Q fever is underestimated in the United States: a comparison of fatal Q fever cases from two national reporting systems

Q fever awareness in Australia: A scoping review

OBJECTIVE

To investigate the level of Q fever awareness in Australia.

METHODS

A scoping review was conducted by searching the electronic databases Medline, PubMed and Web of Science using keywords for Q fever, awareness, knowledge, and Australian locations. The search was initially limited to articles published in the 10 years prior to June 2022 and then extended up to and including August 2023; yielding 387 records.

RESULTS

Fifteen articles were assessed as being eligible. These articles reported on surveys and interviews conducted with farmers, veterinary practitioners and nurses, medical practitioners, policy makers, researchers, industry representatives, animal science students, cat breeders, wildlife rehabilitators, and agriculture show attendees. Farmers were the largest group represented. Level of Q fever awareness amongst these communities, including those at high-risk, was generally low. The need for increased awareness was recognised. General practitioner awareness levels were low and recognised to be so by high-risk groups. Awareness of preventive measures including vaccination was greater among those with greater awareness and risk.

CONCLUSION

With the availability of a highly effective vaccine in Australia, there is a need to increase Q fever knowledge and awareness among high-risk groups and primary health care practitioners.

IMPLICATIONS FOR PUBLIC HEALTH

Strategies to increase awareness and knowledge of Q fever risks and prevention strategies may assist with reducing Q fever burden in Australia.

Coxiella burnetii actively blocks IL-17-induced oxidative stress in macrophages

Coxiella burnetii is a highly infectious pathogen that causes Q fever, a leading cause of culture-negative endocarditis. Coxiella first targets alveolar macrophages and forms a phagolysosome-like compartment called the Coxiella-Containing Vacuole (CCV). Successful host cell infection requires the Type 4B Secretion System (T4BSS), which translocates bacterial effector proteins across the CCV membrane into the host cytoplasm, where they manipulate numerous cell processes. Our prior transcriptional studies revealed that Coxiella T4BSS blocks IL-17 signaling in macrophages. Given that IL-17 is known to protect against pulmonary pathogens, we hypothesize that C. burnetii T4BSS downregulates intracellular IL-17 signaling to evade the host immune response and promote bacterial pathogenesis. Using a stable IL-17 promoter reporter cell line, we confirmed that Coxiella T4BSS blocks IL-17 transcription activation. Assessment of the phosphorylation state of NF-κB, MAPK, and JNK revealed that Coxiella downregulates IL-17 activation of these proteins. Using ACT1 knockdown and IL-17RA or TRAF6 knockout cells, we next determined that IL17RA-ACT1-TRAF6 pathway is essential for the IL-17 bactericidal effect in macrophages. In addition, macrophages stimulated with IL-17 generate higher levels of reactive oxygen species, which is likely connected to the bactericidal effect of IL-17. However, C. burnetii T4SS effector proteins block the IL-17-mediated oxidative stress, suggesting that Coxiella blocks IL-17 signaling to avoid direct killing by the macrophages.

Acute and chronic Q fever national surveillance - United States, 2008-2017

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii and can manifest in an acute or chronic form. Many persons with acute Q fever are asymptomatic, but some develop a febrile illness, pneumonia or hepatitis. Chronic infections are rare and occur in less than 5% of persons exposed. Forms of chronic Q fever include endocarditis, infection of vascular grafts or aneurysms, osteomyelitis and osteoarthritis. Acute and chronic Q fever are nationally notifiable diseases, and presented here are the incidence, demographics and distribution of acute and chronic Q fever in the United States during 2008-2017. We summarized passive surveillance data from the Centers for Disease Control and Prevention's (CDC) National Notifiable Diseases Surveillance System (NNDSS) and supplemental case report forms (CRFs). Health departments reported 1,109 cases of acute Q fever and 272 chronic Q fever cases to NNDSS during this period. The 10-year average annual incidence for acute Q fever was 0.36 cases per million persons, and the average annual incidence for chronic Q fever was 0.09. Males accounted for nearly 75% of both acute and chronic Q fever cases. Average annual incidence was highest among persons aged 60-69 years for both acute and chronic Q fever (0.70 cases per million persons and 0.25, respectively). As reported through CRFs, many Q fever cases did not have a known exposure to C. burnetii; 60% (n = 380) of acute Q fever cases did not report exposure to animals in the 2 months before symptom onset. Almost 90% (n = 558) did not report exposure to unpasteurized milk. Only 40% (n = 247) of persons with reported Q fever were employed in high-risk occupations. Even though Q fever is a rare disease in the United States, incidence doubled from 2008 to 2017.

