Population Screening for Chronic Q-Fever Seven Years after a Major Outbreak

Serosurvey of selected reproductive pathogens in domestic ruminants from Upper Egypt

Toxoplasmosis, neosporosis, and Q fever are among the most important abortifacient diseases in ruminants worldwide. These diseases result in huge economic losses in livestock besides the fact that some of are of public health concern. The present study aimed to update the data about the current seroepidemiological situation of these diseases in Upper Egypt. A total of 411 blood samples were collected from small and large ruminants and serologically tested against the presence of T. gondii, N. caninum, and C. burnetii. Generalized estimating equation (GEE) models were performed to assess the potential risk factors associated with the exposure to these pathogens. The overall seroprevalence of T. gondii was 47.9% (197/411) with an individual seropositivity of 59.4% (63/106), 58.6% (17/29), 38.8% (54/139) and 46% (63/137) in cattle, buffalo, sheep and goats, respectively. Meanwhile, 9.7% (38/411) of the examined animals were tested positive for anti-N. caninum antibodies, with an individual seropositivity of 13.2% (12/106), 34.5% (10/29), 8.6% (12/139) and 2.9% (4/137) in cattle, buffalo, sheep and goats, respectively. Furthermore, the overall prevalence of antibodies against C. burnetii was 17.3% (63/411), and exposure to this pathogen was detected in 4.7% (5/106) of cattle, 19.3% (20/129) of sheep, 29.2% (38/130) of goats but none of the examined buffalo were found to be seropositive. A total of 12.1% (50/411) of the examined animals showed co-exposure to at least two of the tested pathogens. Regarding the potential risk factors, there were statistically significant differences among species in the frequency of exposure to the three tested pathogens. Age (> 6 months) was also shown to be a significant risk factor associated with T. gondii exposure. The results obtained provided updated information about the occurrence of three of the main reproductive pathogens in Upper Egypt. The high seropositivity values found for the tested zoonotic pathogens in most of the analyzed ruminant species suggest the necessity of performing additional in-depth studies to evaluate the epidemiology of these pathogens in the study area.

Cytometry profiling of ex vivo recall responses to Coxiella burnetii in previously naturally exposed individuals reveals long-term changes in both adaptive and innate immune cellular compartments

Introduction

Q fever, caused by the intracellular bacterium Coxiella burnetii, is considered an occupational and biodefense hazard and can result in debilitating long-term complications. While natural infection and vaccination induce humoral and cellular immune responses, the exact nature of cellular immune responses to C. burnetii is incompletely understood. The current study seeks to investigate more deeply the nature of long-term cellular recall responses in naturally exposed individuals by both cytokine release assessment and cytometry profiling.

Methods

Individuals exposed during the 2007-2010 Dutch Q fever outbreak were grouped in 2015, based on a C. burnetii-specific IFNγ release assay (IGRA), serological status, and self-reported clinical symptoms during initial infection, into asymptomatic IGRA-negative/seronegative controls, and three IGRA-positive groups (seronegative/asymptomatic; seropositive/asymptomatic and seropositive/symptomatic). Recall responses following in vitro re-stimulation with heat-inactivated C. burnetii in whole blood, were assessed in 2016/2017 by cytokine release assays (n=55) and flow cytometry (n=36), and in blood mononuclear cells by mass cytometry (n=36).

Results

Cytokine release analysis showed significantly elevated IL-2 responses in all seropositive individuals and elevated IL-1β responses in those recovered from symptomatic infection. Comparative flow cytometry analysis revealed significantly increased IFNγ, TNFα and IL-2 recall responses by CD4 T cells and higher IL-6 production by monocytes from symptomatic, IGRA-positive/seropositive individuals compared to controls. Mass cytometry profiling and unsupervised clustering analysis confirmed recall responses in seropositive individuals by two activated CD4 T cell subsets, one characterized by a strong Th1 cytokine profile (IFNγ+IL-2+TNFα+), and identified C. burnetii-specific activation of CD8 T cells in all IGRA-positive groups. Remarkably, increased C. burnetii-specific responses in IGRA-positive individuals were also observed in three innate cell subpopulations: one characterized by an IFNγ+IL-2+TNFα+ Th1 cytokine profile and lack of canonical marker expression, and two IL-1β-, IL-6- and IL-8-producing CD14+ monocyte subsets that could be the drivers of elevated secretion of innate cytokines in pre-exposed individuals.

