Tissue distribution of Coxiella burnetii and antibody responses in macropods co-grazing with livestock in Queensland, Australia.

Coxiella burnetii, the causative agent of Q fever, is a zoonotic bacteria of global public health significance. The organism has a complex, diverse, and relatively poorly understood animal reservoir but there is increasing evidence that macropods play some part in the epidemiology of Q fever in Australia. The aim of this cross-sectional survey was to estimate the animal- and tissue-level prevalence of coxiellosis amongst eastern grey (Macropus giganteus) and red (Osphranter rufus) kangaroos co-grazing with domestic cattle in a Q fever endemic area in Queensland. Serum, faeces and tissue samples from a range of organs were collected from 50 kangaroos. A total of 537 tissue samples were tested by real-time PCR, of which 99 specimens from 42 kangaroos (84% of animals, 95% confidence interval [CI], 71% to 93%) were positive for the C. burnetii IS1111 gene when tested in duplicate. Twenty of these specimens from 16 kangaroos (32%, 95% CI 20% to 47%) were also positive for the com1 or htpAB genes. Serum antibodies were present in 24 (57%, 95% CI 41% to 72%) of the PCR positive animals. There was no statistically significant difference in PCR positivity between organs and no single sample type consistently identified C. burnetii positive kangaroos. The results from this study identify a high apparent prevalence of C. burnetii amongst macropods in the study area, albeit seemingly with an inconsistent distribution within tissues and in relatively small quantities, often verging on the limits of detection. We recommend Q fever surveillance in macropods should involve a combination of serosurveys and molecular testing to increase chances of detection in a population, noting that a range of tissues would likely need to be sampled to confirm the diagnosis in a suspect positive animal.

Coxiella burnetii effector CvpE maintains biogenesis of Coxiella-containing vacuoles by suppressing lysosome tubulation through binding PI(3)P and perturbing PIKfyve activity on lysosomes.

Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease. Intracellular replication of C. burnetii requires the maturation of a phagolysosome-like compartment known as the replication permissive Coxiella-containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that C. burnetii secreted Coxiella vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca2+ channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and C. burnetii replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.

Bacterial burden and molecular characterization of Coxiella burnetii in shedding pregnant and postpartum ewes from Saint Kitts.

This study aimed to evaluate the bacterial burden and perform molecular characterization of Coxiella burnetii during shedding in pregnant (vaginal, mucus and feces) and postpartum (vaginal mucus, feces and milk) ewes from Saint Kitts. Positive IS1111 DNA (n=250) for C. burnetii samples from pregnant (n=87) and postpartum (n=74) Barbados Blackbelly ewes in a previous investigation were used for this study. Vaginal mucus (n=118), feces (n=100), and milk (n=32) positive IS1111 C. burnetii-DNA were analysed by real time qPCR (icd gene). For molecular characterization of C. burnetii, selected (n=10) IS1111 qPCR positive samples were sequenced for fragments of the IS1111 element and the 16 S rRNA gene. nBLAST, phylogenetic and haplotype analyses were performed. Vaginal mucus, feces and milk had estimated equal amounts of bacterial DNA (icd copies), and super spreaders were detected within the fecal samples. C. burnetii haplotypes had moderate to high diversity, were ubiquitous worldwide and similar to previously described in ruminants and ticks and humans.

One Health approach to Coxiella burnetii in Brazilian indigenous communities.

Indigenous health has posted complex challenges worldwide, particularly due to historical economic, territorial, social and environmental processes, which may lead to emergence and reemergence of pathogens. In addition to few Coxiella burnetii serosurveys in vulnerable populations, especially in developing tropical countries, no comprehensive One Health approach has focused on human-animal infection along with potential environmental determinants. Accordingly, this study aimed to assess the seroprevalence of anti-C. burnetii antibodies in indigenous populations and their dogs from 10 indigenous communities distributed in southern and southeastern Brazil, along with the correspondent healthcare professionals. In overall, 8/893 (0.90%; 95% CI 0.45-1.76) indigenous and 1/406 (0.25%) dog samples were seropositive, with 7/343 (2.04%) individuals the 1/144 (0.69%) dog from the Ocoy community, located in the city of São Miguel do Iguaçu, bordering Argentina at south, and far 10 km at west from Paraguay. All 84 healthcare professionals tested seronegative.

