Coxiella burnetiishedding by dairy cows

Susceptibility, Immunity, and Persistent Infection Drive Endemic Cycles of Coxiellosis on Dairy Farms

Coxiella (C.) burnetii, a zoonotic bacterium, is prevalent in dairy farms. Some cows develop a persistent infection and shed C. burnetii into milk and occasionally by amniotic fluid at calving. Serological diagnosis of Q fever in humans is performed by phase (Ph)-specific antibody tests; PhII antibodies usually indicate an acute infection, while the development of a chronic infection is characterised by elevated PhI antibody titres. Phase-specific tests have now been established for diagnosis of coxiellosis in cattle. Additionally, an interferon-γ (IFN-γ) recall assay has been implemented to assess cellular immunity to C. burnetii in cattle. Milk samples from all lactating cows (n = 2718) of 49 Bavarian dairy farms were collected through a convenience sample and analysed for phase-specific antibodies. Antibody profiles were evaluated by age. Based on the seropositivity of first-lactation cows, three distinct herd profiles were observed: an 'acute' state of herd infection was characterised by a PhI-/PhII+ pattern. The detection of PhI antibodies (PhI+/PhII+) characterised the 'chronic' state, and seronegative results defined the 'silent' state of herd infection. If antibodies had not been detected in multiparous cows, the herd was considered as probably free of coxiellosis. The analysed cattle herds were noted to have an 'acute' (n = 12, 24.5%), 'chronic' (n = 18, 36.8%), or 'silent' state of herd infection (n = 16, 32.6%). Only three farms (6.1%) were classified as 'free' of C. burnetii. The detection of these herd states over a time period of 4 years in one farm indicated that the described states occur in a cyclical manner. Frequently, a wave-like profile was seen, i.e., a circumscribed seronegative age group was flanked by seropositive age groups. In seronegative animals, IFN-γ reactivity was demonstrated. Seroconversion after vaccination was observed by day 7 post-vaccination in chronically infected herds, whereas in the case of silent infection, it started by day 14. These data indicated a pre-existing immunity in seronegative animals in chronically infected herds. Additionally, IFN-γ reactivity was detected in seronegative calves (>3 months) and heifers from chronically infected farms compared to a negative farm. An infection prior to 3 months of age resulted in cellular immunity in the absence of detectable antibodies. An infection around calving would explain this. The aforementioned circumscribed seronegative age groups are, therefore, explained by an infection early in life during active shedding at calving. Based on these results, an endemic cycle of coxiellosis is proposed: Susceptible young heifers get infected by persistently infected cows. Subsequently, shedding of C. burnetii at calving results in infection and then in cellular immunity in offspring. When these calves enter the cow herd two years later, a maximum of herd immunity is achieved, shedding ceases, and new susceptible animals are raised. In an acutely infected dairy farm, the PhI+/PhII+ serological pattern prevailed in second-lactation cows. In this study, stored sera collected since birth were analysed retrospectively. From the earliest seroconversion, the peak of seroconversion took about 33 months. These data suggested a slow spread of infection within herds. The classification of dairy cow herds is a promising basis for further analysis of the clinical impact of coxiellosis.

The lower Saint Lawrence River region of Quebec, a hot spot for sheepfold-associated Q fever in Canada: Review of 258 cases

Background

The lower Saint Lawrence river region (LSLRR), in Quebec, has a 10-fold higher incidence of Q fever compared to the provincial rate. This study aimed to review clinical cases and the Q fever risk exposure in this region.

Methods

Data were retrieved from microbiology laboratory, medical records from Rimouski Regional Hospital and Public Health reports between 1991 and 2018. They were analyzed with Epi Info 7.2.2.6. Patients with confirmed acute, probable acute, and chronic Q fever were classified using standard case definitions and mapped according to the postal code, to assess the correlation between cases and sheep distribution.

Results

Out of 295 cases, 258 were included (241 confirmed acute, seven probable acute, 10 chronic). Median age was 49 years, 76% were male. For acute cases, the prominent symptoms were fever (99%), headache (83%), chills (80%), sweating (72%), myalgia (69%), and fatigue (67%). Clinical presentation was mostly febrile syndrome with mild hepatitis (84%). A seasonal peak was observed from May to July (56% of acute cases). Most cases (56%) occurred within the two counties where sheep production was highest. Exposure to sheep was prominent 93%, including 64% direct contact (15% shepherds, 49% sheepfold visitors), 14% indirect contact, and 15% sheepfold neighbors.

Conclusions

To our knowledge, this is one of the largest retrospective studies of Q fever cases reported in Canada. Q fever in Quebec LSLRR is associated mainly with sheep exposure. Fever and hepatitis were the most common manifestations. Preventive measures should be considered in this region to protect sheepfold workers, visitors, and their neighbors.

Current Status of Q Fever and the Challenge of Outbreak Preparedness in Korea: One Health Approach to Zoonoses

Human Q fever, a zoonosis caused by Coxiella burnetii, presents with diverse clinical manifestations ranging from mild self-limited febrile illnesses to life-threatening complications such as endocarditis or vascular infection. Although acute Q fever is a benign illness with a low mortality rate, a large-scale outbreak of Q fever in the Netherlands led to concerns about the possibility of blood transfusion-related transmission or obstetric complications in pregnant women. Furthermore, a small minority (< 5%) of patients with asymptomatic or symptomatic infection progress to chronic Q fever. Chronic Q fever is fatal in 5-50% of patients if left untreated. In South Korea, Q fever in humans was designated as a notifiable infectious disease in 2006, and the number of Q fever cases has increased sharply since 2015. Nonetheless, it is still considered a neglected and under-recognized infectious disease. In this review, recent trends of human and animal Q fever in South Korea, and public health concerns regarding Q fever outbreaks are reviewed, and we consider how a One Health approach could be applied as a preventive measure to prepare for zoonotic Q fever outbreaks.

Detection of Coxiella burnetii and characterisation by multiple-locus variable-number tandem repeat analysis in bovine bulk tank milk samples

Coxiella burnetii is the aetiological agent of Q fever, which is highly prevalent in Turkiye, but information on the genetic profiles of the bacterium is limited. This study aimed to investigate the presence of C. burnetii in bovine bulk tank milk (BTM) samples by polymerase chain reaction (PCR) and to investigate the genotypes by means of multiple-locus variable-number tandem repeat analysis (MLVA). A total of 25 markets that sold raw cow's milk were analysed by conventional PCR analysis. An MLVA analysis was performed at six loci, namely MS23, MS24, MS27, MS28, MS33, and MS34, to determine the genotypic variations of C. burnetii found in the positive DNA samples. The DNA of C. burnetii was detected in 16% of the BTM samples. The C. burnetii strains identified in the bovine milk samples collected in this study were found to belong to the same genotypic group as those detected in the bovine milk samples gathered in Greece. As a result, both the presence and genotyping studies of C. burnetii on the BTM samples in Turkiye will contribute to the determination of the geographical distribution of the agent.

Tracking the Source of Human Q Fever from a Southern French Village: Sentinel Animals and Environmental Reservoir

Coxiella burnetii, also known as the causal agent of Q fever, is a zoonotic pathogen infecting humans and several animal species. Here, we investigated the epidemiological context of C. burnetii from an area in the Hérault department in southern France, using the One Health paradigm. In total, 13 human cases of Q fever were diagnosed over the last three years in an area comprising four villages. Serological and molecular investigations conducted on the representative animal population, as well as wind data, indicated that some of the recent cases are likely to have originated from a sheepfold, which revealed bacterial contamination and a seroprevalence of 47.6%. However, the clear-cut origin of human cases cannot be ruled out in the absence of molecular data from the patients. Multi-spacer typing based on dual barcoding nanopore sequencing highlighted the occurrence of a new genotype of C. burnetii. In addition, the environmental contamination appeared to be widespread across a perimeter of 6 km due to local wind activity, according to the seroprevalence detected in dogs (12.6%) and horses (8.49%) in the surrounding populations. These findings were helpful in describing the extent of the exposed area and thus supporting the use of dogs and horses as valuable sentinel indicators for monitoring Q fever. The present data clearly highlighted that the epidemiological surveillance of Q fever should be reinforced and improved.

