Role of sex, age, previous valve lesion, and pregnancy in the clinical expression and outcome of Q fever after a large outbreak

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.

First report of an outbreak of "Q" fever IN an abattoir from Argentina

In late October 2021, one of the veterinarians and the occupational physician of a bovine and swine abattoir from Entre Ríos Province, Argentina were alerted about workers with atypical pneumonia symptoms, raising suspicious of a possible Q fever outbreak. An outbreak epidemiological investigation was carried out. Analysis was based on the description of the study population, according to gender, age, symptoms, and position within the abattoir, as well as on outbreak epidemic curve and its probable origin. Cases of Q fever in the workers were confirmed by serology. Measurements of the association between the evaluated variables and the risk of exposure were investigated and calculated as attack rates. The outbreak occurred between October and November 2021, symptomatically affecting 11 workers, out of a total exposed population of 49 individuals. The index case was a 33-year-old male who started with symptoms on 27 October 2021, and the outbreak extended for at least 17 days. Workers in the clean zone of the slaughter floor had a 4.68 times higher risk of contracting Q fever than people located in other areas. Importantly, two pregnant cows were slaughtered a few days before the outbreak began, which could have been the origin of the outbreak. The present study demonstrates the urgent need to consider Q fever when diagnosing abortive diseases of ruminants in Argentina, as well as in zoonotic disease epidemiological surveillance to inform all actors of the health system.

Distribution and Prevalence of Coxiella burnetii in Animals, Humans, and Ticks in Nigeria: A Systematic Review

'Query' (Q) fever is a neglected but emerging or re-emerging zoonotic disease caused by the bacterium Coxiella (C.) burnetii. Several host species are considered or speculated to be the primary reservoir hosts for human infection. In the past, several research groups in Nigeria have evaluated the prevalence of C. burnetii in various vertebrate and invertebrate hosts. Currently, there is a paucity of knowledge regarding the epidemiology of the pathogen in Nigeria with limited or no attention to control and prevention programs. Therefore, this review was undertaken to comprehend the current situation of C. burnetii infection in human, domestic and peri-domestic animals, and some tick species in Nigeria since 1960 with the aim to help identify future research priorities for the country. A comprehensive literature search was performed using the PRISMA guidelines on five scientific databases including Google Scholar, PubMed, AJOL, Science Direct, and Scopus for articles published from Nigeria dealing with the screening of blood, milk, or tick DNA for evidence of C. burnetii using any standard diagnostic approach. Of the 33 published articles subjected to full-text evaluation, more than 48% of the articles met the inclusion criteria and were thus included in this review. We observed different ranges of prevalence for C. burnetii antibodies from four vertebrate hosts including cattle (2.5-23.5%), sheep (3.8-12.0%), goats (3.1-10.9%), and humans (12.0-61.3%). Additionally, the use of molecular diagnostics revealed that the DNA of C. burnetii has been amplified in eight tick species including Hyalomma (Hy) dromedarii, Hy. truncatum, Hy. impeltatum, Hy. rufipes, Hy. impressum, Amblyomma (Am.) variegatum, Rhipicephalus (Rh.) evertsi evertsi, and Rh. annulatus. Two rodent's species (Rattus rattus and Rattus norvegicus) in Nigeria were documented to show evidence of the bacterium with the detection of the DNA of C. burnetii in these two mammals. In conclusion, this review has provided more insight on the prevalence of C. burnetii and its associated host/vector in Nigeria. Domestic animals, peri-domestic animals, and ticks species harbor C. burnetii and could be a source of human infections. Due to the paucity of studies from southern Nigeria, we recommend that research groups with interest on vector-borne diseases need to consider more epidemiological studies in the future on C. burnetii prevalence in diverse hosts to help unravel their distribution and vector potentials in Nigeria as a whole.

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.

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.

Sex and Gender Differences in Bacterial Infections

There is a growing awareness of the importance of sex and gender in medicine and research. Women typically have stronger immune responses to self and foreign antigens than men, resulting in sex-based differences in autoimmunity and infectious diseases. In both animals and humans, males are generally more susceptible than females to bacterial infections. At the same time, gender differences in health-seeking behavior, quality of health care, and adherence to treatment recommendations have been reported. This review explores our current understanding of differences between males and females in bacterial diseases. We describe how genetic, immunological, hormonal, and anatomical factors interact to influence sex-based differences in pathophysiology, epidemiology, clinical presentation, disease severity, and prognosis, and how gender roles affect the behavior of patients and providers in the health care system.

Sero-epidemiological survey of Coxiella burnetii in livestock and humans in Tana River and Garissa counties in Kenya

Background

Coxiella burnetii is a widely distributed pathogen, but data on its epidemiology in livestock, and human populations remain scanty, especially in developing countries such as Kenya. We used the One Health approach to estimate the seroprevalance of C. burnetii in cattle, sheep, goats and human populations in Tana River county, and in humans in Garissa county, Kenya. We also identified potential determinants of exposure among these hosts.

Methods

Data were collected through a cross-sectional study. Serum samples were taken from 2,727 animals (466 cattle, 1,333 goats, and 928 sheep) and 974 humans and screened for Phase I/II IgG antibodies against C. burnetii using enzyme-linked immunosorbent assay (ELISA). Data on potential factors associated with animal and human exposure were collected using a structured questionnaire. Multivariable analyses were performed with households as a random effect to adjust for the within-household correlation of C. burnetii exposure among animals and humans, respectively.

