Q-fever endocarditis in England and Wales, 1975-81

Inpatient Q Fever Frequency Is on the Rise

Background

Q fever is a zoonotic bacterial infection caused by Coxiella burnetii that is reportable in the USA. This infection is often asymptomatic; acute infection usually manifests as a self-limited febrile illness, hepatitis, or pneumonia. Chronic infection (usually infective endocarditis) often affects patients with valvulopathy or immunosuppression. Herein, we study the inpatient frequency of Q fever in the United States.

Methods

We used a nationwide inpatient sample (NIS) for our retrospective cohort study to include hospitalizations with a diagnosis of Q fever between 2010 and 2019. Survey procedures were applied to accommodate for complex sampling design of NIS. Chi-square and least-square means were used for categorical and continuous variables, respectively. Jonckheere-Terpstra test was used to study the trends over the years. SAS 9.4 was used for data mining and analysis.

Results

A total of 2,685 hospitalizations with a diagnosis of Q fever were included, among which 451 (17%) cases had a concurrent diagnosis of infective endocarditis. The mean age of patients was 58 years, and less than a third was female. Our analysis demonstrated that infective endocarditis was the most common cardiac complication associated with Q fever and was associated with increased inpatient mortality (p value <0.001). There is a trend of an increase in cases of inpatient Q fever with or without endocarditis over the years (p value <0.05). Q fever cases were more common across the Pacific and the South Atlantic divisions.

Conclusion

Physicians should be aware of an increasing trend of hospitalized patients with Q fever and the significant association with infective endocarditis. Further studies are needed.

Evaluation of Alternative Doxycycline Antibiotic Regimes in an Inhalational Murine Model of Q Fever

The timing of the initiation of antibiotic treatment has been shown to impact the clinical outcome of many bacterial infections, including Q fever. Delayed, suboptimal or incorrect antibiotic treatment has been shown to result in poor prognosis, resulting in the progression of acute disease to long-term chronic sequalae. Therefore, there is a requirement to identify an optimal, effective therapeutic regimen to treat acute Q fever. In the study, the efficacies of different doxycycline monohydrate regimens (pre-exposure prophylaxis, post-exposure prophylaxis or treatment at symptom onset or resolution) were evaluated in an inhalational murine model of Q fever. Different treatment lengths (7 or 14 days) were also evaluated. Clinical signs and weight loss were monitored during infection and mice were euthanized at different time points to characterize bacterial colonization in the lungs and the dissemination of bacteria to other tissues including the spleen, brain, testes, bone marrow and adipose. Post-exposure prophylaxis or doxycycline treatment starting at symptoms onset reduced clinical signs, and also delayed the systemic clearance of viable bacteria from key tissues. Effective clearance was dependent on the development of an adaptive immune response, but also driven by sufficient bacterial activity to maintain an active immune response. Pre-exposure prophylaxis or post-exposure treatment at the resolution of clinical signs did not improve outcomes. These are the first studies to experimentally evaluate different doxycycline treatment regimens for Q fever and illustrate the need to explore the efficacy of other novel antibiotics.

Immunisation with purified Coxiella burnetii phase I lipopolysaccharide confers partial protection in mice independently of co-administered adenovirus vectored vaccines

Q fever is a highly infectious zoonosis caused by the Gram-negative bacterium Coxiella burnetii. The worldwide distribution of Q fever suggests a need for vaccines that are more efficacious, affordable, and does not induce severe adverse reactions in vaccine recipients with pre-existing immunity against Q fever. Potential Q fever vaccine antigens include lipopolysaccharide (LPS) and several C. burnetii surface proteins. Antibodies elicited by purified C. burnetii lipopolysaccharide (LPS) correlate with protection against Q fever, while antigens encoded by adenoviral vectored vaccines can induce cellular immune responses which aid clearing of intracellular pathogens. In the present study, the immunogenicity and the protection induced by adenoviral vectored constructs formulated with the addition of LPS were assessed. Multiple vaccine constructs encoding single or fusion antigens from C. burnetii were synthesised. The adenoviral vectored vaccine constructs alone elicited strong cellular immunity, but this response was not correlative with protection in mice. However, vaccination with LPS was significantly associated with lower weight loss post-bacterial challenge independent of co-administration with adenoviral vaccine constructs, supporting further vaccine development based on LPS.

