Background
Post infection fatigue syndrome has been described in patients exposed to facultative intracellular bacteria, including
Coxiella burnetii (C.b.) - the causative agent of Q fever, as well as viruses [
1]. The highly infectious (
ca. one organism) rickettsia-like intracellular bacterium infects and multiplies in macrophages. In a previous report of a Q fever outbreak in Birmingham, our group identified a non-infective complex of
C.b. antigens able to survive in the host and provoked aberrant humoral and cell-mediated immunity responses [
2,
3]. The study led to recognition of a possible pathogenic link between infection and subsequent long-term post Q fever chronic fatigue syndrome (QFS).
We report a 19-year old female patient (coded initials BI) who became ill with an acute unexplained febrile encephalitis-like illness, followed by increasingly severe multisystem dysfunction and death ten years later (in 1996). During life, extensive clinical and laboratory investigations from different disciplinary stand points failed to deliver a definitive identification of a cause, but descriptive diagnoses, such as post infection fatigue syndrome, or just before death, Behçet’s syndrome, were proposed. During her last 10 years, BI presented with severe fluctuating headaches, frequent dizziness, fever 40C+, recurrent episodes of extensive pharyngeal ulcerations, muscular pain, persistent fatigue, joint pains, myoclonic seizures, quadriparesis, symptoms suggestive of meningism (neck rigidity and photophobia), bulbar paralysis and a range of gastrointestinal tract symptoms including abdominal pains, nausea, diarrhoea, bloating, oesophageal spasms as well as weight loss. It was noted that before the “encephalitis” there had been a history of inadequate, slow immune resolution on contracting various childhood infections.
At autopsy, standard histo-pathological methods revealed few abnormalities gross, or microscopic - an ulcer of the hard palate and very sparse patchy chronic inflammatory cell infiltration close to the atrio-ventricular node conducting system of the heart. Levels of inflammatory markers such as C-reactive protein (CRP) were within normal range, but with increased erythrocyte sedimentation rate. The negative organ and tissue profile was in sharp contrast to the severity of the symptomatic effects during life that included abnormal disabling fatigability, transient loss of consciousness (“blackouts”), loss of control over electrolyte balance and unexplained tissue oedema.
In view of BI’s early history of abnormal susceptibility to infections, her acute fever and ‘encephalitic’ symptoms with a diagnostic label of severe “post viral infection fatigue syndrome”, we suggested that her chronic persistent and severe multisystem disability might be an incidental systemic side effect (“bystander damage”) of the specialised effector mechanisms, immune mediators and other gene products of facultative intracellular bacteria.
A major challenge remained that despite intense and dedicated investigative efforts from various medical sub-disciplines it had not been possible to identify definitively the factors driving the severe disturbance of homeostasis and organ dysfunction exhibited by the course of BI’s 10-year illness. In anticipation that a changed paradigm for post infection and related fatigue states would eventually emerge, BI’s family had retained the paraffin wax-embedded or fixed slices of blocks of autopsy tissues from the patient’s brain, spleen, liver, lymph nodes (LN), bone marrow (BM), heart, lung and other organs. The post mortem samples were submitted by the family for examination by extended techniques to search for possible changes in the brain using immune-cytochemical markers for astrocytes and microglia. In the course of examining the paraffin wax-embedded tissues for possible neuropathology, prior Q fever infection was considered. BI had previously visited farms a number of times during childhood (see review [
4]). Q fever antigens or specific antibodies had not been previously tested. This led to extended tests with staining for Q fever antigens in the paraffin wax-embedded tissues. This report presents the immunohistochemical and PCR findings of
C.b. antigens and DNA respectively in several organs, including astrocytes, from the patient’s post mortem samples and discusses the association between persistence of the antigens, albeit non-infective, and QFS.
Conclusions
The scope and overall interpretation of our report on the re-evaluation of the fixed, paraffin-embedded tissue samples taken at patient BI’s autopsy are necessarily limited by the absence of diagnostic results of any serological or other tests for candidate infective organisms at the time of the “viral encephalitis” in 1986 (see review [
17]). Nevertheless, taken together, the extended laboratory tests with
C.b. specific monoclonal antibodies and PCR (COM1 and IS1111a genes) on a range of post mortem specimens suggest that the most compelling and coherent explanation of BI’s illness from 1986 to 1996, is one of a severe attack of primary Q fever and a subsequent multisystem organ dysfunction with dissemination of the coxiella throughout the body, ending in 1996 with cardiac and cerebral dysfunction i.e.
, a complex, severe idiopathic illness labelled descriptively at the time as “post (viral) infection fatigue syndrome” (PIFS).
