Q fever in humans and animals in the United States

First Insight into the Prevalence of Coxiella burnetii Infection among Veterinary Medicine Students in Bulgaria

The aim of this study was to assess the prevalence of Coxiella burnetii infection among veterinary medicine students from two Bulgarian Universities, located in Sofia and Stara Zagora. Blood samples were collected from a total of 185 veterinary students for the detection of C. burnetii phase II antibodies and presence of DNA using an enzyme-linked immunosorbent assay (ELISA) and end-point PCR test. Out of all samples, 29.7% were positive for at least one C. burnetii phase II antibody marker or by the result of the PCR test. Veterinary students from Stara Zagora showed a significantly high seropositivity for Q fever (33.6%), as compared to the students in Sofia (23%; p < 0.05). Evidence of recent exposure with detection of anti-C. burnetii phase II IgM (+) antibodies was observed in 14.6% of the students under study. Seroprevalence among students in Stara Zagora was higher (15.3%). Anti-C. burnetii phase II IgG antibodies were detected in 21.6% of examined samples. Our study revealed a higher seropositivity among the male students (32.8%) as compared to females (16.0%; p < 0.05). The end-point PCR assay detected 5.9% blood samples as positive. The relative risk (RR) of Q fever exposure for male students was 40.7%, whereas it was 24.6% in females (p < 0.05). The findings from this study indicate that the C. burnetii infection is widely distributed amongst veterinary students in Bulgaria. This study emphasizes the need for improved safety protocols and infection control measures in veterinary training programs.

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.

Coxiella burnetii in domestic doe goats in the United States, 2019-2020

Coxiella burnetii is a bacterial pathogen capable of causing serious disease in humans and abortions in goats. Infected goats can shed C. burnetii through urine, feces, and parturient byproducts, which can lead to infections in humans when the bacteria are inhaled. Goats are important C. burnetii reservoirs as evidenced by goat-related outbreaks across the world. To better understand the current landscape of C. burnetii infection in the domestic goat population, 4,121 vaginal swabs from 388 operations across the United States were analyzed for the presence of C. burnetii by IS1111 PCR as part of the United States Department of Agriculture, Animal Plant Health Inspection Service, Veterinary Services' National Animal Health Monitoring System Goats 2019 Study. In total, 1.5% (61/4121) of swabs representing 10.3% (40/388) (weighted estimate of 7.8, 95% CI 4.4-13.5) of operations were positive for C. burnetii DNA. The quantity of C. burnetii on positive swabs was low with an average Ct of 37.9. Factors associated with greater odds of testing positive included suspected Q fever in the herd in the previous 3 years, the presence of wild deer or elk on the operation, and the utilization of hormones for estrus synchronization. Factors associated with reduced odds of testing positive include the presence of kittens and treatment of herds with high tannin concentrate plants, diatomaceous earth, and tetrahydropyrimidines. In vitro analysis demonstrated an inhibitory effect of the tetrahydropyrimidine, pyrantel pamoate, on the growth of C. burnetii in axenic media as low as 1 μg per mL. The final multivariable logistic regression modeling identified the presence of wild predators on the operation or adjacent property (OR = 9.0, 95% CI 1.3-61.6, p value = 0.0248) as a risk factor for C. burnetii infection.

Global and regional seroprevalence of coxiellosis in small ruminants: A systematic review and meta-analysis

BACKGROUND

Coxiellosis is a neglected zoonosis for occupationally exposed people in many parts of the world. Sheep and goats are two important small ruminants that act as reservoirs for human contamination; however, there is a lack of comprehensive data on the epidemiological aspects of coxiellosis in sheep and goats at regional and global levels. The aim of this study was to systematically review the available articles on seroprevalence of coxiellosis in sheep and goats and estimate the overall seroprevalence in different regions.

METHODS

A systematic search strategy was performed in five electronic repositories for articles published until December 2021. Relevant data were extracted from the selected articles based on the inclusion criteria. A random effect meta-analysis model was used to analyse the data. Results are presented as the prevalence of seropositivity as a percentage and 95% confidence intervals.

RESULTS

The global pooled seroprevalence of coxiellosis in sheep was 17.38% (95% confidence interval [CI]: 15.59%-19.17%). Overall, the regional level pooled prevalence estimates in sheep ranged from 15.04% (95% CI: 7.68%-22.40%) to 19.14% (95% CI: 15.51%-22.77%), depending on region. The global pooled seroprevalence of coxiellosis in goats was 22.60% (95% CI: 19.54%-25.66%). Overall, the regional level pooled prevalence estimates in goats ranged from 6.33% (95% CI: 2.96%-9.71%) to 55.13% (95% CI: 49.61%-60.65%), depending on the region. The prevalence estimates also varied significantly in both sheep and goats depending on age, sex, and rearing systems of the animals (p < 0.001).

CONCLUSION

Seroprevalence of coxiellosis in both sheep and goats is considerable. Routine monitoring of the sheep and goat populations is needed to prevent spillover infection in other livestock and humans.

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.

Q fever awareness in Australia: A scoping review

OBJECTIVE

To investigate the level of Q fever awareness in Australia.

METHODS

A scoping review was conducted by searching the electronic databases Medline, PubMed and Web of Science using keywords for Q fever, awareness, knowledge, and Australian locations. The search was initially limited to articles published in the 10 years prior to June 2022 and then extended up to and including August 2023; yielding 387 records.

RESULTS

Fifteen articles were assessed as being eligible. These articles reported on surveys and interviews conducted with farmers, veterinary practitioners and nurses, medical practitioners, policy makers, researchers, industry representatives, animal science students, cat breeders, wildlife rehabilitators, and agriculture show attendees. Farmers were the largest group represented. Level of Q fever awareness amongst these communities, including those at high-risk, was generally low. The need for increased awareness was recognised. General practitioner awareness levels were low and recognised to be so by high-risk groups. Awareness of preventive measures including vaccination was greater among those with greater awareness and risk.

CONCLUSION

With the availability of a highly effective vaccine in Australia, there is a need to increase Q fever knowledge and awareness among high-risk groups and primary health care practitioners.

IMPLICATIONS FOR PUBLIC HEALTH

Strategies to increase awareness and knowledge of Q fever risks and prevention strategies may assist with reducing Q fever burden in Australia.