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.

Unravelling animal exposure profiles of human Q fever cases in Queensland, Australia, using natural language processing

Q fever, caused by the zoonotic bacterium Coxiella burnetii, is a globally distributed emerging infectious disease. Livestock are the most important zoonotic transmission sources, yet infection in people without livestock exposure is common. Identifying potential exposure pathways is necessary to design effective interventions and aid outbreak prevention. We used natural language processing and graphical network methods to provide insights into how Q fever notifications are associated with variation in patient occupations or lifestyles. Using an 18-year time-series of Q fever notifications in Queensland, Australia, we used topic models to test whether compositions of patient answers to follow-up exposure questionnaires varied between demographic groups or across geographical areas. To determine heterogeneity in possible zoonotic exposures, we explored patterns of livestock and game animal co-exposures using Markov Random Fields models. Finally, to identify possible correlates of Q fever case severity, we modelled patient probabilities of being hospitalized as a function of particular exposures. Different demographic groups consistently reported distinct sets of exposure terms and were concentrated in different areas of the state, suggesting the presence of multiple transmission pathways. Macropod exposure was commonly reported among Q fever cases, even when exposure to cattle, sheep or goats was absent. Males, older patients and those that reported macropod exposure were more likely to be hospitalized due to Q fever infection. Our study indicates that follow-up surveillance combined with text modelling is useful for unravelling exposure pathways in the battle to reduce Q fever incidence and associated morbidity.

Q fever vaccine efficacy and occupational exposure risk in Queensland, Australia: A retrospective cohort study

Q-VAX® is a vaccine used to prevent Q fever. Administration of the vaccine is complicated by the need to ensure, using intradermal and serological tests, that individuals have no prior immunity. Previous studies suggest that the vaccine is highly efficacious and long-lasting in adults. However, there has been no systematic follow-up of vaccine efficacy and the longevity of immunity using population-level data. We aimed to investigate the vaccine failure rate and duration of immunity in previously vaccinated individuals. We formulated a retrospective cohort study design within a linked data. We used a Q fever vaccination registry linked to Q fever notifications and hospital admissions (1991-2016) in the state of Queensland, which has Australia's highest incidence of Q fever. Q-VAX® failure was defined as occurrence of Q fever > 14 days' after vaccination. The incidence of Q fever in vaccinated and unvaccinated individuals was 5.40 (95% CI: 3.65, 7.72) and 89.50 (95% CI: 70.50, 112.00]) per 100,000 person-years of follow-up, respectively. The hazard ratio (HR) for Q fever was 0.07 (95% CI: 0.04, 0.10) in non-immune vaccinated compared with immune unvaccinated individuals. The overall vaccine effectiveness was found to be 94.37% suggesting that Q-VAX® is highly effective at preventing Q fever. However, the greater incidence observed in unvaccinated individuals considered immune during the pre-vaccination screening may suggest that pre-vaccination screening is sub-optimal among this study population.

Q Fever in Southern California: a Case Series of 20 Patients from a VA Medical Center

Query fever (Q fever), caused by Coxiella burnetii, was first described in southern California in 1947. It was found to be endemic and enzoonotic to the region and associated with exposure to livestock. We describe a series of 20 patients diagnosed with Q fever at a Veterans Affairs hospital in southern California, with the aim of contributing toward the understanding of Q fever in this region. Demographics, laboratory data, diagnostic imaging, risk factors, and treatment regimens were collected via a retrospective chart review of patients diagnosed with Q fever at our institution between 2000 and 2016. Cases were categorized as acute or chronic and confirmed or probable. The majority presented with an acute febrile illness (90%). There was a delay in ordering diagnostic serology from the time of symptom onset (acute cases, average 31.9 days; chronic cases, average 63 days), and 15% progressed from acute to chronic infection. Of the chronic cases, 22.2% had endocarditis, 22.2% had endovascular infection, and 11.1% had both endocarditis and endovascular infection. The geographic distribution revealed that 20% resided in rural areas. Of the cases of Q fever that died, death attributed to Q fever was associated with an average diagnostic delay of 65.5 days. Acute Q fever is underreported in this region largely because of its often nonspecific clinical presentation.

Epidemiological scenario of Q fever hospitalized patients in the Spanish Health System: What's new

OBJECTIVES

The objective of this study was to assess the epidemiology and burden of Q fever (QF) in Spain.

