fever epidemic in the area probably contributed Q-fever related pneumonia cases to the observed additional cases in 2009 and 2010, it cannot explain the association found in later years 2011–2013.

Healthcare utilisation prior to the diagnosis of inflammatory bowel diseases and the influence of livestock exposure: A longitudinal case-control study.

An increased prevalence of the inflammatory bowel diseases, ulcerative colitis and Crohn’s disease, was found amongst residents in a livestock dense area. We hypothesised that exposure to livestock farms might be a substantial environmental factor that contributes to the development of these diseases and that in the lead up to inflammatory bowel diseases potential risk factors can be identified. This study aimed to investigate the contribution of livestock exposure to the development of these diseases and the clinical events prior to the diagnosis. Electronic health records from 2006–2013 of general practices were used. The study population consisted of patients with a new diagnosis of inflammatory bowel diseases resident in areas with a high (n = 141) or lower (n = 109) livestock density. Patients with low back pain (n = 10,469) were used as controls. For those in a livestock dense area, distance to livestock farms was determined. Associations between morbidities and drug prescriptions in the reporting year and three years previous to the diagnosis, and the residential proximity to livestock exposure were investigated with multivariable logistic regression analyses. Acute and chronic morbidity of the gastrointestinal tract and associated drug prescriptions were predictive for the development of inflammatory bowel diseases. In addition, a positive association was found between infections and living within 500 meter of poultry farms and the development of inflammatory bowel diseases [OR: 3.3 (1.1–9.9)]. Nonetheless, overall livestock exposure contributed little to the development of these diseases. These results suggest that exposure to livestock farms on its own contributes minimal to the development of inflammatory bowel diseases. Nonetheless, having infections appeared to be a risk factor for neighbouring residents of poultry farms. More research is warranted to explain the increased prevalence of inflammatory bowel diseases amongst residents in areas with a high density of livestock.

Land Use Regression of Ambient Endotoxin Concentrations in a Livestock Dense Area: Robustness of Model Predictions at Residential Addresses of Health Study Participants

Land Use Regression of Ambient Endotoxin Concentrations in a Livestock Dense Area: Robustness of Model Predictions at Residential Addresses of Health Study Participants

Spatial Variation of Endotoxin Concentrations Measured in Ambient PM10 in a Livestock-Dense Area: Implementation of a Land-Use Regression Approach.

Background:Results from studies on residential health effects of livestock farming are inconsistent, potentially due to simple exposure proxies used (e.g., livestock density). Accuracy of these proxies compared with measured exposure concentrations is unknown.Objectives:We aimed to assess spatial variation of endotoxin in (particulate matter ) at residential level in a livestock-dense area, compare simple livestock exposure proxies to measured endotoxin concentrations, and evaluate whether land-use regression (LUR) can be used to explain spatial variation of endotoxin.Methods:The study area () was located in Netherlands. Ambient was collected at 61 residential sites representing a variety of surrounding livestock-related characteristics. Three to four 2-wk averaged samples were collected at each site. A local reference site was used for temporal variation adjustment. Samples were analyzed for mass by weighing and for endotoxin by using the limulus amebocyte lysate assay. Three LUR models were developed, first a model based on general livestock-related GIS predictors only, followed by models that also considered species-specific predictors and farm type–specific predictors.Results:Variation in concentrations measured between sites was substantial for endotoxin and more limited for (coefficient of variation: 43%, 8%, respectively); spatial patterns differed considerably. Simple exposure proxies were associated with endotoxin concentrations although spatial variation explained was modest (). LUR models using a combination of animal-specific livestock-related characteristics performed markedly better, with up to 64% explained spatial variation.Conclusion:The considerable spatial variation of ambient endotoxin concentrations measured in a livestock-dense area can largely be explained by LUR modeling based on livestock-related characteristics. Application of endotoxin LUR models seems promising for residential exposure estimation within health studies. https://doi.org/10.1289/EHP2252

Distance to pig farms as risk factor for community-onset livestock-associated MRSA CC398 infection in persons without known contact to pig farms-A nationwide study.