Discussion

These data highlight that there are long-term increased responses to C. burnetii in both adaptive and innate cellular compartments, the latter being indicative of trained immunity. These findings warrant future studies into the protective role of these innate responses and may inform future Q fever vaccine design.

Is there a higher risk of exposure to Coxiella burnetii for pre-clinical veterinary students?

Coxiella burnetii is globally distributed but evidence of zoonotic transmission in the Caribbean region is scarce. The bacterium presence is suspected on the Caribbean island of St. Kitts. The risk of exposure of veterinary students was reported in other regions of the world but is not documented in the Caribbean region. The present study aimed to evaluate the risk of exposure to C. burnetii for pre-clinical veterinary students (mostly coming from the U.S.) attending an island-based veterinary school. A cross-sectional study was conducted to compare incoming and outgoing veterinary students' seroprevalence. Serology was performed using indirect immunofluorescence assay to test Coxiella burnetii Phase I and Phase II immunoglobulins M and G. Background data were gathered using a standardized questionnaire. A parallel study enrolled veterinary school employees in the same university. Of the 98 participants (48 incoming and 50 outgoing students), 41 (41.8%, 95 %CI: 31.9-52.2) were seropositive to C. burnetii. There was no significant difference between the two groups (45.8% for incoming vs. 38.0% for outgoing students) (p = 0.4). No risk factors (demographic, animal handling practices or background) were significantly more reported in the seropositive group. In the employee study, the seroprevalence was high with 8/15 seropositives (53.3%, 95 %CI: 26.6-78.7). Pre-clinical veterinary students do not have a higher risk of exposure to C. burnetii by attending the veterinary school in St. Kitts, but they are highly exposed before arrival on the island (seroprevalence of 45.8%). Most of these participants had experience with animals either through farming or previous veterinary technician employment. This indicates a high exposure in the U.S. young population aiming to become veterinarians. There is an urgent need to increase C. burnetii surveillance in animals and humans to apply relevant prevention and control measures, including recommendations for vaccination of students and professionals at risk.

Natural Exposure- and Vaccination-Induced Profiles of Ex Vivo Whole Blood Cytokine Responses to Coxiella burnetii

Q fever is a zoonotic disease caused by the highly infectious Gram-negative coccobacillus, Coxiella burnetii (C. burnetii). The Q fever vaccine Q-VAX® is characterised by high reactogenicity, requiring individuals to be pre-screened for prior exposure before vaccination. To date it remains unclear whether vaccine side effects in pre-exposed individuals are associated with pre-existing adaptive immune responses to C. burnetii or are also a function of innate responses to Q-VAX®. In the current study, we measured innate and adaptive cytokine responses to C. burnetii and compared these among individuals with different pre-exposure status. Three groups were included: n=98 Dutch blood bank donors with unknown exposure status, n=95 Dutch village inhabitants with known natural exposure status to C. burnetii during the Dutch Q fever outbreak of 2007-2010, and n=96 Australian students receiving Q-VAX® vaccination in 2021. Whole blood cytokine responses following ex vivo stimulation with heat-killed C. burnetii were assessed for IFNγ, IL-2, IL-6, IL-10, TNFα, IL-1β, IP-10, MIP-1α and IL-8. Serological data were collected for all three cohorts, as well as data on skin test and self-reported vaccine side effects and clinical symptoms during past infection. IFNγ, IP-10 and IL-2 responses were strongly elevated in individuals with prior C. burnetii antigen exposure, whether through infection or vaccination, while IL-1β, IL-6 and TNFα responses were slightly increased in naturally exposed individuals only. High dimensional analysis of the cytokine data identified four clusters of individuals with distinct cytokine response signatures. The cluster with the highest levels of adaptive cytokines and antibodies comprised solely individuals with prior exposure to C. burnetii, while another cluster was characterized by high innate cytokine production and an absence of C. burnetii-induced IP-10 production paired with high baseline IP-10 levels. Prior exposure status was partially associated with these signatures, but could not be clearly assigned to a single cytokine response signature. Overall, Q-VAX® vaccination and natural C. burnetii infection were associated with comparable cytokine response signatures, largely driven by adaptive cytokine responses. Neither individual innate and adaptive cytokine responses nor response signatures were associated retrospectively with clinical symptoms during infection or prospectively with side effects post-vaccination.