A Narrative Review of Q Fever in Europe

Coxiella burnetii, the causative agent of Q fever, causes abortions in animals. Its effects on humans and the management of Q fever in certain conditions like pregnancy are undetermined. The World Health Organization has estimated that zoonotic diseases cause around one billion cases of infections and millions of deaths globally each year. It is worth noting that many emerging infectious diseases currently being reported worldwide are zoonoses. We reviewed studies reporting on Q fever prevalence and incidence in Europe. Articles from 1937 to 2023 with the following terms "Coxiella burnetii and Europe and Q fever, and seroprevalence studies" were identified in the PubMed database and reports by organizations such as the European Centre for Disease Prevention and Control (ECDC). We included randomized and observational studies, seroprevalence studies, case series, and case reports. According to the ECDC in 2019, 23 countries reported 1069 cases, the majority of which were classified as confirmed cases. The number of reports per 100,000 inhabitants in the EU/EEA was 0.2 for 2019, the same as the previous four years. The highest report rate (0.7 cases per 100,000 population) was observed in Spain, followed by Romania (0.6), Bulgaria (0.5), and Hungary. Considering the typically asymptomatic nature of Q fever infection, it is imperative to strengthen the existing systems to promote the rapid identification and reporting of Q fever outbreaks in animals, particularly in cases of abortion. It is also essential to consider the facilitation of early information exchange between veterinarians and public health counterparts to ensure the timely detection and prevention of potential zoonotic events, including Q fever.

Acute Q Fever Endocarditis: A Paradigm Shift Following the Systematic Use of Transthoracic Echocardiography During Acute Q Fever

BACKGROUND

As Q fever, caused by Coxiella burnetii, is a major health challenge due to its cardiovascular complications, we aimed to detect acute Q fever valvular injury to improve therapeutic management.

METHODS

In the French national reference center for Q fever, we prospectively collected data from patients with acute Q fever and valvular injury. We identified a new clinical entity, acute Q fever endocarditis, defined as valvular lesion potentially caused by C. burnetii: vegetation, valvular nodular thickening, rupture of chorda tendinae, and valve or chorda tendinae thickness. To determine whether or not the disease was superimposed on an underlying valvulopathy, patients' physicians were contacted. Aortic bicuspidy, valvular stenosis, and insufficiency were considered as underlying valvulopathies.

RESULTS

Of the 2434 patients treated in our center, 1797 had acute Q fever and 48 had acute Q fever endocarditis. In 35 cases (72%), transthoracic echocardiography (TTE) identified a valvular lesion of acute Q fever endocarditis without underlying valvulopathy. Positive anticardiolipin antibodies (>22 immunoglobulin G-type phospholipid units [GPLU]) were independently associated with acute Q fever endocarditis (odds ratio [OR], 2.7 [95% confidence interval {CI}, 1.3-5.5]; P = .004). Acute Q fever endocarditis (OR, 5.2 [95% CI, 2.6-10.5]; P < .001) and age (OR, 1.7 [95% CI, 1.1-1.9]; P = .02) were independent predictors of progression toward persistent C. burnetii endocarditis.

CONCLUSIONS

Systematic TTE in acute Q fever patients offers a unique opportunity for early diagnosis of acute Q fever endocarditis and for the prevention of persistent endocarditis. Transesophageal echocardiography should be proposed in men, aged >40 years, with anticardiolipin antibodies >60 GPLU when TTE is inconclusive or negative.

Surveillance for Q Fever Endocarditis in the United States, 1999-2015

Background

Q fever is a worldwide zoonosis caused by Coxiella burnetii. In some persons, particularly those with cardiac valve disease, infection with C. burnetii can cause a life-threatening infective endocarditis. There are few descriptive analyses of Q fever endocarditis in the United States.

Methods

Q fever case report forms submitted during 1999-2015 were reviewed to identify reports describing endocarditis. Cases were categorized as confirmed or probable using criteria defined by the Council for State and Territorial Epidemiologists (CSTE). Demographic, laboratory, and clinical data were analyzed.

Results

Of 140 case report forms reporting endocarditis, 49 met the confirmed definition and 36 met the probable definition. Eighty-two percent were male and the median age was 57 years (range, 16-87 years). Sixty-seven patients (78.8%) were hospitalized, and 5 deaths (5.9%) were reported. Forty-five patients (52.9%) had a preexisting valvulopathy. Eight patients with endocarditis had phase I immunoglobulin G antibody titers >800 but did not meet the CSTE case definition for Q fever endocarditis.

Conclusions

These data summarize a limited set of clinical and epidemiological features of Q fever endocarditis collected through passive surveillance in the United States. Some cases of apparent Q fever endocarditis could not be classified by CSTE laboratory criteria, suggesting that comparison of phase I and phase II titers could be reexamined as a surveillance criterion. Prospective analyses of culture-negative endocarditis are needed to better assess the clinical spectrum and magnitude of Q fever endocarditis in the United States.

Q Fever and Experimental Sheep

In August 1983 a Symposium was held in Vancouver to discuss Q fever as a hazard to humans in contact with infected sheep. On the basis of new preliminary information presented and discussion at the Symposium, an attempt has been made in this document to supplement published guidelines for the conduct of sheep research.

Strategies for early detection of chronic Q-fever: a systematic review

BACKGROUND

Chronic Q-fever, a condition with high morbidity and mortality, may develop after an acute infection with Coxiella burnetii (acute Q-fever). Several strategies have been suggested for early detection of chronic Q-fever, focusing on follow-up of known acute Q-fever patients and detection of asymptomatic or unknown chronic infections. As there is no international standard or consensus, the aims of this study were to summarise the available literature and assess the evidence for different follow-up and screening strategies.

