Q fever: more common than we think, and what this means for prevention

Delayed diagnosis of persistent Q fever: a case series from China

BACKGROUND

Q fever, caused by the zoonotic pathogen Coxiella burnetii, exhibits a worldwide prevalence. In China, Q fever is not recognized as a notifiable disease, and the disease is overlooked and underestimated in clinical practice, leading to diagnostic challenges.

CASE PRESENTATION

We present a case series of three patients diagnosed with persistent Q fever between 2022 and 2023. The average age of our three cases was 63.33 years old, consisting of two males and one female. The medical history of the individuals included previous valve replacement, aneurysm followed by aortic stent-graft placement and prosthetic hip joint replacement. At the onset of the disease, only one case exhibited acute fever, while the remaining two cases were devoid of any acute symptoms. The etiology was initially overlooked until metagenomic next-generation sequencing test identified Coxiella burnetii from the blood or biopsy samples. Delayed diagnosis was noted, with a duration ranging from three months to one year between the onset of the disease and its confirmation. The epidemiological history uncovered that none of the three cases had direct exposure to domestic animals or consumption of unpasteurized dairy products. Case 1 and 2 resided in urban areas, while Case 3 was a rural resident engaged in farming. All patients received combination therapy of doxycycline and hydroxychloroquine, and no recurrence of the disease was observed during the follow-up period.

CONCLUSION

Q fever is rarely diagnosed and reported in clinical practice in our country. We should be aware of persistent Q fever in high-risk population, even with unremarkable exposure history. Metagenomic next-generation sequencing holds great potential as a diagnostic tool for identifying rare and fastidious pathogens such as Coxiella burnetii.

Case Report: Metagenomic Next-Generation Sequencing Clinches the Diagnosis of Acute Q Fever and Verified by Indirect Immunofluorescence Assay

Q fever is a zoonotic infectious disease caused by Coxiella burnetii. The clinical symptoms of acute Q fever are usually atypical, and routine serological tests of C. burnetii are not readily available, making the diagnosis of Q fever a challenge. In this case, we report a male patient who had repeated fevers and was administered empirical anti-infective treatment, but the effect was poor. After conducting relevant laboratory and imagological examinations, the etiology has not yet been confirmed. Subsequently, metagenomic next-generation sequencing (mNGS) identified the sequence reads of C. burnetii from the patient's peripheral blood within 48 h, and then the diagnosis of acute Q fever was established. Moreover, the serological test of indirect immunofluorescence assay (IFA) of the C. burnetii antibody was further performed in the Centers for Disease Control, certifying the result of mNGS. The patient was ultimately treated with doxycycline and recovered well. mNGS is an unbiased and comprehensive method in infrequent or culture-negative pathogen identification. To our knowledge, this is the first case of acute Q fever identified by mNGS and confirmed by IFA in Taizhou, China. A further large-scale prospective clinical cohort study is worth carrying out to compare the diagnostic efficiency of mNGS with traditional serological methods and PCR in acute Q fever.

… İlindeki Q ateşi olgularının retrospektif olarak değerlendirilmesi

Amaç: Q ateşi, özellikle risk grubundaki bireylerde akut ve kronik formda görülebilen, özgül olmayan semptomları nedeniyle tanısı atlanabilen, zoonotik bir hastalıktır. Önceleri sıklıkla yanlış tanı alan bu hastalık olguları, ülkemizden de son yıllarda bildirilmeye başlamıştır. Bu çalışmada Q ateşi olgularının klinik ve laboratuvar parametrelerini retrospektif olarak değerlendirmeyi ve Q ateşi farkındalığını arttırmayı amaçladık. Gereç ve Yöntem: Retrospektif gözlemsel çalışmamızda, 1 Ocak 2018–1 Mart 2021 tarihleri arasında hastanemizde takip ve tedavi edilen, 18 yaş üstü, kesin tanı almış, Q ateşi olguları değerlendirildi. Hastalara ait yaş, cinsiyet, meslek, ikamet edilen yer gibi demografik veriler, kene teması öyküleri, hastalığın geliştiği zaman dilimi (yıl, mevsim, ay), eşlik eden komorbiditeler, semptomlar, fizik muayene ve laboratuvar bulguları, tedaviler, hastaların iyileşme ve mortalite durumları irdelendi. Bulgular: Çalışmaya yaş ortalaması 49,23±12,07 yıl, 7’si (%57) erkek olan 14 olgu dahil edildi. Olguların sadece 5’i (%35,7) çiftçi, dördü (%28,57) hayvancılık yapıyordu. Kırsal alanda yaşama 9 (%64,28) olguda mevcuttu. En sık semptomlar ateş yüksekliği (%100), öksürük (%71,42) ve miyalji (%57,14) idi. Olguların tamamı akut Q ateşi olgusu olup, endokardit hiçbir olguda saptanmadı. Sonuç: Ülkemizin Q ateşi hastalığı için olası endemik bölgelerden olması nedeniyle, özellikle kırsal kesimde yaşayan, hayvancılıkla uğraşma, pastörize edilmemiş süt/süt ürünü tüketme gibi risk faktörleri olan hastalarda pnömoni başta olmak üzere birçok hastalığın ayırıcı tanısında düşünülmesi gerektiğini vurgulamak istedik.