TGF-β/IFN-γ Antagonism in Subversion and Self-Defense of Phase II Coxiella burnetii-Infected Dendritic Cells

Dendritic cells (DCs) belong to the first line of innate defense and come into early contact with invading pathogens, including the zoonotic bacterium Coxiella burnetii, the causative agent of Q fever. However, the pathogen-host cell interactions in C. burnetii-infected DCs, particularly the role of mechanisms of immune subversion beyond virulent phase I lipopolysaccharide (LPS), as well as the contribution of cellular self-defense strategies, are not understood. Using phase II Coxiella-infected DCs, we show that impairment of DC maturation and MHC I downregulation is caused by autocrine release and action of immunosuppressive transforming growth factor-β (TGF-β). Our study demonstrates that IFN-γ reverses TGF-β impairment of maturation/MHC I presentation in infected DCs and activates bacterial elimination, predominantly by inducing iNOS/NO. Induced NO synthesis strongly affects bacterial growth and infectivity. Moreover, our studies hint that Coxiella-infected DCs might be able to protect themselves from mitotoxic NO by switching from oxidative phosphorylation to glycolysis, thus ensuring survival in self-defense against C. burnetii. Our results provide new insights into DC subversion by Coxiella and the IFN-γ-mediated targeting of C. burnetii during early steps in the innate immune response.

Vertical organization of microbial communities in Salineta hypersaline wetland, Spain

Microbial communities inhabiting hypersaline wetlands, well adapted to the environmental fluctuations due to flooding and desiccation events, play a key role in the biogeochemical cycles, ensuring ecosystem service. To better understand the ecosystem functioning, we studied soil microbial communities of Salineta wetland (NE Spain) in dry and wet seasons in three different landscape stations representing situations characteristic of ephemeral saline lakes: S1 soil usually submerged, S2 soil intermittently flooded, and S3 soil with halophytes. Microbial community composition was determined according to different redox layers by 16S rRNA gene barcoding. We observed reversed redox gradient, negative at the surface and positive in depth, which was identified by PERMANOVA as the main factor explaining microbial distribution. The Pseudomonadota, Gemmatimonadota, Bacteroidota, Desulfobacterota, and Halobacteriota phyla were dominant in all stations. Linear discriminant analysis effect size (LEfSe) revealed that the upper soil surface layer was characterized by the predominance of operational taxonomic units (OTUs) affiliated to strictly or facultative anaerobic halophilic bacteria and archaea while the subsurface soil layer was dominated by an OTU affiliated to Roseibaca, an aerobic alkali-tolerant bacterium. In addition, the potential functional capabilities, inferred by PICRUSt2 analysis, involved in carbon, nitrogen, and sulfur cycles were similar in all samples, irrespective of the redox stratification, suggesting functional redundancy. Our findings show microbial community changes according to water flooding conditions, which represent useful information for biomonitoring and management of these wetlands whose extreme aridity and salinity conditions are exposed to irreversible changes due to human activities.

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.

Coxiella burnetii in ticks, livestock, pets and wildlife: A mini-review

Coxiella burnetii is a zoonotic bacterium with an obligatory intracellular lifestyle and has a worldwide distribution. Coxiella burnetii is the causative agent of Q fever in humans and coxiellosis in animals. Since its discovery in 1935, it has been shown to infect a wide range of animal species including mammals, birds, reptiles, and arthropods. Coxiella burnetii infection is of public and veterinary health and economic concern due to its potential for rapid spread and highly infectious nature. Livestock are the primary source of C. burnetii infection in most Q fever outbreaks which occurs mainly through inhalation of contaminated particles. Aside from livestock, many cases of Q fever linked to exposure to wildlife. Changes in the dynamics of human-wildlife interactions may lead to an increased potential risk of interspecies transmission and contribute to the emergence/re-emergence of Q fever. Although C. burnetii transmission is mainly airborne, ticks may act as vectors and play an important role in the natural cycle of transmission of coxiellosis among wild vertebrates and livestock. In this review, we aim to compile available information on vectors, domestic, and wild hosts of C. burnetii, and to highlight their potential role as bacterial reservoirs in the transmission of C. burnetii.

HISTOLOGIC LESIONS IN PLACENTAS OF NORTHERN FUR SEALS (CALLORHINUS URSINUS) FROM A POPULATION WITH HIGH PLACENTAL PREVALENCE OF COXIELLA BURNETII

Coxiella burnetii is an intracellular bacterial pathogen that can be associated with significant reproductive disease or acute mortality in livestock and wildlife. A novel marine mammal-associated strain of C. burnetii has been identified in pinnipeds of the northwestern Pacific Ocean. Little is known about C. burnetii infection in regard to reproductive success or population status. Our objective was to characterize the severity and extent of histologic lesions in 117 opportunistically collected placentas from presumed-normal northern fur seals (Callorhinus ursinus) in July 2011 on St. Paul Island, Alaska, US, where a high placental prevalence of C. burnetii had been reported. Sections were examined by histology and immunohistochemistry and impression smears with modified acid-fast stain. The nature and frequency of histologic changes were compared with target COM1 PCR-confirmed C. burnetii positive and negative placentas. Overall, histologic changes were similar to placental lesions described in aborting ruminants; however, changes were variable within and between placentas. Vasculitis and occasional intracellular bacteria were seen only in C. burnetii PCR-positive placentas. Dystrophic mineralization, edema, and inflammation were seen in PCR-positive and negative placentas, although they were statistically more common in PCR-positive placentas. Results suggest that C. burnetti and associated pathologic changes are multifocal and variable in placentas from these presumably live-born pups. Therefore, multiple sections of tissue from different placental areas should be examined microscopically, and screened by PCR, to ensure accurate diagnosis as the genomes per gram of placenta may not necessarily represent the severity of placental disease. These limitations should inform field biologists, diagnosticians, and pathologists how best to screen and sample for pathogens and histopathology in marine mammal placental samples.

Clinical Evidence and Risk Factors for Reproductive Disorders Caused by Bacterial Infections in Meat Goats in Northeastern Thailand

The objective of this study was to identify risk factors related to reproductive disorders caused by bacterial infections in goats in northeastern Thailand. Two hundred twenty farms were investigated, and 49 herds were found to have clinical reproductive disorders. Moreover, 96% (47/49) of herds showing clinical reproductive failure preferred to circulate bucks between herds. A total of 118 sera, including 85 clinical reproductive disorder cases such as abortion (n = 70), abortion with arthritis (n = 1), orchitis (n = 3), repeat breeder (n = 6), sterile (n = 1), and weak kids (n = 4), and 33 bucks’ circulations were serologically tested for bacterial infections caused by Coxiella burnetii, Chlamydophila abortus, and Brucella spp. Results showed 69% (81/118 cases) were seropositive for Q fever (n = 55; 46.61%), brucellosis (n = 8; 6.78), and chlamydiosis (n = 18; 15.25%), respectively; 82% of herds (40/49 herds) were infected with at least one of those diseases. Moreover, 40% of infected herds (16/40) had coinfection among the three of those diseases. Approximately 60% (20/33) of buck circulation showed seropositivity to at least one of the diseases, and 85% of infected bucks were seropositive for Q fever (17/20). Buck circulation between herds is a risk factor for diseases on farms ( $p=0.001$ ); odds ratio (OR = 109.29; 95% confidence interval (CI) = 6.61–1,807.38). Moreover, the annual brucellosis test is a protective factor against reproductive failure cases on farms ( $p=0.022$ ; OR = 0.45; 95% CI = 0.23–0.89). Reproductive disorder cases can be caused by sexual transmission, so buck circulation can yield Q fever, brucellosis, and chlamydiosis in communities. This investigation is the first report of chlamydiosis infection in our area. Concerning Q fever, chlamydiosis, and brucellosis are zoonotic diseases that impact animal health and production losses. Control and prevention measures related to risk factors together with active surveillance programs should be incorporated into client education.

