Chronic Q fever: Review of the literature and a proposal of new diagnostic criteria

Q fever endocarditis of the tricuspid valve transmitted in an urban setting with no livestock exposure: Case report

BACKGROUND

Coxiella burnetii is a bacterium with extreme tenacity and contagiousness that is mainly transmitted by inhalation of contaminated aerosols. Nevertheless, a transmission by ticks is under discussion. We report a case of Q fever in an urban environment and far away from sheep breeding that caused a rare right-sided endocarditis.

CASE PRESENTATION

A 55-year-old man who was in good health before the event developed a C. burnetii -endocarditis of the tricuspid valve. He had no contact with sheep and no recent travel in a rural or even endemic area. The infection originated in a strictly urban environment, and the patient's occupation as a cemetery gardener in Berlin, coupled with the close temporal and local exposure to wild boar, made a transmission by these animals a plausible hypothesis. The infection was confirmed by the German Reference Laboratory, and the patient recovered completely after treatment with doxycycline and hydrochlorquine.

CONCLUSIONS

The specialities of this case report are the right-sided endocarditis and the transmission of C. burnetii in a metropolitan area without sheep contact. We think that this case should serve to increase awareness of the potential for Q fever infection even in non-rural areas.

Treatment of persistent focalized Q fever: time has come for an international randomized controlled trial

Q fever is a worldwide zoonosis due to Coxiella burnetii, responsible for endocarditis and endovascular infections. Since the 1990s, the combination hydroxychloroquine + doxycycline has constituted the curative and prophylactic treatment in persistent focalized Q fever. This combination appears to have significantly reduced the treatment's duration (from 60 to 26 months), yet substantial evidence of effectiveness remains lacking. Data are mostly based on in vitro and observational studies. We conducted a literature review to assess the effectiveness of this therapy, along with potential alternatives. The proposed in vitro mechanism of action describes the inhibition of Coxiella replication by doxycycline through the restoration of its bactericidal activity (inhibited in acidic environment) by alkalinization of phagolysosome-like vacuoles with hydroxychloroquine. So far, the rarity and heterogeneous presentation of cases have made it challenging to design prospective studies with statistical power. The main studies supporting this treatment are retrospective cohorts, dating back to the 1990s-2000s. Retrospective studies from the large Dutch outbreak of Q fever (>4000 cases between 2007 and 2010) did not corroborate a clear benefit of this combination, notably in comparison with other regimens. Thus, there is still no consensus among the medical community on this issue. However insufficient the evidence, today the doxycycline + hydroxychloroquine combination remains the regimen with the largest clinical experience in the treatment of 'chronic' Q fever. Reinforcing the guidelines' level of evidence is critical. We herein propose the creation of an extensive international registry, followed by a prospective cohort or ideally a randomized controlled trial.

Homemade pericardial bifurcated graft for Q fever-infected abdominal aortic aneurysm open repair: a case report

Q fever is a zoonotic infection caused by Coxiella burnetii. In rare cases, it can lead to vascular complications, including infected aneurysms. Successful treatment involves surgery and antibiotics, but there is no established consensus or clear recommendation for the choice of material graft. We report a case of abdominal aortic aneurysm infected by C. burnetii treated by open surgery with complete resection of the aneurysm and homemade bovine pericardial bifurcated graft reconstruction and long-term antibiotherapy using doxycycline. One year postoperatively, the patient had no sign of persistent infection or vascular complication. Moreover, C. burnetii immunoglobulins titers decreased 6 months postoperatively.

The Prognostic Value of Serology in Persistent Q Fever Infection

Background: Q fever has significant consequences for patients with persistent localized infection. A combination of doxycycline with hydroxychloroquine, for at least 18-24 months, is the first-line therapy. The use of serology as a prognostic marker during therapy is controversial. Methods: A retrospective, observational cohort study in two outpatient clinics in northern Israel. All adults with persistent Q fever (2015-2021) were included in the study. Clinical failure was defined as relapse or death related to Q fever after end of treatment (EOT). Serological cure was defined as phase 1 IgG ≤800 or a four-fold decrease at EOT. Results: Twenty-two patients were included in the study, with a median follow up of 40 months (IQR = 28.5-63.5), and median treatment duration of 28.5 months (IQR = 21.8-50.5). Clinical cure occurred in 18 patients (82%), serological cure in 10 (45%). Phase 1 IgG at presentation was significantly higher in the clinical failure group (median 9600 vs. 3200 in the clinical cure group, p = 0.019), and at 6-12 months after EOT (median 6400 vs. 800 respectively, p = 0.03). Phase 1 IgG levels at 1 year and EOT were similar in both groups. Positive phase 2 IgM after one year of therapy correlated with clinical failure (p = 0.038), but not at EOT or after EOT. Conclusion: Phase 1 IgG levels at presentation, phase 2 IgM at 1 year, and Phase 1 IgG 6-12 months after EOT were associated with clinical failure in patients with persistent Q fever.

Coxiella burnetii outbreak, Northern Italy 2021

OBJECTIVE

We report an outbreak of 14 cases of Q fever among tourists caused by an infected calf and characterized by respiratory transmission and a high attack rate in humans.

MATERIALS AND METHODS

Following the identification of an index case of Q fever in September 2021, an epidemiological investigation was conducted in collaboration with local Health and Veterinary authorities and an unknown outbreak was discovered and terminated.

RESULTS

The outbreak originated from the delivery by an infected cow, with spread of C. burnetii by air and infection via the respiratory route. The transmission period was calculated, and 25 potentially exposed tourists were identified: 14 were infected (56%) based on serological investigations, four were hospitalized, there were no deaths. All the 22 cows were tested by PCR for C. burnetii: 3 cows (14%) were positive on milk samples and one, the index animal, was also positive on blood.

CONCLUSIONS

Timely diagnosis in a human patient was pivotal to identify the outbreak since involved animals were asymptomatic. The close collaboration between veterinary and human Public Health services in six different geographical areas of two countries was crucial for the rapid termination of the outbreak.

Increased recognition of Q fever aortitis as a chronic manifestation of Q fever in tropical North Queensland, Australia

Aortitis is a life-threatening, manifestation of chronic Q fever. We report a series of 5 patients with Q fever aortitis who have presented to our hospital in tropical Australia since 2019. All diagnoses were confirmed with polymerase chain reaction (PCR) testing of aortic tissue. Only one had a previous diagnosis of acute Q fever, and none had classical high-risk exposures that might increase clinical suspicion for the infection. All patients underwent surgery: one died and 3 had significant complications. Q fever aortitis may be underdiagnosed; clinicians should consider testing for Coxiella burnetii in people with aortic pathology in endemic areas.

Q fever - immune responses and novel vaccine strategies

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. It is an occupational risk for employees of animal industries and is associated with contact with wildlife and domestic animals. Although Q fever infection may be asymptomatic, chronic sequelae such as endocarditis occur in 5% of symptomatic individuals. Disease outcomes may be predicted through measurement of immune correlates. Vaccination is the most efficient method to prevent Q fever. Currently, Q-VAX is the only licenced human vaccine. Q-VAX is highly effective; however, individuals previously exposed to C. burnetii are at risk of adverse reactions. This review examines the immunological responses of acute and chronic Q fever and the efforts to provide a safer and cost-effective Q fever vaccine.