DESIGN

We conducted a systematic review by searching PubMed and Embase. Twenty articles were included, of which fourteen only provided information on follow-up of known acute Q-fever cases, four presented data on identification of previously unknown C. burnetii infections, and two had information on both topics.

RESULTS

The conversion rate of acute to chronic Q-fever ranged from 0 to 5.0%. Most studies advised serological follow-up of acute Q-fever patients, but without consistent advice on optimum timing and duration. The recommendation to use echocardiography for all acute Q-fever patients to detect valvular damage remains controversial. Screening of high-risk patients in an outbreak setting is advised by studies investigating such strategy.

CONCLUSIONS

There is sufficient evidence to support serological follow-up of all known acute Q-fever patients at least once during the first year following the acute infection, and more frequently in patients with known risk factors for chronic disease, such as heart valve- or vascular prosthesis. Screening of risk groups should be considered in outbreaks of Q-fever.

Q Fever: an old but still a poorly understood disease

Q fever is a bacterial infection affecting mainly the lungs, liver, and heart. It is found around the world and is caused by the bacteria Coxiella burnetii. The bacteria affects sheep, goats, cattle, dogs, cats, birds, rodents, and ticks. Infected animals shed this bacteria in birth products, feces, milk, and urine. Humans usually get Q fever by breathing in contaminated droplets released by infected animals and drinking raw milk. People at highest risk for this infection are farmers, laboratory workers, sheep and dairy workers, and veterinarians. Chronic Q fever develops in people who have been infected for more than 6 months. It usually takes about 20 days after exposure to the bacteria for symptoms to occur. Most cases are mild, yet some severe cases have been reported. Symptoms of acute Q fever may include: chest pain with breathing, cough, fever, headache, jaundice, muscle pains, and shortness of breath. Symptoms of chronic Q fever may include chills, fatigue, night sweats, prolonged fever, and shortness of breath. Q fever is diagnosed with a blood antibody test. The main treatment for the disease is with antibiotics. For acute Q fever, doxycycline is recommended. For chronic Q fever, a combination of doxycycline and hydroxychloroquine is often used long term. Complications are cirrhosis, hepatitis, encephalitis, endocarditis, pericarditis, myocarditis, interstitial pulmonary fibrosis, meningitis, and pneumonia. People at risk should always: carefully dispose of animal products that may be infected, disinfect any contaminated areas, and thoroughly wash their hands. Pasteurizing milk can also help prevent Q fever.

Guidelines for the diagnosis and antibiotic treatment of endocarditis in adults: a report of the Working Party of the British Society for Antimicrobial Chemotherapy

The BSAC guidelines on treatment of infectious endocarditis (IE) were last published in 2004. The guidelines presented here have been updated and extended to reflect developments in diagnostics, new trial data and the availability of new antibiotics. The aim of these guidelines, which cover both native valve and prosthetic valve endocarditis, is to standardize the initial investigation and treatment of IE. An extensive review of the literature using a number of different search criteria has been carried out and cited publications used to support any changes we have made to the existing guidelines. Publications referring to in vitro or animal models have only been cited if appropriate clinical data are not available. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking and therefore a consensus approach has again been adopted for most recommendations; however, we have attempted to grade the evidence, where possible. The guidelines have also been extended by the inclusion of sections on clinical diagnosis, echocardiography and surgery.

Long-term outcome of Q fever endocarditis: a 26-year personal survey

BACKGROUND

Q fever endocarditis caused by Coxiella burnetii is a potentially fatal disease characterised by a chronic evolution. To assess the long-term outcome and identify prognostic factors for mortality, surgical treatment, and serological changes in Q fever endocarditis, we did a retrospective study in the French National Referral Centre.

METHODS

Patients included were diagnosed with Q fever endocarditis at our centre from May, 1983, to June, 2006, and followed up for a minimum of 3 years for each patient, history and clinical characteristics were recorded with a standardised questionnaire. Prognostic factors associated with death, surgery, serological cure, and serological relapse were assessed by Cox regression analysis. Excised heart valve analysis was assessed according to duration of treatment.

FINDINGS

104 patients were identified for inclusion in the study, although one was lost to follow-up; median follow-up was 100 months (range 37-310 months). 18 months of treatment was sufficient to sterilise the valves of all the patients except three, and 2 years of treatment sterilised all valves except one. In a multivariate Cox regression analysis, the major determinants associated with mortality were age (hazard ratio 1.11, 95% CI 1.05-1.18, p=0.003), stroke at diagnosis (7.09, 2.00-25.10, p=0.001), endocarditis on a prosthetic valve (6.04, 1.47-24.80, p=0.044), an absence of a four-times decrease of phase I IgG and IgA at 1 year (5.69, 1.00-32.22, p=0.049), or the presence of phase II IgM at 1 year (12.08, 3.11-46.85, p=0.005). Surgery was associated with heart failure (2.68, 1.21-5.94, p=0.015) or a cardiac abscess (4.71, 1.64-13.50, p=0.004). The determinants of poor serological outcome were male sex (0.47, 0.26-0.86, p=0.014), a high level of phase I IgG (0.65, 0.45-0.95, p=0.027), and a delay in the start of treatment with hydroxychloroquine (0.20, 0.04-0.91, p=0.037). Factors associated with relapse were endocarditis on a prosthetic valve (21.3, 2.05-221.86, p=0.01) or treatment duration less than 18 months (9.69, 1.08-86.72, p=0.042).