Results

The overall apparent seroprevalence estimates of C. burnetii in livestock and humans were 12.80% (95% confidence interval [CI]: 11.57–14.11) and 24.44% (95% CI: 21.77–27.26), respectively. In livestock, the seroprevalence differed significantly by species (p < 0.01). The highest seroprevalence estimates were observed in goats (15.22%, 95% CI: 13.34-17.27) and sheep (14.22%, 95% CI: 12.04–16.64) while cattle (3.00%, 95% CI: 1.65–4.99) had the lowest seroprevalence. Herd-level seropositivity of C. burnetii in livestock was not positively associated with human exposure. Multivariable results showed that female animals had higher odds of seropositivity for C. burnetii than males, while for animal age groups, adult animals had higher odds of seropositivity than calves, kids or lambs. For livestock species, both sheep and goats had significantly higher odds of seropositivity than cattle. In human populations, men had a significantly higher odds of testing positive for C. burnetii than women.

Conclusions

This study provides evidence of livestock and human exposure to C. burnetii which could have serious economic implications on livestock production and impact on human health. These results also highlight the need to establish active surveillance in the study area to reduce the disease burden associated with this pathogen.

Q fever caused by Coxiella burnetii is a significant zoonotic disease that affects wildlife, domestic animals and humans. This study determined the prevalence of antibodies to C. burnetii in livestock (cattle, sheep, and goats) and human populations in arid and semi-arid areas of Kenya between December 2013 and February 2014. We also identified potential factors that were associated with exposure among the above-targeted hosts. Results from this study showed considerable exposure in both livestock and human populations. However, human exposure to this pathogen at the household level was not correlated with herd-level seropositivity. Further studies are needed to elucidate the transmission routes of this pathogen among humans.

Coxiella burnetii vascular graft infection

Q fever, a zoonotic infection caused by Coxiella burnetii, can present with a wide spectrum of clinical manifestations. The organism is typically transmitted from sheep, goats, or cattle to humans via contaminated aerosols. On average, 1–5% of patients with acute Q fever will develop chronic infection months to decades after their primary infections. We report a case of a chronic vascular graft infection due to Coxiella burnetii in a 61-year-old man without direct exposure to animals who presented with recurrent fever. Indium-111-labeled white blood cell scan with single-emission positron computed tomography demonstrated findings suggesting a graft infection. C. burnetii phase I and phase II IgG antibody titers were > 1:32,768 and polymerase chain reaction performed on the explanted graft was positive for C. burnetii. Q fever should be considered in the differential diagnosis of vascular infections in patients who have a pre-existing lesion such as an aneurysm, or vascular prosthesis even in the absence of a history of direct animal exposure.

From Coxiella burnetii Infection to Pregnancy Complications: Key Role of the Immune Response of Placental Cells

The infection of pregnant animals and women by Coxiella burnetii, an intracellular bacterium, compromises both maternal health and foetal development. The placenta is targeted by C. burnetii, as demonstrated by bacteriological and histological evidence. It now appears that placental strains of C.&nbsp;burnetii are highly virulent compared to reference strains and that placental injury involves different types of placental cells. Trophoblasts, the major placental cells, are largely infected by C. burnetii and may represent a replicating niche for the bacteria. The placenta also contains numerous immune cells, including macrophages, dendritic cells, and mast cells. Placental macrophages are infected and activated by C. burnetii in an unusual way of M1 polarisation associated with bacterial elimination. Placental mast cells eliminate bacteria through a mechanism including the release of extracellular actin filaments and antimicrobial peptides. In contrast, C. burnetii impairs the maturation of decidual dendritic cells, favouring bacterial pathogenicity. Our aim is to review C. burnetii infections of human placentas, paying special attention to both the action and function of the different cell types, immune cells, and trophoblasts targeted by C. burnetii in relation to foetal injury.

Q fever: a rare but potentially life-threatening zoonotic disease

Q fever can present as a fever of unknown aetiology and can be challenging to diagnose because of the rare incidence. It can present as an acute illness with manifestations, including influenza-like symptoms, hepatitis, pneumonia or chronic disease involving the cardiovascular system. We present a case of a 39-year-old woman in the USA, who developed acute Q fever with associated sepsis and severe hepatitis. She received treatment with recovery from acute infection but currently has symptoms of post Q fever syndrome.

Acute kidney injury in acute Q fever

Coxiella burnetii infection is not known to involve directly the kidneys. Kidney injury associated with Q fever usually manifests in the setting of chronic infection or endocarditis with development of immune complex deposition. Acute kidney injury (AKI) in the context of acute Q fever infection may be more pathologically heterogeneous. We describe two cases of severe AKI secondary to acute Q fever infection, each with marked differences in pathological characteristics, and clinical course.

Q-fever prosthetic valve endocarditis in a patient with SLE and antiphospholipid antibody syndrome

Q fever prosthetic valve endocarditis in association with antiphospholipid antibody syndrome (APS) in systemic lupus erythematosus (SLE) has not been previously reported. Here, we report a 22-year-old Saudi female diagnosed with SLE and APS. She had mitral valve replacement with bio-prosthesis five years earlier for Libman-Sack endocarditis. She presented with two months' history of fever, cough, palpitations, and progressive shortness of breath. A transthoracic echocardiogram showed a degenerative mitral valve prosthesis with a large mass causing severe obstruction. Open heart surgery revealed multiple masses on the mitral valve. PCR from the resected tissues was positive for Coxiella burnetii DNA. Q fever serology showed phase two IgG 1:2048, phase one IgG 1:512, and IgM 1:1024. The valve was replaced with a bio-prosthesis. She was well at 12 months of follow-up.

Overview of infection causing hepatitis other than non-A to E hepatitis virus during pregnancy

Abnormal liver function tests during pregnancy are common. While hepatic injury during pregnancy mostly has minimal adverse influence on maternal and fetal outcomes, severe maternal and fetal morbidities, and even death, sometimes occur. Here, we review the epidemiology, clinical features, diagnosis, and management of hepatitis during pregnancy caused by the less common pathogens, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex viruses (HSVs), dengue fever, malaria, leptospirosis, Q fever, typhoid fever, and other occasional infections, as well as the implications on breastfeeding of the infants. Hepatitis during pregnancy with fever and systemic clinical presentations, which are not attributable to the common infectious agents, should raise the suspicion of infection with above-mentioned pathogens, and appropriate laboratory tests are required. Early recognition of severe hepatitis or acute liver failure is critical in initiating appropriate and specific therapy, together with systemic supportive care, to reduce maternal and fetal mortality and long-term sequelae.