Genome-wide epitope mapping across multiple host species reveals significant diversity in antibody responses to Coxiella burnetii vaccination and infection

Coxiella burnetii is an important zoonotic bacterial pathogen of global importance, causing the disease Q fever in a wide range of animal hosts. Ruminant livestock, in particular sheep and goats, are considered the main reservoir of human infection. Vaccination is a key control measure, and two commercial vaccines based on formalin-inactivated C. burnetii bacterins are currently available for use in livestock and humans. However, their deployment is limited due to significant reactogenicity in individuals previously sensitized to C. burnetii antigens. Furthermore, these vaccines interfere with available serodiagnostic tests which are also based on C. burnetii bacterin antigens. Defined subunit antigen vaccines offer significant advantages, as they can be engineered to reduce reactogenicity and co-designed with serodiagnostic tests to allow discrimination between vaccinated and infected individuals. This study aimed to investigate the diversity of antibody responses to C. burnetii vaccination and/or infection in cattle, goats, humans, and sheep through genome-wide linear epitope mapping to identify candidate vaccine and diagnostic antigens within the predicted bacterial proteome. Using high-density peptide microarrays, we analyzed the seroreactivity in 156 serum samples from vaccinated and infected individuals to peptides derived from 2,092 open-reading frames in the C. burnetii genome. We found significant diversity in the antibody responses within and between species and across different types of C. burnetii exposure. Through the implementation of three different vaccine candidate selection methods, we identified 493 candidate protein antigens for protein subunit vaccine design or serodiagnostic evaluation, of which 65 have been previously described. This is the first study to investigate multi-species seroreactivity against the entire C. burnetii proteome presented as overlapping linear peptides and provides the basis for the selection of antigen targets for next-generation Q fever vaccines and diagnostic tests.

Q fever screening among pregnant women with pre-term delivery in northern Israel: An observational study

The relationship between Q fever, caused by Coxiella burnetii, and obstetrical complications is debatable. Since Q fever is endemic in Israel, we aimed to assess its seroprevalence and clinical characteristics in pre-term deliveries. Between 1 August 2017 and 31 December 2019, we conducted serological screening for C. burnetii in pregnant women who presented to Rambam Health Care Campus with pre-term delivery (before 37 weeks of gestation). Anti-C. burnetii antibodies were tested first by enzyme-linked immunosorbent assay for the detection of phase I-IgG, phase II-IgG and phase II-IgM. Positive results were confirmed by indirect immunofluorescence with titre determination. Seropositivity was classified into past, acute and chronic infection. Demographic and clinical data of mothers and neonates were collected and compared between seropositive and seronegative women. Out of 386 pregnant women screened for anti-C. burnetii antibodies, 16 (4.1%) were seropositive, of whom three were diagnosed with past, 12 with acute and one with chronic infection. A higher percentage of seropositive women were immunosuppressed, 2/16 (12.5%) compared with 7/370 (1.9%) in seronegative women, (p = .05). Neonates with small for gestational age were born to 2/16 (12.5%) seropositive women compared with 29/370 (7.8%) to seronegative women, (p = .35). The seroprevalence of Q fever among pregnant women with pre-term birth reached 4% in northern Israel. This high rate in an endemic setting encourages investigating the role of routine screening for Q fever during pregnancy. Special attention should be given to pregnant immunosuppressed women at risk for exposure to Q fever.

Spinal infection caused by Coxiella burnetii

BACKGROUND

Spinal infection caused by Coxiella burnetii is rare and difficult to diagnose. Here we reported a case of spinal infection from Coxiella burnetii detected by the metagenomic next-generation sequencing (mNGS).

CASE PRESENTATION

A 66-year-old male farmer with no medical history reported severe sharp low back pain, numbness and lower limb weakness for three years. Magnetic resonance imaging (MRI) revealed bone destruction and spinal cord compression within L1 and L2. mNGS testing showed that the inspected specimen collected from spinal lesion was detected positively for Coxiella burnetii. After receiving the combined treatment of antibiotic therapy and surgical intervention, the patient recovered well, and the sagittal MRI showed that vertebral edema signals disappeared and the graft of bone fused 16 months after surgery.

CONCLUSION

The mNGS may be benefit for early diagnosis and intervention of non-specific spinal infection, and future studies should validate its effectiveness for clinical use in spinal infections. Additionally, antibiotic therapy combined with surgical intervention plays an important role on the treatment of spinal infection caused by Coxiella burnetii.

Impact of Coxiella burnetii vaccination on humoral immune response, vaginal shedding, and lamb mortality in naturally pre-infected sheep

Introduction

Sheep are considered to be one of the main reservoirs for Coxiella burnetii, a gram-negative bacterium with high zoonotic potential. Infected sheep shed tremendous amounts of the pathogen through birth products which caused human Q fever epidemics in several countries. Information about the impact of an inactivated C. burnetii Phase I vaccine on humoral immune response, vaginal shedding, and lamb mortality in naturally pre-infected sheep is scarce.

Methods

Two identically managed and naturally C. burnetii-infected sheep flocks were examined for two lambing seasons (2019 and 2020). One flock (VAC) received a primary vaccination against Q fever before mating and the second flock served as control (CTR). In each flock, one cohort of 100 ewes was included in follow-up investigations. Serum samples at eight different sampling dates were analyzed by C. burnetii phase-specific ELISAs to differentiate between the IgG Phase I and II responses. Vaginal swabs were collected within three days after parturition and examined by a C. burnetii real-time PCR (IS1111). Lamb losses were recorded to calculate lamb mortality parameters.

Results

After primary vaccination, almost all animals from cohort VAC showed a high IgG Phase I response up until the end of the study period. In cohort CTR, the seropositivity rate varied from 35.1% to 66.3%, and the Phase I and Phase II pattern showed an undulating trend with higher IgG Phase II activity during both lambing seasons. The number of vaginal shedders was significantly reduced in cohort VAC compared to cohort CTR during the lambing season in 2019 (p < 0.0167). There was no significant difference of vaginal shedders in 2020. The total lamb losses were low in both cohorts during the two investigated lambing seasons (VAC 2019: 6.8%, 2020: 3.2%; CTR 2019: 1.4%, 2020: 2.7%).

Discussion

Neither the C. burnetii vaccine nor the C. burnetii infection seem to have an impact on lamb mortality. Taken together, the inactivated C. burnetii Phase I vaccine induced a strong IgG Phase I antibody response in naturally pre-infected sheep. It might also reduce vaginal shedding in the short term but seems to have little beneficial impact on lamb mortality.