Coxiella burnetii Seroprevalence and Associated Risk Factors in Cattle, Sheep, and Goats in Estonia

Q fever, a disease caused by Coxiella burnetii (CB), is an emerging zoonotic health problem. The prevalence data from potential sources are valuable for assessing the risk to human and animal health. To estimate the prevalence of CB antibodies in Estonian ruminants, pooled milk and serum samples from cattle (Bos taurus) and pooled serum samples from sheep (Ovis aries) and goats (Capra hircus) were analyzed. Additionally, bulk tank milk samples (BTM; n = 72) were analyzed for the presence of CB DNA. Questionnaires and herd-level datasets were used to identify the risk factors for exposure using binary logistic regression analysis. The prevalence of CB-positive dairy cattle herds (27.16%) was significantly higher than that in beef cattle herds (6.67%) and sheep flocks (2.35%). No CB antibodies were detected in the goat flocks. CB DNA was found in 11.36% of the BTM samples. The odds of seropositivity were higher in dairy cattle herds, with an increasing number of cattle in the herd, and with location in southwestern, northeastern and northwestern Estonia. Dairy cattle herds had higher odds of testing positive for CB in BTM if the dairy cows were kept loose and lower odds if the herd was located in northwestern Estonia.

QuilA® adjuvanted Coxevac® sustains Th1-CD8+-type immunity and increases protection in Coxiella burnetii-challenged goats

Coxevac® is the EMA-approved veterinary vaccine for the protection of cattle and goats against Q fever, a zoonotic bacterial disease due to Coxiella burnetii. Since Coxevac® reduces bacterial shedding and clinical symptoms but does not prevent infection, novel, ready-to-use vaccine formulations are needed to increase its immunogenicity. Here, a goat vaccination-challenge model was used to evaluate the impact of the commercially available saponin-based QuilA® adjuvant on Coxevac® immunity. Upon challenge, the QuilA®-Coxevac® group showed a stronger immune response reflected in a higher magnitude of total IgG and an increase in circulating and splenic CD8⁺ T-cells compared to the Coxevac® and challenged-control groups. The QuilA®-Coxevac® group was characterized by a targeted Th1-type response (IFNγ, IP10) associated with increased transcripts of CD8⁺ and NK cells in spleens and γδ T cells in bronchial lymph nodes. Coxevac® vaccinated animals presented an intermediate expression of Th1-related genes, while the challenged-control group showed an immune response characterized by pro-inflammatory (IL1β, TNFα, IL12), Th2 (IL4 and IL13), Th17 (IL17A) and other immunoregulatory cytokines (IL6, IL10). An intriguing role was observed for γδ T cells, which were of TBX21- and SOX4-types in the QuilA®-Coxevac® and challenged control group, respectively. Overall, the addition of QuilA® resulted in a sustained Th1-type activation associated with an increased vaccine-induced bacterial clearance of 33.3% as compared to Coxevac® only. QuilA® could be proposed as a readily-applied veterinary solution to improve Coxevac® efficacy against C. burnetii infection in field settings.

Coxiella burnetii and its risk factors in cattle in Egypt: a seroepidemiological survey

Animal production is greatly affected by Q fever. As a result of a lack of methodology and financial means to perform extensive epidemiological surveys, the disease's underdiagnosis has proven to be a challenge for effective control. The present study aimed to determine the seroprevalence of C. burnetii in cattle raising in four governorates situated at Nile Delta of Egypt and assess the associated risk factors for infection. A total of 480 serum samples were collected from cattle and examined for presence of anti-C. burnetii antibodies using indirect ELISA assay. The overall seroprevalence of C. burnetii among examined cattle was 19.8%, with the Qalyubia governorate having the highest prevalence. The results of multivariable logistic regression analysis revealed significant association between C. burnetii seropositivity and age, communal grazing and/or watering, contact with small ruminants and history of infertility. According to the findings of this work, C. burnetii is circulating among cattle living in Nile Delta. It is suggested that adequate hygiene procedures and biosecurity measures should be implemented to limit the transmission of pathogens within cow herds and potential human exposure.

Coxiella burnetii (Q-fever) outbreak associated with non-occupational exposure in a semi-urban area of western Croatia in 2022

In March 2022, an outbreak of Q fever (Coxiella burnetii) with non-occupational exposure was confirmed in a semi-urban area in Čavle, Croatia. Veterinary and human epidemiological investigations were conducted to identify the source of the outbreak and to implement appropriate control measures. Three farms were settled next to each other near the homes of the first human cases at the end of the street. The closest farm was less than 500 meters away. These farms contained 161 adult sheep and goats. Among the animal samples analysed, all 16 goats (100%) and 24/50 sheep (48%) tested positive for C. burnetii IgM/IgG antibodies, phase I and II. One out of five sheeps' vaginal swabs were C. burnetti DNA positive. Human testing revealed 20 confirmed and three probable cases (9/23 pneumonia, 2/23 hepatitis, 21/23 fever), with three hospitalizations, and one death. Twenty-seven cases were discarded following negative laboratory results. The epidemiological investigation revealed airborne transmission as the most likely route of transmission. Multiple logistic regression analyses were used to evaluate risk factors for Q fever infection. Persons who were near the farms (≤750 m) (OR 4.5; 95% CI = 1.1-18.3) and lived in the nearest street to the farms had the highest risk of contracting Q fever (OR 3.7; 95% CI = 1.1-13.6). Decreased rainfall compared to monthly averages was recorded in the months prior to the outbreak with several days of strong wind in January preceding the outbreak. This was the largest Q fever outbreak in the county in the last 16 years, which was unexpected due to its location and non-occupational exposure. To stop the outbreak, numerous intensive biosecurity measures were implemented. The outbreak highlights the importance of urban development strategies to limit the number of animal housing near residential areas while providing regular biosecurity measures to prevent infections in livestock.

Screening for Coxiella Burnetii in Dairy Cattle Herds in Poland

Introduction

The intracellular bacterium Coxiella burnetii is the aetiological agent of Q fever, a zoonosis affecting many animal species worldwide. Cattle and small ruminants are considered the major reservoirs of the bacteria and they shed it through multiple routes.

Material and Methods

A total of 2,180 sera samples from 801 cattle herds in all Polish voivodeships were tested by ELISA for the presence of specific antibodies. Milk samples were obtained from seropositive cows in 133 herds as part of a separate study. The milk samples were examined by ELISA and real-time PCR tests.

Results

Seroprevalence at the animal level was 7.06% and true positive seroprevalence was 6.0% (95% confidence interval (CI) 1.1-9.4). Seroprevalence at the herd level was estimated at 11.1% and true positive seroprevalence was 10.5% (95% CI 3.2-15.8). Shedding of the pathogen in milk was detected by real-time PCR in 33 out of 133 tested herds (24.81%, 95% CI 17.74-33.04%) and the presence of C. burnetii antibodies was confirmed in 85 of them (63.9%, 95% CI 55.13-72.05%). The highest level of conformity between ELISA and real-time PCR results was obtained for bulk tank milk samples.

Conclusion

Coxiella burnetii infections are quite common in cattle herds across the country, which emphasises the crucial roles of surveillance and adequate biosecurity measures in the prevention and limitation of Q fever spread in Poland.

Coxiella burnetii in cattle and their human contacts in a gaushala (cattle shelter) from India and its partial com1 gene sequence-based phylogenetic analysis

Q fever caused by Coxiella burnetii is an important zoonosis and has great public health significance. A total of 905 clinical samples from 387 cattle [serum (n = 387); vaginal swabs (n = 387); milk (n = 131)] and 59 serum samples from humans were collected from gaushala (cattle shelter) and screened for anti-C. burnetii IgG antibodies in the sera using an indirect-ELISA kit. Further, the samples were tested for C. burnetii DNA employing TaqMan real-time and conventional PCR assays targeting the com1 gene. In ELISA, 9.56% and 6.78% of animal and human sera samples were positive for anti-C. burnetii antibodies, respectively. Upon pathogen detection, 3.87% sera, 1.81% vaginal swabs, and 6.87% milk samples from cattle tested positive in TaqMan real-time PCR and 1.55% sera, 0.52% vaginal swabs, and 3.05% milk samples were found positive in conventional PCR. In humans, one serum sample was positive in both the PCR assays. The PCR positive samples (n = 12) were partially sequenced and the phylogenetic tree was constructed using com1 gene sequences (n = 42) from a different host and geographical areas. The study highlights infection of cattle and their human contacts in gaushala and identifies relationships between strains identified in the gaushala and those in other parts of the globe.