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 during pregnancy: a narrative review

BACKGROUND

Coxiella burnetii, the causative agent of Q fever, causes abortions in animals. Its effects on pregnancy in humans and the management of Q fever in pregnancy are uncertain.

OBJECTIVES

To summarize data on the effects of Q fever on pregnancy in women, the effects of pregnancy on Q fever complications and the optimal screening and management of Q fever during pregnancy.

SOURCES

We searched for studies reporting on Q fever during pregnancy in women. We included randomized and observational studies, seroprevalence studies, case series and case reports, including clinical and histopathological studies.

CONTENT

The accumulating data seems convincing that Q fever increases the risk of abortions in early pregnancy and prematurity or intrauterine fetal demise in late pregnancy. Data are based on sero-epidemiological associations of Q fever and adverse pregnancy outcomes and case reports showing the presence and effects of C. burnetii on the placenta and the fetus. Based on observational studies, acquisition of Q fever during pregnancy also increases the risk for maternal chronic Q fever. Treatment of recently infected women seems to improve these outcomes, based on case series only, but the optimal duration of treatment has not been studied. The efficacy of active surveillance during pregnancy, timing and frequency have not been determined in high-endemicity settings. Obstetricians should be aware of the risk for transmission of the disease during delivery. Currently available data are based mostly on case series and case reports, with some discrepancy between the French experience in chronic endemicity settings and Dutch experience in outbreak settings.

IMPLICATIONS

Since infection with Q fever is largely asymptomatic, we believe that the accumulating information linking Q fever to adverse pregnancy outcomes justifies screening in the high-endemicity setting and treatment of infected women. High-quality research addressing the questions raised by this review is needed to determine the optimal public health policy.

Clinical characteristics of acute Q fever patients in South Korea and time from symptom onset to serologic diagnosis

BACKGROUND

Acute Q fever usually presents as a nonspecific febrile illness, and its occurrence is rapidly increasing in South Korea. This study investigated the clinical characteristics of acute Q fever patients in South Korea and the time from symptom onset to serologic diagnosis. The clinical courses were examined according to antibiotic treatment.

METHODS

Data of patients diagnosed with acute Q fever at Chungbuk National University Hospital between January 2015 and February 2018 were retrospectively collected. Demographic and epidemiologic data were reviewed. The time from symptom onset to serologic diagnosis by an immunofluorescence assay (IFA) was analyzed. Clinical courses and the percentage of patients with a high phase I immunoglobulin G titer (≥ 1:1024) were compared between patients administered antibiotics with anti-Coxiella burnetii activity and patients not administered such antibiotics.

RESULTS

Forty-eight patients (median age: 51.5 years) were included. Most were male (95.8%) and had no history of animal contact (91.7%). The median time from illness onset to serologic diagnosis was 21 days. Thirty-nine patients received antibiotics with anti-C. burnetii activity. The length of hospital stay and fever duration did not significantly differ between patients who received antibiotics with anti-C. burnetii activity (7 and 15 days) and those who did not (5 and 8 days) (P = 0.110 and P = 0.137, respectively). The percentage of patients with a high phase I immunoglobulin G titer (≥ 1:1024) did not significantly differ between patients who received antibiotics with anti-C. burnetii activity and those who did not (P = 0.340).

CONCLUSIONS

Most acute Q fever patients had a nonspecific febrile illness with mild elevation of transaminases and no history of animal contact or occupational risk. The time from symptom onset to a positive IFA test was longer than the fever duration in most acute Q fever patients. Consequently, it may be difficult for clinicians to serologically diagnose acute Q fever. However, inappropriate antibiotic treatment was not associated with prolongation of symptoms or progression to chronic Q fever.

Introduction to Measurement of Avidity of Anti-Coxiella burnetii IgG in Diagnosis of Q Fever

Due to the atypical serological profile of some patients with primary Q fever infection who do not develop IgM against Coxiella burnetii, we developed an avidity test to distinguish recent or past infections. We tested 39 serum samples by immunofluorescence with conventional assay and after urea treatment from 26 patients at different stages of the disease. We observed a strong avidity in the 15 serum samples from patients with infections of >6 months and a low avidity for sera from patients with recent infections. A complete denaturation of the antibody-antigen complex was observed for patients for whom the time since the beginning of infection was <1 month and a mean of 2.06 ± 0.54 lowered titers when the infection was less than 3 months old. That was statistically significant compared to sera from patients with infections of greater than 6 months (mean 0.20 ± 0.41) and with infections between 3 and 6 months (mean, 1.17 ± 0.41) (P = 0.0022 and P < 0.0001, respectively). These results were visualized by Western blotting. We concluded that high avidity (≤1 lowered titer) ruled out infection during the last 6 months and that complete denaturation was related to an infection which had occurred within the previous 3 months. Between these two situations, the avidity test is inconclusive. We suggest using an avidity test for atypical Q fever serology that could be misclassified as residual antibodies (IgG against C. burnetii detected without active or recent infection) and for pregnant women risking obstetrical complications. This new test will dramatically improve the diagnosis and management of patients with Q fever.

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.

Q Fever in the First Trimester: A Case Report from Northern Rural New South Wales

Pregnant women are significantly more likely to have an asymptomatic acute infection with C. burnetii which, untreated, has been associated with poor obstetric outcomes including miscarriage, stillbirth, intrauterine growth restriction, and premature delivery. As such, Q fever is a potentially under-recognised and treatable cause of adverse pregnancy outcomes in rural Northern New South Wales, with testing of Q fever polymerase chain reaction (PCR)—whether on maternal sera or placental tissue—not currently recommended by the Perinatal Society of Australia and New Zealand for Stillbirth.