Targeted Screening for Chronic Q Fever, the Netherlands

Early detection of and treatment for chronic Q fever might prevent potentially life-threatening complications. We performed a chronic Q fever screening program in general practitioner practices in the Netherlands 10 years after a large Q fever outbreak. Thirteen general practitioner practices located in outbreak areas selected 3,419 patients who had specific underlying medical conditions, of whom 1,642 (48%) participated. Immunofluorescence assay of serum showed that 289 (18%) of 1,642 participants had a previous Coxiella burnetii infection (IgG II titer >1:64), and 9 patients were suspected of having chronic Q fever (IgG I y titer >1:512). After medical evaluation, 4 of those patients received a chronic Q fever diagnosis. The cost of screening was higher than estimated earlier, but the program was still cost-effective in certain high risk groups. Years after a large Q fever outbreak, targeted screening still detected patients with chronic Q fever and is estimated to be cost-effective.

Serological Prevalence of and Risk Factors for Coxiella burnetti Infection in Women of Punjab Province, Pakistan

Background: Coxiella burnetii, the etiological agent of Q (query) fever, provokes abortions in ruminants and is suspected to cause adverse pregnancy outcomes in women. Infection of pregnant women is linked with high mortality and morbidity of the fetus and the mother is at high risk to acquire chronic Q fever. This research was conducted to evaluate the prevalence of Q fever in women and to detect associated risk factors in four districts of Punjab Province, Pakistan. Methods: A total of 297 blood samples were obtained from 147 pregnant and 150 non-pregnant women of the districts Okara, Jhang, Chiniot and Faisalabad of Punjab, Pakistan. Data related to risk factors and demographic parameters were collected using a questionnaire. Serum samples were screened for phase I and phase II specific IgG antibodies for antigens of phase I and phase II using ELISA tests. Univariate and binary regression were used to analyze important risk factors of Q fever. Results: Twenty-five serum samples (8.4%) were found seropositive for Q fever. Seventeen women were positive for Phase-I and twenty-one were positive for phase-II antibodies. Highest and statistically significant (p < 0.05) seroprevalence of 17.1% was observed in Faisalabad. Age, urbanicity, living status, pregnancy status, abortion history, occupation, and consumption of tap water were positively correlated (p < 0.05) with Q fever, while being aged, urbanity, low income, contact with animals and consumption of tap water was identified as potential risk factors. Conclusions: Q fever is prevalent in women of Pakistan. There is a need for an awareness program about the importance of C. burnetii infections and prevention strategies in women during pregnancy to minimize adverse pregnancy outcomes.

Impact of Q-fever on physical and psychosocial functioning until 8 years after Coxiella burnetii infection: An integrative data analysis

Background

This study aimed to determine short- and long-term physical and psychosocial impact of Coxiella burnetii infection in three distinct entities: Q-fever fatigue syndrome (QFS), chronic Q-fever, and patients with past acute Q-fever without QFS or chronic Q-fever.

Methods

Integrative data analysis was performed, combining original data from eight studies measuring quality of life (QoL), fatigue, physical and social functioning with identical validated questionnaires, from three months to eight years after onset infection. Linear trends in each outcome were compared between Q-fever groups using multilevel linear regression analyses to account for repeated measures within patients.

Results

Data included 3947 observations of 2313 individual patients (228 QFS, 135 chronic Q-fever and 1950 patients with past acute Q-fever). In the first years following infection, physical and psychosocial impact was highest among QFS patients, and remained high without significant improvements over time. In chronic Q-fever patients, QoL and physical functioning worsened significantly over time. Levels of fatigue and social participation in patients with past acute Q-fever improved significantly over time.

Conclusion

The impact differs greatly between the three Q-fever groups. It is important that physicians are aware of these differences, in order to provide relevant care for each patient group.

Coxiella burnetii Infection Associated With Thromboangiitis Obliterans-like Phenomena With Digital Autoamputation: A Case Report and Review of Q Fever-Associated Autoimmunity

We present a case of a patient with chronic Q fever who presented with digital necrosis, autoamputations, and positive anticentromere antibody, mimicking a scleroderma vasculopathy or thromboangiitis obliterans. Coxiella burnetii infection has long been associated with the presence of autoantibodies and autoimmune phenomena including vasculitis. Clinicians should consider Q fever testing in patients with new-onset autoimmune diseases or autoantibodies and appropriate exposure histories.

Molecular diagnosis of Coxiella burnetii in culture negative endocarditis and vascular infection in South Korea

BACKGROUND

Q fever endocarditis is a major cause of culture-negative endocarditis. The role of Coxellia burnetii is underestimated because it is difficult to diagnose. We investigated the significance of C. burnetii as the cause of culture-negative endocarditis and vascular infection by examining blood and tissue specimens using serological testing and polymerase chain reaction (PCR).

METHODS

All patients with infective endocarditis or large vessel vasculitis were prospectively enrolled at a tertiary-care hospital from May 2016 through September 2020. Q fever endocarditis and vascular infection were diagnosed based on: (1) positive PCR for a cardiac valve or vascular tissue, (2) positive PCR for blood or phase I immunoglobulin G (IgG) ≥ 6400, or (3) phase I IgG ≥ 800 and < 6400 with morphologic abnormality. PCR targeted C. burnetii transposase gene insertion element IS1111a.

RESULTS

Of the 163 patients, 40 (25%) had culture-negative endocarditis (n = 35) or vascular infection (n = 5). Of the 40 patients, 24 (60%) were enrolled. Eight (33%) were diagnosed with Q fever endocarditis or vascular infection. Of these 8 patients, 6 had suspected acute Q fever endocarditis or vascular infection with negative phase I IgG. Six patients were not treated for C. burnetii, 4 were stable after surgery. One patient died due to surgical site infection after 5 months post-operatively and one died due to worsening underlying disease.

CONCLUSIONS

Approximately one-third of patients with culture-negative endocarditis and vascular infection was diagnosed as Q fever. Q fever endocarditis and vascular infection may be underestimated in routine clinical practice in South Korea.KEY MESSAGEQ fever endocarditis and vascular infection may be underestimated in routine clinical practice, thus, try to find evidence of C. burnetti infection in suspected patients by all available diagnostic tests including PCR.

Development of High-Throughput Multiplex Serology to Detect Serum Antibodies against Coxiella burnetii

The causative agent of Q fever, the bacterium Coxiella burnetii (C. burnetii), has gained increasing interest due to outbreak events and reports about it being a potential risk factor for the development of lymphomas. In order to conduct large-scale studies for population monitoring and to investigate possible associations more closely, accurate and cost-effective high-throughput assays are highly desired. To address this need, nine C. burnetii proteins were expressed as recombinant antigens for multiplex serology. This technique enables the quantitative high-throughput detection of antibodies to multiple antigens simultaneously in a single reaction. Based on a reference group of 76 seropositive and 91 seronegative sera, three antigens were able to detect C. burnetii infections. Com1, GroEL, and DnaK achieved specificities of 93%, 69%, and 77% and sensitivities of 64%, 72%, and 47%, respectively. Double positivity to Com1 and GroEL led to a combined specificity of 90% and a sensitivity of 71%. In a subgroup of seropositives with an increased risk for chronic Q fever, the double positivity to these markers reached a specificity of 90% and a sensitivity of 86%. Multiplex serology enables the detection of antibodies against C. burnetii and appears well-suited to investigate associations between C. burnetii infections and the clinical manifestations in large-scale studies.