Seroepidemiologic evidence of Q fever and associated factors among workers in veterinary service laboratory in South Korea

The incidence of Q fever has rapidly increased in South Korea since 2015. This study was undertaken to investigate the seroprevalence and seroreactivity of Q fever and the risk factors associated with its seroprevalence among workers in the veterinary service laboratory (VSL) in South Korea. This seroepidemiologic study was conducted in a total of 661 human subjects out of 1,328 subjects working in 50 VSL existing in South Korea between July 15 and July 29, 2019. Data were collected by administering survey questionnaires and by analyzing collected blood samples to determine the presence of antibodies against Coxiella burnetii. The seroprevalence and seroreactivity of C. burnetii infection were determined based on serum titers as (phase II IgG ≥1:256 and/or IgM ≥1:16) and (phase II IgG ≥1:16 and/or IgM ≥1:16) as determined by indirect immunofluorescent assay. Work, work environment, behavioral risk and protective factors associated with seroprevalence of Q fever were assessed by employing multivariable logistic regression analysis. Among the 661, the seroprevalence and seroreactivity of C. burnetii infection were 7.9% and 16.0%, respectively. Multivariate logistic regression analysis showed the risk factors significantly associated with seroprevalence were the antemortem inspection of cattle, goats, or sheep (APR (adjusted prevalence ratio), 2.52; 95% CI, 1.23–4.70)), animal blood splashed into or around eyes (APR, 2.24; 95% CI, 1.04–4.41), and contact with animals having Q fever (APR, 6.58; 95% CI, 3.39–10.85) during the previous year. This study suggests the need for precautions when contact with cattle, goats, or sheep is expected, especially during the antemortem inspection, when dealing with C. burnetii infected animals, or when there is a risk of ocular contact with animal derivatives. Therefore, we recommend the consistent use of appropriate personal protective equipment and other protective measures including PPE treatment and washing of body surfaces after work to prevent C. burnetii infections among VSL staff in South Korea.

Coxiella burnetii infections in mice: Immunological responses to contemporary genotypes found in the US

Coxiella burnetii is an obligate intracellular bacterium that causes the human disease Q fever, which can manifest as an acute flu-like illness or a long-term chronic illness, such as endocarditis. Three genotypes (ST8, ST16, and ST20) of Coxiella burnetii are commonly found in the contemporary US and are associated with specific animal hosts. Although all three genotypes have been isolated from humans with Q fever, studies comparing virulence between C. burnetii sequence types have been rare. Here, groups of mice were infected via aerosol inoculation with isolates derived from cow's milk, environmental, animal, and human samples. Mice were monitored for weight loss and blood samples were takenweekly. Animals were euthanized at 2- and 12-weeks post-infection, and bacterial burden was determined for tissues by real-time PCR. The levels of anti-Coxiella antibodies and selected inflammatory cytokines were determined for serum samples. Weight loss and splenomegaly were observed in mice infected with ST20 and ST16 isolates but were absent in the mice infected with ST8 isolates. Bacterial concentrations in the tissues were lower in the ST8 isolates at 2 weeks post-infection relative to all other isolates. ST16 and ST20 isolates induced robust antibody and cytokine responses, while ST8 isolates produced significantly lower anti-C. burnetii titers early in the infection but saw increased titers in some animals several weeks post-infection. The data suggest that the ST8 isolates are less virulent in this mouse model, as they produce less robust antibody responses that are slow to develop, relative to the ST16 and ST20 isolates.

Q Fever: A troubling disease and a challenging diagnosis

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

Seroprevalence of Coxiella burnetii in patients presenting with acute febrile illness at Marigat District Hospital, Baringo County, Kenya

Q fever is not routinely diagnosed in Kenyan hospitals. This study reports on Q fever in patients presenting at Marigat District Hospital, Kenya, with febrile illness. ELISA was used to detect Coxiella burnetii phase antigens. Of 406 patients, 45 (11.1%) were judged to have acute disease (phase II IgM or IgG > phase I IgG), 2 (0.5%) were chronic (phase I IgG titer >800 or phase I IgG > phase II IgG), while 26 (6.4%) had previous exposure (phase I IgG titer <800). Age (6–10 years, p = 0.002) and contact with goats (p = 0.014) were significant risk factors. Compared to immunofluorescence antibody test, the sensitivity and specificity for phase I IgG were 84% and 98%, respectfully, 46% and 100% for phase II IgG and 35% and 89% for phase II IgM. It is concluded that the low sensitivity of phase II ELISA underestimated the true burden of acute Q fever in the study population.

Update on prevalence and distribution pattern of tick-borne diseases among humans in India: a review

In the present scenario, tick-borne diseases (TBDs) are well known for their negative impacts on humans as well as animal health in India. The reason lies in their increased incidences due to global warming, environmental and ecological changes, and availability of suitable habitats. On a global basis, they are now considered a serious threat to human as well as livestock health. The major tick-borne diseases in India include Kyasanur forest disease (KFD), Crimean-congo hemorrhagic fever (CCHF), Lyme disease (LD), Q fever (also known as coxiellosis), and Rickettsial infections. In recent years, other tick-borne diseases such as Babesiosis, Ganjam virus (GANV), and Bhanja virus (BHAV) infections have also been reported in India. The purpose of this paper is to review the history and the current state of knowledge of tick-borne diseases in the country. The conclusion of this review is extending the requirement of greater efforts in research and government management for the diagnosis and treatment and as well as prevention of these diseases so that tick-borne disease burden should be minimizing in India.

Q fever: a rare but potentially life-threatening zoonotic disease

Q fever can present as a fever of unknown aetiology and can be challenging to diagnose because of the rare incidence. It can present as an acute illness with manifestations, including influenza-like symptoms, hepatitis, pneumonia or chronic disease involving the cardiovascular system. We present a case of a 39-year-old woman in the USA, who developed acute Q fever with associated sepsis and severe hepatitis. She received treatment with recovery from acute infection but currently has symptoms of post Q fever syndrome.