MRSA CC398 is an emerging MRSA strain found in livestock, mainly in pigs. Direct occupational livestock contact is the principal risk factor for human MRSA CC398 infection. Nonetheless, in recent years, an increasing number of MRSA CC398 cases has been observed in persons without known pig contact. Such cases, referred to as MRSA CC398 of unknown origin (MUO CC398), have, like livestock-onset (LO) MRSA CC398 cases, been found concentrated in rural, livestock-producing areas. The presence of MUO CC398 cases indicates alternative and unknown MRSA CC398 transmission pathways into the community. We performed a nationwide study in Denmark of the geographic distributions of MRSA cases in general and persons with MUO CC398 or LO MRSA CC398 infections (1 January 2006-11 February 2015), with the Danish population as background population. Place of living of study persons was mapped using the ArcGIS software, and information on pig farms was retrieved from the Central Husbandry Register. The incidence of MUO CC398 infections was clearly higher in rural than in urban areas, and such cases lived on average closer to pig farms than the general population. However, within three pig-farming-dense municipalities, patients with MUO CC398 infections did not live closer to pig farms than population controls. This shows that direct environmental spread from neighbouring pig farms of MRSA CC398 is unlikely. Instead, community spread through other means of transmission than direct spread from farms may more likely explain the clustering of MUO CC398 in livestock-dense areas.

Remarkable spatial variation in the seroprevalence of Coxiella burnetii after a large Q fever epidemic

BackgroundPrior to the 2007–2010 Q fever epidemic in the Netherlands, the seroprevalence of antibodies against Coxiella burnetii in the general population was 1.5%, which is low compared to other countries. We aimed to determine the seroprevalence after the Q fever epidemic among people living in the affected area, compare the seroprevalence with the incidence of Q fever notifications during the 2007–2010 Q fever epidemic, and to identify farm exposures associated with having antibodies against C. burnetii.MethodsDuring the period March 2014–February 2015, residents aged 18–70 years from two provinces were invited by general practitioners to complete a questionnaire on their symptoms and personal characteristics and to submit a blood sample. We used the mandatory provincial database of livestock licences to calculate distance to farms/farm animals for each participant. To compare ELISA-positive participants for C. burnetii antibodies with those who were negative, we calculated prevalence ratios (PR) using binominal regression. We compared the C. burnetii seroprevalence in the period March 2014–February 2015 with the incidence of Q fever notifications during the 2007–2010 Q fever epidemic at municipal level by calculating the Spearman correlation coefficient.ResultsOf the 2296 participants (response rate: 34%), 6.1% (n = 139, 95% CI 5.1–7.1%) had C. burnetii antibodies (range in municipalities: 1.7–14.1%). C. burnetii seroprevalence was higher in individuals living within 1000 m of goat farms (PR 3.0; 95% CI 1.4–6.4) or within 1000 m of > 50 goats (PR 1.9; 95% CI 1.2–3.0). Seroprevalence increased with decreasing distance to the closest goat farm that was infected during the epidemic years (< 500 m, PR 9.5, 95% CI 2.8–32; 500–1000 m, PR 4.5, 95% CI 2.6–7.7; 1000–1500 m, PR 2.2, 95% CI 1.1–4.3, 1500–2000 m, PR 1.2, 95% CI 0.6–2.5; > 2000 reference group). There was no significant correlation between C. burnetii seroprevalence and Q fever incidence during the 2007–2010 epidemic (rs = 0.42, p = 0.156).ConclusionsResults showed a remarkable spatial variation in C. burnetii seroprevalence in a relatively small livestock dense area. It confirms previous evidence that the Q fever epidemic was primarily the result of airborne C. burnetii transmission from Q fever affected goat farms.

Prevalence and risk factors for colonization of Clostridium difficile among adults living near livestock farms in the Netherlands.