A case of tick-transmitted Q fever in Lishui, China diagnosed by next-generation sequencing

Q fever is a zoonotic disease caused by Coxiella burnetii. Most patients have non-specific symptoms at onset. In addition, routine diagnostic tests for C. burnetii are not sensitive, and the bacterium cannot grow in general culture medium. The diagnosis of Q fever therefore poses a challenge. This case study describes a man with a clear history of tick bite who had recurrent fever, pneumonia, and liver damage. Routine tests and bacterial cultures failed to clarify the pathogeny, but laboratory and imaging data suggested infection. After routine tests were exhausted, we detected the presence of C. burnetii in a whole blood sample using next-generation sequencing (NGS). To our knowledge, this is the first report of Q fever associated with Coxiella burnetii detected directly from blood samples in Lishui, China. NGS has revolutionized the diagnosis of infectious diseases, especially those caused by rare or newly discovered pathogens, and patient responses have finally proved its substantial benefits. NGS has important clinical significance for the early diagnosis of chronic Q fever. This proof-of-concept study is worthy of promotion in clinical practice.

High incidence of asymptomatic phase I IgG seroconversion after acute Q fever episode: implications for chronic Q fever diagnosis

BACKGROUND

The aim of this study was to describe the natural history of acute Q fever, including its clinical and serological evolution and progression to chronic Q fever.

METHODS

Observational cohort study (January 2011-September 2020) performed at Valme University Hospital (Seville, Spain). Inclusion criteria: 1) Patients over the age of eighteen; 2) Acute Q fever diagnosis, defined as suggestive symptoms in the presence of phase II IgG titer > 1:256; 3) At least 6 months follow-up after the acute Q fever episode. The incidence of seroconversion to a chronic Q fever serological pattern, defined as phase I IgG titers ≥ 1:1024 six months after acute Q fever diagnosis, was assessed.

RESULTS

During the study period, 117 patients were included. Thirty-four (29%) patients showed phase I IgG titers ≥ 1:1024 six months after acute Q fever diagnosis. All patients with classic serologic criteria for chronic Q fever diagnosis remained asymptomatic despite no specific treatment, with a median (Q1-Q3) follow-up of 26.5 (14-44) months in this subgroup. No cases of Q fever endocarditis neither other persistent focalized infection forms were observed during the study period.

CONCLUSIONS

A significant proportion of acute Q fever patients develops classic serologic criteria for chronic Q fever diagnosis in the absence of additional data of chronic Q fever. Consequently, phase I IgG cutoff titer > 1:800 should not be used as a criterion to consider such a diagnosis. The incidence of persistent focalized infection forms after acute Q fever is extremely low and does not justify the use of prophylaxis strategies.

Q Fever: A troubling disease and a challenging diagnosis

Q fever is a disease caused by the bacterial pathogen Coxiella burnetii. This hardy organism can easily spread long distances in the wind, and only a few infectious aerosolized particles are necessary to cause serious illness. Presentations of Q fever disease can be wide-ranging, allowing it to masquerade as other illnesses and highlight the importance of laboratory testing for diagnosis and treatment. This review summarizes Q fever's epidemiology and clinical presentations and presents classical laboratory diagnostic assays and novel approaches to detecting this troubling disease.

Incidence of chronic Q fever and chronic fatigue syndrome: A 6 year follow-up of a large Q fever outbreak

Acute Q fever is a generally self-limiting infection caused by the intracellular gram-negative bacterium Coxiella burnetii. For yet unknown reasons, a subset of patients develops chronic infection. Furthermore, chronic fatigue syndrome (CFS) as post-acute Q fever sequelae has been described. We here investigated the rates of chronic Q fever and incidences of CFS 6 years after one of the largest European Q fever outbreaks that occurred in Jena, Germany in 2005 with 331 reported cases, who lived in proximity of a grazing flock of sheep. A total of 80 patients and their 52 non-diseased household members from the former outbreak, were enrolled 6 years after the outbreak. Blood samples were collected and tested for chronic Q fever which was determined by seroprevalence using referenced immunofluorescence assays. Also, the presence of CFS was assessed using the Short Form Symptom Inventory developed by the Centers (United States) for Disease Control and Prevention (SF CDC- SI). In 80 out of 132 (60.6%) study participants, previous Q fever infection was confirmed serologically, while no previous infection was detected in the 52 household members. None of the participants fulfilled the serological criteria of chronic Q fever. The evaluation of the CDC-SI did not show any differences between the two groups. Also, there was no difference between both groups regarding fulfillment of CFS-defining criteria (n = 3 (3.8%; sero-positive) versus n = 2 (3.8%; sero-negative), p = 0.655). Our 6-year follow-up study of a large Q fever outbreak did not find evidence of chronic Q fever or post Q fever CFS. There was no asymptomatic sero-positivity in household members of Q fever patients.

High Prevalence and New Genotype of Coxiella burnetii in Ticks Infesting Camels in Somalia

Coxiella burnetii is the causative agent of Q fever. It can infect animals, humans, and birds, as well as ticks, and it has a worldwide geographical distribution. To better understand the epidemiology of C. burnetii in Somalia, ticks infesting camels were collected from five different regions, including Bari, Nugaal, Mudug, Sool, and Sanaag, between January and March 2018. Collected ticks were tested for C. burnetii and Coxiella-like endosymbiont DNA by using IS1111, icd, and Com1-target PCR assays. Moreover, sequencing of the 16S-rRNA was conducted. Molecular characterization and typing were done by adaA-gene analysis and plasmid-type identification. Further typing was carried out by 14-marker Multi-Locus Variable-Number Tandem Repeats (MLVA/VNTR) analysis. The investigated ticks (n = 237) were identified as Hyalomma spp. (n = 227, 95.8%), Amblyomma spp. (n = 8, 3.4%), and Ripicephalus spp. (n = 2, 0.8%), and 59.1% (140/237) of them were positive for Coxiella spp. While Sanger sequencing and plasmid-type identification revealed a C. burnetii that harbours the QpRS-plasmid, MLVA/VNTR genotyping showed a new genotype which was initially named D21. In conclusion, this is the first report of C. burnetii in ticks in Somalia. The findings denote the possibility that C. burnetii is endemic in Somalia. Further epidemiological studies investigating samples from humans, animals, and ticks within the context of "One Health" are warranted.