Ultraviolet C inactivation of Coxiella burnetii for production of a structurally preserved whole cell vaccine antigen.

Q fever, a worldwide-occurring zoonotic disease, can cause economic losses for public and veterinary health systems. Vaccines are not yet available worldwide and currently under development. In this regard, it is important to produce a whole cell antigen, with preserved structural and antigenic properties and free of chemical modifications. Thus, inactivation of Coxiella burnetii with ultraviolet light C (UVC) was evaluated. C. burnetii Nine Mile phase I (NMI) and phase II (NMII) were exposed to decreasing intensities in a time-dependent manner and viability was tested by rescue cultivation in axenic medium or cell culture. Effects on the cell structure were visualized by transmission electron microscopy and antigenicity of UVC-treated NMI was studied by immunization of rabbits. NMI and NMII were inactivated at UVC intensities of 250 µW/cm2 for 5 min or 100 µW/cm2 for 20 min. Reactivation by DNA repair was considered to be unlikely. No morphological changes were observed directly after UVC inactivation by transmission electron microscopy, but severe swelling and membrane degradation of bacteria with increasing severity occurred after 24 and 48 h. Immunization of rabbits resulted in a pronounced antibody response. UVC inactivation of C. burnetii resulted in a structural preserved, safe whole cell antigen and might be useful as antigen for diagnostic purposes or as vaccine candidate.

Prevalence and associated risk factors of anti-Coxiella burnetii antibodies in dairy cattle herds using bulk tank milk analysis in Kabylia area, north Algeria.

Coxiella burnetii, or Q fever agent, has notable implications for human and livestock health. Infections in cattle primarily manifest through reproductive issues where infected animals shed the bacterium in birth fluids, placental tissues, and milk, serving as potential sources of transmission. Bovine herds become reservoirs, contributing to the environmental contamination of farming areas. Comprehensive studies on the prevalence, transmission routes, and associated risk factors among cattle contribute to the development of effective control strategies, ultimately safeguarding both livestock and public health.Here we determine the prevalence of Coxiella burnetii antibodies against in dairy cattle farms from Kabylia (northern Algeria) and identify the associated risk factors. Bulk tank milk samples from 184 farms were analyzed by indirect ELISA technique, 49 of them were tested positive which corresponds to a prevalence rate of 26.63% (95% CI 20.25-33.01%). Multivariate analysis by logistic regression showed that the risk factors associated with detection of anti-Coxiella burnetii antibodies are: cohabitation of cattle with small ruminants(OR = 3.74 95% CI [1.41-8.92]), exposure to prevailing winds (OR = 5.12 95% CI [2.11-13.45]), and the veterinarian visits frequency(OR = 5.67 95% CI [2.55-13.60]). These findings underscore the susceptibility of dairy cattle to Q fever in the Kabylia region, highlighting practices that pose risks. We recommend the implementation of hygienic measures and adherence to proper farming conditions to mitigate the transmission of Q fever and reduce the associated zoonotic risk.

Risk factors associated with Coxiella burnetii in wild boars: A study in South Korea.

Coxiella burnetii is a Gram-negative bacterium that causes the zoonotic disease Q fever. Wild boars serve as reservoirs for C. burnetii. This study aimed to identify the risk factors associated with C. burnetii infection in wild boars. We analyzed the data from 975 wild boar samples collected from June to November 2021 in South Korea. We utilized the indirect ELISA to detect antibodies against C. burnetii. A sample optical density to positive-control optical density value exceeding 50% was classified as positive. We gathered data on the forestation, terrain, weather, agriculture, and animal density of the region where the samples were collected. Continuous variables were categorized into tertiles. We performed a univariate logistic regression analysis and included variables with a p-value < 0.2 in the final multivariable logistic regression model. In our multivariable logistic regression analysis to identify risk factors for C. burnetii infection in wild boars, we used a forward selection method to enter variables based on the order of their significance. We performed the final multivariable logistic regression analyses using either continuous variables or variables categorized into tertiles. The prevalence of C. burnetii was 14.6% (n=142). Locations with the highest maximum wind speeds (3.92-8.24 m/s) showed a 59% increase in infection odds compared to locations with the lowest speeds (1.45-3.25 m/s)(p=0.044). For each 1 m/s increase in maximum wind speed, infection odds increased by 24.1% (p=0.037). Regions with the highest percentage of paddy fields per area (8.3-45%) showed a 76% increase in infection odds compared to regions with the lowest percentage (0-1.5%)(p=0.011). For each 1% increase in the proportion of paddy fields per area, infection odds increased by 3.3% (p=0.003). High maximum wind speed and a high percentage of paddy field were identified as significant risk factors for C. burnetii infection in wild boars.