Prevalence of Coxiella burnetii seropositivity and shedding in farm, pet and feral cats and associated risk factors in farm cats in Quebec, Canada

Cats represent a potential source of Coxiella burnetii, the aetiological agent of Q fever in humans. The prevalence and risk factors of C. burnetii infection in farm, pet and feral cats were studied in Quebec, Canada, using a cross-sectional study. Serum samples were tested using a specific enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies against C. burnetii, whereas rectal swabs were assayed using real-time quantitative polymerase chain reaction (qPCR) for the molecular detection of the bacteria. Potential risk factors for farm cats were investigated using clinical examinations, questionnaires and results from a concurrent study on C. burnetii farm status. A total of 184 cats were tested: 59 from ruminant farms, 73 pets and 52 feral cats. Among farm cats, 2/59 (3.4%) were ELISA-positive, 3/59 (5.1%) were ELISA-doubtful and 1/59 (1.7%) was qPCR-positive. All pets and feral cats were negative to C. burnetii ELISA and qPCR. Farm cat positivity was associated with a positive C. burnetii status on the ruminant farm (prevalence ratio = 7.6, P = 0.03). Our results suggest that although pet and feral cats do not seem to pose a great C. burnetii risk to public health, more active care should be taken when in contact with cats from ruminant farms.

A Novel Marmoset (Callithrix jacchus) Model of Human Inhalational Q Fever

Common marmosets (Callithrix jacchus) were shown to be susceptible to inhalational infection with Coxiella burnetii, in a dose-dependent manner, producing a disease similar to human Q fever, characterized by a resolving febrile response. Illness was also associated with weight loss, liver enzyme dysfunction, characteristic cellular activation, circulating INF-γ and bacteraemia. Viable C. burnetii was recovered from various tissues during disease and from 75% of the animal's lungs on 28 days post challenge, when there were no overt clinical features of disease but there was histological evidence of macrophage and lymphocyte infiltration into the lung resulting in granulomatous alveolitis. Taken together, these features of disease progression, physiology and bacterial spread appear to be consistent with human disease and therefore the common marmoset can be considered as a suitable model for studies on the pathogenesis or the development of medical counter measures of inhalational Q fever.

First isolation and molecular phylogenetic analysis of Coxiella burnetii in lactating cows

Q fever is an infectious disease of animals and humans, caused by globally distributed C. burnetii. In Iraq, there are no previous studies associated with the detection of the organism in cattle. An overall of 130 lactating cows were submitted to direct collection of milk samples. Initially, the samples of milk were tested using the molecular polymerase chain reaction (PCR) assay targeting three genes (16S rRNA, IS1111a transposase, and htpB). However, positive results (18.46%; 24/130) were detected only with the 16s rRNA gene. Concerning risk factors, the highest prevalence of C. burnetii was showed in the district of Badra (42.86%), whereas the lowest - in Al-Numaniyah and Al-Suwaira districts (P=0.025). There was no significant variation in positivity between the months of sampling period (P=0.082) and between age groups (P=0.076). Crossbred cows (20.69%) showed a higher positivity than local and pure breeds (P=0.043). Milk of positive samples (n=24) was used for cultivation of C. burnetii into specific pathogen free-embryonated chicken eggs (SPF-ECEs). After three passages into SPF-ECEs, contents of yolk sac were collected, subjected for DNA extraction, and re-tested by PCR assay using the primer of 16s rRNA gene only. Of 24 cultivated milk samples, 12.5% (3/24) were positive for C. burnetii. Finally, the positive local isolates were analysed phylogenetically and reported in NCBI-Genbank under the accession numbers of MN121700.1, MN121701.1, and MN121702.1. In conclusion, this is a unique study as it detected C. burnetii in Iraqi lactating cows, and confirmed that organism was shed actively through milk, suggesting that these animals can play a role as a reservoir for organism with potential risk for transmission of infection from these animals to humans as well as to other animal species.

Coxiella burnetii in Dromedary Camels (Camelus dromedarius): A Possible Threat for Humans and Livestock in North Africa and the Near and Middle East?

The "One Health" concept recognizes that human health is connected to animal health and to the ecosystems. Coxiella burnetii-induced human Q fever is one of the most widespread neglected zoonosis. The main animal reservoirs responsible for C. burnetii transmission to humans are domesticated ruminants, primarily goats, sheep, and cattle. Although studies are still too sparse to draw definitive conclusions, the most recent C. burnetii serosurvey studies conducted in herds and farms in Africa, North Africa, Arabian Peninsula, and Asia highlighted that seroprevalence was strikingly higher in dromedary camels (Camelus dromedarius) than in other ruminants. The C. burnetii seroprevalence in camel herds can reach more than 60% in Egypt, Saudi Arabia, and Sudan, and 70 to 80% in Algeria and Chad, respectively. The highest seroprevalence was in female camels with a previous history of abortion. Moreover, C. burnetii infection was reported in ticks of the Hyalomma dromedarii and Hyalomma impeltatum species collected on camels. Even if dromedary camels represent <3% of the domesticated ruminants in the countries of the Mediterranean basin Southern coast, these animals play a major socioeconomic role for millions of people who live in the arid zones of Africa, Middle East, and Asia. In Chad and Somalia, camels account for about 7 and 21% of domesticated ruminants, respectively. To meet the growing consumers demand of camel meat and milk (>5 million tons/year of both raw and pasteurized milk according to the Food and Agriculture Organization) sustained by a rapid increase of population (growth rate: 2.26-3.76 per year in North Africa), dromedary camel breeding tends to increase from the Maghreb to the Arabic countries. Because of possible long-term persistence of C. burnetii in camel hump adipocytes, this pathogen could represent a threat for herds and breeding farms and ultimately for public health. Because this review highlights a hyperendemia of C. burnetii in dromedary camels, a proper screening of herds and breeding farms for C. burnetii is urgently needed in countries where camel breeding is on the rise. Moreover, the risk of C. burnetii transmission from camel to human should be further evaluated.

Minimizing the risk of occupational Q fever exposure: A protocol for ensuring Coxiella burnetii-negative pregnant ewes are used for medical research

Q fever is a worldwide zoonosis caused by Coxiella burnetii that can lead to abortion, endocarditis, and death in humans. Researchers utilizing parturient domestic ruminants, including sheep, have an increased risk of occupational exposure. This study evaluated the effectiveness of our screening protocol in eliminating C. burnetii-positive sheep from our facility. From August 2010 to May 2018, all ewes (N  =  306) and select lambs (N  =  272; ovis aries) were screened twice for C. burnetii utilizing a serum Phase I and Phase II antibody immunofluorescence assay (IFA). The first screen was performed by the vendor prior to breeding, and the second screen was performed on arrival to the research facility. Ewes that were positive on arrival screening were quarantined and retested using repeat IFA serology, enzyme-linked immunosorbent assay, buffy coat polymerase chain reaction (PCR), and amniotic fluid PCR. The overall individual seroprevalence of C. burnetii in the flocks tested by the vendor was 14.2%. Ewes with negative Phase I and Phase II IFA results were selected for transport to the research facility. Upon arrival to the facility, two (0.7%) ewes had positive Phase I IFA results. Repeat testing demonstrated seropositivity in one of these two ewes, though amniotic fluid PCR was negative in both. The repeat seropositive ewe was euthanized prior to use in a research protocol. No Q fever was reported among husbandry, laboratory or veterinary staff during the study period. Serologic testing for C. burnetii with IFA prior to transport and following arrival to a research facility limits potential exposure to research staff.