Phenotype of Coxiella burnetii Strains of Different Sources and Genotypes in Bovine Mammary Gland Epithelial Cells

Despite the high prevalence of C. burnetii in dairy herds and continuous shedding via milk by chronically infected cows, bovine milk is not recognized as a relevant source of human Q fever. We hypothesized that the bovine mammary gland epithelial cell line PS represents a suitable in vitro model for the identification of C. burnetii-strain-specific virulence properties that may account for this discrepancy. Fifteen C. burnetii strains were selected to represent different host species and multiple loci variable number of tandem repeat analysis (MLVA) genotypes (I, II, III and IV). The replication efficiencies of all strains were similar, even though strains of the MLVA-genotype II replicated significantly better than genotype I strains, and bovine and ovine isolates replicated better than caprine ones. Bovine milk isolates replicated with similar efficiencies to isolates from other bovine organs. One sheep isolate (Cb30/14, MLVA type I, isolated from fetal membranes) induced a remarkable up-regulation of IL-1β and TNF-α, whereas prototypic strains and bovine milk isolates tended to suppress pro-inflammatory responses. While infection with strain Nine Mile I rendered the cells partially refractory to re-stimulation with E. coli lipopolysaccharide, Cb30/14 exerted a selective suppressive effect which was restricted to IL-6 and TNF-α and spared IL-1β. PS cells support the replication of different strains of C. burnetii and respond in a strain-specific manner, but isolates from bovine milk did not display a common pattern, which distinguishes them from strains identified as a public health concern.

First serological evidence of Q fever in large ruminants and its associated risk factors in Punjab, Pakistan

Coxiellosis, also known as Q fever, is a zoonotic disease caused by Coxiella burnetii, a gram-negative bacterium that exerts a significant deleterious impact on the productive and reproductive capabilities of livestock, severely effecting the economics of this sector. In this study, 448 sera samples from cattle (n = 224) and buffalo (n = 224) were collected from 112 farms in Pakistan and examined for antibodies against C. burnetii using an indirect ELISA. Ticks were also collected from these animals. Serological analysis revealed a 23.66% and 27.23% seroprevalence of Q fever in cattle and buffalo, respectively. Odds ratio (OR) analysis of the factors associated with C. burnetii seropositivity was performed, and a multivariable logistic model identified five main variables associated with the seropositivity for coxiellosis. These were: (i) the absence of acaricide use (OR 5.61; 95% CI 2.97-10.94); (ii) the presence of ticks (OR 3.23; 95% CI 1.87-5.69); (iii) the abortion history during the preceding year on the farm (OR 14.96; 95% CI 8.09-29.34); (iv) the presence of sheep and goats (OR 2.47; 95% CI 1.20-5.35); and (v) the absence of a separate parturition area (OR 3.17; 95% CI 1.76-5.86). This study provides new insights into the seroprevalence of Q fever in large ruminants across seven studied districts of Punjab, Pakistan, also providing baseline data to inform improved herd management and on-farm practices for the prevention and control of Q fever in large ruminants in the region. Results of this work suggest that further molecular investigation of coxiellosis is warranted to provide a more thorough evaluation of C. burnetii epidemiology in Pakistan.

Tick-Borne-Agents Detection in Patients with Acute Febrile Syndrome and Ticks from Magdalena Medio, Colombia

Acute febrile illness (AFI) is a morbid condition with a sudden onset of fever with at least seven days of evolution, where no signs or symptoms related to an apparent infection have been identified. In Latin America, a high proportion of disease is typically due to malaria and arboviruses. However, among the infectious etiologies, tick-borne diseases (TBDs) should also be considered, especially in areas where people come into direct contact with these arthropods. This study aims to describe the etiology and epidemiology related to tick-borne agents in patients with AFI and the tick’s natural infection by agents of TBD in the rural tropical Magdalena Medio region in Colombia, and explore the factors associated with the presence of Coxiella burnetii infection. We conduct a cohort study enrolling 271 patients with AFI to detect the bacteria of the genera Anaplasma, Ehrlichia, Coxiella, Rickettsia, Borrelia, and Francisella through molecular techniques, and additionally evaluate the presence of IgG antibodies with commercially available kits. We also conduct tick collection in the patient’s households or workplaces for the molecular screening of the same bacterial genera. Seropositivity to IgG antibodies was obtained for all the bacteria analyzed, with Francisella being the most common at 39.5% (107/271), followed by R. rickettsii at 31.4% (85/271), Ehrlichia at 26.9% (73/271), R. typhi at 15.5% (42/271), Anaplasma at 14.4% (39/271), and Borrelia at 6.6% (18/271). However, these bacteria were not detected by the molecular techniques used. Coxiella burnetii infection was detected in 39.5% of the patients: 49.5% only by phase I and II IgG antibodies, 33.6% only by real-time PCR, and 16.8% had a concordant positive result for both techniques. A total of 191 adult ticks, 111 females and 80 males, were collected and identified as Rhipicephalus sanguineus s.l. and Rhipicephalus microplus. In the 169 adult ticks in which natural infection was evaluated, Ehrlichia spp. was detected in 21.3% (36/169), Coxiella spp. in 11.8% (20/169), and Anaplasma spp. in 4.7% (8/169). In conclusion, we identified the prior exposition to Francisella, Anaplasma, Ehrlichia, Rickettsia, Borrelia, and Coxiella in patients through serological tests. We also detected the infection of C. burnetii using molecular techniques. In the ticks, we identified bacteria of the genera Coxiella, Anaplasma, and Ehrlichia. These results suggest the importance of these zoonotic agents as possible causes of AFI in this region.

Q Fever—A Neglected Zoonosis

Q fever remains a neglected zoonosis in many developing countries including Pakistan. The causing agent Coxiella (C.) burnetii is resistant to environmental factors (such as drying, heat and many disinfectants), resulting in a long-lasting infection risk for both human and animals. As the infection is usually asymptomatic, it mostly remains undiagnosed in animals until and unless adverse pregnancy outcomes occur in a herd. In humans, the infection leads to severe endocarditis and vascular infection in chronic cases. Limited data are available on molecular epidemiology and evolution of this pathogen, especially in ruminants. Genomic studies will help speculating outbreak relationships in this scenario. Likewise, pathogenesis of C. burnetii needs to be explored by molecular studies. Awareness programs and ensuring pasteurization of the dairy milk before human consumption would help preventing Q fever zoonosis.

Serological, Molecular Prevalence and Genotyping of Coxiella burnetii in Dairy Cattle Herds in Northeastern Algeria

In Algeria, data on the epidemiology of coxiellosis in cattle are still lacking. In this study, bulk tank milk (BTM) samples from 200 randomly selected dairy cattle herds from Setif province of Algeria were analyzed by an indirect enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Results highlighted that 37% (95% CI: 30.31–43.69%) and 9% (95% CI: 5.03–12.96%) of BTM samples contained Coxiella burnetii antibodies and DNA, respectively. Based on Cohen’s kappa coefficient, a very low agreement between the ELISA and PCR results was found (k = 0.0849) (95% CI: 0.00–0.189). For a second experiment, 186 whole blood samples of cows from farms with reproduction disorders were analyzed by molecular tools to detect C. burnetii. This study revealed an overall prevalence of 6.98% (95% CI: 3.32–10.65%). All positive samples determined by conventional PCR were analyzed by real-time quantitative PCR (qPCR). Eleven samples with cycle threshold (Ct) values lower than 35 were selected for genotyping by the multispacer sequence typing (MST) method. The MST12 genotype in BTM samples, the MST32 genotype and a new MST genotype (partial profile) in whole blood samples were identified. Obtained results have allowed us to better understand the epidemiology of bovine coxiellosis in the region of Setif.