No Influence of Previous Coxiella burnetii Infection on ICU Admission and Mortality in Emergency Department Patients Infected with SARS-CoV-2

BACKGROUND

the geographical similarities of the Dutch 2007-2010 Q fever outbreak and the start of the 2020 coronavirus disease 19 (COVID-19) outbreak in the Netherlands raised questions and provided a unique opportunity to study an association between Coxiella burnetii infection and the outcome following SARS-CoV-2 infection.

METHODS

We performed a retrospective cohort study in two Dutch hospitals. We assessed evidence of previous C. burnetii infection in COVID-19 patients diagnosed at the ED during the first COVID-19 wave and compared a combined outcome of in-hospital mortality and intensive care unit (ICU) admission using adjusted odds ratios (OR).

RESULTS

In total, 629 patients were included with a mean age of 68.0 years. Evidence of previous C. burnetii infection was found in 117 patients (18.6%). The combined primary outcome occurred in 40.2% and 40.4% of patients with and without evidence of previous C. burnetii infection respectively (adjusted OR of 0.926 (95% CI 0.605-1.416)). The adjusted OR of the secondary outcomes in-hospital mortality, ICU-admission and regular ward admission did not show an association either.

CONCLUSION

no influence of previous C. burnetii infection on the risk of ICU admission and/or mortality for patients with COVID-19 presenting at the ED was observed.

The Feasibility of Using Coxiella burnetii Avirulent Nine Mile Phase II Viable Bacteria as a Live Attenuated Vaccine Against Q fever

This study aimed to explore if viable C. burnetii avirulent Nine Mile phase II (NMII) can elicit protective immunity against virulent NM phase I (NMI) infection. Interestingly, mice immunized with viable NMII elicited significant protection against NMI infection at different time points post-immunization. Viable NMII induced a dose-dependent NMI-specific IgG response in mice, but all doses of NMII-immunized mice conferred a similar level of protection. Comparing different routes of immunization indicated that intranasally immunized mice showed significantly higher levels of protection than other immunization routes. The observation that viable NMII induced a similar level of long-term protection against NMI challenge as the formalin-inactivated NMI vaccine (PIV) suggests that viable NMII bacteria can induce a similar level of long-term protection against virulent NMI challenge as the PIV. Viable NMII also induced significant protection against challenge with virulent Priscilla and Scurry strains, suggesting that viable NMII can elicit broad protection. Immune sera and splenocytes from viable NMII-immunized mice are protective against NMI infection, but immune serum-receiving mice did not control NMI replication. Additionally, viable NMII conferred a comparable level of protection in wild-type, CD4⁺ T cell-deficient, and CD8⁺ T cell-deficient mice, and partial protection in B cell-deficient mice. However, NMII-immunized T cell-deficient mice were unable to prevent C. burnetii replication. Thus, both B cells and T cells are required for viable NMII-induced protective immunity but T cells may play a critical role. Collectively, this study demonstrates the feasibility of using avirulent NMII as a live attenuated vaccine against human Q fever.

Whole Blood Interferon γ Release Is a More Sensitive Marker of Prior Exposure to Coxiella burnetii Than Are Antibody Responses

For the zoonotic disease Q fever, serological analysis plays a dominant role in the diagnosis of Coxiella burnetii infection and in pre-screening for past exposure prior to vaccination. A number of studies suggest that assessment of C. burnetii-specific T-cell IFNγ responses may be a more sensitive tool to assess past exposure. In this study, we assessed the performance of a whole blood C. burnetii IFNγ release assay in comparison to serological detection in an area of high Q fever incidence in 2014, up to seven years after initial exposure during the Dutch Q fever outbreak 2007-2010. In a cohort of >1500 individuals from the Dutch outbreak village of Herpen, approximately 60% had mounted IFNγ responses to C. burnetii. This proportion was independent of the Coxiella strain used for stimulation and much higher than the proportion of individuals scored sero-positive using the serological gold standard immunofluorescence assay. Moreover, C. burnetii-specific IFNγ responses were found to be more durable than antibody responses in two sub-groups of individuals known to have sero-converted as of 2007 or previously reported to the municipality as notified Q fever cases. A novel ready-to-use version of the IFNγ release assay assessed in a subgroup of pre-exposed individuals in 2021 (10-14 years post exposure) proved again to be more sensitive than serology in detecting past exposure. These data demonstrate that C. burnetii-induced IFNγ release is indeed a more sensitive and durable marker of exposure to C. burnetii than are serological responses. In combination with a simplified assay version suitable for implementation in routine diagnostic settings, this makes the assessment of IFNγ responses a valuable tool for exposure screening to obtain epidemiological data, and to identify previously exposed individuals in pre-vaccination screens.