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.

Pulmonary manifestations of Q fever: analysis of 38 patients

Background

Lung involvement in both acute and chronic Q fever is not well described with only a few reported cases of pseudotumor or pulmonary fibrosis in chronic Q fever. The aim of this study was to better understand the pulmonary manifestations of Q fever.

Methods

We conducted a retrospective cohort study of patients with diagnosis of Q fever at Mayo Clinic Rochester. A total of 69 patients were initially identified between 2001 and 2014. Thirty-eight patients were included in this study as 3 were pediatric patients, 20 did not meet serologic criteria for Q fever, and 8 did not have imaging available at time of initial diagnosis. Descriptive analysis was conducted using JMP software.

Results

The median age was 57 years [interquartile range (IQR) 43, 62], 84% from the Midwest, and 13% worked in an occupation involving animals. The most common presentation was fevers (61%). Respiratory symptoms, such as cough, were noted in only 4 patients (11%). Twelve patients (29%) had abnormal imaging studies attributed to Q fever. Three patients (25%) with acute Q fever had findings of consolidation, lymphadenopathy, pleural effusions, and nonspecific pulmonary nodules. Radiographic findings of chronic Q fever were seen in 9 patients (75%) and included consolidation, ground-glass opacities, pleural effusions, lymphadenopathy, pulmonary edema, and lung pseudotumor.

Conclusions

Our results demonstrate that pulmonary manifestations are uncommon in Q fever but include cough and consolidation for acute Q fever and radiographic findings of pulmonary edema with pleural effusions, consolidation, and pseudotumor in those with chronic Q fever.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change

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

Waning population immunity prior to a large Q fever epidemic in the south of The Netherlands

Historical survey data suggest that the seroprevalence of antibodies against Coxiella burnetii in the general population of The Netherlands decreased from more than 40% in 1983 to 2·4% in 2007, just before the start of the large 2007-2010 Q fever epidemic. To assess whether the sharp decline in seroprevalence was real, we performed a cross-sectional study using historical samples. We tested samples using a contemporary commercial indirect immunofluorescence assay. In plasma samples from the south of The Netherlands from 1987, we found an age- and sex-standardized seroprevalence of 14·4% (95% confidence interval 11·2-18·3). This was significantly lower than a 1983 estimate from the same area (62·5%), but significantly higher than 2008 (1·0%) and 2010 (2·3%) estimates from the same area. The study suggests that there was a steady and sharp decline in Q fever seroprevalence in the south of The Netherlands from 1987 to 2008. We assume that seroprevalence has decreased in other parts of The Netherlands as well and seroprevalence surveys in other European countries have shown a similar declining trend. Waning population immunity in The Netherlands may have contributed to the scale of the 2007-2010 Q fever epidemic. For a better understanding of the infection dynamics of Q fever, we advocate an international comparative study of the seroprevalence of C. burnetii.

18F-FDG PET/CT as a central tool in the shift from chronic Q fever to Coxiella burnetii persistent focalized infection: A consecutive case series

Because Q fever is mostly diagnosed serologically, localizing a persistent focus of Coxiella burnetii infection can be challenging. F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) could be an interesting tool in this context.We performed a retrospective study on patients diagnosed with C burnetii infection, who had undergone F-FDG PET/CT between 2009 and 2015. When positive F-FDG PET/CT results were obtained, we tried to determine if it changed the previous diagnosis by discovering or confirming a suspected focus of C burnetii infection.One hundred sixty-seven patients benefited from F-FDG PET/CT. The most frequent clinical subgroup before F-FDG PET/CT was patients with no identified focus of infection, despite high IgG1 serological titers (34%). For 59% (n = 99) of patients, a hypermetabolic focus was identified. For 62 patients (62.6%), the positive F-FDG PET/CT allowed the diagnosis to be changed. For 24 of them, (38.7%), a previously unsuspected focus of infection was discovered. Forty-two (42%) positive patients had more than 1 hypermetabolic focus. We observed 21 valvular foci, 34 vascular foci, and a high proportion of osteoarticular localizations (n = 21). We also observed lymphadenitis (n = 27), bone marrow hypermetabolism (n = 11), and 9 pulmonary localizations.We confirmed thatF-FDG PET/CT is a central tool in the diagnosis of C burnetii focalized persistent infection. We proposed new diagnostic scores for 2 main clinical entities identified using F-FDG PET/CT: osteoarticular persistent infections and lymphadenitis.

The contribution of genomics to the study of Q fever

Coxiella burnetii is the etiological agent of Q fever, a worldwide zoonosis that can result in large outbreaks. The birth of genomics and sequencing of C. burnetii strains has revolutionized many fields of study of this infection. Accurate genotyping methods and comparative genomic analysis have enabled description of the diversity of strains around the world and their link with pathogenicity. Genomics has also permitted the development of qPCR tools and axenic culture medium, facilitating the diagnosis of Q fever. Moreover, several pathophysiological mechanisms can now be predicted and therapeutic strategies can be determined thanks to in silico genome analysis. An extensive pan-genomic analysis will allow for a comprehensive view of the clonal diversity of C. burnetii and its link with virulence.

[Description of a case of severe Q fever]

The paper considers a rare clinical case of severe Q fever in a young man with no compromised premorbid background. It describes and analyzes clinical manifestations and laboratory findings with consideration for the current data available in the literature. The issues of the differential diagnosis, laboratory diagnosis, and treatment of Q fever are discussed.