Research Trends and Hotspots of Q Fever Research: A Bibliometric Analysis 1990-2019

Q fever is a worldwide distributed zoonosis caused by Coxiella burnetii, a Gram-negative bacterium. Despite existence of large amount of research data on the developments related to Q fever, no bibliometric analysis of this subject is available to our knowledge. Bibliometric studies are an essential resource to track scholarly trends and research output in a subject. This study is aimed at reporting a bibliometric analysis of publications related to Q fever (2,840 articles published in the period 1990-2019) retrieved from Science Citation Index Expanded, an online database of Clarivate Analytics Web of Science Core Collection. Data was retrieved using keywords “Q fever” or “Coxiella burnetii” in title, abstract, and author keywords to describe important research indicators such as the kind and language of articles, the most important publications, research journals and categories, authors, institutions, and the countries having the most significant contribution to this subject. Finally, the emerging areas in field of diagnosis, host range, and clinical presentation were identified. Word cluster analysis of research related to Q fever revealed that major focus of research has been on zoonosis, seroprevalence, laboratory diagnosis (mainly using ELISA and PCR), clinical manifestations (abortion and endocarditis), vectors (ticks), and hosts (sheep, goat, and cattle). This bibliometric study is intended to visualize the existing research landscape and future trends in Q fever to assist in future knowledge exchange and research collaborations.

Coxiella burnetii abortion in a dairy farm selling artisanal cheese directly to consumers and review of Q fever as a bovine abortifacient in South America and a human milk-borne disease

Coxiella burnetii is a highly transmissible intracellular bacterium with a low infective dose that causes Q fever (coxiellosis), a notifiable zoonotic disease distributed worldwide. Livestock are the main source of C. burnetii transmission to humans, which occurs mostly through the aerogenous route. Although C. burnetii is a major abortifacient in small ruminants, it is less frequently diagnosed in aborting cattle. We report a case of C. burnetii abortion in a lactating Holstein cow from a dairy farm producing and selling artisanal cheese directly to consumers in Uruguay, and review the literature on coxiellosis as a bovine abortifacient in South America and as a milk-borne disease. The aborted cow had severe necrotizing placentitis with abundant intratrophoblastic and intralesional C. burnetii confirmed by immunohistochemistry and PCR. After primo-infection in cattle, C. burnetii remains latent in the lymph nodes and mammary glands, with milk being a significant and persistent excretion route. Viable C. burnetii has been found in unpasteurized milk and cheeses after several months of maturing. The risk of coxiellosis after the consumption of unpasteurized dairy products, including cheese, is not negligible. This report raises awareness on bovine coxiellosis as a potential food safety problem in on-farm raw cheese manufacturing and sales. The scant publications on abortive coxiellosis in cattle in South America suggest that the condition has probably gone underreported in all countries of this subcontinent except for Uruguay. Therefore, we also discuss the diagnostic criteria for laboratory-based confirmation of C. burnetii abortion in ruminants as a guideline for veterinary diagnosticians.

Prevalence of Coxiella burnetii in bovine placentas in Hungary and Slovakia: Detection of a novel sequence type - Short communication

Cotyledons (n = 167) from 30 Hungarian and 5 Slovakian dairy cattle herds were analysed for Coxiella burnetii by real-time PCR targeting the IS1111 gene. Eighty (88.9%) out of the 90 cotyledons from retained placentas and 31 (40.3%) out of the 77 cotyledons from normally separated placentas tested positive. Seventeen out of the 80 positive samples (21.3%) originating from retained placentas were found to be highly loaded with C. burnetii with a cycle threshold (Ct) value lower than or equal to 27.08, ranging between 11.92 and 27.08. The rest of the positive samples from retained fetal membranes and from normally separated placentas were moderately loaded with C. burnetii DNA. Five out of the ten samples showing the strongest positivity (Ct 11.92-18.28) from retained placentas were genotyped by multispacer sequence typing based on ten loci, which revealed sequence type (ST) 61, a type that had not been detected in Hungary and Slovakia previously. Retained placenta was more likely in cows with C. burnetii PCR-positive cotyledons (odds ratio: 12.61, P = 0.0023). The high C. burnetii DNA load found in retained fetal membranes may be a potential risk factor for human infection and may also be associated with the retention of fetal membranes.

Serological Evidence of Human Infection with Coxiella burnetii after Occupational Exposure to Aborting Cattle

Cattle are broadly deemed a source of Coxiella burnetii; however, evidence reinforcing their role in human infection is scarce. Most published human Q fever outbreaks relate to exposure to small ruminants, notably goats. Anti-phase II C. burnetii IgG and IgM were measured by indirect fluorescent antibody tests in 27 farm and veterinary diagnostic laboratory workers to ascertain whether occupational exposure to cattle aborting due to C. burnetii was the probable source of exposure. Four serological profiles were identified on the basis of anti-phase II IgG and IgM titres. Profile 1, characterised by high IgM levels and concurrent, lower IgG titres (3/27; 11.1%); Profile 2, with both isotypes with IgG titres higher than IgM (2/27; 7.4%); Profile 3 with only IgG phase II (5/27; 18.5%); and Profile 4, in which neither IgM nor IgG were detected (17/27; 63.0%). Profiles 1 and 2 are suggestive of recent C. burnetii exposure, most likely 2.5-4.5 months before testing and, hence, during the window of exposure to the bovine abortions. Profile 3 suggested C. burnetii exposure that most likely predated the window of exposure to aborting cattle, while Profile 4 represented seronegative individuals and, hence, likely uninfected. This study formally linked human Q fever to exposure to C. burnetii infected cattle as a specific occupational hazard for farm and laboratory workers handling bovine aborted material.

Serological survey of Coxiella burnetii infections in dairy cattle, sheep, goats and zoo animals in Hungary - Short communication

Q fever is a disease of high zoonotic potential, but interest in its causative agent is rather low although it causes some public health problems in Hungary. The prevalence of Q fever is highly variable by country. The main reservoirs of the disease are the same domestic ruminant species everywhere, but the epidemiological profile depends on the features of the specific reservoir. The aim of this large-scale study was to demonstrate the importance of Q fever in different species as a possible source for human infection in most regions of Hungary. A total of 851 serum samples from 44 dairy farms, 16 sheep flocks, 4 goat farms and 3 zoos located in different parts of Hungary were tested. The presence of antibodies to Coxiella burnetii was surveyed in dairy cattle (n = 547), goats (n = 71), sheep (n = 200) and zoo animals (n = 33). The animal species tested in Hungary showed different seroprevalence values of C. burnetii infection. Seropositivity by the enzyme-linked immunosorbent assay was found in 258 out of 547 (47.2%) cows and in 69 out of 271 (25.5%) small ruminants, among them in 47 out of 200 (23.5%) sheep and in 22 out of 71 (31.0%) goats. Antibodies to C. burnetii were not detected in zoo animals. Seropositivity was demonstrated in 44 out of 44 (100%) dairy cattle farms, with at least one serum sample found to be positive on each farm. The seropositivity rate of small ruminant farms was 55.0% (11 positive out of 20 tested), with 9 out of 16 (56.3%) sheep flocks and 2 out of 4 (50.0%) goat herds showing seropositivity.

Epidemiological study of Coxiella burnetii in dairy cattle and small ruminants in Québec, Canada

The bacterium Coxiella burnetii (C. burnetii) can infect a wide range of animals, most notably ruminants where it causes mainly asymptomatic infections and, when clinical, it is associated with reproductive disorders such as abortion. It is also the etiological agent of Q fever in humans, a zoonosis of increasingly important public health concern. A cross-sectional study was performed to estimate the apparent prevalence and spatial distribution of C. burnetii positivity in dairy cattle and small ruminant herds of two regions of Québec, Canada, and identify potential risk factors associated with positivity at animal and herd levels. In dairy cattle herds, individual fecal samples and repeated bulk tank milk samples (BTM) were collected. In small ruminant herds, serum and feces were sampled in individual animals. ELISA analyses were performed on serum and BTM samples. Real-time quantitative PCR (qPCR) was done on fecal and BTM samples. An animal was considered C. burnetii-positive when at least one sample was revealed positive by ELISA and/or qPCR, while a herd was considered C. burnetii-positive when at least one animal inside that herd was revealed positive. None of the 155 cows had a qPCR-positive fecal sample, whereas 37.2 % (95 % CI = 25.3-49.1) of the 341 sheep and 49.2 % (95 % CI = 25.6-72.7) of the 75 goats were C. burnetii-positive. The apparent prevalence of C. burnetii-positive herds was 47.3 % (95 % CI = 35.6-59.3) in dairy cattle herds (n = 74), 69.6 % (95 % CI = 47.1-86.8) in sheep flocks (n = 23) and 66.7 % (95 % CI = 22.3-95.7) in goat herds (n = 6). No spatial cluster of positive herds was detected. At the individual level, the only significant association with positivity in multivariable regressions was higher parity number in small ruminants. At the herd level, the use of calving group pen, the distance to the closest positive bovine herd, and small ruminant herd density in a 5 km radius were associated with dairy cattle herd positivity, whereas small ruminant herds with more than 100 animals and with a dog on the farm had greater odds of C. burnetii positivity. Our study shows that the infection is frequent on dairy cattle and small ruminant herds from the two studied regions and that some farm and animal characteristics might influence the transmission dynamics of the C. burnetii infection.