Utility of positron emission tomography imaging in the diagnosis of chronic Q fever: A Systematic Review

Chronic Q fever is a diagnostic challenge. Diagnosis relies on serology and/or the detection of DNA from blood or tissue samples. PET-CT identifies tissues with increased glucose metabolism, thus identifying foci of inflammation. Our aim was to review the existing literature on the use of PET-CT to help diagnose chronic Q fever. A literature search was conducted in PubMed and Google Scholar to ascertain publications that included the terms 'Positron Emission Tomography' and 'PET CT' in combination with subheadings 'chronic Q fever' and 'Coxiella burnetii' within the search. To broaden our search retrieval, we used the terms 'chronic Q fever' and 'PET-CT'. Published literature up to 16^th April 2020 was included. 274 articles were initially identified. Post-exclusion criteria, 46 articles were included. Amongst case reports and series, the most frequent focus of infection was vascular, followed by musculoskeletal then cardiac. 79.5% of patients had a focus detected with 55.3% of these having proven infected prosthetic devices. Amongst the retrospective and prospective studies, a total of 394 positive sites of foci were identified with 186 negative cases. Some had follow-up scans (53), with 75.5% showing improvement or resolution. Average timeframe for documented radiological resolution post-initiating treatment was 8.86 months. PET-CT is a useful tool in the management of chronic Q fever. Knowledge of a precise focus enables for directed surgical management helping reduce microbial burden, preventing future complications. Radiological resolution of infection can give clinicians reassurance on whether antimicrobial therapy can be ceased earlier, potentially limiting side effects.

Still new chronic Q fever cases diagnosed eight years after a large Q fever outbreak

BACKGROUND

Chronic Q fever usually develops within two years after primary infection with Coxiella burnetii. We determined the interval between acute Q fever and diagnosis of chronic infection, assessed what factors contribute to a longer interval, and evaluated the long-term follow-up.

METHODS

From 2007-2018, patients with chronic Q fever were included from 45 participating hospitals. The interval between acute and chronic infection was calculated in patients with a known day of first symptoms and/or serological confirmation of acute Q fever. Chronic Q fever-related complications and mortality were assessed by two investigators based on predefined criteria.

RESULTS

In total, 313 (60.3%) proven, 81 (15.6%) probable and 125 (24.1%) possible chronic Q fever patients were identified. The date of acute Q fever was known in 200 patients: in 45 (22.5%) the interval was longer than two years with the longest observed interval being 9.2 years. Patients in whom serological follow-up was performed after acute Q fever were diagnosed less often after this two-year interval (OR 0.26, 95% CI 0.12-0.54). Chronic Q fever-related complications occurred in 216 patients (41.6%). Chronic Q fever-related mortality occurred in 83 (26.5%) of proven and 3 (3.7%) of probable chronic Q fever patients.

CONCLUSIONS

Chronic Q fever is still being diagnosed and mortality keeps occurring eight years after a large outbreak. Intervals between acute Q fever and diagnosis of chronic infection can reach over 9 years. We urge physicians to perform microbiological testing for chronic Q fever even many years after an outbreak or acute Q fever disease.

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.

Humoral immune response to Q fever vaccination of three sheep flocks naturally pre-infected with Coxiella burnetii

Qfever is a zoonotic disease caused by the bacterium Coxiella burnetii; Coxiella-infected ruminants are the main reservoir shedding the pathogen during abortion or parturition through birth products. Germany has a long history of small-scale Q fever epidemics in the human population mostly associated with lambing sheep. Therefore, fast and efficient control measures are essentially required to prevent transmission from infected sheep flocks to humans. In our present study, three sheep flocks were vaccinated with an inactivated C.burnetii phase I vaccine after a field infection with C.burnetii was diagnosed. Serum samples and vaginal swabs were collected at different time points to evaluate the extent of the outbreak and the consequences of the vaccination. The serum samples were examined by phase-specific IgG phase I and phase II ELISAs and a commercial ELISA, simultaneously detecting both phase variations. Moreover, vaginal swabs were analysed by qPCR. The fourth flock with no Q fever history and non-vaccinated animals were used as a control group to evaluate the phase-specific ELISAs. The inactivated C.burnetii phase I vaccine induced an IgG phase II response and boosted the humoral immune reaction against natural pre-infections. Furthermore, the longevity of vaccine-induced antibodies seems to depend on previous infections. Around 16 months after primary vaccination, mainly IgG phase I antibodies were detectable. Vaccination did not prevent shedding at the next lambing season. Most interestingly, the phase-specific ELISAs revealed more C.burnetii positive animals than the blended ELISA-Assay. Taken together, phase-specific ELISAs are suitable tools to provide insights into natural- or vaccine-induced humoral immune responses to C.burnetii in sheep.

Q fever vertebral osteomyelitis among adults: a case series and literature review

BACKGROUND

Q fever osteoarticular infections are a rare complication of the chronic form of Q fever. We aimed to characterize chronic Q fever vertebral osteomyelitis through our experience and a review of the literature.

METHODS

Four adult patients with Q fever vertebral osteomyelitis diagnosed in a tertiary hospital in northern Israel between 2016 to 2020 are described. In addition, a 30 years' literature review of Q fever vertebral osteomyelitis, characterizing predisposing factors, clinical presentation, course of disease, treatment and outcomes, was performed.

RESULTS

Thirty-four adult patients with Q fever vertebral osteomyelitis were identified. The vast majority were male (30/34, 88%) with a mean age of 67.2 ± 10 years. Involvement of the adjacent aorta, likely the origin of the infection, was observed in 23/34 (68%) of the patients, usually among patients with aortic graft or aneurysm. Clinical presentation was insidious and fever was frequently absent. Delayed diagnosis for months to years after symptoms onset was frequently reported. Vascular infections were managed with or without extraction of the infected aneurysm/aorta and graft placement. The outcome was variable with limited follow-up data in most cases. Patients were usually treated with prolonged antimicrobial therapy, most commonly doxycycline and hydroxychloroquine combination therapy.

CONCLUSION

Q fever should be included in the differential diagnosis of vertebral osteomyelitis in endemic settings, in particular when concomitant adjacent vascular infection exists.

Vector competence of the African argasid tick Ornithodoros moubata for the Q fever agent Coxiella burnetii

Q fever is a widespread zoonotic disease caused by the intracellular bacterium Coxiella burnetii. While transmission is primarily but not exclusively airborne, ticks are usually thought to act as vectors on the basis of early microscopy studies. However, recent observations revealed that endosymbionts of ticks have been commonly misidentified as C. burnetii, calling the importance of tick-borne transmission into question. In this study, we re-evaluated the vector competence of the African soft tick Ornithodoros moubata for an avirulent strain of C. burnetii. To this end, we used an artificial feeding system to initiate infection of ticks, specific molecular tools to monitor further infections, and culture assays in axenic and cell media to check for the viability of C. burnetii excreted by ticks. We observed typical traits associated with vector competence: The exposure to an infected blood meal resulted in viable and persistent infections in ticks, trans-stadial transmissions of infection from nymphs to adults and the ability of adult ticks to transmit infectious C. burnetii. However, in contrast to early studies, we found that infection differed substantially between tick organs. In addition, while adult female ticks were infected, we did not observe C. burnetii in eggs, suggesting that transovarial transmission is not effective. Finally, we detected only a sporadic presence of C. burnetii DNA in tick faeces, but no living bacterium was further isolated in culture assays, suggesting that excretion in faeces is not a common mode of transmission in O. moubata.