Chronic Q Fever in a renal transplant recipient: a case report

Q fever is a zoonosis caused by Coxiella burnetii that presents with a wide spectrum of acute and chronic manifestations. Progression to chronic Q fever is frequently associated with valve and vascular prosthesis, aneurisms, pregnancy, immunosuppression, and advanced chronic kidney disease. We present a case of a kidney transplant recipient with persistent fever of unknown origin, negative blood cultures, anemia, and increased erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Q fever serological tests were suggestive of chronic Q fever and the patient was diagnosed with probable chronic Q fever according to the Dutch Fever Consensus Group Guidelines. Initiation of doxycycline 200 mg/d and hydroxychloroquine 600 mg/d resulted in clinical remission. Chronic Q fever is a high-morbidity and -mortality disease if untreated and special attention has to be given to high-risk patients, such as kidney transplant recipients.

Coxiella burnetii Infection Is Lower in Children than in Adults After Community Exposure: Overlooked Cause of Infrequent Q Fever Reporting in the Young

BACKGROUND

Q fever is rarely reported in children/adolescents. Although lower reporting rates are commonly attributed to milder disease and subsequent underdiagnosis in infected children/adolescents, pertinent evidence is scarce. We present data from a large, well-defined single-point source outbreak of Q fever to fill this gap.

METHODS

We compared (A) Q fever testing and notification rates in children/adolescents who were 0-19 years of age with those in adults 20+ years of age in October 2009; (B) serological attack rates of acute Q fever in children/adolescents with the rates in adults after on-source exposure on the outbreak farm's premises; (C) incidence of Q fever infection in children/adolescents with that in adults after off-source exposure in the municipality located closest to the farm.

RESULTS

(A) Children/adolescents represented 19.3% (59,404 of 307,348) of the study area population, 12.1% (149 of 1217) of all subjects tested in October 2009 and 4.3% (11 of 253) of notified laboratory-confirmed community cases. (B) Serological attack rate of acute Q fever in children with on-source exposure was 71% (12 of 17), similar to adults [68% (40 of 59)]. (C) Incidence of infection in children/adolescents after community (off-source) exposure was 4.5% (13 of 287) versus 11.0% (12 of 109) in adults (adjusted odds ratio: 0.36; 95% confidence interval: 0.16-0.84; P = 0.02). No children/adolescents reported clinical symptoms. Proportion of notified infections was significantly lower in children/adolescents (2.5%) than in adults (10.4%; risk ratio: 0.26; 95% confidence interval: 0.08-0.80, P = 0.02).

CONCLUSION

Notified Q fever was less frequent in children/adolescents than in adults. Although underrecognition contributed to this phenomenon, lower rates of infection in children after community exposure played an unexpected major role. On-source (presumed high-dose) exposure, by contrast, was associated with high serological and clinical attack rates not only in adults but also in children/adolescents. Our findings allow for improved age-specific clinical and public health risk assessment in Q fever outbreaks.

Q fever and pregnancy: experience from the Limoges Regional University Hospital

INTRODUCTION

Q fever is an ubiquitous zoonosis caused by Coxiella burnetii. Its tropism for the uterus is a potential source of obstetric complications.

MATERIALS AND METHODS

We describe the obstetric consequences of Q fever diagnosed during pregnancy from a series of cases. When an antenatal diagnosis was made, antibiotic therapy with roxithromycin (Rulid(®)) was started until delivery.

RESULTS

Between 2007 and 2012, 30 patients were treated for Q fever diagnosed during pregnancy, i.e. 1.9 cases per 1000 people. The most common reasons for performing serology was intrauterine growth retardation, preterm labor and oligoamnios. Q fever was diagnosed as acute and chronic in 26 and 4 cases, respectively. Progression to chronic disease occurred in 8 % of acute forms of the diseases. The prevalence of obstetric complications was 66 %, including 10 % foetal deaths, 31 % preterm delivery and 27 % low birthweight <10th percentile. The obstetric complication rate amongst the 22 patients treated with ante partum macrolides was 60, 30 % of which involved prematurity and 33 % involved low growth. No cases of foetal death were found on treatment and no congenital malformation and placental or neonatal injury was found. No case of disease reactivation was diagnosed in the eight patients who became pregnant again.

CONCLUSION

Q fever during pregnancy is responsible for severe obstetric complications. It must be diagnosed early and its clinical forms known in order to start appropriate antibiotic therapy.

Coxiella burnetii infections in sheep or goats: an opinionated review

Q fever is an almost ubiquitous zoonosis caused by Coxiella burnetii, which is able to infect several animal species, as well as humans. Cattle, sheep and goats are the primary animal reservoirs. In small ruminants, infections are mostly without clinical symptoms, however, abortions and stillbirths can occur, mainly during late pregnancy. Shedding of C. burnetii occurs in feces, milk and, mostly, in placental membranes and birth fluids. During parturition of infected small ruminants, bacteria from birth products become aerosolized. Transmission to humans mainly happens through inhalation of contaminated aerosols. In the last decade, there have been several, sometimes large, human Q fever outbreaks related to sheep and goats. In this review, we describe C. burnetii infections in sheep and goats, including both advantages and disadvantages of available laboratory techniques, as pathology, different serological tests, PCR and culture to detect C. burnetii. Moreover, worldwide prevalences of C. burnetii in small ruminants are described, as well as possibilities for treatment and prevention. Prevention of shedding and subsequent environmental contamination by vaccination of sheep and goats with a phase I vaccine are possible. In addition, compulsory surveillance of C. burnetii in small ruminant farms raises awareness and hygiene measures in farms help to decrease exposure of people to the organism. Finally, this review challenges how to contain an infection of C. burnetii in small ruminants, bearing in mind possible consequences for the human population and probable interference of veterinary strategies, human risk perception and political considerations.

Adverse pregnancy outcomes and Coxiella burnetii antibodies in pregnant women, Denmark

Q fever may be associated with complications, but overall risk is low.