Industrial Dairy Cattle Farms in Hungary Source of Coxiella burnetii Infection in Humans

Previous research has demonstrated a high prevalence of Coxiella burnetii in the bulk tank milk on large industrial dairy farms of the central and eastern European region. The aim of this survey was to estimate the prevalence of specific IgG antibodies to C. burnetii proving previous infection among dairy farm workers and to determine the possible risk factors. Serum samples from veterinarians, inseminators, animal caretakers, milking parlor workers, and herd managers working on dairy farms were tested for the presence of IgG to phase I and phase II of C. burnetii using an indirect microimmunofluorescence assay. Antibodies phase II to C. burnetii were detected in 59 out of 70 individuals tested (84.3%). All occupational groups are highly exposed to C. burnetii infection. Veterinarians, inseminators, and animal caretakers had 100% seropositivity rate of phase II, whereas the seropositivity rate found among herd managers and milking parlor workers was 71.4% and 47%, respectively. The findings of this survey suggest that the risk of C. burnetii infection is correlated with cattle density in the large dairy farms and also with occupational groups.

Current perspectives on the occurrence of Q fever: highlighting the need for systematic surveillance for a neglected zoonotic disease in Indian subcontinent

Coxiellosis or Q fever is an important global occupational zoonotic disease caused by one of the most contagious bacterial pathogens - Coxiella burnetii, which ranks one among the 13 global priority zoonoses. The detection of C. burnetii infection is exhibiting an increasing trend in high-risk personnel around the globe. It has increasingly been detected from foods of animal origin (including bulk milk, eggs, and meat) as well as tick vectors in many parts of the world. Coxiellosis is reported to be an important public health threat causing spontaneous abortions in humans and potential reproductive failure, which would result in production losses among livestock. Further, comprehensive coverage of the reports and trends of Q fever in developing countries, where this infection is supposed to be widely prevalent appears scarce. Also, the pathogen remains grossly neglected and underreported. Moreover, policymakers and funding agencies do not view it as a priority problem, especially in the Indian subcontinent, including Sri Lanka, Bhutan, Pakistan, Nepal, Bangladesh and Maldives. Here, we review the occurrence and epidemiology of the disease in a global context with special emphasis on its status in the Indian subcontinent.

Molecular prevalence of Coxiella burnetii in bulk-tank milk from bovine dairy herds: Systematic review and meta-analysis

Coxiella burnetii is an obligate intracellular zoonotic bacterium that causes Q fever. Ruminants, including cattle, are broadly known to be reservoirs for this bacterium. Since 2006, many research groups have evaluated the herd-level prevalence of C. burnetii in cattle by molecular techniques on composite milk samples. This study explored the global C. burnetii herd-level prevalence from studies done on bovine bulk-tank milk (BTM) samples using PCR-based analysis. Also, moderators were investigated to identify sources of heterogeneity. Databases (CAB Abstracts, Medline via Ovid, PubMed, Web of Science and Google Scholar) were searched for index articles on C. burnetii prevalence in BTM samples by PCR published between January-1973 and November-2018. Numerous studies (1054) were initially identified, from which seventeen original publications were included in the meta-analysis based on the pre-defined selection criteria. These studies comprised 4031 BTM samples from twelve countries. A random-effects model was used because of considerable heterogeneity (I² = 98%) to estimate the herd-level prevalence of C. burnetii as 37.0%(CI_95%25.2–49.5%). The average herd size appeared to account for a high level of the heterogeneity. No other moderators (geographic location, gross national income or notification criteria for Q fever) seemed to be determinant. This systematic evaluation demonstrated a high molecular prevalence of C. burnetii in BTM samples both in European and non-European countries, evidencing a widespread herd-level circulation of this agent in bovine dairy farms around the world. Meta-regression showed herd size as the most relevant moderator with the odds of a BTM sample testing positive doubling with every unit increase.

•

First meta-analysis of the PCR-based prevalence of C. burnetii in bovine milk

•

Results showed a high molecular prevalence of C. burnetii in bulk-tank milk samples.

•

C. burnetii is widely distributed in dairy farms in Europe and the wider world.

•

Current results reinforce the need for further investigations on this zoonosis.

Prevalence of shedding and antibody to Coxiella burnetii in post-partum dairy cows and its association with reproductive tract diseases and performance: A pilot study

The bacterium Coxiella burnetii has been associated with reproduction disorders in dairy cattle. A cross-sectional study was conducted in Québec, Canada, to estimate the prevalence of C. burnetii in dairy cows from C. burnetii RT-PCR-positive and/or ELISA-positive herds. As a secondary objective, the associations between C. burnetii-positivity and three reproductive outcomes (purulent vaginal discharge, cytological endometritis, and success at first service) were assessed. A total of 202 post-parturient dairy cows from nine herds were sampled at 35 ± 7 days in milk. Vaginal mucus and composite milk were collected from each cow and screened for the presence of C. burnetii by real-time PCR (RT-PCR) and ELISA, respectively. Purulent vaginal discharge and cytological endometritis were evaluated using a Metricheck device and a modified cytobrush, respectively. The first insemination postpartum was done following an ovulation synchronization protocol around 70 days in milk, and success at first service was recorded. Multilevel logistic regressions adjusted for parity were used to model purulent vaginal discharge, cytological endometritis and success at first service according to C. burnetii cow status. All 202 RT-PCR-assayed vaginal samples were C. burnetii-negative. A positive result for anti-C. burnetii antibodies detection in composite milk was obtained in 25/202 samples and a doubtful result in 4/202 samples. After adjustment for sampling weights, the 202 ELISA-assayed composite milk samples gave an estimated overall prevalence of C. burnetii positive cows of 12.9 % (CI = 6.1-19.6 %) and of doubtful cows of 1.4 % (CI = 0.0-3.3 %). The proportion of ELISA-positive cows was lower in first parity (0%) compared to second (17.1 %) or third parity cows (20.0 %). The associations between ELISA positivity and reproductive outcomes were not statistically significant, perhaps due to the limited sample size, but could be used as pilot estimate for large-scale studies investigating the impact of C. burnetii infection on reproduction disorders in dairy cattle.

Evaluation of the Diagnostic Potential of Recombinant Coxiella burnetii Com1 in an ELISA for the Diagnosis of Q Fever in Sheep, Goats and Cattle

Coxiella burnetii is the causative agent of Q fever, a zoonosis infecting domestic ruminants and humans. Currently used routine diagnostic tools offer limited sensitivity and specificity and symptomless infected animals may be missed. Therefore, diagnostic tools of higher sensitivity and specificity must be developed. For this purpose, the C. burnetii outer membrane protein Com1 was cloned and expressed in Escherichia coli. The His-tagged recombinant protein was purified and used in an indirect enzyme-linked immunosorbent assay (ELISA). Assay performance was tested with more than 400 positive and negative sera from sheep, goats and cattle from 36 locations. Calculation of sensitivity and specificity was undertaken using receiver operating characteristic (ROC) curves. The sensitivities and specificities for sheep were 85% and 68% (optical density at 450nm, OD₄₅₀ cut-off value 0.32), for goats 94% and 77% (OD₄₅₀ cut-off value 0.23) and for cattle 71% and 70% (OD₄₅₀ cut-off value 0.18), respectively. These results correspond to excellent, outstanding and acceptable discrimination of positive and negative sera. In summary, recombinant Com1 can provide a basis for more sensitive and specific diagnostic tools in veterinary medicine.