METHODS

We designed a retrospective descriptive study using the minimum basic data set in patients admitted to hospitals of the National Health System between 1998 and 2015 with a diagnosis of Q fever (ICD-9: 083.0.).

RESULTS

We found 4214 hospitalized patients with a mean age (±SD) of 50.9±19.3 years. The male/female ratio was 3:1. The incidence rate was between 0.41 and 0.65 cases per 100,000 person-years over the 18-year period. The highest incidence of cases was from March to August (p=0.024). 21.1% patients had pneumonia, 17.5% had liver disease, and only 3.2% had endocarditis. The average hospital stay was 13.8 days (±12.8). A total of 117 (2.8%) patients died. The total mean cost of QF is approximately €154,232,779 (€36,600±139,422 per patient).

CONCLUSIONS

QF is an important zoonosis in Spain with a stable incidence rate and high cost for hospitalization. Older patients have a more severe clinical picture and higher mortality, which can be decreased with early clinical suspicion.

Expression of human TLR4/myeloid differentiation factor 2 directs an early innate immune response associated with modest increases in bacterial burden during Coxiella burnetii infection

Human TLR4 (hTLR4) and mouse TLR4 molecules respond differently to hypo-acylated LPS. The LPS of Coxiella burnetii is hypo-acylated and heavily glycosylated and causes a minimal response by human cells. Thus, we hypothesized that mice expressing hTLR4 molecules would be more susceptible to C. burnetii infection. Our results show that transgenic mice expressing hTLR4 and the human myeloid differentiation factor 2 (MD-2) adaptor protein (hTLR4/MD-2) respond similarly to wild type mice with respect to overall disease course. However, differences in bacterial burdens in tissues were noted, and lung pathology was increased in hTLR4/MD2 compared to wild type mice. Surprisingly, bone marrow chimera experiments indicated that hTLR4/MD-2 expression on non-hematopoietic cells, rather than the target cells for C. burnetii infection, accounted for increased bacterial burden. Early during infection, cytokines involved in myeloid cell recruitment were detected in the plasma of hTLR4/MD2 mice but not wild type mice. This restricted cytokine response was accompanied by neutrophil recruitment to the lung in hTLR4/MD2 mice. These data suggest that hTLR4/MD-2 alters early responses during C. burnetii infection. These early responses are precursors to later increased bacterial burdens and exacerbated pathology in the lung. Our data suggest an unexpected role for hTLR4/MD-2 in non-hematopoietic cells during C. burnetii infection.

Q Fever in Rural Australia: Education Versus Vaccination

BACKGROUND

Q fever is an infection caused by Coxiella burnetii, a zoonotic disease acquired from both wild and domestic animals. Northern rural New South Wales (NSW) communities in Australia have an increased risk of exposure to this organism. Both the acute and chronic phases of the infection are associated with significant morbidity, which is often increased by delayed recognition and treatment. Recent termination of vaccination programs in Australia may increase the risk of infection in these populations.

MATERIALS AND METHODS

This cross-sectional study evaluated the current knowledge base and overall understanding of clinicians on the epidemiology, presentation, and diagnosis of Q fever in the Northern New South Wales Local Health District.

RESULTS

Forty-five participants responded to the survey. Among those, 35 participants (78%) were hospital based and 10 (22%) were from doctors working in the community. Thirty-one (72%) clinicians answered bacteria as the cause of Q fever, 34 (79.1%) participants selected animals as the reservoir of Q fever infection, and 22 (51%) identified inhalation as the form of transmission. The majority identified livestock rearing occupations (84%) as a high-risk group; however, only 65-70% identified stock yard and meat workers as groups also at risk. Furthermore, 23 (51%) of the participants considered those living in rural and remote communities as high risk.

CONCLUSIONS

Our results identified gaps in knowledge of clinicians in the epidemiology and diagnosis of acute Q fever infection. With the termination of vaccination programs, this study highlights the need for education programs that can increase Q fever awareness toward prompt identification and treatment.

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: an under-reported reportable communicable disease

The objective of this study was to provide real-world clinical laboratory-based data to supplement Centers for Disease Control and Prevention (CDC) reporting of Q fever. We analysed titre results of specimens submitted to a large US clinical laboratory for Coxiella burnetii IgG antibody testing from 2010 through 2016. Presumptive Q fever was defined as acute (phase II IgG titre ⩾1:128, phase I titre <1:1024) or chronic (phase I IgG titre ⩾1:1024), based on the results from a single serum specimen. During 2010-2016, an average of 328 presumptive acute Q fever cases were identified at Quest each year, nearly three times the annual average reported to the CDC (122). During the same period, the number of chronic cases identified annually at Quest Diagnostics (34) was similar to that reported to the CDC (29). These findings suggest that CDC data may underestimate the incidence of acute Q fever.