A cross-sectional study was performed among 2494 adults not living or working on a farm to assess prevalence of Clostridium difficile (CD) colonization and risk factors in a livestock dense area. CD prevalence was 1·2%. Twenty-one persons were colonized with a toxigenic strain and nine with a non-toxigenic strain. CD-positive persons did not live closer to livestock farms than individuals negative for CD. Antibiotic exposure in the preceding 3 months was a risk factor for CD colonization (odds ratio 3·70; 95% confidence interval 1·25-10·95).

Livestock-associated risk factors for pneumonia in an area of intensive animal farming in the Netherlands.

Previous research conducted in 2009 found a significant positive association between pneumonia in humans and living close to goat and poultry farms. However, as this result might have been affected by a large goat-related Q fever epidemic, the aim of the current study was to re-evaluate this association, now that the Q-fever epidemic had ended. In 2014/15, 2,494 adults (aged 20–72 years) living in a livestock-dense area in the Netherlands participated in a medical examination and completed a questionnaire on respiratory health, lifestyle and other items. We retrieved additional information for 2,426/2,494 (97%) participants from electronic medical records (EMR) from general practitioners. The outcome was self-reported, physician-diagnosed pneumonia or pneumonia recorded in the EMR in the previous three years. Livestock license data was used to determine exposure to livestock. We quantified associations between livestock exposures and pneumonia using odds ratios adjusted for participant characteristics and comorbidities (aOR). The three-year cumulative frequency of pneumonia was 186/2,426 (7.7%). Residents within 2,000m of a farm with at least 50 goats had an increased risk of pneumonia, which increased the closer they lived to the farm (2,000m aOR 1.9, 95% CI 1.4–2.6; 500m aOR 4.4, 95% CI 2.0–9.8). We found no significant associations between exposure to other farm animals and pneumonia. However, when conducting sensitivity analyses using pneumonia outcome based on EMR only, we found a weak but statistically significant association with presence of a poultry farm within 1,000m (aOR: 1.7, 95% CI 1.1–2.7). Living close to goat and poultry farms still constitute risk factors for pneumonia. Individuals with pneumonia were not more often seropositive for Coxiella burnetii, indicating that results are not explained by Q fever. We strongly recommend identification of pneumonia causes by the use of molecular diagnostics and investigating the role of non-infectious agents such as particulate matter or endotoxins.

Hepatitis E virus seroprevalence among the general population in a livestock-dense area in the Netherlands: a cross-sectional population-based serological survey

BackgroundRecent serological studies indicate that hepatitis E virus (HEV) is endemic in industrialised countries. The increasing trend in the number of autochthonous cases of HEV genotype 3 in Western European countries, stresses the importance to get insight in the exact routes of exposure. Pigs are the main animal reservoir, and zoonotic food-borne transmission of HEV is proven. However, infected pigs can excrete large amounts of virus via their faeces enabling environmental transmission of HEV to humans. This might pose a risk for of neighbouring residents of livestock farming.MethodsWithin a large study on the health of people living in the vicinity of livestock farming we performed a cross-sectional population-based serological survey among 2,494 non-farming adults from the general population in a livestock-dense area in the south of the Netherlands. Participants completed risk factor questionnaires and blood samples of 2,422 subjects (median age 58 years, range 20–72) were tested for anti-HEV IgG using an enzyme immune assay (Wantai). The aim of this study was to determine the HEV seroprevalence and to assess whether seropositivity in adults was associated with living in the vicinity of pig farms.ResultsThe average seroprevalence of HEV was 28.7% (95% CI: 26.9–30.5). Determinants associated with an increased risk for HEV seropositivity were male gender and low level of education. There was a clear trend of increasing prevalence with increasing age (Chi-square test for linear trend, X2 = 83.1; p < 0.001). A high number of pigs within 1,000 m of the residential address was not a risk factor for seropositivity.ConclusionsThis study confirmed the high HEV seroprevalence (29%) in the general population of the Netherlands, but presence of antibodies was not associated with residential proximity to pig farms. The prevalence increased with age from 10% in adolescents to 33% among those aged 50 and above, supporting the assumption of a cumulative lifetime exposure to HEV in the Netherlands as well as a higher infection pressure in the past. Our findings cannot refute the assumption that transmission is primarily food-borne.