Comparison of Coxiella burnetii Excretion between Sheep and Goats Naturally Infected with One Cattle-Associated Genotype

The main reservoir of Coxiella (C.) burnetii are ruminants. They shed the pathogen through birth products, vaginal mucus, faeces and milk. A direct comparison of C. burnetii excretions between naturally infected sheep and goats was performed on the same farm to investigate species-specific differences. The animals were vaccinated with an inactivated C. burnetii phase I vaccine at the beginning of the study period for public health reasons. Vaginal and rectal swabs along with milk specimens were taken monthly during the lambing period and once again at the next lambing season. To estimate the environmental contamination of the animals' housings, nasal swabs from every animal were taken simultaneously. Moreover, dust samples from the windowsills and straw beddings were collected. All samples were examined by qPCR targeting the IS1111 gene and the MLVA/VNTR typing method was performed. Whole genome sequencing was applied to determine the number of IS1111 copies followed by a calculation of C. burnetii genome equivalents of each sample. The cattle-associated genotype C7 was detected containing 29 IS1111 copies. Overall, goats seem to shed more C. burnetii through vaginal mucus and in particular shed more and for longer via the rectal route than sheep. This is supported by the larger quantities of C. burnetii DNA detected in caprine nasal swabs and environmental samples compared to the ovine ones. Transmission of C. burnetii from cattle to small ruminants must also be considered.

Identification of risk factors associated with Coxiella burnetii infection in cattle and buffaloes in India

The etiological agent Coxiella burnetii is a highly infectious gram-negative bacterium that can affect multiple species. Many reports confirm its presence in humans, domestic ruminants and rodents in India. This study was aimed to investigate the risk factors associated with C. burnetii infection in bovine populations in Punjab, India. This study was conducted using a stratified two-stage random sampling approach. Twenty-two villages representing all districts of the state were selected. Bovine farmers were interviewed and detailed information about their management and husbandry practices was collected using a structured questionnaire. Blood, milk and genital swab samples were collected from the cattle and buffaloes owned by the farmers. An animal was declared C. burnetii infected by using a combination of tests in parallel, i.e. if it was positive in serological or molecular tests (IgG indirect ELISA or Trans-PCR assay). A herd was considered positive if at least one animal in the herd was declared C. burnetii infected using the above definition. Three binomial logistic regression models were constructed to evaluate the association of (a) geographical location, herd characteristics, and farm management practices with the herd status (herd model), (b) individual animal related factors with the C. burnetii infection status (individual animal model), and (c) production and health related factors with C. burnetii infection status in adult females (adult female model). We collected a total of 610 blood, 610 genital swabs and 361 milk samples from 378 cattle and 232 buffaloes in 179 herds/households. The practice of throwing away aborted materials outside the farm as compared to burial/burning (adjusted odds ratio [OR] 3.0, 95 % confidence interval [CI] 1.14-7.87, p = 0.02) was associated with larger odds of being a C. burnetii infected herd. On the other hand, separation of the animals from the rest of the herd during parturition had a protective effect for being a C. burnetii infected herd (adjusted OR 0.31, 95 % CI 0.18-0.77, p = 0.01). Being cattle as compared to buffalo (adjusted OR 3.37, 95 % CI 1.23-9.20, p = 0.02) and older (adjusted OR 3.37, 95 % CI 1.23-9.20, p = 0.02) were associated with larger odds of C. burnetii infection. The current study highlights that farm practices such as improper aborted material disposal and not separating the animals from the rest of the herd during parturition are important risks for the occurrence of C. burnetii infection in the bovine populations in the state.

Molecular detection of Coxiella burnetii in livestock farmers and cattle from Magdalena Medio in Antioquia, Colombia

Coxiella burnetii causes Q fever in humans and coxiellosis in animals. In humans, it causes acute febrile illnesses like influenza, pneumonia, hepatitis, and chronic illnesses such as endocarditis, vascular infection, and post-infectious fatigue syndrome. It is widely distributed worldwide, and its main reservoirs are sheep, goats, and cattle. This study aimed to determine the frequency of C. burnetii infection using molecular detection and to identify the associated factors in livestock farmers and cattle from the Magdalena Medio region of Antioquia, Colombia. Using real-time polymerase chain reaction (PCR), molecular detection was performed for the IS1111 insertion sequence of C. burnetii using genomic DNA collected from the peripheral blood of 143 livestock farmers and 192 cattle from 24 farms located in Puerto Berrío, Puerto Nare, and Puerto Triunfo. To confirm the results, bidirectional amplicon sequencing of 16S rRNA was performed in four of the positive samples. Additionally, factors associated with C. burnetii were identified using a Poisson regression with cluster effect adjustment. Real-time PCR showed positive results in 25.9% and 19.5% of livestock farmer samples and cattle samples, respectively. For livestock farmers, factors associated with C. burnetii were the area where the farm was located [Puerto Berrío, adjusted prevalence ratio (aPR): 2.13, 95% confidence interval (CI): 1.10-4.11], presence of hens (aPR: 1.47, 95% CI: 1.21-1.79), horses (aPR: 1.61, 95% CI: 1.54-1.67), and ticks (aPR: 2.36, 95% CI: 1.03-5.42) in the residence, and consumption of raw milk (aPR: 1.47, 95% CI: 1.26-1.72). For cattle, the factors associated with Coxiella genus were municipality (Puerto Nare; aPR: 0.39, 95% CI: 0.37-0.41) and time of residence on the farm (≥49 months; aPR: 2.28, 95% CI: 1.03-5.20). By analyzing sequences of the 16S rRNA molecular marker, C. burnetii infection was confirmed in livestock farmers. However, in cattle, only the presence of Coxiella-type bacteria was identified. Further research is necessary to determine the potential role that these types of bacteria have as etiological agents for disease in livestock farmers and cattle from the study area.

Occurrence and Genotyping of Coxiella burnetii in Hedgehogs in China

Coxiella burnetii is the causative agent of query fever (Q fever), and distributes broadly in environment. Livestock are identified as main reservoirs, which may infect people through their contaminative urine, feces, milk, and birth products. Wild animals can also be the potential carriers and transmitters of C. burnetii. To understand the geographic distribution and host species of C. burnetii in China, we investigated the prevalence of C. burnetii in hedgehogs (Erinaceus amurensis) in Hubei Province. Hedgehogs were tested for C. burnetii with PCR targeting three genes (com1, rrs, and icd) followed by multispacer sequence typing (MST). We found that 12.2% (5/41) hedgehogs were PCR positive for C. burnetii. MST revealed presence of two novel genotypes and phylogenetic analysis revealed that the strains were similar to a group of isolates from chronic Q fever patients and mammals. This study showed that C. burnetii are highly prevalent in hedgehogs in Hubei Province in central China, suggesting that hedgehogs may play an important role in the ecology and transmission of C. burnetii to humans because it is captured and used as traditional medicine in China.

Cross-sectional serosurvey of Coxiella burnetii in healthy cattle and sheep from extensive grazing system in central Italy

A cross-sectional survey was carried out to estimate the seroprevalence of Coxiella burnetii in extensively grazed cattle and sheep from central Italy and to identify the related risk factors. Data on notified human Q fever cases in the area were also collected and described. A two-stage cluster sampling was performed. A total of 5083 animals (2210 cattle; 2873 sheep) belonging to 186 farms (92 herds; 94 flocks) were tested for the presence of antibodies against C. burnetii using a commercial enzyme-linked immunosorbent assay kit. The prevalence at the animal-level resulted three times higher in sheep compared to cattle (37.8% vs. 12.0%; χ2 = 270.10, P < 0.001). The prevalence at the herd-level was also higher in sheep than in cattle (87.2% vs. 68.5%; χ2 = 9.52, P < 0.01). The multivariate analysis showed a higher risk of seropositivity for cattle aged 67-107 months (OR 2.79, 95% CI 1.86-4.18), cattle >107 months of age (OR 2.07, 95% CI 1.36-3.14) and mixed breed cattle (OR 1.74, 95% CI 1.11-2.72). A herd size >92 animals was recognized as herd-level risk factor in cattle (OR 6.88, 95% CI 1.67-28.37). The risk of being seropositive was double in sheep belonging to flocks >600 animals (odds ratio (OR) 2.04, 95% CI 1.63-2.56). Sheep were confirmed to be the most exposed species. Nevertheless, the prevalence observed in cattle also suggests the potential involvement of this species in the circulation of the pathogen in the area. Seven confirmed human Q fever cases were reported. In five out of seven cases there was at least one exposed herd within a 5 km buffer. Even though the source of the infection was not identified, the possibility of C. burnetii circulating in the livestock and human population in the study area cannot be overlooked. The integration between veterinary and human surveillance will be crucial to understand the spread of this zoonosis and to support the adoption of appropriate control measures.