Long-term serological follow-up after primary Coxiella burnetii infection in patients with vascular risk factors for chronic Q fever

We evaluated the long-term serological follow-up of patients with vascular risk factors for chronic Q fever that were previously Coxiella burnetii seropositive. C. burnetii phase I IgG titers were reevaluated in patients that gave informed consent or retrospectively collected in patients already deceased or lost to follow-up. Of 107 patients, 25 (23.4%) became seronegative, 77 (72.0%) retained a profile of past resolved Q fever infection, and five (4.7%) developed chronic Q fever. We urge clinicians to stay vigilant for chronic Q fever beyond two years after primary infection and perform serological testing based on clinical presentation.

High prevalence of Coxiella burnetii infection in humans and livestock in Assiut, Egypt: A serological and molecular survey

BACKGROUND AND AIM

Q fever is considered a neglected zoonotic disease and is caused by Coxiella burnetii. Very little information is available on C. burnetii infections in cattle, sheep, and goat populations in Egypt. The aim of this study was to identify the seroprevalence of C. burnetii in humans and livestock and to test for the presence of C. burnetii DNA in sera from seropositive animals and humans.

MATERIALS AND METHODS

Blood samples were collected from 160 apparently healthy farm animals and 120 patients from three hospitals of the Assiut Governorate throughout 2017/2018. These populations were tested for antibodies against C. burnetii phase II antigen by immunofluorescence assay [IFA] and enzyme-linked immunosorbent assay (ELISA). Seropositive samples were subjected to real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The results of the IFA revealed C. burnetii seroprevalence rates of 45.3%, 56.0%, 45.7%, and 53.3% in cattle, sheep, goats, and humans, respectively. In humans, the seroprevalence rates were 52.1%, 30.4%, 37.5%, 74.1%, and 62.5% in patients with fever of unknown origin, influenza, kidney dialysis, hepatitis C virus, and hepatitis B virus, respectively. Likewise, by ELISA, the seroprevalence in bovine was 50.7%; sheep, 60.0%; goats, 51.4%; and humans, 55.0% (54.3%, 30.4%, 37.5%, 77.8%, and 62.5% in patients with fever of unknown origin, influenza, kidney dialysis, hepatitis C virus, and hepatitis B virus, respectively). RT-qPCR targeting the repetitive element IS1111 confirmed the presence of C. burnetii DNA.

CONCLUSION

These results proved that apparently healthy cattle, sheep, and goats may be very important reservoirs of C. burnetii infection. In light of these data, the effect of Q fever on the replication of hepatitis virus remains unclear. Although hepatitis is one of the main aspects of acute Q fever, the influence of hepatitis on Q fever remains to be investigated. Q fever is not a reportable disease in Egypt, and clinical cases may rarely be recognized by the health-care system. Additional information on the epidemiology of C. burnetii in Egypt is warranted, including other associated problems such as the distribution of infections, pathologic hallmarks, and molecular typing.

Cost-effectiveness of Screening Program for Chronic Q Fever, the Netherlands

In the aftermath of a large Q fever (QF) epidemic in the Netherlands during 2007-2010, new chronic QF (CQF) patients continue to be detected. We developed a health-economic decision model to evaluate the cost-effectiveness of a 1-time screening program for CQF 7 years after the epidemic. The model was parameterized with spatial data on QF notifications for the Netherlands, prevalence data from targeted screening studies, and clinical data from the national QF database. The cost-effectiveness of screening varied substantially among subpopulations and geographic areas. Screening that focused on cardiovascular risk patients in areas with high QF incidence during the epidemic ranged from cost-saving to €31,373 per quality-adjusted life year gained, depending on the method to estimate the prevalence of CQF. The cost per quality-adjusted life year of mass screening of all older adults was €70,000 in the most optimistic scenario.

Risk of chronic Q fever in patients with cardiac valvulopathy, seven years after a large epidemic in the Netherlands

BACKGROUND

From 2007 through 2010, a large epidemic of acute Q fever occurred in the Netherlands. Patients with cardiac valvulopathy are at high risk to develop chronic Q fever after an acute infection. This patient group was not routinely screened, so it is unknown whether all their chronic infections were diagnosed. This study aims to investigate how many chronic Q fever patients can be identified by routinely screening patients with valvulopathy and to establish whether the policy of not screening should be changed.

