Q Fever

Q fever is a zoonosis with a worldwide distribution with the exception of New Zealand. The disease is caused by Coxiella burnetii, a strictly intracellular, gram-negative bacterium. Many species of mammals, birds, and ticks are reservoirs of C. burnetii in nature. C. burnetii infection is most often latent in animals, with persistent shedding of bacteria into the environment. However, in females intermittent high-level shedding occurs at the time of parturition, with millions of bacteria being released per gram of placenta. Humans are usually infected by contaminated aerosols from domestic animals, particularly after contact with parturient females and their birth products. Although often asymptomatic, Q fever may manifest in humans as an acute disease (mainly as a self-limited febrile illness, pneumonia, or hepatitis) or as a chronic disease (mainly endocarditis), especially in patients with previous valvulopathy and to a lesser extent in immunocompromised hosts and in pregnant women. Specific diagnosis of Q fever remains based upon serology. Immunoglobulin M (IgM) and IgG antiphase II antibodies are detected 2 to 3 weeks after infection with C. burnetii, whereas the presence of IgG antiphase I C. burnetii antibodies at titers of >/=1:800 by microimmunofluorescence is indicative of chronic Q fever. The tetracyclines are still considered the mainstay of antibiotic therapy of acute Q fever, whereas antibiotic combinations administered over prolonged periods are necessary to prevent relapses in Q fever endocarditis patients. Although the protective role of Q fever vaccination with whole-cell extracts has been established, the population which should be primarily vaccinated remains to be clearly identified. Vaccination should probably be considered in the population at high risk for Q fever endocarditis.     

Q Fever in Tunisia

Q fever is a common zoonosis with almost a worldwide distribution caused by Coxiella burnetii. Farm animals and pets are the main reservoirs of infection and transmission to humans is usually via inhalation of contaminated aerosols. Infection in humans is often asymptomatic, but it can manifest as an acute disease (usually a self-limited flu-like illness, pneumonia or hepatitis) or as a chronic form (mainly endocarditis, but also hepatitis and chronic-fatigue syndrome). In Tunisia, although prevalence of anti-Coxiella burnetii was high among blood donors, Q fever was rarely reported and frequently miss diagnosed by physicians. This study is a review of epidemiological and clinical particularities of Q fever in Tunisia.     

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.     

Microbiological Challenges in the Diagnosis of Chronic Q Fever

Diagnosis of chronic Q fever is difficult. PCR and culture lack sensitivity; hence, diagnosis relies mainly on serologic tests using an immunofluorescence assay (IFA). Optimal phase I IgG cutoff titers are debated but are estimated to be between 1:800 and 1:1,600. In patients with proven, probable, or possible chronic Q fever, we studied phase I IgG antibody titers at the time of positive blood PCR, at diagnosis, and at peak levels during chronic Q fever. We evaluated 200 patients, of whom 93 (46.5%) had proven, 51 (25.5%) had probable, and 56 (28.0%) had possible chronic Q fever. Sixty-five percent of proven cases had positive Coxiella burnetii PCR results for blood, which was associated with high phase I IgG. Median phase I IgG titers at diagnosis and peak titers in patients with proven chronic Q fever were significantly higher than those for patients with probable and possible chronic Q fever. The positive predictive values for proven chronic Q fever, compared to possible chronic Q fever, at titers 1:1,024, 1:2,048, 1:4,096, and ≥1:8,192 were 62.2%, 66.7%, 76.5%, and ≥86.2%, respectively. However, sensitivity dropped to <60% when cutoff titers of ≥1:8,192 were used. Although our study demonstrated a strong association between high phase I IgG titers and proven chronic Q fever, increasing the current diagnostic phase I IgG cutoff to >1:1,024 is not recommended due to increased false-negative findings (sensitivity < 60%) and the high morbidity and mortality of untreated chronic Q fever. Our study emphasizes that serologic results are not diagnostic on their own but should always be interpreted in combination with clinical parameters.     

Q Fever in Adults: Review of 66 Clinical Cases

Sixty-six cases of Q fever in adults, serologically confirmed by indirect immunofluorescence, were studied to analyze the epidemiological, clinical and therapeutic aspects of the disease. Eighty-three percent of the patients were male, and the mean age was 44.7 years. Contact with animals was recorded in 24 patients. The main clinical form of presentation was pneumonia (37 cases); eight patients had hypoxia, and five had respiratory failure. The empirical treatment consisted of macrolides in 36% of cases. Evolution was favorable in all cases. Electronic Publication     

High Coxiella burnetii DNA Load in Serum during Acute Q Fever Is Associated with Progression to a Serologic Profile Indicative of Chronic Q Fever