Coxiella burnetii-Infected NK Cells Release Infectious Bacteria by Degranulation

Natural killer (NK) cells are critically involved in the early immune response against various intracellular pathogens, including Coxiella burnetii and Chlamydia psittaci Chlamydia-infected NK cells functionally mature, induce cellular immunity, and protect themselves by killing the bacteria in secreted granules. Here, we report that infected NK cells do not allow intracellular multiday growth of Coxiella, as is usually observed in other host cell types. C. burnetii-infected NK cells display maturation and gamma interferon (IFN-γ) secretion, as well as the release of Coxiella-containing lytic granules. Thus, NK cells possess a potent program to restrain and expel different types of invading bacteria via degranulation. Strikingly, though, in contrast to Chlamydia, expulsed Coxiella organisms largely retain their infectivity and, hence, escape the cell-autonomous self-defense mechanism in NK cells.

Detection of Coxiella burnetii antibodies in sheep and cattle on a veterinary campus in St. Kitts: Implications for one health in the Caribbean region

Coxiella burnetii is a ubiquitous zoonotic bacterium reported worldwide that causes Q-fever. Infections result in profound economic losses to livestock producers by causing abortions and low birth weights. Current information about the disease in the Caribbean region is scarce. With multiple small islands and territories, it is often considered that the bacterium is absent or circulates at a low prevalence. Our study aimed to determine whether sheep and cattle housed at a veterinary campus in St Kitts had previous exposure to C. burnetii. Blood samples were taken from cattle (n = 63; 72% of the herd) and sheep (n = 133; 71% of the flock). Antibodies to C. burnetii were detected by a commercial indirect enzyme-linked immunosorbent assay (IDvet® ELISA) test. The seroprevalence was estimated at 26.3% (95% CI: 19.1–34.7%) in sheep and 0% (95% CI: 0–5.7%) in cattle. Sheep importation to St. Kitts is very rare, thus, these results suggest that C. burnetii is present on the island. The seronegativity of all the cattle highlights the absence of the bacterium on the veterinary campus. The high seroprevalence in sheep, however, has potentially important implications for animal health and public health as well as for wildlife conservation. Further investigation about animal seroprevalence and human exposure are warranted in St. Kitts and in the Caribbean region.

•

Seroprevalence in sheep from a veterinary university was 26.3%

•

No cattle from the university were seropositive

•

Risk for human and animal health is likely to be important in St. Kitts

•

There is a need to investigate the prevalence of Coxiella burnetii in Caribbean region

Molecular Detection of Rickettsia Spp. and Coxiella Burnetii in Cattle, Water Buffalo, and Rhipicephalus (Boophilus) Microplus Ticks in Luzon Island of the Philippines

Rickettsia and Coxiella burnetii are zoonotic, tick-borne pathogens that can cause febrile illnesses with or without other symptoms in humans, but may cause subclinical infections in animals. There are only a few reports on the occurrence of these pathogens in cattle and water buffalo in Southeast Asia, including the Philippines. In this study, molecular detection of Rickettsia and C. burnetii in the blood and in the Rhipicephalus (Boophilus) microplus ticks of cattle and water buffalo from five provinces in Luzon Island of the Philippines was done. A total of 620 blood samples of cattle and water buffalo and 206 tick samples were collected and subjected to DNA extraction. After successful amplification of control genes, nested PCR was performed to detect gltA of Rickettsia and com1 of C. burnetii. No samples were positive for Rickettsia, while 10 (cattle = 7, water buffaloes = 3), or 1.6% of blood, and five, or 1.8% of tick samples, were C. burnetii-positive. Sequence analysis of the positive amplicons showed 99-100% similarity to reported C. burnetii isolates. This molecular evidence on the occurrence of C. burnetii in Philippine ruminants and cattle ticks and its zoonotic nature should prompt further investigation and surveillance to facilitate its effective control.

Q Fever in Southern California: a Case Series of 20 Patients from a VA Medical Center

Query fever (Q fever), caused by Coxiella burnetii, was first described in southern California in 1947. It was found to be endemic and enzoonotic to the region and associated with exposure to livestock. We describe a series of 20 patients diagnosed with Q fever at a Veterans Affairs hospital in southern California, with the aim of contributing toward the understanding of Q fever in this region. Demographics, laboratory data, diagnostic imaging, risk factors, and treatment regimens were collected via a retrospective chart review of patients diagnosed with Q fever at our institution between 2000 and 2016. Cases were categorized as acute or chronic and confirmed or probable. The majority presented with an acute febrile illness (90%). There was a delay in ordering diagnostic serology from the time of symptom onset (acute cases, average 31.9 days; chronic cases, average 63 days), and 15% progressed from acute to chronic infection. Of the chronic cases, 22.2% had endocarditis, 22.2% had endovascular infection, and 11.1% had both endocarditis and endovascular infection. The geographic distribution revealed that 20% resided in rural areas. Of the cases of Q fever that died, death attributed to Q fever was associated with an average diagnostic delay of 65.5 days. Acute Q fever is underreported in this region largely because of its often nonspecific clinical presentation.

The Effect of pH on Antibiotic Efficacy against Coxiella burnetii in Axenic Media

Coxiella burnetii, the etiologic agent of Q fever, replicates in an intracellular phagolysosome with pH between 4 and 5. The impact of this low pH environment on antimicrobial treatment is not well understood. An in vitro system for testing antibiotic susceptibility of C. burnetii in axenic media was set up to evaluate the impact of pH on C. burnetii growth and survival in the presence and absence of antimicrobial agents. The data show that C. burnetii does not grow in axenic media at pH 6.0 or higher, but the organisms remain viable. At pH of 4.75, 5.25, and 5.75 moxifloxacin, doxycycline, and rifampin are effective at preventing growth of C. burnetii in axenic media, with moxifloxacin and doxycycline being bacteriostatic and rifampin having bactericidal activity. The efficacy of doxycycline and moxifloxacin improved at higher pH, whereas rifampin activity was pH independent. Hydroxychloroquine is thought to inhibit growth of C. burnetii in vivo by raising the pH of typically acidic intracellular compartments. It had no direct bactericidal or bacteriostatic activity on C. burnetii in axenic media, suggesting that raising pH of acidic intracellular compartments is its primary mechanism of action in vivo. The data suggest that doxycycline and hydroxychloroquine are primarily independent bacteriostatic agents.