INTERPRETATION

The optimum duration of treatment with doxycycline and hydroxychloroquine in Q fever endocarditis is 18 months for native valves and 24 months for prosthetic valves. This duration should be extended only in the absence of favourable serological outcomes. Patients should be serologically monitored for at least 5 years because of the risk of relapse.

FUNDING

French National Referral Centre for Q Fever.

Q fever endocarditis: a case report and review of the literature

The case of a 31-year-old man from Alberta diagnosed with Q fever endocarditis is presented. To the authors' knowledge, this is the first case of Q fever endocarditis diagnosed in the province of Alberta. The patient had undergone open valvulotomy for congenital aortic stenosis as an infant. He presented with congestive heart failure secondary to severe aortic regurgitation and underwent mechanical aortic valve replacement. Early failure of the mechanical prosthesis and numerous laboratory abnormalities prompted an investigation for endocarditis, which was initially negative. Markedly positive serology eventually established the diagnosis of chronic Q fever. The patient subsequently underwent a second aortic valve replacement following initiation of appropriate antimicrobials directed against Coxiella burnetii. The present report reviews the clinical presentation and diagnosis of Q fever endocarditis. It highlights the insidious and nonspecific nature of the presenting symptoms, and emphasizes the use of serology for diagnosis. Increased awareness and earlier diagnosis can significantly decrease the morbidity and mortality associated with this disease.

Chronic Q fever in the United States

Infections due to Coxiella burnetii, the causative agent of Q fever, are uncommon in the United States. Cases of chronic Q fever are extremely rare and most often manifest as culture-negative endocarditis in patients with underlying valvular heart disease. We describe a 31-year-old farmer from West Virginia with a history of congenital heart disease and recurrent fevers for 14 months who was diagnosed with Q fever endocarditis based on an extremely high antibody titer against Coxiella burnetii phase I antigen. Despite treatment with doxycycline, he continued to have markedly elevated Coxiella burnetii phase I antibody titers for 10 years after the initial diagnosis. To our knowledge, this case represents the longest follow-up period for a patient with chronic Q fever in the United States. We review all cases of chronic Q fever reported in the United States and discuss important issues pertaining to epidemiology, diagnosis, and management of this disease.

The value of follow-up after acute Q fever infection

This is a case report of a 53-year-old woman involved in an outbreak of Q fever, in whom Q fever endocarditis was diagnosed 18 months after acute Q fever infection. At the time of diagnosis, she was completely asymptomatic and without screening for chronic Q fever, this severe potentially life-threatening infection would probably not have been recognised until significant valvular destruction had taken place. Early diagnosis enabled prompt, potentially curative medical treatment to start without the need for valvular heart surgery. The authors advocate that serological monitoring should be carried out every 4 months for a period of 2 years after acute Q fever and patients with high phase 1 IgG titres (>800) be investigated further and/or followed more closely depending on the clinical scenario. The case report also discusses the use of complement fixation testing in the diagnosis of Q fever endocarditis. The authors recommend that in cases of culture negative endocarditis, a single negative complement fixation test is not sufficient to exclude the diagnosis of Q fever endocarditis. Micro-immunofluorescence or repeat complement fixation testing is recommended when Q fever endocarditis is suspected clinically.

Endocarditis After Acute Q Fever in Patients with Previously Undiagnosed Valvulopathies

We describe 3 cases of endocarditis after acute Q fever in 3 patients with clinically silent, undiagnosed valvulopathies, including mitral valve prolapse, minimal valvular leak, and biscuspid aortic valve. We conclude that, to prevent endocarditis, these minor valvulopathies must be actively searched for with echocardiography after diagnosis of acute Q fever.

Guidelines for the antibiotic treatment of endocarditis in adults: report of the Working Party of the British Society for Antimicrobial Chemotherapy

The BSAC Guidelines on Endocarditis were last published in 1998. The Guidelines presented here have been updated and extended to reflect changes in both the antibiotic resistance characteristics of causative organisms and the availability of new antibiotics. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking, and therefore a consensus approach has again been adopted. The Guidelines cover diagnosis and laboratory testing, suitable antibiotic regimens and causative organisms. Special emphasis is placed on common causes of endocarditis, such as streptococci and staphylococci, however, other bacterial causes (such as enterococci, HACEK organisms, Coxiella and Bartonella) and fungi are considered. The special circumstances of prosthetic endocarditis are discussed.