Occupational exposure to Coxiella burnetii during cardiac surgery: A case report and review of the literature.

We report a case of exposure to Coxiella burnetii in a surgical nurse who underwent an injury of her finger with a scalpel blade during a native aortic valve replacement with a bio-prosthetic cardiac valve conducted on a patient suffering from C. burnetii aortic endocarditis. Given the positivity of C. burnetii culture and PCR from the patient's aortic valve, she was prescribed prophylactic doxycycline 100 mg twice a day for 10 days. Q fever is an occupational zoonosis resulting usually of exposure to infected animals by inhalation of infected aerosols or consumption of contaminated raw milk. Apart from materno-foetal transmission, about 180 cases of human-to-human C. burnetii transmission have been published from 1949 to today, including transmission by blood transfusion, sexual relations, transmission in the healthcare setting to staff, patient attendants and other patients that were likely infected from inhalation of aerosol from respiratory or placental products, transmission to staff during autopsies of patients with Q fever and transmission in familial settings. As C. burnetii is a highly infectious bacterium, that may cause infection with a low inoculum, it should be added to the list of organisms which may be of concern following blood exposure among healthcare professionals.

Molecular detection and characterization of Coxiella burnetii in aborted samples of livestock in China.

Coxiella burnetii is the causative agent of zoonotic Q fever. Animals are the natural reservoirs of C. burnetii, and domestic livestock represent the major sources of human infection. C. burnetii infection in pregnant females may causes abortion during late pregnancy, whereby massive shedding of C. burnetii with abortion products becomes aerosolized and persists in the environment. Therefore, monitoring and surveillance of this infection in livestock is important for the prevention of the C. burnetii transmission. Previous serological surveys have shown that C. burnetii infection is endemic in livestock in China. However, few data are available on the diagnosis of C. burnetii as a cause of abortion by molecular methods in livestock. To get a better understanding of the impact of C. burnetii infection on domestic livestock in China, a real-time PCR investigation was carried out on collected samples from different domestic livestock suffering abortion during 2021-2023. A total of 338 samples collected from eight herds of five livestock species were elected. The results showed that 223 (66 %) of the collected samples were positive for C. burnetii DNA using real-time PCR. For the aborted samples, 82 % (128/15) of sheep, 81 % (34/42) of goats, 44 % (15/34) of cattle, 69 % (18/26) of camels, and 50 % (17/34) of donkeys were positive for C. burnetii. Besides, 44 % (8/18) and 4 % (1/25) of asymptomatic individuals of sheep and donkey were also positive for C. burnetii. In addition, the positive samples were further confirmed by amplification and sequencing of the C. burnetii-specific isocitrate dehydrogenase (icd) gene. Phylogenetic analysis based on specific gene fragments of icd genes revealed that the obtained sequences in this study were clustered into two different groups associated with different origin of hosts and geographic regions. This is the first report confirming that C. burnetii exists in aborted samples of sheep, goats, cattle, donkeys and camels in China. Further studies are needed to fully elucidate the epidemiology of this pathogen in livestock as well as the potential risks to public health.

Drosophila melanogaster Sting mediates Coxiella burnetii infection by reducing accumulation of reactive oxygen species.

The Gram-negative bacterium Coxiella burnetii is the causative agent of query fever in humans and coxiellosis in livestock. C. burnetii infects a variety of cell types, tissues, and animal species including mammals and arthropods, but there is much left to be understood about the molecular mechanisms at play during infection in distinct species. Human stimulator of interferon genes (STING) induces an innate immune response through the induction of type I interferons (IFNs), and IFN promotes or suppresses C. burnetii replication, depending on tissue type. Drosophila melanogaster contains a functional STING ortholog (Sting) which activates NF-κB signaling and autophagy. Here, we sought to address the role of D. melanogaster Sting during C. burnetii infection to uncover how Sting regulates C. burnetii infection in flies. We show that Sting-null flies exhibit higher mortality and reduced induction of antimicrobial peptides following C. burnetii infection compared to control flies. Additionally, Sting-null flies induce lower levels of oxidative stress genes during infection, but the provision of N-acetyl-cysteine (NAC) in food rescues Sting-null host survival. Lastly, we find that reactive oxygen species levels during C. burnetii infection are higher in Drosophila S2 cells knocked down for Sting compared to control cells. Our results show that at the host level, NAC provides protection against C. burnetii infection in the absence of Sting, thus establishing a role for Sting in protection against oxidative stress during C. burnetii infection.