METHODS

In a cross-sectional study (2016-2017) in a hospital at the epicentre of the Q fever epidemic, a blood sample was taken from patients 18 years and older who presented with cardiac valvulopathy. The sample was tested for IgG antibodies against phase I and II of Coxiella burnetii using an immunofluorescence assay. An IgG phase II titre of ≥1:64 was considered serological evidence of a previous Q fever infection. An IgG phase I titre of ≥1:512 was considered suspicious for a chronic infection, and these patients were referred for medical examination.

RESULTS

Of the 904 included patients, 133 (15%) had evidence of a previous C. burnetii infection, of whom 6 (5%) had a chronic infection on medical examination.

CONCLUSIONS

In a group of high-risk patients with a heart valve defect, we diagnosed new chronic Q fever infections seven years after the epidemic, emphasizing the need for screening of this group to prevent complications in those not yet diagnosed in epidemic areas.

Seroprevalence of Q fever among high-risk occupations in the Ilam province, the west of Iran

Background

Q fever is a zoonotic disease of great public health importance in Iran. This disease is presented with high phase I antibody development in chronic and high phase II antibody in the acute form of illness. This study was conducted to evaluate the seroprevalence of Q fever among high-risk occupations in the Ilam province in Western Iran.

Methods and findings

In this cross-sectional study, 367 sera samples were collected from five groups comprised of animal husbandry workers, farmers, butchers, slaughterhouse workers, and park rangers. The collected sera were tested for IgG antibodies against Coxiella burnetii using ELISA. The seroprevalence of antibodies against C. burnetii in phase I and II was 24.38% and 26.37%, respectively (i.e., 32.42% overall). Low educational level, living in rural areas, keeping sheep/goats, ages older than 50 years, and a history of arthropod bites positively correlated with increased risk of Q fever infection. Animal husbandry workers (45.13%) were at higher risk of contracting Q fever compared with other occupations in the study (17.11%).

Conclusions

High seroprevalence of C. burnetii among high-risk occupations is a serious challenge in the Ilam province. In addition, the high seroprevalence of endemic Q fever in rural and nomadic areas and a higher concentration of occupations who are directly engaged with livestock demonstrate the critical need for preventive medicine education and training in regards to mitigating risk for disease contraction in susceptible groups.

Promiscuous Coxiella burnetii CD4 Epitope Clusters Associated With Human Recall Responses Are Candidates for a Novel T-Cell Targeted Multi-Epitope Q Fever Vaccine

Coxiella burnetii, the causative agent of Q fever, is a Gram-negative intracellular bacterium transmitted via aerosol. Regulatory approval of the Australian whole-cell vaccine Q-VAX® in the US and Europe is hindered by reactogenicity in previously exposed individuals. The aim of this study was to identify and rationally select C. burnetii epitopes for design of a safe, effective, and less reactogenic T-cell targeted human Q fever vaccine. Immunoinformatic methods were used to predict 65 HLA class I epitopes and 50 promiscuous HLA class II C. burnetii epitope clusters, which are conserved across strains of C. burnetii. HLA binding assays confirmed 89% of class I and 75% of class II predictions, and 11 HLA class II epitopes elicited IFNγ responses following heterologous DNA/DNA/peptide/peptide prime-boost immunizations of HLA-DR3 transgenic mice. Human immune responses to the predicted epitopes were characterized in individuals naturally exposed to C. burnetii during the 2007–2010 Dutch Q fever outbreak. Subjects were divided into three groups: controls with no immunological evidence of previous infection and individuals with responses to heat-killed C. burnetii in a whole blood IFNγ release assay (IGRA) who remained asymptomatic or who experienced clinical Q fever during the outbreak. Recall responses to C. burnetii epitopes were assessed by cultured IFNγ ELISpot. While HLA class I epitope responses were sparse in this cohort, we identified 21 HLA class II epitopes that recalled T-cell IFNγ responses in 10–28% of IGRA+ subjects. IGRA+ individuals with past asymptomatic and symptomatic C. burnetii infection showed a comparable response pattern and cumulative peptide response which correlated with IGRA responses. None of the peptides elicited reactogenicity in a C. burnetii exposure-primed guinea pig model. These data demonstrate that a substantial proportion of immunoinformatically identified HLA class II epitopes show long-lived immunoreactivity in naturally infected individuals, making them desirable candidates for a novel human multi-epitope Q fever vaccine.