PCR is very effective in diagnosing acute Q fever in the early stages of infection, when bacterial DNA is present in the bloodstream but antibodies have not yet developed. The objective of this study was to further analyze the diagnostic value of semiquantitative real-time PCR (qPCR) in diagnosing acute Q fever in an outbreak situation. At the Jeroen Bosch Hospital, in 2009, qPCR testing for Coxiella burnetii DNA was performed for 2,715 patients suspected of having acute Q fever (positive, n = 385; negative, n = 2,330). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the qPCR assay were calculated for patients with negative qPCR results with a follow-up sample obtained within 14 days (n = 305) and qPCR-positive patients with at least one follow-up sample (n = 369). The correctness of the qPCR result was based on immunofluorescence assay results for samples submitted for qPCR and follow-up testing. The sensitivity of the Q fever qPCR assay was 92.2%, specificity 98.9%, PPV 99.2%, and NPV 89.8%. Patients who later developed serologic profiles indicative of chronic Q fever infection had significantly higher C. burnetii DNA loads during the acute phase than did patients who did not (P < 0.001). qPCR testing is a valuable tool for the diagnosis of acute Q fever and should be used in outbreak situations when the onset of symptoms is <15 days earlier. Special attention is needed in the follow-up monitoring of patients with high C. burnetii DNA loads during the acute phase, as this might be an indicator for the development of a serologic profile indicative of chronic infection.     

Emergence of macrolide resistant Streptococcus pyogenes strains in pediatric patients in France

A total of 206 recent throat isolates of Streptococcus pyogenes collected between 2002 and 2004 from children were tested for their susceptibility to penicillin, amoxycillin, erythromycin, clarythromycin and clindamycin. The erythromycin resistant isolates were further studied for their genetic mechanism of resistance by means of PCR. In all, 14.5% of the strains were erythromycin resistant and 13.5 and 1% expressed the constitutive MLS(B) and M resistance phenotypes and harbored the ermB and mef A genes respectively.     

Investigation of a Slaughterhouse-Related Outbreak of Q Fever in the French Alps

The aim of the study presented here was to describe the different epidemiological methods used to investigate an outbreak of Q fever that occurred in the spring of 1996 among inhabitants of Brian?on, a small town in the French Alps. Three approaches were used: (i) a comparison between a 2-month exhaustive serological survey among blood donors and a retrospective serological survey performed on frozen plasma collected by the transfusion centre in the spring of 1995; (ii) a serological survey performed in the general population by cluster sampling, using dried blood on blotting paper; and (iii) a case-control study. A total of 29 cases of acute Q fever were diagnosed by physicians during hospitalisations of the patients or ambulatory care. The case-control study suggested that the outbreak resulted from airborne transmission of contaminated sheep waste, which had been left uncovered in the slaughterhouse area. Such transmission may have been facilitated by the nearby heliport. The comparison between the cumulative incidence of Q fever among blood donors during the spring seasons of 1995 and 1996 confirmed the outbreak (0.38% vs. 2.58%, respectively; P<0.0001). Health authorities promptly decided to close the slaughterhouse. The use of complementary epidemiological methods allows investigators to focus on major issues related to an outbreak: timely detection of cases, identification of the source, estimations of incidence, and public health intervention. Rapid recognition and management of outbreaks in the general population of a rural region need to be improved, particularly at a time when airborne agents could be used as biological weapons. Electronic Publication     

Q Fever: A Troubling Disease and a Challenging Diagnosis

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

发热、瓣膜赘生物及血培养阴性——Q热

1 临床资料1.1 病史患者,男,61岁.因发热4月余入院.患者于4个月前出现间断午后发热,伴畏寒、寒战,体温最高40.2℃,无咳嗽、腹痛、腹泻、尿急、关节肿痛,服扑热息痛后热退;伴全身散在少量充血性丘疹,伴瘙痒.此后反复发热,间隔时间逐渐缩短,由每周1次发展为每日发热,午后为著,体温高峰38.2～38.5℃,偶尔高达39℃～40℃,可自行退热;伴乏力、盗汗,先后予多种抗生素治疗无效.体质量下降5 kg.既往体健,否认结核接触史及病畜接触史.吸烟20支/d×30年,饮白酒2两/d×30年.     

Ribonucleic Acid and Protein Synthesis in Guinea Pig Liver During Q Fever

Protein and ribonucleic acid (RNA) syntheses increase in the liver during Q fever, coincident with progressive increments in cortisol levels. Cell-free protein-synthesizing systems indicate that the pH 5 enzyme fraction was chiefly responsible for enhanced activity. Although the polysome profiles from normal and infected livers were similar, the number of liver ribosomes doubled during infection. There was a concomitant increase in orotate incorporation in the 28s, 18s, and 4s RNA species of infected liver.     

Septic Arthritis and Concern for Osteomyelitis in a Child with Rat Bite Fever

Rat bite fever is a rare infection usually caused by Streptobacillus moniliformis. A case of septic arthritis and possible osteomyelitis as sequelae of rat bite fever in a pediatric patient is described.