Molecular detection and MST genotyping of Coxiella burnetii in ruminants and stray dogs and cats in Northern Algeria.

Aiming at identifying the reservoir and contamination sources of Coxiella burnetii in Northern Algeria, we investigated the molecular presence of the bacterium in 599 samples (blood, placenta, liver, spleen, and uterus) collected from cattle, sheep, dogs and cats. Our qPCR results showed that 15/344 (4.36%) blood samples and six/255 (2.35%) organ specimens were positive for C. burnetii. In cattle, three (4%) blood and liver samples were positive. In sheep, one blood (1.19%) and 3 (8.57%) placenta samples were positive. At the Algiers dog pound, 8 (10%) and 3 (5%) blood samples were qPCR positivein dogs and cats, respectively. In addition, MST genotyping showed that MST 33 was present in cattle and sheep, MST 20 in cattle,andMST 21 in dogs and cats.

Coxiella burnetii seroprevalence in domestic goat does in the United States: Prevalence, distribution, and associated risk factors.

Infection with the bacterium Coxiella burnetii can cause coxiellosis in animals and Q fever in humans. Coxiellosis a consistently underreported infectious disease. The infection can result in reproductive consequences for humans and animals. Ruminants are a reservoir for infection and humans are generally infected via aerosolized secretions, making it a public health concern. Studies of ruminant seroprevalence are generally limited in size and scope. This study determined seroprevalence in a large-scale U.S. population of female goats using serum samples from 7736 does from 24 states. This study identified C. burnetii seroprevalence in the United States domestic goat population. Overall, 14.5 % (SE = 2.3) of does were seropositive and 21.0 % (SE = 2.4) of operations had at least 1 seropositive doe. Further, operation demographics and herd management practices associated with seropositivity were as follows: the suspected or confirmed presence of caprine arthritis encephalitis (CAE), caseous lymphadenitis (CL), Johne's disease, or sore mouth in the herd in the previous 3 years, not cleaning or disinfecting the kidding areas or removing aborting does from other does, allowing visitors to access the kidding areas, and a lower percentage of adult goat inventory that were adult bucks or wethers. Furthermore, goat breed was associated with seropositivity. These data show C. burnetii seroprevalence in the United States and identify operation and animal characteristics and management practices associated with C. burnetii seropositivity. Together, this information can be used to help limit animal transmission, inform public health measures, and help educate and protect individuals working with goats.

Coxiella burnetii infections from animals and ticks in South Africa: a systematic review.

Coxiella burnetii is a zoonotic intracellular bacterium that is widely distributed and affects domestic animals, wildlife, humans and non-mammalian species. This systematic review was aimed at synthesizing research findings on C. burnetii in both domestic and wild animals of South Africa. The systematic review protocol was registered with Open Society Foundations of systematic reviews ( https://doi.org/10.17605/OSF.IO/8WS ). PRISMA guidelines were followed to collect and evaluate relevant scientific articles published on C. burnetii infecting domestic and wild animals in South Africa. Published articles were sourced from five electronic databases, namely, Google Scholar, PubMed and ScienceDirect, EBSCO and Scopus. Results showed 11 eligible studies involving four domestic animals, three wild animals and one ectoparasite species from seven provinces across South Africa. The occurrence of C. burnetii infection was high in Ceratotherium simum (white rhinoceros) (53.9%), medium in sheep (29.0%) and low in pigs (0.9%). Limpopo province (26%) had the most recorded infections followed by KwaZulu-Natal (19%) and Free State (3%) had the least reported occurrence of C. burnetii. The current study discovered that there is scarcity of published research on prevalence and distribution of C. burnetii infecting domestic and wild animals in South Africa, and this is of concern as this bacterium is an important zoonotic pathogen of "One Health" importance.