Coxiella seroprevalence and risk factors in large ruminants in Bihar and Assam, India

Coxiellosis is a zoonotic disease caused by the ubiquitous bacteria Coxiella burnetii, which can be spread either through ticks or through body fluids. In humans the infection is characterized by a febrile disease; ruminants may abort and reduce their milk yield, causing serious production losses for the farmer. In India, the disease has been known to be present since the 1970s, but little is known about the epidemiology in most states. In this cross-sectional survey in the two states of Assam and Bihar, 520 households were interviewed for risk factors, and serum samples from 744 dairy animals were analyzed using ELISA as well as PCR. Out of the farms, 17.4% had at least one seropositive animal, with significantly higher seroprevalence in Bihar (27.1%) than Assam (5.8%); and significantly more sero-positive farms in urban areas (23.1%) than rural (12.2%). On an individual animal level, 14.1% were seropositive, with higher prevalence among buffaloes than cows (28.0% versus 13.6%). Out of the seropositive animals, 10.6% had aborted during the last three years, and 37.5% had experienced problems with repeat breeding: both higher than in non-seropositive animals. In conclusion, this study indicates that coxiellosis is potentially an important cause of reproductive failures and production losses in dairy animals. The high prevalence, especially in urban areas, is a public health risk. Further research is needed to elucidate the epidemiology and identify mitigation options that could work in the different settings of different Indian states.

Serological evidence of Coxiella burnetii infection in cattle and farm workers: is Q fever an underreported zoonotic disease in Ecuador?

Background: Q fever is an underreported zoonotic disease of cattle and men in most countries of the world. Very little information about the prevalence of Coxiella burnetii infection in animals and humans comes from South and Central America and systematic studies are lacking. Methods: A seroprevalence survey for Q fever amongst cattle, farm workers and students was conducted in Ecuador using a commercial ELISA kit. Results: Survey results showed an unexpectedly high prevalence of Coxiella burnetii antibodies in dairy cattle (43%) and in farm workers (34%). In addition, a clinical case in a human of acute Q fever in the convalescent stage was detected. Conclusion: We conclude that the disease is endemic in Ecuador but is overlooked by medical and laboratory personnel. Q fever should be considered a public health issue in Ecuador and further research into the clinical relevance of this infection is recommended.

Is a One Health Approach Utilized for Q Fever Control? A Comprehensive Literature Review

Q fever, a zoonotic disease transmitted from animals to humans, is a significant public health problem with a potential for outbreaks to occur. Q fever prevention strategies should incorporate human, animal, and environmental domains. A One Health approach, which engages cross-sectoral collaboration among multiple stakeholders, may be an appropriate framework and has the underlying principles to control Q fever holistically. To assess whether components of One Health for Q fever prevention and control have been applied, a comprehensive literature review was undertaken. We found 16 studies that had practiced or recommended a One Health approach. Seven emerging themes were identified: Human risk assessment, human and animal serology, integrated human⁻animal surveillance, vaccination for at-risk groups, environmental management, multi-sectoral collaboration, and education and training. Within the multi-sectoral theme, we identified five subthemes: Policy and practice guidelines, information sharing and intelligence exchange, risk communication, joint intervention, and evaluation. One Health practices varied between studies possibly due to differences in intercountry policy, practice, and feasibility. However, the key issue of the need for multi-sectoral collaboration was highlighted across most of the studies. Further research is warranted to explore the barriers and opportunities of adopting a One Health approach in Q fever prevention and control.

Trends in Q fever serologic testing by immunofluorescence from four large reference laboratories in the United States, 2012-2016

Laboratory testing for Q fever (Coxiella burnetii) is essential for a differential diagnosis, yet little is known about Q fever diagnostic testing practices in the United States. We retrospectively analyzed Q fever immunoglobulin G (IgG) indirect immunofluorescence assay (IFA) testing data between 1/1/2012–10/31/2016 from ARUP, LabCorp, Mayo Medical Laboratories, and Quest Diagnostics. Data included IgG phase I and phase II titers, patient age and sex, and state and date of specimen collection. On average, 12,821 specimens were tested for Q fever annually by the participating laboratories. Of 64,106 total specimens, 84.1% tested negative for C. burnetii-specific antibodies. Positive titers ranged from 16 to 262,144 against both phase I and phase II antigens. Submission of specimens peaked during the summer months, and more specimens were submitted from the West North Central division. Testing occurred more frequently in males (53%) and increased with age. In conclusion, few U.S. Q fever cases are reported, despite large volumes of diagnostic specimens tested. Review of commercial laboratory data revealed a lack of paired serology samples and patterns of serology titers that differ from case reporting diagnostic criteria.

Tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran: A systematic review

BACKGROUND

Tick-borne zoonoses in the Order Rickettsiales and Legionellales cause infections that often manifest as undifferentiated fevers that are not easy to distinguish from other causes of acute febrile illnesses clinically. This is partly attributed to difficulty in laboratory confirmation since convalescent sera, specific diagnostic reagents, and the required expertise may not be readily available. As a result, a number of tick-borne zoonoses are underappreciated resulting in unnecessary morbidity, mortality and huge economic loses. In Iran, a significant proportion of human infectious diseases are tick-borne, with anecdotal evidence suggesting that tick-borne zoonoses are widespread but underreported in the country. Epidemiological review is therefore necessary to aid in the effective control and prevention of tick-borne zonooses in Iran. The aim of this review is to provide an in-depth and comprehensive overview of anaplasmosis, ehrlichiosis, spotted fever group rickettsioses and coxiellosis in Iran.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, all relevant publications on tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran were searched using a number of search terms. The search was confined to authentic resources from repositories of popular data bases among them PubMed, Web of Science, Google Scholar, Science Direct, SpringerLink and SCOPUS. The search items included peer reviewed journals, books and book chapters published between 1996 and 2017.

RESULTS

A total of 1 205 scientific publications and reports were sourced, of which 63 met the search criteria and were reviewed. Of the 63 articles reviewed, 36 (57.1%) reported on coxiellosis, 15 (23.8%) on anaplasmosis, 11 (17.5%) on ehrlichiosis and 1(1.6%) on spotted fever group rickettsiae in a large scale study involving four countries, among them Iran. The existence of tick-borne pathogens in the Order Rickettsiales and Legionellales was confirmed by molecular, serological and microscopic techniques conducted on samples obtained from sheep, cattle, goats, camels, poultry, animal products (milk and eggs), dogs, ticks and even human subjects in different parts of the country; pointing to a countrywide distribution.

DISCUSSION

Based on the review, coxiellosis, anaplasmosis, ehrlichiosis, and SFG rickettsiae can be categorized as emerging tick-borne zoonotic diseases in Iran given the presence of their causiative agents (C. burnetii, A. phagocytophilum, A. marginale, A. bovis, A. ovis, A. central, E. canis, E. ewingii, E. chaffeensis and R. conorii) collectively reported in a variety of domestic animals, animal products, arthropods and human beings drawn from 22 provinces in Iran.