An epidemiological and clinical association between laboratory-confirmed primary acute Q fever infection and a post infection fatigue syndrome was described in 1996/8 in meat workers and farmers in Australia and in patients in the wind-borne sheep-associated Q fever outbreak in the non-occupationally exposed populations of South Birmingham UK [
18,
19]. At first the post Q fever syndrome (QFS) tended to be interpreted as a psychogenic response by patients to a chronic debilitating illness. Since then, however, the association has been described in many countries. For example, an independent follow up of patients in a goat-associated Q fever outbreak in Alberta, Canada included a patient with severe unresolved cerebral symptoms but
C.b. was not isolated from the CNS [
20]. The recent major prevalence (>4000 cases) of goat-associated Q fever in the Netherlands, allowed well-controlled surveys for “post infection fatigue syndromes” and again confirmed prevalence of QFS and vascular complications after an initial infection [
21].
Some of the scepticism and difficulty of acceptance of QFS may have rested on a mistaken assumption that the model of infection with the small intracellular bacterium,
Coxiella burnetii, would follow a familiar set of characteristics of invasion, bacteraemia, inflammatory responses, finally resolution with rising antibody levels, acquired cellular immune responses and elimination of the invading organism [
2]. Investigations of QFS by the Q fever Research Group in Adelaide (Australia) have not supported this simple model [
2,
3]. Notably, long term persistence in the host of various components of the coxiella antigens shown e.g. LPS Phase I antigen, coxiella genomic DNA sequences and low level lgG class antibody in the human host to
C.b. Phase I & II antigens were often present in QFS patients more than 10 years after the original infection [
3]. On the other hand, in perplexing contrast, efforts to demonstrate consistent presence of the readily serial cultivable coccobacilliary form of the coxiella (small cell variant, SCV) in such materials have mostly failed [
2,
3,
18‐
20].
The SCV, the infectious particle, is found in the environment and is metabolically inactive. When internalized into a cell the SCV is transformed into the metabolically active large cell variant (LCV) [
22]. The LCV develops in response to acidification of the endosome and is associated with the development of the parasitophorous vacuole (PV) by the host cell that allows the organism to replicate. There is evidence to suggest that the highly acidic PV is regulated by the LCV and provides an excellent environment for it to grow. Further studies will be required to determine the relationship of the SCV with the PV [
23,
24].
In the acute phase of Q fever,
C.b. SCV is widely distributed in the host but in general they do not persist as they transition to the LCV form. In contrast non-infective
C.b. components - complexes of Phase 1 LPS, antigens, DNA sequences or insertion elements have been detected in PBMC, bone marrow aspirates or valve vegetations [
2,
3,
18,
19]. Such residual complexes of coxiella cell components persisted for 12–17 years after infection in the patients in the Birmingham UK Q fever outbreak [
3]. Despite some partial “immune” responses the
C.b. materials are not cleared and IL-2 is down-regulated, IFN-γ responses distorted and IL-6 responses are enhanced [
25,
26]. The effect is supported by robust ability of
C.b. to interfere with pathogen-initiated apoptosis upon infection of mammalian cells [
27,
28] and by the activation of type IV intracellular organism effector repertoire [
29,
30].
In summary, the recorded history, clinical findings and indices for patient BI, and the series of reports on QFS patients from the Adelaide Q fever Research Group in Australia and Birmingham UK, support a hypothesis that there is an association to be tested between persistence of C.b. components - as described above - the modified macrophage as a PV. The terms PIFS or QFS - while correctly labelling a major clinical presentation - do not do justice to the range of different effects or multiple host organ systems involved, particularly as illustrated in an unusual and exceptionally severe case such as patient BI.
Ethics approval and consent
Not applicable.
Consent for publication
Written informed consent was obtained from the patient’s parent for publication of this Case Report. A copy of the written consent is available for review by the Editor of this journal.
Availability of data and materials
All data supporting the findings are within the manuscript.
Acknowledgements
Professor Barrie P. Marmion passed away in July 2014. The authors would like to express our deep respect for the enormous contributions that Professor BPM made to Q Fever research, to the introduction of the Q Fever vaccine in Australia and the establishment of major virology research – in particular Hepatitis B. Two of his postgraduate students (AI, T-WK) and postdoctoral scientist (OS) are profoundly honoured to have been mentored by BPM.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
OS, T-WK, PB and BPM designed, analysed and interpreted the data; OS, JM, TWK, MT and PB did the immune-histochemical, IF and PCR tests and analysis; OS, T-WK, AI, PB and BPM drafted the manuscript. All authors approved the final manuscript.