Cell death induction facilitates egress of Coxiella burnetii from infected host cells at late stages of infection.

Intracellular bacteria have evolved mechanisms to invade host cells, establish an intracellular niche that allows survival and replication, produce progeny, and exit the host cell after completion of the replication cycle to infect new target cells. Bacteria exit their host cell by (i) initiation of apoptosis, (ii) lytic cell death, and (iii) exocytosis. While bacterial egress is essential for bacterial spreading and, thus, pathogenesis, we currently lack information about egress mechanisms for the obligate intracellular pathogen C. burnetii, the causative agent of the zoonosis Q fever. Here, we demonstrate that C. burnetii inhibits host cell apoptosis early during infection, but induces and/or increases apoptosis at later stages of infection. Only at later stages of infection did we observe C. burnetii egress, which depends on previously established large bacteria-filled vacuoles and a functional intrinsic apoptotic cascade. The released bacteria are not enclosed by a host cell membrane and can infect and replicate in new target cells. In summary, our data argue that C. burnetii egress in a non-synchronous way at late stages of infection. Apoptosis-induction is important for C. burnetii egress, but other pathways most likely contribute.

Q fever - immune responses and novel vaccine strategies.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. It is an occupational risk for employees of animal industries and is associated with contact with wildlife and domestic animals. Although Q fever infection may be asymptomatic, chronic sequelae such as endocarditis occur in 5% of symptomatic individuals. Disease outcomes may be predicted through measurement of immune correlates. Vaccination is the most efficient method to prevent Q fever. Currently, Q-VAX is the only licenced human vaccine. Q-VAX is highly effective; however, individuals previously exposed to C. burnetii are at risk of adverse reactions. This review examines the immunological responses of acute and chronic Q fever and the efforts to provide a safer and cost-effective Q fever vaccine.

Q fever is a disease that is spread by some animals, such as sheep and cattle, to humans. Although most people will recover if they get Q fever, some become very ill. There is a vaccine for Q fever (Q-VAX), but it can cause a reaction when given to some people. Research is ongoing into how the human immune system reacts to the bacteria that causes Q fever. A small number of people who get Q fever will develop a prolonged disease that can be serious and affect the heart, which is why there is also research into developing new vaccines for this disease. This research will look at those parts of the germ that causes Q fever that can be used for a new vaccine.

Identification and Characterization of an HtrA Sheddase Produced by Coxiella burnetii.

Having previously shown that soluble E-cadherin (sE-cad) is found in sera of Q fever patients and that infection of BeWo cells by C. burnetii leads to modulation of the E-cad/ß-cat pathway, our purpose was to identify which sheddase(s) might catalyze the cleavage of E-cad. Here, we searched for a direct mechanism of cleavage initiated by the bacterium itself, assuming the possible synthesis of a sheddase encoded in the genome of C. burnetii or an indirect mechanism based on the activation of a human sheddase. Using a straightforward bioinformatics approach to scan the complete genomes of four laboratory strains of C. burnetii, we demonstrate that C. burnetii encodes a 451 amino acid sheddase (CbHtrA) belonging to the HtrA family that is differently expressed according to the bacterial virulence. An artificial CbHtrA gene (CoxbHtrA) was expressed, and the CoxbHtrA recombinant protein was found to have sheddase activity. We also found evidence that the C. burnetii infection triggers an over-induction of the human HuHtrA gene expression. Finally, we demonstrate that cleavage of E-cad by CoxbHtrA on macrophages-THP-1 cells leads to an M2 polarization of the target cells and the induction of their secretion of IL-10, which "disarms" the target cells and improves C. burnetii replication. Taken together, these results demonstrate that the genome of C. burnetii encodes a functional HtrA sheddase and establishes a link between the HtrA sheddase-induced cleavage of E-cad, the M2 polarization of the target cells and their secretion of IL-10, and the intracellular replication of C. burnetii.

A simple method for enrichment of phase I Coxiella burnetii.