Notification data and criteria during a large Q-fever epidemic reassessed

From 2007 to 2010, the largest reported Q-fever epidemic occurred in the Netherlands with 4026 notified laboratory-confirmed cases. During the course of the epidemic, health-seeking behaviour changed and awareness among health professionals increased. Changes in laboratory workflows were implemented. The aim of this study was to analyse how these changes instigated adjustments of notification criteria and how these adjustments affected the monitoring and interpretation of the epidemic. We used the articles on laboratory procedures related to the epidemic and a description of the changes that were made to the notification criteria. We compared the output of a regional laboratory with notifications to the regional Public Health Service and the national register of infectious diseases. We compared the international notification criteria for acute Q-fever. Screening with ELISA IgM phase II and PCR was added to the diagnostic workflow. In the course of the epidemic, serology often revealed a positive IgG/IgM result although cases were not infected recently. With increasing background seroprevalence, the presence of IgM antibodies can only be suggestive for acute Q-fever and has to be confirmed either by seroconversion of IgG or a positive PCR result. Differences in sero-epidemiology make it unlikely that full harmonisation of notification criteria between countries is feasible.

Screening for Q fever. A tertiary care hospital-based experience in central Saudi Arabia

OBJECTIVES

To evaluate the presence of Coxiella burnetii  (C. brunetii) infection among patients presenting with fever of unknown origin (FUO).

METHODS

A cross-sectional study of 100 patients (54 men and 46 women; mean age: 34.3 ± 19.2 years) with FUO was conducted at King Khalid University Hospital, Riyadh, Saudi Arabia between March 2015 and June 2016. Phase 1 and phase 2 C. burnetii-specific antibodies in serum samples were detected by enzyme-linked immunosorbent assay.

RESULTS

Coxiella burnetii phase 1 and phase 2 antibodies were detected in 16% of the patients. Phase 2 IgM was present in 2% of the patients, whereas phase 2 IgG antibodies were detected in 11%  of the patients. Coxiella burnetii-specific phase 1 IgG was found in 2% of the patients, and 8% of the patients harbored phase 1 IgA antibodies in their serum.

CONCLUSION

The presence of C. burnetii-specific antibodies in many patients suffering from FUO highlights the importance of Q fever screening among patients presenting with febrile illness.

Q fever in Egypt: Epidemiological survey of Coxiella burnetii specific antibodies in cattle, buffaloes, sheep, goats and camels

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Clinical presentation in humans varies from asymptomatic to flu-like illness and severe sequelae may be seen. Ruminants are often sub-clinically infected or show reproductive disorders such as abortions. In Egypt, only limited data on the epidemiology of Q fever in animals are available. Using a stratified two stage random sampling approach, we evaluated the prevalence of Coxiella burnetii specific antibodies among ruminants and camels in 299 herds. A total of 2,699 blood samples was investigated using enzyme-linked-immunosorbent assay (ELISA). Coxiella burnetii specific antibodies were detected in 40.7% of camels (215/528), 19.3% of cattle (162/840), 11.2% of buffaloes (34/304), 8.9% of sheep (64/716) and 6.8% of goats (21/311), respectively. Odds of seropositivity were significantly higher for cattle (aOR: 3.17; 95% CI: 1.96-5.13) and camels (aOR: 9.75; 95% CI: 6.02-15.78). Significant differences in seropositivity were also found between domains (Western Desert, Eastern Desert and Nile Valley and Delta) and 25 governorates (p < 0.001), respectively. Animal rearing in the Eastern Desert domain was found to be a significant risk factor (aOR: 2.16; 95% CI: 1.62-2.88). Most seropositive animals were older than four years. No correlation between positive titers and husbandry practices or animal origin were found (p > 0.05). Only 8.7% of the interviewed people living on the farms consumed raw camel milk and none reported prior knowledge on Q fever. Findings from this nationwide study show that exposure to Coxiella burnetii is common in ruminants and camels. Disease awareness among physicians, veterinarians and animal owners has to be raised. Future epidemiological investigations have to elucidate the impact of Q fever on human health and on the economy of Egypt.

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

Background

Prior 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.

Methods

During 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.

Results

Of 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 (r_s = 0.42, p = 0.156).