Q fever endocarditis in the United States

Infections due to Coxiella burnetii, the causative organism of Q fever, are extremely rare in North America. Endocarditis due to the organism has an unusual presentation and poses echocardiographic and laboratory challenges in establishing a diagnosis. We describe the presentation and clinical course of a 40-year-old American man with Q fever endocarditis and briefly discuss the salient issues regarding this entity.

[Prosthetic valve endocarditis due to Coxiella burnetii: six cases]

PURPOSE

Prosthetic valve endocarditis is a dangerous complication of valvular surgery (3-6%). Among involved pathogens, Coxiella burnetii is an occasional agent, though isolated with increasing frequency. We report our experience with this peculiar endocarditis and lay stress on specific diagnostic and therapeutic difficulties.

METHODS

Between 1990 and 1995, six patients retrospectively met the diagnosis criteria for definite endocarditis due to Coxiella burnetii.

RESULTS

Five Algerian men and one French woman presented with prosthetic valve endocarditis with negative blood cultures (on bioprosthesis: four cases, on mechanical valve: two cases). The main clinical and biological feature was febrile congestive heart failure with hepatomegaly, splenomegaly, hepatic and renal abnormalities, inflammatory syndrome, hypergammaglobulinemia, anemia and lymphopenia. Serological testing for Coxiella burnetii provided diagnosis in all cases. Echocardiography displayed vegetations in all cases. Valvular replacement was performed in four patients. With antibiotic therapy including doxycycline or/and hydroxychloroquine, quinolones or rifampicine, all patients experienced complete clinical, biological and echographic remission.

CONCLUSION

Q fever prosthetic valve endocarditis presents as a systemic disorder occurring in patients with valvular heart disease. From now on, early diagnosis and efficient medical treatment may provide permanent prosthetic sterilization.

Risks factors and prevention of Q fever endocarditis

Coxiella burnetii causes acute and chronic Q fever. To evaluate the risk factors of development of chronic endocarditis following Q fever and to assess the best preventive therapy, a retrospective study of patients diagnosed as having Q fever during 1985-2000 was conducted. Twelve patients with acute Q fever who developed endocarditis and 102 patients with Q fever endocarditis were included in the study. When compared to 200 control patients with acute Q fever, preexisting valvular disease (P<10(-7)), especially a prosthetic valve (P=.01), were encountered more often among patients with endocarditis. Among patients with valvular defects, we estimate the risk of developing endocarditis to be 39%. A combination of doxycycline plus hydroxychloroquine was better at preventing the development of endocarditis than doxycycline alone (P=.009). Our results should encourage physicians to detect valvular lesions in patients with acute Q fever and to search for acute Q fever in patients with a valvulopathy and unexplained fever. A proper treatment for such patients and a scheduled follow-up should reduce the risk of developing endocarditis.

Endocarditis due to rare and fastidious bacteria

The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.

Q fever seroprevalence and associated risk factors among students from the Veterinary School of Zaragoza, Spain

Q fever is a zoonosis related to the existence of Coxiella burnetii infected animals. The authors studied the seroprevalence and risk factors associated to C. burnetii infection in veterinary students in Zaragoza (Spain). Sera were collected at the beginning and the end of the academic year (1994-1995) and were tested by Complement fixation test to detect antibodies against C. burnetii. 10.02 and 11.02% seroprevalences were observed at the beginning and the end of the study respectively. The cumulative incidence through the period of study was 0.0157. Risk factors associated to C. burnetii were multiple: students coursing the speciality in Food Inspection and Technology or the speciality of Animal Production; to practise with living animals in general and particularly with ruminants and to contact frequently with persons who worked with animals, particularly with veterinarians, farmers and animal traders. In parallel, the students coursing the first course showed a significant lower seroprevalence. Male students from the fifth course were significantly more seroprevalent than females, where sex was a protection factor. Concerning the clinical signs asked in the questionnaire, cardiovascular disturbances, flu and/or pneumonia, sweating, transient hyperthermia or spondylitis were associated factors. Conversely, a good response after treatment of symptoms was a protection factor. The only risk factor associated with incidence along the year of study was practising in farms. The authors recommend a revision of hygiene measures to control risk factors and the diagnostic of C. burnetii infection when populations at risk show the associated symptoms.