Occurrence of Coxiella burnetii in Polish dairy cattle herds based on serological and PCR tests

The aim of the research was to assess the prevalence of antibodies to Coxiella burnetii in dairy cattle herds in Poland and to compare the results of real-time PCR and ELISA tests performed on bulk tank milk (BTM) samples. In total, 2635 serum samples collected from 969 dairy cattle herds from all provinces were tested using ELISA. Additionally, BTM specimens from 101 herds were analysed by ELISA and real-time PCR targeting IS1111 element. Presence of anti-C. burnetii antibodies was confirmed in 25.39% of serum samples in 237 herds (24.46%) and the herd-level seroprevalence in Voivodeships varied from 2.5% to 61.4%. Moreover, 46 (45.5%) of analysed bulk tank milk samples gave postive result in ELISA and microbial DNA was detected in 40 (39.6%) of tested herds. The comparative analysis of ELISA and real-time PCR results obtained for BTM samples using the chi-square test showed statistically significant relationship between results of both methods.

Seroprevalence and risk factors of Coxiella burnetii infection in cattle in northeast Algeria

A cross-sectional study was conducted to determine the seroprevalence and the risk factors associated with C. burnetii infection in cattle in the state of Setif in northeastern Algeria from March 2016 to April 2018. A total of 678 cows animals aged at least 24 months and belonging to 90 herds were randomly selected. A serum sample from each cow was tested for antibodies against C. burnetii using an indirect enzyme-linked immunosorbent assay (ELISA). A structured questionnaire focusing on risk factors for C. burnetii infection was administered to farm owners involved in the study. The individual animal prevalence was 11.36% (77/678) (95%CI 8.97-13.75%), the herd prevalence was 45.56% (41/90) (95%CI 35.27-55.84%), and the within-herd prevalence ranged from 9.09 to 57.14% (mean 23.71%; Q1 11.11%, Q2 or median 20%, Q3 30%). Multivariable logistic regression analysis revealed that contact with other herds (odds ratio (OR) 1.95, 95 CI 1.12-3.42) and purchased animals (OR 2.05, 95 CI 1.14-3.68) was identified as risk factors for seropositivity to C. burnetii, while the use of disinfectants (OR 0.32, 95 CI 0.14-0.72) was identified as protective factor. The results from the present study indicate that C. burnetii is circulating into cattle herds in the region of Setif in Northeastern of Algeria. It is recommended to implement good hygienic practices and measures of biosecurity to reduce the spread of infection between cattle herds and possible exposure of humans.

Coxiella burnetii associated with BVDV (Bovine Viral Diarrhea Virus), BoHV (Bovine Herpesvirus), Leptospira spp., Neospora caninum, Toxoplasma gondii and Trypanosoma vivax in reproductive disorders in cattle

This is a cross-sectional study to assess the presence of antibodies in ruminants against selected pathogens associated with reproductive disorders in cattle in four Brazilian states, including the zoonotic agent Coxiella burnetii. The used tests were Virus Neutralization Assay for IBR and BVD, Microscopic Agglutination Test for Leptospira spp., Indirect Fluorescent Antibody Test (IFAT) for C. burnetii and Toxoplasma gondii, and Enzyme-Linked Immunosorbent Assay for Neospora caninum and Trypanosoma vivax. Seropositivity for C. burnetii was 13.7% with titers from 128 to 131,072; 57.8% for BoHV-1, with titers between 2 and 1,024; 47.1% for BVDV-1a, with titers from 10 to 5,120; 89.2% for N. caninum; 50% for T. vivax; and 52.0% for Leptospira spp., with titers between 100 to 800 (the following serovars were found: Tarassovi, Grippotyphosa, Canicola, Copenhageni, Wolffi, Hardjo, Pomona and Icterohaemorrhagiae); 19.6% for T. gondii with titer of 40. This is the first study that has identified C. burnetii in cattle associated with BoHV and BVDV, N. caninum, Leptospira spp., T. gondii and T. vivax. Thus, future studies should be conducted to investigate how widespread this pathogen is in Brazilian cattle herds.

Real-time quantitative PCR-based detection of Coxiella burnetii in unpasteurized cow's milk sold for human consumption

Coxiella burnetii is a zoonotic pathogen with a worldwide distribution that is responsible for Q fever in humans. It is a highly infectious bacterium that can be transmitted from cattle to humans through the consumption of unpasteurized milk. We report the molecular identification of C. burnetii in raw cow's milk being sold directly for human consumption in Brazil without official inspection or pasteurization. One hundred and twelve samples of raw milk were analysed by real-time quantitative PCR (qPCR), and C. burnetii was detected in 3.57% (4/112) of the samples at a concentration ranging from 125 to 404 bacteria per millilitre. The identification of this zoonotic pathogen in raw milk sold directly for human consumption is a public health concern since C. burnetii can be transmitted through the oral route. This result indicates that health education and other preventive measures should be officially implemented in Brazil to prevent the spread of infection. To our knowledge, this is the first qPCR-based detection of C. burnetii in raw milk samples from cows sold in Brazil that do not undergo official inspection or pasteurization.

Swab cloths as a tool for revealing environmental contamination by Q fever in ruminant farms

Q fever is a zoonotic abortive disease of ruminants mostly transmitted by inhalation of aerosols contaminated by Coxiella burnetii. Clusters of cases or even epidemics regularly occur in humans but, to date, there is no consensus about the best way to carry out outbreak investigations in order to identify potential farms at risk. Although environmental samples might be useful during such investigations, there are few baseline data on the presence of C. burnetii in the environment of ruminant farms. We thus investigated dust samples from cattle, sheep and goat farm buildings in order to (a) estimate C. burnetii detection frequency and bacterial loads in the environment, and (b) determine whether this environmental contamination is associated with series of abortions attributed to Q fever. We considered 113 herds with a recent abortive episode potentially related (n = 60) or not (n = 53) to C. burnetii. Dust was sampled using a swab cloth and tested by a quantitative PCR method targeting the IS1111 gene. Coxiella burnetii DNA was detected on 9 of 50 cattle farms, 13 of 19 goat farms and 30 of 40 sheep farms. On 16 cloths, bacterial loads were higher than 10⁸ genome equivalents, levels as high as in infectious materials such as placentas and aborted foetuses. Overall, the probability of detecting C. burnetii DNA was higher on small ruminant farms than cattle farms, in herds suspected of Q fever and in large herds. We conclude that swab cloths are a putative indicator of contamination of ruminant farms by C. burnetii.

First molecular and serological evidence of Coxiella burnetti infection among sheep and goats of Jammu province of India

The epidemiology and prevalence of Q fever in India is largely unknown. There are very few serologic and molecular reports of Q fever in India and these are old reports. The objective of this study was to investigate, for the first time, the presence of Coxiella burnetii infection in sheep and goat flocks of Jammu province of Jammu and Kashmir, India. A total of 148 milk (110 sheep and 38 goats) samples, 282 sera (170 sheep and 112 goats), and 152 vaginal swabs (123 sheep and 29 goats) were collected from farms with incidences of repeated abortion. The LSI Q fever ruminant serum/milk ELISA kit was used to identify anti-C. burnetii antibodies and nested PCR was employed to detect DNA in vaginal swabs. Overall, 42 (38.2%; 95% CI: 29.2-47.9) sheep and 9 (23.7%; 95% CI: 12.0-40.6) goat milk samples, and 21 (12.4%; 95% CI: 8.0-18.5) sheep and 11 (9.8%; 95% CI: 5.2-17.3) goat sera were ELISA positive. In addition, nine (7.3%; 95% CI: 3.6-13.8) vaginal swabs from sheep tested positive by nested PCR; however, C. burnetii could not be found in any of the vaginal swabs from goat. These results indicate that sheep seem to be a more important reservoir of C. burnetii than goats posing a risk for human infection in this area.