A high risk for obstetric complications has been reported among women infected with Coxiella burnetii, the causative agent of Q fever, but recent studies have failed to confirm these findings. We reviewed national data collected in Denmark during 2007–2011 and found 19 pregnancies in 12 women during which the mother had a positive or equivocal test for antibodies to C. burnetii (IgM phase I and II titers >64, IgG phase I and II titers >128). Of these 12 women, 4 experienced obstetric complications (miscarriage, preterm delivery, infant small for gestational age, oligohydramnion, fetal growth restriction, or perinatal death); these complications occurred in 9 pregnancies (47% of the 19 total pregnancies identified). Our findings suggest an association between Q fever and adverse pregnancy outcomes, but complications were identified in only 9 pregnancies during the study’s 5-year period, indicating that the overall risk is low.

Persistent high antibody titres against Coxiella burnetii after acute Q fever not explained by continued exposure to the source of infection: a case-control study

BACKGROUND

From 2007 to 2010, (the southern part of) the Netherlands experienced a large Q fever epidemic, with more than 4,000 reported symptomatic cases. Approximately 1 - 5% of the acute Q fever patients develop chronic Q fever. A high IgG antibody titre against phase I of Coxiella burnetii during follow-up is considered a marker of chronic Q fever. However, there is uncertainty about the significance and cause of persistence of high IgG phase I antibody titres in patients that do not have any additional manifestations of chronic Q fever. We studied whether continued or repeated exposure to the source of infection could explain elevated IgG phase I antibody levels.

METHODS

A case-control study was performed to analyze predictors for possible chronic Q fever. Possible chronic Q fever cases (n = 53) are patients with phase I IgG antibody titre ≥1:1,024 at any point in the 9 - 18 months after acute Q fever diagnosis, with a negative PCR test result for C. burnetii DNA and without other disease manifestations. Controls (n = 110) are acute Q fever patients that did not develop chronic Q fever, and who consistently had phase I IgG antibody titre <1:1,024 during the 9 - 18 months follow-up. Binary logistic regression was performed to analyze the effect of living close to an infected farm on the high antibody titres. A longitudinal analysis described the serological profiles of cases and controls.

RESULTS

Proximity to infected farms and contact with animal placental material were not associated with an increased risk for possible chronic Q fever. Possible chronic Q fever patients have high IgG phase II as well as IgG phase I antibody titres, even after 48 months of follow-up.

CONCLUSION

We were unable to explain the cause of persistent high IgG phase I titres among possible chronic Q fever patients by being continuously exposed to the source of infection.

Q fever in the Netherlands - 2007-2010: what we learned from the largest outbreak ever

Q fever is a zoonosis caused by Coxiella burnetii with a presentation ranging from asymptomatic seroconversion to possibly fatal chronic Q fever. The Netherlands faced an exceptionally large outbreak of Q fever from 2007 to 2010: 4026 human cases were notified, which makes it the largest Q fever outbreak ever reported. This outbreak, because of its size, allowed collecting a wide range of information on the natural history of Q fever, as well as on its transmission and clinical presentation. It also posed unprecedented public healthcare problems, especially for the concomitant management of the epizootic by veterinarian authorities and public health authorities, but also for the management of transmission risk related to blood donation. The need for cost efficient measures emerged rapidly because of the great number of infected individuals or at risk of infection, with a need for guidance on follow-up of acute Q fever patients, screening of pregnant women, or implementation of diagnostic algorithms. The acute outbreak was controlled by drastic veterinarian measures but chronic Q fever will remain a problem for the coming years.

Epidemiology of Coxiella burnetii infection in Africa: a OneHealth systematic review

Background

Q fever is a common cause of febrile illness and community-acquired pneumonia in resource-limited settings. Coxiella burnetii, the causative pathogen, is transmitted among varied host species, but the epidemiology of the organism in Africa is poorly understood. We conducted a systematic review of C. burnetii epidemiology in Africa from a “One Health” perspective to synthesize the published data and identify knowledge gaps.

Methods/Principal Findings

We searched nine databases to identify articles relevant to four key aspects of C. burnetii epidemiology in human and animal populations in Africa: infection prevalence; disease incidence; transmission risk factors; and infection control efforts. We identified 929 unique articles, 100 of which remained after full-text review. Of these, 41 articles describing 51 studies qualified for data extraction. Animal seroprevalence studies revealed infection by C. burnetii (≤13%) among cattle except for studies in Western and Middle Africa (18–55%). Small ruminant seroprevalence ranged from 11–33%. Human seroprevalence was <8% with the exception of studies among children and in Egypt (10–32%). Close contact with camels and rural residence were associated with increased seropositivity among humans. C. burnetii infection has been associated with livestock abortion. In human cohort studies, Q fever accounted for 2–9% of febrile illness hospitalizations and 1–3% of infective endocarditis cases. We found no studies of disease incidence estimates or disease control efforts.

Conclusions/Significance

C. burnetii infection is detected in humans and in a wide range of animal species across Africa, but seroprevalence varies widely by species and location. Risk factors underlying this variability are poorly understood as is the role of C. burnetii in livestock abortion. Q fever consistently accounts for a notable proportion of undifferentiated human febrile illness and infective endocarditis in cohort studies, but incidence estimates are lacking. C. burnetii presents a real yet underappreciated threat to human and animal health throughout Africa.

Coxiella burnetii is a bacterium that can cause acute and chronic fever illness and pneumonia in humans. It is also a known cause of abortion in livestock species, and is principally transmitted to humans through contact with infected animal birth products. With growing awareness of the over-diagnosis and misclassification of malaria as the cause of fever illnesses in the tropics, including Africa, there is increased interest in the role of non-malarial causes of fever, such as C. burnetii. We performed a systematic review of the published literature on the epidemiology of C. burnetii in Africa to consolidate knowledge and identify knowledge gaps regarding the extent of this infection in humans and animals and the risk factors for infection transmission. Few studies on prevalence of infection in humans and animals used random sampling strategies, and among these only two studied linked human and animal populations. C. burnetii appears to be a common cause of severe fever illness in humans, but population-level incidence estimates are lacking. The differential risks for C. burnetii infection and potential control strategies within the various animal husbandry systems in Africa remain largely unexplored. We conclude that C. burnetii is an underappreciated threat to human and animal health throughout Africa.