Q fever 1985-1998. Clinical and epidemiologic features of 1,383 infections

In order to describe the clinical features and the epidemiologic findings of 1,383 patients hospitalized in France for acute or chronic Q fever, we conducted a retrospective analysis based on 74,702 sera tested in our diagnostic center, National Reference Center and World Health Organization Collaborative Center for Rickettsial Diseases. The physicians in charge of all patients with evidence of acute Q fever (seroconversion and/or presence of IgM) or chronic Q fever (prolonged disease and/or IgG antibody titer to phase I of Coxiella burnetii > or = 800) were asked to complete a questionnaire, which was computerized. A total of 1,070 cases of acute Q fever was recorded. Males were more frequently diagnosed, and most cases were identified in the spring. Cases were observed more frequently in patients between the ages of 30 and 69 years. We classified patients according to the different clinical forms of acute Q fever, hepatitis (40%), pneumonia and hepatitis (20%), pneumonia (17%), isolated fever (17%), meningoencephalitis (1%), myocarditis (1%), pericarditis (1%), and meningitis (0.7%). We showed for the first time, to our knowledge, that different clinical forms of acute Q fever are associated with significantly different patient status. Hepatitis occurred in younger patients, pneumonia in older and more immunocompromised patients, and isolated fever was more common in female patients. Risk factors were not specifically associated with a clinical form except meningoencephalitis and contact with animals. The prognosis was usually good except for those with myocarditis or meningoencephalitis as 13 patients died who were significantly older than others. For chronic Q fever, antibody titers to C. burnetii phase I above 800 and IgA above 50 were predictive in 94% of cases. Among 313 patients with chronic Q fever, 259 had endocarditis, mainly patients with previous valvulopathy; 25 had an infection of vascular aneurysm or prosthesis. Patients with endocarditis or vascular infection were more frequently immunocompromised and older than those with acute Q fever. Fifteen women were infected during pregnancy; they were significantly more exposed to animals and gave birth to only 5 babies, only 2 with a normal birth weight. More rare manifestations observed were chronic hepatitis (8 cases), osteoarticular infection (7 cases), and chronic pericarditis (3 cases). Nineteen patients were observed who experienced first a documented acute infection, then, due to underlying conditions, a chronic infection. To our knowledge, we report the largest series of Q fever to date. Our results indicate that Q fever is a protean disease, grossly underestimated, with some of the clinical manifestations being only recently reported, such as Q fever during pregnancy, chronic vascular infection, osteomyelitis, pericarditis, and myocarditis. Our data confirm that chronic Q fever is mainly determined by host factors and demonstrate for the first time that host factors may also play a role in the clinical expression of acute Q fever.

Prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk in England and Wales

In the United Kingdom, the infection of people with Coxiella burnetii, the causative agent of Q fever, is of significant public health importance and is associated with contact with dairy cattle. An ELISA was developed for the detection of IgG antibodies against C burnetii in bulk tank milk, and in a survey of randomly selected samples from dairy herds in England and Wales, 21 per cent showed serological evidence of C burnetii infection.

Infective endocarditis due to unusual or fastidious microorganisms

Infective endocarditis due to fastidious microorganisms is commonly encountered in clinical practice. Some organisms such as fungi account for up to 15% of cases of prosthetic valve infective endocarditis, whereas organisms of the HACEK group (Haemophilus parainfluenzae, H. aphrophilus, and H. paraphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) cause 3% of community-acquired cases of infective endocarditis. Special techniques are necessary to identify these microorganisms. A history of contact with mammals or birds may suggest infection caused by Coxiella burnetii (Q fever), Brucella species, or Chlamydia psittaci. A nosocomial cluster of postsurgical infective endocarditis may be caused by Legionella species or Mycobacterium species. If risk factors that are commonly associated with fungal infections (cardiac surgical treatment, prolonged hospitalization, indwelling central venous catheters, and long-term antibiotic use) are present, fungal endocarditis is possible. Patients with endocarditis and a history of periodontal disease or dental work in whom routine blood cultures are negative might have infection due to nutritionally variant streptococci or bacteria of the HACEK group. Communication between the microbiologist and the clinician is of crucial importance for identification of these microorganisms early during the course of the infection before complications such as embolization or valvular failure occur. In this article, we review the microbiologic and clinical features of these organisms and provide recommendations for diagnosis and treatment.

Q fever endocarditis in Israel and a worldwide review

The worldwide epidemiology and population-based incidence of Q fever endocarditis (QFE) have been less well studied than those for uncomplicated Q fever. An exhaustive literature review revealed 408 patients with QFE reported between 1949 and 1994, mostly from 3 large geographic areas. Underlying valvular heart disease was almost invariably present, and 38% had prosthetic valves. The most common clinical manifestations were fever and congestive heart failure. The mortality rate dropped over the years from 65% to 25%, but a meta-analysis of published data showed the death rate to be significantly lower among patients receiving combination therapy (12/65, 18%), as compared to patients treated with tetracycline alone (18/41, 44%, p = 0.005). A 10-year (1983-1992) retrospective nationwide survey of QFE in Israel revealed 35 patients with QFE, representing an annual incidence of 0.75 cases per 1 million population. Underlying heart disease, clinical manifestations and outcome in the Israeli group were not substantially different from those described in the world literature. The current state-of-the-art clinical approach includes early diagnosis, prompt initiation of combination therapy for at least 3 years, and long-term clinical and serologic follow-up. Adherence to these rules might have contributed to the improved prognosis in recent years.

The risk of acquiring Q fever on farms: a seroepidemiological study

OBJECTIVES

To determine the occupational risk of Q fever.

DESIGN

Cohort study.

SETTING

Community: five English local authority districts.