The intracellular bacterium Coxiella burnetii is the agent of Q fever, a widespread zoonotic disease. Some early detection reports and microscopy studies identified ticks as vectors of Q fever but more recent studies and molecular analyses revealed that endosymbionts of ticks have been commonly misidentified as C. burnetii: It raises questions of whether ticks play an important role in Q fever transmission. In our study, we therefore experimentally re-evaluate the vector competence of the African soft tick Ornithodoros moubata for C. burnetii. We found that O. moubata can be infected by C. burnetii after the exposure to an infected blood meal. It resulted in viable and persistent infections in ticks, a trans-stadial transmission and the ability of adult ticks to transmit infection when feeding. Infection was however not transmitted transovarially or by faeces as early reported. Overall, we conclude that O. moubata may act as a driver of the transmission and of the spatial dispersal of Q fever among vertebrates where this tick is present in Africa.

In the Search of Potential Serodiagnostic Proteins to Discriminate Between Acute and Chronic Q Fever in Humans. Some Promising Outcomes

Coxiella burnetii is the agent that causes acute and chronic Q fever infections in humans. Although the isolates studied so far have shown that the two forms of the disease differ in virulence potential thus, implying a variance in their proteomic profile, the methods used do not deliver enough discriminatory capability and often, human infections may be mis-diagnosed. The current study adds further knowledge to the results that we have already published on the Coxiella outer membrane protein 1 (Com1). Herein we identified the proteins GroEL, Ybgf, OmpH, and UPF0422 as candidates for serodiagnostics of Q fever; following cloning, expression and purification they were further used as antigens in ELISA for the screening of patients' sera associated with chronic Q fever endocarditis, sera negative for phase I IgG, sera with at least one sample positive for phase I IgG and sera from patients who suffered from various rheumatic diseases. Blood donors were used as the controls. Sensitivity, specificity, positive predictive value, negative predictive value, and Cohen's kappa coefficient (κ) were calculated and we also performed binary logistic regression analysis to identify combinations of proteins with increased diagnostic yield. We found that proteins GroEL and Ybgf, together with Com1, play the most significant role in the correct diagnosis of chronic Q fever. Of these three proteins, it was shown that Com1 and GroEL present the highest sensitivity and specificity altogether. The results add to the existing knowledge that an antigen-based serodiagnostic test that will be able to correctly diagnose chronic Q fever may not be far from reality.

Objective cognitive performance and subjective complaints in patients with chronic Q fever or Q fever fatigue syndrome

BACKGROUND

Primary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account. Second, we investigated whether objective cognitive performance was related to subjective cognitive complaints or psychological wellbeing.

METHODS

Cognitive functioning was assessed with a neuropsychological test battery measuring the domains of processing speed, episodic memory, working memory and executive functioning. Tests for performance validity and premorbid intelligence were also included. Validated questionnaires were administered to assess self-reported fatigue, depressive symptoms and cognitive complaints.

RESULTS

In total, 30 patients with chronic Q fever, 32 with QFS and 35 controls were included. A high percentage of chronic Q fever patients showed poor performance validity (38%) compared to controls (14%, p = 0.066). After exclusion of participants showing poor performance validity, no significant differences between patients and controls were found in the cognitive domains. QFS patients reported a high level of cognitive complaints compared to controls (41.2 vs 30.4, p = 0.023). Cognitive complaints were not significantly related to cognitive performance in any of the domains for this patient group.

CONCLUSIONS

The high level of self-reported cognitive complaints in QFS patients does not indicate cognitive impairment. A large proportion of the chronic Q fever patients showed suboptimal mental effort during neuropsychological assessment. More research into the underlying explanations is needed. Our findings stress the importance of assessing cognitive functioning by neuropsychological examination including performance validity, rather than only measuring subjective cognitive complaints.

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.

Should Acute Q-Fever Patients be Screened for Valvulopathy to Prevent Endocarditis?

Background

Echocardiographic screening of acute Q-fever patients and antibiotic prophylaxis for patients with cardiac valvulopathy is considered an important approach to prevent chronic Q-fever-related endocarditis. During a large Q-fever epidemic in the Netherlands, routine screening echocardiography was discontinued, raising controversy in the international literature. We followed a cohort of acute Q-fever patients to estimate the risk for developing chronic Q-fever, and we evaluated the impact of screening in patients who were not yet known to have a valvulopathy.

Methods

The study population consisted of patients diagnosed with acute Q-fever in 2007 and 2008. We retrospectively reviewed all screening echocardiographs and checked for development of chronic Q-fever 8 years after the acute episode. Risks of developing chronic Q-fever in relation to the presence or absence of valvulopathy were analyzed with logistic regression.

Results

The cohort included 509 patients, of whom 306 received echocardiographic screening. There was no significant difference (P-value = .22) in occurrence of chronic Q-fever between patients with a newly detected valvulopathy (2/84, 2.4%) and those with no valvulopathy (12/202, 5.9%). Two patients with a newly detected valvulopathy, who did not receive antibiotic prophylaxis, developed chronic Q-fever at a later stage.

Conclusions

We found no difference in outcome between patients with and without a valvulopathy newly detected by echocardiographic screening. In retrospect, the 2 above-mentioned patients could have benefitted from antibiotic prophylaxis, but its omission must be weighed against the unnecessary large-scale and long-term use of antibiotics that would have resulted from universal echocardiographic screening.

Q Fever Endocarditis in Iran

Patients with the underlying valvular heart disease are at the high risk of developing sub-acute or chronic endocarditis secondary to Coxiella burnetii. Q fever endocarditis is the most common manifestation along with persistent the infection. There is some serologic and molecular evidence of C. burnetii infection in humans and livestock in Iran. As it is possible to observe chronic Q fever in Iran, it seems necessary to study the prevalence of Q fever endocarditis in this country. In the present study, Infective Endocarditis (IE) patients (possible or definite based on Duke Criteria) hospitalized in Rajaie Cardiovascular Medical and Research Center were enrolled from August 2016 to September 2018. Culture-negative endocarditis patients were evaluated by Raoult criteria for diagnosis Q fever endocarditis. The serological results for brucellosis were negative for all subjects. All blood and tissue samples including valve samples were tested for C. burnetii infection using serology and Polymerase Chain Reaction (PCR). In this study, 126 patients who were admitted to the hospital were enrolled; of which 52 subjects were culture-negative IE. Among the participants, 16 patients (30.77%) were diagnosed with Q fever IE and underwent medical treatment. The mean age of patients was 46.6 years ranging from 23 to 69 years and 75% of them were male. Considering the high prevalence of Q fever IE, evaluation of the patients with culture-negative IE for C. burnetii infections was highly recommended.

Treatment of Chronic Q Fever: Clinical Efficacy and Toxicity of Antibiotic Regimens

Background

Evidence on the effectiveness of first-line treatment for chronic Q fever, tetracyclines (TET) plus hydroxychloroquine (HCQ), and potential alternatives is scarce.

Methods

We performed a retrospective, observational cohort study to assess efficacy of treatment with TET plus quinolones (QNL), TET plus QNL plus HCQ, QNL monotherapy, or TET monotherapy compared to TET plus HCQ in chronic Q fever patients. We used a time-dependent Cox proportional hazards model to assess our primary (all-cause mortality) and secondary outcomes (first disease-related event and therapy failure).