CONCLUSION

Given the asymptomatic nature of some of these zoonoses, there is a high likelihood of silent transmission to humans in many parts of the country, which should be considered a public health concern. Presently, information on the transmission intensity of tick-borne zoonoses caused by pathogens in the Order Rickettsiales and Legionellales to humans and its public health impact in Iran is scanty.

Seroreactivity to Q Fever Among Slaughterhouse Workers in South Korea

Objectives

Q fever is a zoonotic disease that occurs worldwide; however, little is known about its prevalence in South Korea. We attempted to determine the prevalence of Q fever seroreactivity among Korean slaughterhouse workers and the risk factors for seroreactivity according to the type of work.

Methods

The study was conducted among 1503 workers at a total of 73 slaughterhouses and 62 residual-product disposal plants. During the study period, sites were visited and surveys were administered to employees involved in slaughterhouse work, and serological tests were performed on blood samples by indirect immunofluorescence assays. Serological samples were grouped by job classification into those of slaughter workers, residual-product handlers, inspectors and inspection assistants, and grading testers and testing assistants. Employee risk factors were analyzed according to the type of work.

Results

Out of 1481 study subjects who provided a blood sample, 151 (10.2%) showed reactive antibodies. When these results were analyzed in accordance with the type of work, the result of slaughter workers (11.3%) was similar to the result of residual-product handlers (11.4%), and the result of inspectors and assistants (5.3%) was similar to the result of grading testers and assistants (5.4%). Among those who answered in the affirmative to the survey question, “Has there been frequent contact between cattle blood and your mouth while working?” the proportions were 13.4 and 4.6%, respectively, and this was identified as a risk factor that significantly varied between job categories among slaughterhouse workers.

Conclusions

This study found a Q fever seroreactivity rate of 10.2% for slaughterhouse workers, who are known to be a high-risk population. Contact with cattle blood around the mouth while working was the differential risk factor between job categories among slaughterhouse workers.

Estimating the incubation period of acute Q fever, a systematic review

Estimates of the incubation period for Q fever vary substantially between different reviews and expert advice documents. We systematically reviewed and quality appraised the literature to provide an evidence-based estimate of the incubation period of the Q fever by the aerosolised infection route. Medline (OVIDSP) and EMBASE were searched with the search limited to human studies and English language. Eligible studies included persons with symptomatic, acute Q fever, and defined exposure to Coxiella burnetti. After review of 7115 titles and abstracts, 320 records were screened at full-text level. Of these, 23 studies contained potentially useful data and were quality assessed, with eight studies (with 403 individual cases where the derivation of incubation period was possible) being of sufficient quality and providing individual-level data to produce a pooled summary. We found a median incubation period of 18 days, with 95% of cases expected to occur between 7 and 32 days after exposure.

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.

Domestic sheep show average Coxiella burnetii seropositivity generations after a sheep-associated human Q fever outbreak and lack detectable shedding by placental, vaginal, and fecal routes

Coxiella burnetii is a globally distributed zoonotic bacterial pathogen that causes abortions in ruminant livestock. In humans, an influenza-like illness results with the potential for hospitalization, chronic infection, abortion, and fatal endocarditis. Ruminant livestock, particularly small ruminants, are hypothesized to be the primary transmission source to humans. A recent Netherlands outbreak from 2007–2010 traced to dairy goats resulted in over 4,100 human cases with estimated costs of more than 300 million euros. Smaller human Q fever outbreaks of small ruminant origin have occurred in the United States, and characterizing shedding is important to understand the risk of future outbreaks. In this study, we assessed bacterial shedding and seroprevalence in 100 sheep from an Idaho location associated with a 1984 human Q fever outbreak. We observed 5% seropositivity, which was not significantly different from the national average of 2.7% for the U.S. (P>0.05). Furthermore, C. burnetii was not detected by quantitative PCR from placentas, vaginal swabs, or fecal samples. Specifically, a three-target quantitative PCR of placenta identified 0.0% shedding (exact 95% confidence interval: 0.0%-2.9%). While presence of seropositive individuals demonstrates some historical C. burnetii exposure, the placental sample confidence interval suggests 2016 shedding events were rare or absent. The location maintained the flock with little or no depopulation in 1984 and without C. burnetii vaccination during or since 1984. It is not clear how a zero-shedding rate was achieved in these sheep beyond natural immunity, and more work is required to discover and assess possible factors that may contribute towards achieving zero-shedding status. We provide the first U.S. sheep placental C. burnetii shedding update in over 60 years and demonstrate potential for C. burnetii shedding to reach undetectable levels after an outbreak event even in the absence of targeted interventions, such as vaccination.

Evaluation of the stability of lyophilized loop-mediated isothermal amplification reagents for the detection of Coxiella burnetii

Coxiella burnetii, the causative pathogen for Q fever, is an obligate intracellular bacterium and designated as a biosafety level 3 agent. Detection and quantification of the bacteria with conventional culturing methods is time-consuming and poses significant health risks. Polymerase chain reaction (PCR)-based assays have been developed for detecting C. burnetii and could provide rapid diagnosis. However, they require specialized equipment, including a cold chain for PCR reagents that maintains their stability during storage and transport. These requirements limit the advantage of PCR-based methods, especially in resource-limited areas.

Previously, we had developed a lyophilized loop-mediated isothermal amplification (LAMP) assay to detect the presence of C. burnetii. To simplify and improve this assay, the reagents for the LAMP assay and the detecting reagent, SYBR green, were lyophilized together. The stability of the lyophilized reagents was evaluated by measuring changes in detection limit for plasmid DNA encoding a C. burnetii gene upon storage at 4 °C, 25 °C, or 37 °C. Our data indicate that the lyophilized reagents remain stable for 24 months when stored at 4 °C, 28 days at 25 °C, and 2 days at 37 °C. This improved LAMP assay can be easily performed in a simple water bath or heating block. The stability at ambient temperature, the simplicity of assay procedure, and the availability of low cost equipment make this method ideal for use in resource-limited settings where Q fever is endemic.

Diagnosis of Acute Q Fever by Detection of Coxiella burnetii DNA using Real-Time PCR, Employing a Commercial Genesig Easy Kit

INTRODUCTION

Query (Q) fever is an important zoonosis and a cause of concern for humans, due to the potential bioterrorism threat posed by the causative agent, Coxiella burnetii. Because of the danger of contracting the illness, isolation attempts are seldom made. Serological and molecular diagnostic tests are the main option.

AIM

To study the prevalence of acute Q fever in Puducherry and surrounding districts of Tamil Nadu, India, employing a new commercial Real-Time Polymerase Chain Reaction (RT-PCR) kit and confirming it by the gold standard Immunofluorescence Assay (IFA).