Role of Coxiella burnetii in the development of fever of unknown origin: А mini review

Q fever is a widespread zoonosis throughout the world in the form of numerous natural and agricul-tural outbreaks. C. burnetii infects various hosts, including humans, ruminants and pets and in rare cases, reptiles, birds, and ticks. This bacterium is excreted in urine, milk, faeces, and birth products. In humans Q fever occurs as acute or chronic disease with diverse clinical presentation, as isolated cases and epidemics. It affects various organs and systems, and in pregnant women can cause miscar-riage or premature birth. Untreated Q fever can become chronic with adverse effects on patients. Diversity in the clinical picture in the absence of specific pathological syndrome often hinders accurate diagnosis and proper etiological significance. Therefore, improvement of diagnostic methods and in particular the development and introduction of new molecular diagnostic methods is the basis of effective therapeutic and prophylactic approach. Тhe purpose of the review is to renew the interest to Q fever – on one hand, because of its serious impact on human health and agricultural systems, and on the other, the ability for development and introduction of new molecular diagnostic methods.

Management of Coxiella burnetii infection in livestock populations and the associated zoonotic risk: A consensus statement

Infections caused by Coxiella burnetii, commonly referred to as coxiellosis when occurring in animals and Query fever when occurring in humans, are an important cause of abortions, decreased reproductive efficiency, and subclinical infections in ruminants. The organism also represents an important zoonotic concern associated with its ability to aerosolize easily and its low infectious dose. Available diagnostic tests have limited sensitivity, which combined with the absence of treatment options in animals and limited approaches to prevention, result in difficulty managing this agent for optimal animal health and zoonotic disease outcomes. The purpose of this consensus statement is to provide veterinarians and public health officials with a summary of the available information regarding management of C. burnetii infection in livestock populations. A discussion of currently available testing options and their interpretation is provided, along with recommendations on management practices that can be implemented on‐farm in the face of an outbreak to mitigate losses. Emphasis is placed on biosecurity measures that can be considered for minimizing the zoonotic transmission risk in both field and veterinary facilities.

Detection and Genotyping of Coxiella burnetii in Pigs, South Korea, 2014-2015

We assessed Coxiella burnetii prevalence and genotypes in pigs in South Korea during 2014–2015. Prevalence was low among 1,030 samples tested by ELISA and immunofluorescent assay and 1,124 samples tested by PCR. Despite this finding, possible transmission of C. burnetii from pigs to humans cannot be excluded.

Coxiella burnetii (Q fever) infection in dairy cattle and associated risk factors in Latvia

The purpose of this study was to describe prevalence and spatial distribution of Coxiella burnetii infections in dairy cow sheds in Latvia and to investigate risk factors contributing to C. burnetii infections. Blood serum samples from abortion cases from 1010 sheds have been tested by ELISA for the presence of C. burnetii antibodies and bulk tank milk (BTM) samples from 252 sheds have been tested by real time polymerase chain reaction and ELISA for the presence of C. burnetii DNA and antibodies. Prevalence of C. burnetii antibody-positive sheds in cases of abortion was 13·4%. A total of 10·7% and 13·2% of dairy cow sheds tested positive for the presence of C. burnetii DNA and antibodies in BTM, respectively. Two distinct areas of clustering of test-positive dairy cattle sheds were identified by spatial scan statistics of abortion cases and randomly sampled BTM samples. Three factors were identified as significantly contributing to the risk of C. burnetii DNA presence in BTM - number of cattle in shed (>200 animals/shed) (OR 3·93), location of the shed within risk area in Northern Latvia (OR 8·29) and for the first time, purchasing cattle from abroad has been shown to significantly increase risk (OR 2·68) of C. burnetii infection in dairy cows in Latvia.

Environmental sampling coupled with real-time PCR and genotyping to investigate the source of a Q fever outbreak in a work setting

A Q fever outbreak was declared in February 2016 in a company that manufactures hoists and chains and therefore with no apparent occupational-associated risk. Coxiella burnetii infection was diagnosed by serology in eight of the 29 workers of the company; seven of them had fever or flu-like signs and five had pneumonia, one requiring hospitalisation. A further case of C. burnetii pneumonia was diagnosed in a local resident. Real-time PCR (RTi–PCR) showed a widespread distribution of C. burnetii DNA in dust samples collected from the plant facilities, thus confirming the exposure of workers to the infection inside the factory. Epidemiological investigations identified a goat flock with high C. burnetii seroprevalence and active shedding which was owned and managed by one of the workers of the company as possible source of infection. Genotyping by multispacer sequence typing (MST) and a 10-loci single-nucleotide polymorphism (SNP) discrimination using RTi–PCR identified the same genotype (MST18 and SNP type 8, respectively) in the farm and the factory. These results confirmed the link between the goat farm and the outbreak and allowed the identification of the source of infection. The circumstances and possible vehicles for the bacteria entering the factory are discussed.

Permissiveness of bovine epithelial cells from lung, intestine, placenta and udder for infection with Coxiella burnetii

Ruminants are the main source of human infections with the obligate intracellular bacterium Coxiella (C.) burnetii. Infected animals shed high numbers of C. burnetii by milk, feces, and birth products. In goats, shedding by the latter route coincides with C. burnetii replication in epithelial (trophoblast) cells of the placenta, which led us to hypothesize that epithelial cells are generally implicated in replication and shedding of C. burnetii. We therefore aimed at analyzing the interactions of C. burnetii with epithelial cells of the bovine host (1) at the entry site (lung epithelium) which govern host immune responses and (2) in epithelial cells of gut, udder and placenta decisive for the quantity of pathogen excretion. Epithelial cell lines [PS (udder), FKD-R 971 (small intestine), BCEC (maternal placenta), F3 (fetal placenta), BEL-26 (lung)] were inoculated with C. burnetii strains Nine Mile I (NMI) and NMII at different cultivation conditions. The cell lines exhibited different permissiveness for C. burnetii. While maintaining cell viability, udder cells allowed the highest replication rates with formation of large cell-filling Coxiella containing vacuoles. Intestinal cells showed an enhanced susceptibility to invasion but supported C. burnetii replication only at intermediate levels. Lung and placental cells also internalized the bacteria but in strikingly smaller numbers. In any of the epithelial cells, both Coxiella strains failed to trigger a substantial IL-1β, IL-6 and TNF-α response. Epithelial cells, with mammary epithelial cells in particular, may therefore serve as a niche for C. burnetii replication in vivo without alerting the host’s immune response.

Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves

Background

Bacterial endocarditis is a recognised disease in humans and animals. In humans, infection with Coxiella burnetii can cause endocarditis, but this has not been investigated thoroughly in animals. Endocarditis in cattle is a common post-mortem finding in abattoirs and studies have identified Trueperella pyogenes as a major cause. Despite exposure of cattle to C. burnetii, the significance of this particular bacterium for development and progression of endocarditis has not been studied in detail. Cardiac valves of cattle affected with endocarditis (n = 100) were examined by histology, fluorescence in situ hybridization (FISH) and real time quantitative polymerase chain reaction (PCR). Serum was examined for anti-C. burnetii antibodies by enzyme-linked immunosorbent assay (ELISA).

Results

Serology revealed that 70% of the cattle were positive for antibodies to C. burnetii, while PCR analysis identified 25% of endocarditis valve samples as being positive. C. burnetii was not detected by FISH, probably due to the low infection levels. Most cattle had chronic valvular vegetative endocarditis with lesions being characterised by a core of fibrous tissue covered by significant amounts of fibrin, sometimes with areas of liquefaction, and with a coagulum covering the surface. In a few cases, including the case with the highest infection level, lesions were characterized by extensive fibrosis and calcification. Histologically, bacteria other than C. burnetii were observed in most cases.

Conclusions

The presence of C. burnetii DNA is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes–like bacteria were present in the inflamed valves; a bacterium able to induce the observed lesions. Heart valves of normal cattle should be investigated to assess if C. burnetii may be present without preexisting lesions.