Results

We assessed 322 chronic Q fever patients; 276 (86%) received antibiotics. Compared to TET plus HCQ (n = 254; 92%), treatment with TET plus QNL (n = 49; 17%), TET plus QNL plus HCQ (n = 29, 10%), QNL monotherapy (n = 93; 34%), or TET monotherapy (n = 54; 20%) were not associated with primary or secondary outcomes. QNL and TET monotherapies were frequently discontinued due to insufficient clinical response (n = 27, 29% and n = 32, 59%). TET plus HCQ, TET plus QNL, and TET plus QNL plus HCQ were most frequently discontinued due to side effects (n = 110, 43%; n = 13, 27%; and n = 12, 41%).

Conclusions

Treatment of chronic Q fever with TET plus QNL appears to be a safe alternative for TET plus HCQ, for example, if TET plus HCQ cannot be tolerated due to side effects. Treatment with TET plus QNL plus HCQ was not superior to treatment with TET plus HCQ, although this may be caused by confounding by indication. Treatment with TET or QNL monotherapy should be avoided; switches due to subjective, insufficient clinical response were frequently observed.

Coxiella burnetii infection of the spine requiring neurosurgical intervention

Background:

Infections from Coxiella burnetii, resulting in what is known as Q fever, are relatively rare and difficult to diagnose. Very few reports of spinal infection from C. burnetii have been reported rarely have these cases required surgical intervention.

Case Description:

We report a patient with the previous vascular surgery and Q fever spinal osteomyelitis. Previously reported cases with spinal involvement have described initial infection of vascular grafts in proximity to the spine. Literature on spinal infection from C. burnetii reports only one case that required surgical intervention of the spine. We report a patient with L5-S1 diskitis who required surgical intervention and subsequent percutaneous drainage.

Conclusion:

Spinal infections from C. burnetii are rare; however, in the setting of a patient with osteodiscitis with negative cultures as well as a history of significant vascular disease with stents, the diagnosis of Q fever should be entertained. Operative and interventional procedures should also be considered in these patients to help alleviate pain and maintain neurologic function.

Coxiella burnetii Epitope-Specific T-Cell Responses in Patients with Chronic Q Fever

Infection with Coxiella burnetii, the causative agent of Q fever, can result in life-threatening persistent infection. Reactogenicity hinders worldwide implementation of the only licensed human Q fever vaccine. We previously demonstrated long-lived immunoreactivity in individuals with past symptomatic and asymptomatic Coxiella infection (convalescents) to promiscuous HLA class II C. burnetii epitopes, providing the basis for a novel T-cell targeted subunit vaccine. In this study, we investigated in a cohort of 22 individuals treated for persistent infection (chronic Q fever) whether they recognize the same set of epitopes or distinct epitopes that could be candidates for a therapeutic vaccine or aid in the diagnosis of persistent infection. In cultured enzyme-linked immunosorbent spot (ELISpot) assays, individuals with chronic Q fever showed strong class II epitope-specific responses that were largely overlapping with the peptide repertoire identified previously for convalescents. Five additional peptides were recognized more frequently by chronic subjects, but there was no combination of epitopes uniquely recognized by or nonreactive in subjects with chronic Q fever. Consistent with more recent/prolonged exposure, we found, however, stronger ex vivo responses by direct ELISpot to both whole-cell C. burnetii and individual peptides in chronic patients than in convalescents. In conclusion, we have validated and expanded a previously published set of candidate epitopes for a novel T-cell targeted subunit Q fever vaccine in treated patients with chronic Q fever and demonstrated that they successfully mounted a T-cell response comparable to that of convalescents. Finally, we demonstrated that individuals treated for chronic Q fever mount a broader ex vivo response to class II epitopes than convalescents, which could be explored for diagnostic purposes.

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.

Chronic Q fever associated with systemic sclerosis

BACKGROUND

After the Q fever outbreak in the Netherlands between 2007 and 2010, more than 300 patients with chronic Q fever have been identified. Some patients were also diagnosed with systemic sclerosis, a rare immune-mediated disease. We aimed to increase awareness of concomitant chronic Q fever infection and systemic sclerosis and to give insight into the course of systemic sclerosis during persistent Q fever infection.

MATERIALS AND METHODS

Chronic Q fever patients were identified after the Dutch Q fever outbreak in 2007-2010. Systemic sclerosis was diagnosed by a scleroderma expert and patients fulfilled the 2013 Classification Criteria for Systemic Sclerosis.

RESULTS

Four cases presented with chronic Q fever, persistent Coxiella burnetii infection, shortly preceded or followed by the diagnosis of limited cutaneous systemic sclerosis. The three male patients of 60 years or older developed a relatively mild systemic sclerosis, which did not require immunosuppressive therapy during adequate treatment of the chronic Q fever infection. The 58-year-old female patient used immunosuppressives for her newly diagnosed systemic sclerosis at the time she likely developed a chronic Q fever infection.

CONCLUSIONS

In this case series, chronic Q fever preceding systemic sclerosis was associated with a mild course of systemic sclerosis without the necessity of immunosuppressive drugs, while chronic Q fever development due to immunocompromised state was associated with a more deteriorating course of systemic sclerosis.

The effect of measuring serum doxycycline concentrations on clinical outcomes during treatment of chronic Q fever

Background

First choice treatment for chronic Q fever is doxycycline plus hydroxychloroquine. Serum doxycycline concentration (SDC) >5 μg/mL has been associated with a favourable serological response, but the effect on clinical outcomes is unknown.

Objectives

To assess the effect of measuring SDC during treatment of chronic Q fever on clinical outcomes.

Methods

We performed a retrospective cohort study, to assess the effect of measuring SDC on clinical outcomes in patients treated with doxycycline and hydroxychloroquine for chronic Q fever. Primary outcome was the first disease-related event (new complication or chronic Q fever-related mortality); secondary outcomes were all-cause mortality and PCR-positivity. Multivariable analysis was performed with a Cox proportional hazards model, with shared-frailty terms for different hospitals included.

Results

We included 201 patients (mean age 68 years, 83% male): in 167 patients (83%) SDC was measured, 34 patients (17%) were treated without SDC measurement. First SDC was >5 μg/mL in 106 patients (63%), all with 200 mg doxycycline daily. In patients with SDC measured, dosage was adjusted in 41% (n = 68), concerning an increase in 64 patients. Mean SDC was 4.1 μg/mL before dosage increase, and 5.9 μg/mL afterwards. SDC measurement was associated with a lower risk for disease-related events (HR 0.51, 95% CI 0.26-0.97, P = 0.04), but not with all-cause mortality or PCR-positivity.

Conclusions

SDC measurement decreases the risk for disease-related events, potentially through more optimal dosing or improved compliance. We recommend measurement of SDC and striving for SDC >5 μg/mL and <10 μg/mL during treatment of chronic Q fever.