SUBJECTS AND METHODS

Prevalence and incidence of immunoglobulin G (IgG) specific antibody to Coxiella burnetii phase II antigen was measured in a representative (study) cohort of farm workers in the United Kingdom, and detailed exposure data were collected. Also seroprevalence of Q fever in a (control) cohort of police and emergency service personnel was measured.

RESULTS

Prevalence was significantly (P < 0.01) higher in the study cohort (105/385 v 43/395). During the first 12 month period after enrollment no seroconversions were found (upper 95% confidence limit: 1318/100,000/year). During the second 12 month period after enrollment two seroconversions were found, equalling an incidence of 813/100,000/year (95% confidence interval (95% CI) 98-2937/100,000/year). No association was found between seroprevalence and age. In the study cohort, extent of total contact with farm animals seemed more important than exposure to any specific animal: full time employees were more than four times more likely to be antibody positive than part time employees (P < 0.05). Exposure to cattle, but not sheep, goats, cats, raw milk, and hay (all reported sources of Q fever) was associated with being positive to Coxiella burnetii IgG by univariate analysis but this association was not independent of total farm animal contact.

CONCLUSIONS

The risk of Q fever on livestock farms is related to contact with the farm environment rather than any specific animal exposure. The absence of an increasing prevalence with age suggests that exposure may occur as clusters in space and time (outbreaks).

Infective endocarditis

IE is a fascinating disease that continues to challenge the clinicians. Over the last several decades, there have been marked changes in its presentation. The morbidity and mortality have markedly improved by early diagnosis and prompt treatment using highly effective antibiotic regimens and early valve replacement surgery whenever necessary. Early diagnosis is possible by improvement in blood culture techniques and advances in transthoracic and transesophageal echocardiographic approaches. This article has reviewed the pathogenesis, microbiology, clinical presentation, diagnostic methodology, treatment, and prevention of IE.

Isolation of Coxiella burnetii from heart valves of patients treated for Q fever endocarditis

Coxiella burnetii was isolated from the valve material of two patients who underwent valvectomy because of progressive congestive heart failure due to endocarditis. In each case antibiotic therapy was administered for several months prior to valvectomy. Classical histopathological examination of the valves did not reveal an etiology. However, coxiella-like organisms were demonstrated in valvular material with Köster, Stamp, and Giemsa stains, and the organisms were grown in cell culture. Antibody titers were consistent with the diagnosis of chronic C. burnetii infection. This report illustrates the advantage of simple and fast staining techniques and cell culture for the demonstration and isolation of C. burnetii in the heart valve tissue of patients with Q fever endocarditis.

Coxiella burnetii infection of pseudoaneurysm of an aortic bypass graft with contiguous vertebral osteomyelitis

We report the case of a 67-year-old man who had an infection of a pseudoaneurysm of an aortic graft with contiguous vertebral osteomyelitis. The infectious organism was identified as Coxiella burnetii, a strict intracellular pathogen causing Q fever infection in humans. The patient was treated successfully with removal of the infected material in conjunction with extraanatomic bypass and specific antibiotic therapy. He is doing well after more than 3 years, with no evidence of recurrent periaortic infection on successive computed tomographic scans. We suspect that C. burnetii vascular graft infections could be underdiagnosed, because this cause is not frequently evoked. We suggest that extending the etiologic search to C. burnetii could decrease the number of undocumented vascular graft infections.

A large Q fever outbreak in the West Midlands: clinical aspects

In the spring of 1989 the largest outbreak of acute Q fever recorded in the United Kingdom occurred in Solihull and surrounding areas of the West Midlands. The diagnosis was confirmed in 147 people, mainly males of working age. Windborne spread from farmland to the south of the urban area was the most likely route of infection. Fever was the commonest symptom, seen in 101/102 (99%) cases, followed by weight loss reported by 83/101 (82%). Headache, often severe, was experienced by 69/101 (68%). The commonest respiratory symptom was breathlessness, 65/102 (64%), followed by cough, 52/102 (51%), and chest pain, 46/102 (45%). Neurological features, seen in 23% of cases, were more prominent in this outbreak than is commonly recognized. Persisting ill health 6 months following the acute episode not due to chronic Q fever was also a prominent feature of this largely urban outbreak.

[Coxiella burnetii endocarditis on a bioprosthetic valve: review of the literature apropos of a case]

A 51-year-old woman, originating from Algeria, developed Q fever endocarditis on porcine bioprosthetic mitral valve. She had chronic course with nonspecific symptoms, such as dyspnea and fever, hepatosplenomegaly, and developed progressive cardiac failure. Worsening of hemodynamic state led to prosthetic valve replacement. Hemocultures were all negative, and the diagnosis of Q fever was unexpectedly performed by systematic screening for specific serum antibody to Coxiella burnetti. High phase I and II specific IgG and IgA antibody titers against C burnetii were found. The patient was treated by doxycycline and ofloxacin, and improved rapidly. Prosthetic valve constitutes likely predisposing factor for the development of chronic Q fever endocarditis. This observation emphasizes the need to search for Q fever in prosthetic valve dysfunction, in particular when hemocultures are negative.