Summary of Notifiable Infectious Diseases and Conditions - United States, 2015

The Summary of Notifiable Infectious Diseases and Conditions - United States, 2015 (hereafter referred to as the summary) contains the official statistics, in tabular and graphical form, for the reported occurrence of nationally notifiable infectious diseases and conditions in the United States for 2015. Unless otherwise noted, data are final totals for 2015 reported as of June 30, 2016. These statistics are collected and compiled from reports sent by U.S. state and territories, New York City, and District of Columbia health departments to the National Notifiable Diseases Surveillance System (NNDSS), which is operated by CDC in collaboration with the Council of State and Territorial Epidemiologists (CSTE). This summary is available at https://www.cdc.gov/MMWR/MMWR_nd/index.html. This site also includes summary publications from previous years.

Community-acquired pneumonia related to intracellular pathogens

Community-acquired pneumonia (CAP) is associated with high rates of morbidity and mortality worldwide; the annual incidence of CAP among adults in Europe has ranged from 1.5 to 1.7 per 1000 population. Intracellular bacteria are common causes of CAP. However, there is considerable variation in the reported incidence between countries and change over time. The intracellular pathogens that are well established as causes of pneumonia are Legionella pneumophila, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Chlamydophila psittaci, and Coxiella burnetii. Since it is known that antibiotic treatment for severe CAP is empiric and includes coverage of typical and atypical pathogens, microbiological diagnosis bears an important relationship to prognosis of pneumonia. Factors such as adequacy of initial antibiotic or early de-escalation of therapy are important variables associated with outcomes, especially in severe cases. Intracellular pathogens sometimes appear to cause more severe disease with respiratory failure and multisystem dysfunction associated with fatal outcomes. The clinical relevance of intracellular pathogens in severe CAP has not been specifically investigated. We review the prevalence, general characteristics, and outcomes of severe CAP cases caused by intracellular pathogens.

Type I Interferon Counters or Promotes Coxiella burnetii Replication Dependent on Tissue

Coxiella burnetii is an intracellular pathogen and the cause of Q fever. Gamma interferon (IFN-γ) is critical for host protection from infection, but a role for type I IFN in C. burnetii infection has not been determined. Type I IFN supports host protection from a related pathogen, Legionella pneumophila, and we hypothesized that it would be similarly protective in C. burnetii infection. In contrast to our prediction, IFN-α receptor-deficient (IFNAR(-/-)) mice were protected from C. burnetii-induced infection. Therefore, the role of type I IFN in C. burnetii infection was distinct from that in L. pneumophila Mice treated with a double-stranded-RNA mimetic were protected from C. burnetii-induced weight loss through an IFNAR-independent pathway. We next treated mice with recombinant IFN-α (rIFN-α). When rIFN-α was injected by the intraperitoneal route during infection, disease-induced weight loss was exacerbated. Mice that received rIFN-α by this route had dampened interleukin 1β (IL-1β) expression in bronchoalveolar lavage fluids. However, when rIFN-α was delivered to the lung, bacterial replication was decreased in all tissues. Thus, the presence of type I IFN in the lung protected from infection, but when delivered to the periphery, type I IFN enhanced disease, potentially by dampening inflammatory cytokines. To better characterize the capacity for type I IFN induction by C. burnetii, we assessed expression of IFN-β transcripts by human macrophages following stimulation with lipopolysaccharide (LPS) from C. burnetii Understanding innate responses in C. burnetii infection will support the discovery of novel therapies that may be alternative or complementary to the current antibiotic treatment.

Q fever in the United States: summary of case reports from two national surveillance systems, 2000-2012

Q fever is a worldwide zoonosis historically associated with exposure to infected livestock. This study summarizes cases of Q fever, a notifiable disease in the United States, reported to the Centers for Disease Control and Prevention through two national surveillance systems with onset during 2000-2012. The overall incidence rate during this time was 0.38 cases per million persons per year. The reported case fatality rate was 2.0%, and the reported hospitalization rate was 62%. Most cases (61%) did not report exposure to cattle, goats, or sheep, suggesting that clinicians should consider Q fever even in the absence of livestock exposure. The prevalence of drinking raw milk among reported cases of Q fever (8.4%) was more than twice the national prevalence for the practice. Passive surveillance systems for Q fever are likely impacted by underreporting and underdiagnosis because of the nonspecific presentation of Q fever.