Conclusions

Results 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.

Involvement of matrix metalloproteinases in chronic Q fever

OBJECTIVES

Chronic Q fever is a persistent infection with the intracellular Gram-negative bacterium Coxiella burnetii, which can lead to complications of infected aneurysms. Matrix metalloproteinases (MMPs) cleave extracellular matrix and are involved in infections as well as aneurysms. We aimed to study the role of MMPs in the pathogenesis of chronic Q fever.

METHODS

We investigated gene expression of MMPs through microarray analysis and MMP production with ELISA in C. burnetii-stimulated peripheral blood mononuclear cells (PBMCs) of patients with chronic Q fever and healthy controls. Twenty single nucleotide polymorphisms (SNPs) of MMP and tissue inhibitor of MMP genes were genotyped in 139 patients with chronic Q fever and 220 controls with similar cardiovascular co-morbidity. Additionally, circulating MMPs levels in patients with chronic Q fever were compared with those in cardiovascular controls with and without a history of past Q fever.

RESULTS

In healthy controls, the MMP pathway involving four genes (MMP1, MMP7, MMP10, MMP19) was significantly up-regulated in C. burnetii-stimulated but not in Escherichia coli lipopolysaccharide -stimulated PBMCs. Coxiella burnetii induced MMP-1 and MMP-9 production in PBMCs of healthy individuals (both p<0.001), individuals with past Q fever (p<0.05, p<0.01, respectively) and of patients with chronic Q fever (both p<0.001). SNPs in MMP7 (rs11568810) (p<0.05) and MMP9 (rs17576) (p<0.05) were more common in patients with chronic Q fever. Circulating MMP-7 serum levels were higher in patients with chronic Q fever (median 33.5 ng/mL, interquartile range 22.3-45.7 ng/mL) than controls (20.6 ng/mL, 15.9-33.8 ng/mL).

CONCLUSION

Coxiella burnetii-induced MMP production may contribute to the development of chronic Q fever.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change

Coxiella burnetii is the agent of Q fever, or "query fever," a zoonosis first described in Australia in 1937. Since this first description, knowledge about this pathogen and its associated infections has increased dramatically. We review here all the progress made over the last 20 years on this topic. C. burnetii is classically a strict intracellular, Gram-negative bacterium. However, a major step in the characterization of this pathogen was achieved by the establishment of its axenic culture. C. burnetii infects a wide range of animals, from arthropods to humans. The genetic determinants of virulence are now better known, thanks to the achievement of determining the genome sequences of several strains of this species and comparative genomic analyses. Q fever can be found worldwide, but the epidemiological features of this disease vary according to the geographic area considered, including situations where it is endemic or hyperendemic, and the occurrence of large epidemic outbreaks. In recent years, a major breakthrough in the understanding of the natural history of human infection with C. burnetii was the breaking of the old dichotomy between "acute" and "chronic" Q fever. The clinical presentation of C. burnetii infection depends on both the virulence of the infecting C. burnetii strain and specific risks factors in the infected patient. Moreover, no persistent infection can exist without a focus of infection. This paradigm change should allow better diagnosis and management of primary infection and long-term complications in patients with C. burnetii infection.

The health status of a village population, 7 years after a major Q fever outbreak

From 2007 to 2010, The Netherlands experienced a major Q fever outbreak with more than 4000 notifications. Previous studies suggested that Q fever patients could suffer long-term post-infection health impairments, especially fatigue. Our objective was to assess the Coxiella burnetii antibody prevalence and health status including fatigue, and assess their interrelationship in Herpen, a high-incidence village, 7 years after the outbreak began. In 2014, we invited all 2161 adult inhabitants for a questionnaire and a C. burnetii indirect fluorescence antibody assay (IFA). The health status was measured with the Nijmegen Clinical Screening Instrument (NCSI), consisting of eight subdomains including fatigue. Of the 70·1% (1517/2161) participants, 33·8% (513/1517) were IFA positive. Of 147 participants who were IFA positive in 2007, 25 (17%) seroreverted and were now IFA negative. Not positive IFA status, but age <50 years, smoking and co-morbidity, were independent risk factors for fatigue. Notified participants reported significantly more often fatigue (31/49, 63%) than non-notified IFA-positive participants (150/451, 33%). Although fatigue is a common sequel after acute Q fever, in this community-based survey we found no difference in fatigue levels between participants with and without C. burnetii antibodies.