Coxiella burneti endocarditis in a patient with positive chlamydial serology

A 41-year-old man who habitually slept in a car park presented with a culture-negative endocarditis. Serological tests indicated infection with both Coxiella burneti and Chlamydia psittaci. He was treated with doxycycline and clindamycin and required aortic valve replacement. Culture of the excised value for both agents was negative but electron microscopy was suggestive of coxiella endocarditis.

Pathogenesis of rickettsial infections emphasis on Q fever

The underlying mechanisms at the organismic, cellular and molecular levels that account for rickettsial pathogenesis are beginning to be revealed. In the case of Coxiella burnetii infection, relatively recent genetic and biochemical data, as well as drug susceptibility studies, indicate a correlation between isolate type and clinical disease--chronic or short-term acute. The use of cultured cells as model host systems has revealed that, indeed, different isolates from the major classified strains of C. burnetii cause different host cell responses. Use of this and other models (guinea pigs, mice) have revealed other characteristics and properties of the rickettsiae and the infected hosts and host cells that may account, in part, for acute disease and persistent infection culminating in chronic disease. The virulence factors involved apparently include the agent's surface lipopolysaccharide; other unidentified factors have not been excluded. Molecular cloning will play a major role in elucidating the roles of these factors and in identifying other virulence determinants.

Q fever in Plymouth, 1972-88. A review with particular reference to neurological manifestations

Between 1972 and 1988 we have serologically confirmed 103 Coxiella burnetii infections: 46 were acute, 5 were chronic, 52 represented past infections. Details of 61 cases are presented. Of acute cases 80% had respiratory involvement; at least 63% had pneumonias. The incidence (22%) of neurological complications was of particular interest; 40% of these patients had prolonged sequelae. One acutely ill patient died of fulminating hepatitis. Patients with pre-existing pathology or immunosuppression were especially susceptible to C. burnetii. In the absence of acute sera, the complement fixation test alone provided inadequate differentiation between recent and past Q fever: phase II titres persisted at greater than or equal to 80 for more than 1 year after the acute infection in 15 cases; maximum duration of persistence was 14 years. Three patients acquired high phase I titres. Only 5% of cases had chronic Q fever, but in view of the diverse sequelae observed in this series, we suggest that long-term serological and clinical follow-up of all cases of Q fever is fully justified.

A comparison of Q fever endocarditis with native valve endocarditis

We compared 10 episodes (8 patients) of Q fever endocarditis with 27 episodes (27 patients) of native valve endocarditis. Patients with Q fever endocarditis were more likely to have weight loss (p less than 0.003), experience fatigue (p less than 0.07), have clubbing of the fingers (p less than 0.005), have a diastolic murmur at the time of admission (p less than 0.03), be anemic (p less than 0.05), have a normal white blood cell count (p less than 0.005), and have a higher serum globulin concentration (p less than 0.007). While valve replacement was required for 50% of the episodes in both groups of patients, it was required later--mean 107 days following the onset of treatment--for the Q fever patients than for the native valve patients--mean 27 days. The mortality rates for these two diseases were not significantly different (30% for native endocarditis vs. 12.5% for Q fever endocarditis), but the Q fever patients experienced significantly fewer complications.

Chronic Q fever with mixed cryoglobulinaemia

A 47 year old woman presented with a six month history of vasculitic rash, splenomegaly, and cardiac murmurs. Investigations showed the presence of mixed cryoglobulinaemia and raised titres to Coxiella burnetii consistent with chronic Q fever infection. The patient was treated with tetracycline (1 g four times a day).

Enzyme-linked immunosorbent assay for diagnosis of chronic Q fever

From 1982 through 1987 we diagnosed 13 chronic Q fever cases. Clinically these patients presented a culture-negative endocarditis, and all but two had high complement-fixing antibody titers to Coxiella burnetii phase I (reciprocal titer above 200). With the enzyme-linked immunosorbent assay (ELISA), titers of immunoglobulin G (IgG) to phases I and II of C. burnetii averaged 158,000 and 69,900, respectively, whereas they reached 300 and 3,200 in acute Q fever cases. Similarly, IgA to both phases of C. burnetii and IgM to phase I were consistently higher during chronic than acute Q fever. The serological follow-up of one patient with chronic Q fever over a 4-year period showed a good correlation between the titers of IgG and IgM antibody titers detected by ELISA and indirect fluorescent-antibody test (IFA) to both phases of C. burnetii. Few discrepancies appeared with IgA. Shortly after initiation of antibiotic treatment, a slow and steady decrease of the antibody titers to C. burnetii phases I and II was observed. The complement fixation, IFA, and ELISA tests showed the same type of antibody response. The ELISA proved to be an excellent diagnostic test for chronic Q fever. It distinguished negative from positive reactions clearly, and results were highly reproducible. The reading is objective, and the test is simple to perform and more sensitive than the IFA and complement fixation tests. The ELISA is recommended for serologic evaluation of patients with chronic Q fever.