Serological follow-up in patients with aorto-iliac disease and evidence of Q fever infection

The aim of this study was to provide data on the risk of developing chronic Q fever in patients with aorto-iliac disease and evidence of previous Q fever infection. Patients with an aortic and/or iliac aneurysm or aorto-iliac reconstruction (aorto-iliac disease) and evidence of previous Q fever infection were included. The presence of phase I and II Coxiella burnetii IgG antibodies was assessed periodically using immunofluorescence assay. A total of 111 patients with aorto-iliac disease were divided into three groups, based upon the serological profile [mean follow-up: 16 ± 9 months (mean ± standard deviation)]. Group 1 consisted of 30 patients with a serological trace of C. burnetii infection (negative IgG phase I, IgG phase II titer of 1:32). Of these, 36.7% converted to serological profile matching past resolved Q fever. Group 2 included 49 patients with negative IgG phase I titer and IgG phase II titer ≥1:64. No patients developed chronic Q fever, but 14.3% converted to a positive IgG phase I titer. Group 3 consisted of 32 patients with positive IgG phase I and positive IgG phase II titers, of which 9.4% developed chronic Q fever (significantly different from group 2, p = 0.039). The IgG phase I titer increased in 28.1% of patients (from 1:64 to 1:4,096). The risk of developing chronic Q fever in patients with aorto-iliac disease and previous Q fever infection with a positive IgG phase I titer was 9.4%. The IgG phase I titer increases or becomes positive in a substantial number of patients. A standardized serological follow-up is proposed.

Chronic Q fever in the Netherlands 5 years after the start of the Q fever epidemic: results from the Dutch chronic Q fever database

Coxiella burnetii causes Q fever, a zoonosis, which has acute and chronic manifestations. From 2007 to 2010, the Netherlands experienced a large Q fever outbreak, which has offered a unique opportunity to analyze chronic Q fever cases. In an observational cohort study, baseline characteristics and clinical characteristics, as well as mortality, of patients with proven, probable, or possible chronic Q fever in the Netherlands, were analyzed. In total, 284 chronic Q fever patients were identified, of which 151 (53.7%) had proven, 64 (22.5%) probable, and 69 (24.3%) possible chronic Q fever. Among proven and probable chronic Q fever patients, vascular infection focus (56.7%) was more prevalent than endocarditis (34.9%). An acute Q fever episode was recalled by 27.0% of the patients. The all-cause mortality rate was 19.1%, while the chronic Q fever-related mortality rate was 13.0%, with mortality rates of 9.3% among endocarditis patients and 18% among patients with a vascular focus of infection. Increasing age (P=0.004 and 0.010), proven chronic Q fever (P=0.020 and 0.002), vascular chronic Q fever (P=0.024 and 0.005), acute presentation with chronic Q fever (P=0.002 and P<0.001), and surgical treatment of chronic Q fever (P=0.025 and P<0.001) were significantly associated with all-cause mortality and chronic Q fever-related mortality, respectively.

Prevalence of Coxiella burnetii in women exposed to livestock animals, Denmark, 1996 to 2002

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Evolution from acute Q fever to endocarditis is associated with underlying valvulopathy and age and can be prevented by prolonged antibiotic treatment

BACKGROUND

 The prevention of Q fever endocarditis through the use of systematic echocardiography and antibiotic prophylaxis in patients with acute Q fever and valvulopathy has never been validated in a cohort study.

METHODS

 From 2007 to 2012, all patients followed at the French National Referral Center for acute Q fever were included in a cohort study. The prevention of endocarditis included a systematic transthoracic echocardiography (TTE) and a 12-month course of doxycycline and hydroxychloroquine prophylaxis in patients with significant valvulopathy. Transesophageal echocardiography (TEE) was performed in patients with a negative TTE and a rapid rise of phase I immunoglobulin G titers.

RESULTS

 Seventy-two patients were included with a median follow-up time of 22 months. A valvulopathy was identified in 31 patients (43%), being previously unknown in 24 (33%) and diagnosed only upon TEE or a second TTE in 7 (10%). The major determinants associated with endocarditis were age (hazard ratio [HR], 1.07; 95% confidence interval [CI], 1.006-1.13; P = .03), aortic regurgitation (HR, 10.2; 95% CI, 3.2-32.2; P < .001), and mitral regurgitation (HR, 4.78; 95% CI, 1.4-16.0; P = .01). Antibiotic prophylaxis was highly effective (HR, 0.002; 95% CI, .00-.77; P = .04) for the 31 patients with valvulopathy.

CONCLUSIONS

 Acute Q fever could be associated with an increased prevalence of valvulopathy. The evolution from acute Q fever to endocarditis is associated with age and valvulopathy and can be entirely prevented by antibiotic prophylaxis. Although the name "chronic Q fever" suggests otherwise, rapid evolution (<1 month) was observed.

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.

Delayed diagnosis of chronic Q fever and cardiac valve surgery

Untreated chronic Q fever causes a high number of complications and deaths. We present cases of chronic Q fever that were not diagnosed until after the patients underwent cardiac valve surgery. In epidemic areas, Q fever screening of valve surgery patients secures early initiation of treatment and can prevent illness and death.

No excess risk of adverse pregnancy outcomes among women with serological markers of previous infection with Coxiella burnetii: evidence from the Danish National Birth Cohort

BACKGROUND

Q fever caused by Coxiella burnetii is transmitted to humans by inhalation of aerosols from animal birth products. Q fever in pregnancy is suspected to be a potential cause of fetal and maternal morbidity and fetal mortality but the pathogenesis is poorly understood, and even in Q fever endemic areas, the magnitude of a potential association is not established.We aimed to examine if presence of antibodies to C. burnetii during pregnancy or seroconversion were associated with adverse pregnancy outcomes.