Coxiella burnetii is the bacterial causative agent of the zoonosis Q fever. This bacterium undergoes lipopolysaccharide (LPS) phase transition similar to Enterobacteriaciae upon in vitro passage. Full-length, phase I C. burnetii LPS is a critical virulence factor and profoundly impacts vaccine-induced immunogenicity; thus, LPS phase is an important consideration in C. burnetii experimentation and Q fever vaccine design. Typically, phase I LPS-expressing organisms are obtained from the tissues of infected experimental animals. In this process, residual phase II LPS-expressing organisms are thought to be cleared by the host immune system. Here, we propose an efficient and non-animal-based method for the enrichment of C. burnetii phase I LPS-expressing bacteria in vitro. We utilize both Vero cell culture to selectively enrich solutions with phase I and intermediate phase LPS-expressing bacteria. This simple and quick method decreases reliance on experimental animals and is a sustainable solution for Q fever diagnostic and vaccine development hurdles.

Modulation of the E-cadherin in human cells infected in vitro with Coxiella burnetii.

High concentration of soluble E-cadherin (E-cad) was previously found in sera from Q fever patients. Here, BeWo cells which express a high concentration of E-cad were used as an in vitro model to investigate the expression and function of E-cad in response to infection by Coxiella burnetii, the etiological agent of Q fever. Infection of BeWo cells with C. burnetii leads to a decrease in the number of BeWo cells expressing E-cad at their membrane. A shedding of soluble E-cad was associated with the post-infection decrease of membrane-bound E-cad. The modulation of E-cad expression requires bacterial viability and was not found with heat-inactivated C. burnetii. Moreover, the intracytoplasmic cell concentration of ß-catenin (ß-cat), a ligand of E-cad, was reduced after bacterial infection, suggesting that the bacterium induces modulation of the E-cad/ß-cat signaling pathway and CDH1 and CTNNB1 genes transcription. Finally, several genes operating the canonical Wnt-Frizzled/ß-cat pathway were overexpressed in cells infected with C. burnetii. This was particularly evident with the highly virulent strain of C. burnetii, Guiana. Our data demonstrate that infection of BeWo cells by live C. burnetii modulates the E-cad/ß-cat signaling pathway.

Interaction between host cell mitochondria and Coxiella burnetii.

In order to successfully establish a replicative niche, intracellular bacterial pathogens must influence eukaryotic cell biology. Vesicle and protein traffic, transcription and translation, metabolism and innate immune signaling are all important elements of the host-pathogen interaction that can be manipulated by intracellular bacterial pathogens. The causative agent of Q fever, Coxiella burnetii, is a mammalian adapted pathogen that replicates in a lysosome-derived pathogen-modified vacuole. C. burnetii establishes this replicative niche by using a cohort of novel proteins, termed effectors, to hijack the mammalian host cell. The functional and biochemical roles of a small number of effectors have been discovered and recent studies have demonstrated that mitochondria are a bona fide target for a subset of these effectors. Various approaches have begun to unravel the role these proteins play at mitochondria during infection, with key mitochondrial functions, including apoptosis and mitochondrial proteostasis, likely influenced by mitochondrially localized effectors. Additionally, mitochondrial proteins likely contribute to the host response to infection. Thus, investigating the interplay between host and pathogen elements at this central organelle will uncover important new understanding of the C. burnetii infection process. With the advent of new technologies and sophisticated omics approaches, we are poised to explore the interaction between host cell mitochondria and C. burnetii with unprecedented spatial and temporal resolution.

Seroprevalence of arthropod-borne bacterial infections in homeless individuals in Hamburg in 2020.

PURPOSE: The number of homeless people in Germany is steadily increasing. Due to their often precarious living conditions, this specific population may be increasingly exposed to ectoparasites that can transmit various pathogens. To assess the prevalence and thus the risk of such infections, we analyzed the seropositivity of rickettsiosis, Q fever, tularemia and bartonellosis in homeless individuals. METHODS: A total of 147 homeless adults from nine shelters in Hamburg, Germany, were included. The individuals underwent questionnaire-based interviewing, physical examination, and venous blood was drawn between May and June 2020. Blood samples were analyzed for antibodies against rickettsiae (Rickettsia typhi and R. conorii), Coxiella burnetii, Francisella tularensis and bartonellae. RESULTS AND CONCLUSION: A very low seroprevalence of R. typhi and F. tularensis infection was found (0-1%), while antibodies against R. conorii and C. burnetii were more common (7% each), followed by a relatively high seroprevalence of 14% for bartonellosis. Q fever seroprevalence was associated with the country of origin, whereas bartonellosis seroprevalence was associated with the duration of homelessness. Preventive measures targeting ectoparasites, especially body lice, should be put in place continuously.