Current perspectives on the transmission of Q fever: Highlighting the need for a systematic molecular approach for a neglected disease in Africa

Q fever is a bacterial worldwide zoonosis (except New Zealand) caused by the Gram-negative obligate intracellular bacterium Coxiella burnetii (C. burnetii). The bacterium has a large host range including arthropods, wildlife and companion animals and is frequently identified in human and livestock populations. In humans, the disease can occur as either a clinically acute or chronic aetiology, affecting mainly the lungs and liver in the acute disease, and heart valves when chronic. In livestock, Q fever is mainly asymptomatic; however, the infection can cause abortion, and the organism is shed in large quantities, where it can infect other livestock and humans. The presence of Q fever in Africa has been known for over 60 years, however while our knowledge of the transmission routes and risk of disease have been well established in many parts of the world, there is a significant paucity of knowledge across the African continent, where it remains a neglected zoonosis. Our limited knowledge of the disease across the African sub-continent have relied largely upon observational (sero) prevalence studies with limited focus on the molecular epidemiology of the disease. This review highlights the need for systematic studies to understand the routes of C. burnetii infection, and understand the disease burden and risk factors for clinical Q fever in both humans and livestock. With such knowledge gaps filled, the African continent could stand a better chance of eradicating Q fever through formulation and implementation of effective public health interventions.

Seroprevalence of Coxiella burnetii antibodies and chronic Q fever among post-mortal and living donors of tissues and cells from 2010 to 2015 in the Netherlands

After a large Q fever outbreak in the Netherlands in the period from 2007 to 2010, the risk of Q fever transmission through tissue and cell transplantation from undiagnosed chronic Q fever cases became a potential issue. Aim: We aimed to evaluate the risk of Q fever transmission through tissue and cell transplantation. Methods: We performed a retrospective observational cohort study among 15,133 Dutch donors of tissues and stem cells from 2010 to 2015 to assess seroprevalence of Coxiella burnetii antibodies, to identify factors associated with presence of C. burnetii antibodies, and to assess the proportion of undiagnosed chronic Q fever cases. Results: The study population consisted of 9,478 (63%) femoral head donors, 5,090 (34%) post-mortal tissue donors and 565 (4%) cord blood donors. Seroprevalence of C. burnetii antibodies gradually decreased after the outbreak, from 2.1% in 2010 to 1.4% in 2015, with a significant trend in time (p < 0.001). Of 301 seropositive donors, seven (2.3%) were newly detected with chronic Q fever (0.05% of all screened donors). Conclusion: This study shows that seroprevalence of C. burnetii antibodies among donors of tissues and cells in the Netherlands after 2014 was similar to pre-outbreak levels in the general population. The proportion of newly detected chronic Q fever patients among donors of tissues and cells was smaller than 0.1%. This study may prompt discussion on when to terminate the screening programme for chronic Q fever in donors of tissues and cells in the Netherlands.

Genetic evidence of Coxiella burnetii infection in acute febrile illnesses in Iran

Mounting evidence suggests that Q-fever is more prevalent in Iran than originally believed. However, in most parts of the country, clinicians do not pay enough attention to Q fever in their differential diagnosis. The aim of this study was to investigate the prevalence of Coxiella burnetii in suspected cases of acute Q fever in north-western Iran using molecular techniques. Febrile patients were enrolled in the study and investigated for C. burnetii infection. Sera samples were tested using real-time PCR for detection of IS1111 gene, and positive samples were confirmed with nested PCR. Nine patients (4.2%) out of 216 suspected cases were positive for C. burnetii. Weakness and fatigue, headache, and lethargy were the most prevalent clinical symptoms in acute Q fever patients. According to the results of this study and other reports of human cases in Iran, the diagnosis system of Q fever in Iran should be urgently revamped.

Q fever is a zoonotic infectious disease caused by Coxiella burnetii. Domestic ruminants are the most common source of human infection. Main route of transmission to humans is inhalation of infected aerosols and dust with C. burnetii. Acute Q fever is usually presented as a non-specific febrile and self-limiting influenza-like illness, but in severe acute cases, may manifest as atypical pneumonia or hepatitis. In Iran, Q fever is an endemic disease with high seroprevalence among humans and domestic animals. However, human Q fever cases remain undiagnosed in most regions of Iran, especially because most clinicians fail to spot this disease in their differential diagnosis. The aim of this study was to investigate the prevalence of acute Q fever in suspected cases (216 suspected cases) using molecular techniques. Nine acute Q fever patients were diagnosed by Real-time PCR and Nested PCR. Weakness and fatigue, headache, and lethargy were the most prevalent clinical symptoms in positive cases. Human Q fever cases described in this, and previous studies, indicate the need to implement diagnostic techniques for this disease across the country.

Coxiella burnetii in non-Hodgkin lymphoma tissue samples: Innocent until proven otherwise?

PURPOSE

Coxiella burnetii has been suggested as a potential cause of B-cell non-Hodgkin lymphoma (B-NHL), as C. burnetii was detected in B-NHL tissues. To further investigate this potential relationship, we hypothesized that among subjects previously exposed to C. burnetii, the bacterium is more frequently detectable in tissues of patients with B-NHL (cases) compared to patients without B-NHL (controls).

METHODS

We aimed to evaluate this hypothesis by assessing the presence of C. burnetii with polymerase chain reaction (PCR), immunofluorescence staining (IF) and fluorescent in-situ hybridization (FISH). Eligible patients were those previously exposed to C. burnetii.

RESULTS

Samples were available for 13 cases and 16 controls. C. burnetii was demonstrated in tissues of 8/29 patients in total (28%), with either PCR, IF or FISH: in 5/13 cases (38%) and 3/16 controls (19%), p = 0.41. Negative and positive control samples were all negative and positive appropriately for all three diagnostic methods.

CONCLUSIONS

In patients previously exposed to C. burnetii the bacterium was detected in tissue samples from subjects with and without B-NHL, without significant differences in the proportion positive samples. Therefore, we conclude that detection of C. burnetii in tissues of patients previously exposed to C. burnetii is a non-specific finding.

Trends in Q fever serologic testing by immunofluorescence from four large reference laboratories in the United States, 2012-2016

Laboratory testing for Q fever (Coxiella burnetii) is essential for a differential diagnosis, yet little is known about Q fever diagnostic testing practices in the United States. We retrospectively analyzed Q fever immunoglobulin G (IgG) indirect immunofluorescence assay (IFA) testing data between 1/1/2012–10/31/2016 from ARUP, LabCorp, Mayo Medical Laboratories, and Quest Diagnostics. Data included IgG phase I and phase II titers, patient age and sex, and state and date of specimen collection. On average, 12,821 specimens were tested for Q fever annually by the participating laboratories. Of 64,106 total specimens, 84.1% tested negative for C. burnetii-specific antibodies. Positive titers ranged from 16 to 262,144 against both phase I and phase II antigens. Submission of specimens peaked during the summer months, and more specimens were submitted from the West North Central division. Testing occurred more frequently in males (53%) and increased with age. In conclusion, few U.S. Q fever cases are reported, despite large volumes of diagnostic specimens tested. Review of commercial laboratory data revealed a lack of paired serology samples and patterns of serology titers that differ from case reporting diagnostic criteria.