METHODS

The Danish National Birth Cohort collected blood samples and interview data from 100,418 pregnant women (1996-2002). We sampled 397 pregnant women with occupational or domestic exposure to cattle or sheep and a random sample of 459 women with no animal exposure. Outcome measures were spontaneous abortion, preterm birth, birth weight and Small for Gestational Age (SGA).Blood samples collected in pregnancy were screened for antibodies against C. burnetii by enzyme-linked immunosorbent assay (ELISA). Samples positive for IgG or IgM antibodies in the ELISA were confirmed by immunofluorescence antibody test (IFA).

RESULTS

Among the 856 women, 169 (19.7%) women were IFA positive; 147 (87%) of these had occupational or domestic contact with livestock (IFA cutoff > =1:128).Two abortions were IFA positive vs. 6 IFA negative (OR: 1.5; 95%CI: 0.3-7.6). Three preterm births were IFA positive vs. 38 IFA negative (OR: 0.4; 95% CI: 0.1-1.1). There was a significant difference in birth weight of 168 g (95% CI: 70-267 g) with IFA positive being heavier, and the risk of being SGA was not increased in the newborns of IFA positive women (OR: 0.4; 95%CI: 0.8-1.0).Most seropositive women were IgG positive indicating previous exposure. Seroconversion during pregnancy was found in 10 women; they all delivered live babies at term, but two were SGA.

CONCLUSION

We found no increased risk of adverse pregnancy outcome in women with verified exposure to C. burnetii.To our knowledge, this is the first population-based seroepidemiologic study evaluating pregnancy outcome in women with serologically verified exposure to C. burnetii against a comparable reference group of seronegative women.

Antigenic analysis for vaccines and diagnostics

Coxiella burnetii infection is frequently unrecognized or misdiagnosed, as symptoms generally mimic an influenza-like illness. However, the disease (Q fever) may result in chronic infection, usually manifesting as potentially fatal endocarditis. The development of a chronic fatigue-like sequela may also occur. Infected ruminants are the major reservoir for infection in humans, primarily through exposure to birth products or aerosols that transmit the bacterium over wide regions. A vaccine against C. burnetii infection has been in use in Australia for abattoir and agricultural workers for many years. The possibility of adverse reactions in those with previous exposure to the agent has prevented its use elsewhere. Subunit vaccines, utilizing chemical extraction of components thought to cause adverse reactions, are in development, but none are yet licensed. Others have sought to combine immunogenic peptides with or without selected lipopolysaccharide components to produce a vaccine without the possibility of adverse reactions. Selected immunogenic proteins have been shown to induce both humoral and cellular immune responses. Although current diagnosis of infection relies on serological testing, the presentation of specific antibody occurs 7-15 days following the onset of symptoms, delaying treatment that may result in prolonged morbidity. PCR detection of DNA to specific C. burnetii antigens in the blood is possible early in infection, but PCR may become negative when PII IgG antibodies appear. PCR is useful for early diagnosis when Q fever is suspected, as in large epidemics, and shortens the delay in the identification of Q fever endocarditis. Others have combined PCR with ELISA or other methods to increase the ability to detect infection at any stage. The search for new diagnostic reagents and vaccines has utilized new methods for discovery of immunoreactive proteins. DNA analysis of the heterogeneity of C. burnetii isolates has led to a greater understanding of the diversity of isolates and a means to determine whether there is a correlation between strain and disease severity. 2-D SDS PAGE of immunogenic proteins reactive with human or animal infection sera and mass spectrometric analysis of specific secreted or outer membrane proteins have identified candidate antigens. Microarrays have allowed the analysis of peptide libraries of open reading frames to evaluate the immunogenicity of complete genomes.

Maternofetal consequences of Coxiella burnetii infection in pregnancy: a case series of two outbreaks

Background

A high complication rate of Q fever in pregnancy is described on the basis of a limited number of cases. All pregnant women with proven Q fever regardless of clinical symptoms should therefore receive long-term cotrimoxazole therapy. But cotrimoxazole as a folic acid antagonist may cause harm to the fetus. We therefore investigated the Q fever outbreaks, Soest in 2003 and Jena in 2005, to determine the maternofetal consequences of Coxiella burnetii infection contracted during pregnancy.

Methods

Different outbreak investigation strategies were employed at the two sides. Antibody screening was performed with an indirect immunofluorescence test. Medical history and clinical data were obtained and serological follow up performed at delivery. Available placental tissue, amniotic fluid and colostrum/milk were further investigated by polymerase chain reaction and by culture.

Results

11 pregnant women from Soest (screening rate: 49%) and 82 pregnant women from Jena (screening rate: 27%) participated in the outbreak investigation. 11 pregnant women with an acute C. burnetii infection were diagnosed. Three women had symptomatic disease.

Three women, who were infected in the first trimester, were put on long-term therapy. The remaining women received cotrimoxazole to a lesser extent (n=3), were treated with macrolides for three weeks (n=1) or after delivery (n=1), were given no treatment at all (n=2) or received antibiotics ineffective for Q fever (n=1). One woman and her foetus died of an underlying disease not related to Q fever. One woman delivered prematurely (35^th week) and one child was born with syndactyly. We found no obvious association between C. burnetii infection and negative pregnancy outcome.

Conclusions

Our data do not support the general recommendation of long-term cotrimoxazole treatment for Q fever infection in pregnancy. Pregnant women with symptomatic C. burnetii infections and with chronic Q fever should be treated. The risk-benefit ratio of treatment in these patients, however, remains uncertain. If cotrimoxazole is administered, folinic acid has to be added.