MATERIALS AND METHODS

Acute phase blood samples from 72 consecutive febrile patients and 24 healthy individuals were included in this prospective study. DNA was extracted from the buffy coats and preserved at -80°C. Detection of C. burnetii was carried out employing a commercial Real-Time PCR kit. Serum samples were tested for IgM (Phase I+II) and IgG (Phase I+II) by QM-120 and QG-120, Coxiella burnetii IFA Fuller Laboratories, California, USA. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated keeping IFA as the reference.

RESULTS

Presumptive diagnosis of acute Q fever was made in two febrile patients by the Genesig Easy kit (2.78%). In addition to these two PCR positive cases, one more patient was positive for both Phase II IgM and Phase II IgG antibodies by the gold standard IFA. All 24 healthy controls were negative for Q fever by both PCR and IFA. The sensitivity, specificity, NPV and PPV for Genesig Easy kit PCR were: 66.67%, 100%, 100% and 98.57 % respectively against IFA as the reference.

CONCLUSION

The true prevalence of Q fever in India and other developing countries is poorly understood, owing to the difficulties in the diagnosis of this infection. Since molecular diagnostic tests have good specificity and are mandated for confirmation of single acute samples, validation of commercial Q fever PCR kits is the need of the hour. Genesig Easy kit in our hands was found to be reliable with the moderate sensitivity and high specificity. Performing both PCR (with acute specimens) and IFA (with paired sera) would be ideal for Q fever diagnosis.

Unreliability of three commercial Coxiella burnetii phase II IgM ELISA kits for the seroscreening of acute Q fever in human cases

BACKGROUND & OBJECTIVES

Seroprevalence of Q fever (QF) caused by Coxiella burnetii has been reported from different parts of India. Usually serological/molecular tests are employed for detection of infection. The present study was undertaken to verify the validity of three different QF phase II IgM ELISA kits for acute QF diagnosis by comparing with the gold standard indirect fluorescent antibody assay (IFA).

METHODS

Fifty eight serum samples collected from 42 patients (26 patients provided acute sample only and 16 both acute and convalescent samples) which were examined by all three commercial kits, were cross-checked with QF Phase II IgM IFA for confirmation.

RESULTS

Eleven patients were positive for C. burnetii antibodies by IFA in acute and/or convalescent serum samples. Taking IFA as a reference, percentages of sensitivity, specificity, positive predictive value and negative predictive value for Virion-Serion/Vircell/NovaTec were 36.36, 61.29, 25.00, 73.08; 81.82, 35.48, 31.03, 84.62 and 100, 25.81, 32.35, 100 per cent, respectively.

INTERPRETATION & CONCLUSIONS

The three different ELISA kits exhibited poor agreement amongst them and unacceptable level of false positivity. IFA remains to be the only option for diagnosing acute QF. Discrepancy between the clinical findings and IFA/ELISA results needs confirmation by C. burnetii DNA detection in real-time polymerase chain reaction.

Prevalence and Risk Factors of Coxiella burnetii Antibodies in Bulk Milk from Cattle, Sheep, and Goats in Jordan

This large-scale cross-sectional study was conducted to determine the prevalence, geographical distribution, and risk factors for the presence of antibodies against Coxiella burnetii in bulk tank milk derived from dairy cattle, sheep, and goats in Jordan. Bulk milk samples were collected from 78 dairy cattle, 48 sheep, and 23 goat farms from various places in Jordan according to the density of these animal species in each region of the country. The samples were tested for C. burnetii antibodies using the CHEKIT Q-Fever Antibody ELISA kit. A standardized questionnaire was also used to collect data from each farm to identify and rank the risk factors for the presence of C. burnetii antibodies. The results revealed that 62.9% (95% confidence interval: 55.1 to 70.0%) of the tested ruminant farms were positive for C. burnetii antibodies. Positive results were obtained from 70.9% (60.6 to 79.5%) of dairy cattle farms, 52.1% (38.3 to 65.5%) of sheep farms, and 56.0% (37.1 to 73.3%) of goat farms. Six factors were associated with the presence of these antibodies on cattle farms, and five factors were associated with these antibodies on sheep and goat farms (chi-square test). The multivariate logistic regression model revealed that large dairy cattle farms, farms that add new animals to the herd, farms that infrequently clean the feeders, and farms in particular areas are 28.6, 19.9, 8.0, and 6.4 times more likely, respectively, to have animals with C. burnetii antibodies. Sheep and goat farms that mix their animals with those from other farms, graze more than 5 km, and infrequently sanitize the feeders were 8.0, 0.06, and 13.6 times more likely, respectively, to have animals with C. burnetii antibodies. These data reveal the widespread exposure of Jordanian ruminants to C. burnetii and suggest a high risk for public health.

Coxiella burnetii Employs the Dot/Icm Type IV Secretion System to Modulate Host NF-κB/RelA Activation

Coxiella burnetii is the causative agent of Q fever and an obligate intracellular pathogen in nature that survives and grows in a parasitophorous vacuole (PV) within eukaryotic host cells. C. burnetii promotes intracellular survival by subverting apoptotic and pro-inflammatory signaling pathways that are typically regulated by nuclear transcription factor-κB (NF-κB). We and others have demonstrated that C. burnetii NMII proteins inhibit expression of pro-inflammatory cytokines and induce expression of anti-apoptotic genes during infection. Here, we demonstrate that C. burnetii promotes intracellular survival by modulating NF-κB subunit p65 (RelA) phosphorylation, and thus activation, in a Type Four B Secretion System (T4BSS)-dependent manner. Immunoblot analysis of RelA phosphorylated at serine-536 demonstrated that C. burnetii increases NF-κB activation via the canonical pathway. However, RelA phosphorylation levels were even higher in infected cells where bacterial protein or mRNA synthesis was inhibited. Importantly, we demonstrate that inhibition of RelA phosphorylation impairs PV formation and C. burnetii growth. We found that a T4BSS-defective mutant (CbΔdotA) elicited phosphorylated RelA levels similar to those of wild type C. burnetii infection treated with Chloramphenicol. Moreover, cells infected with CbΔdotA or wild type C. burnetii treated with Chloramphenicol showed similar levels of GFP-RelA nuclear localization, and significantly increased localization compared to wild type C. burnetii infection. These data indicate that without de novo protein synthesis and a functional T4BSS, C. burnetii is unable to modulate NF-κB activation, which is crucial for optimal intracellular growth.

Genotyping and Axenic Growth of Coxiella burnetii Isolates Found in the United States Environment

Coxiella burnetii is a gram-negative bacterium that is the etiologic agent of the zoonotic disease Q fever. Common reservoirs of C. burnetii include sheep, goats, and cattle. These animals shed C. burnetii into the environment, and humans are infected by inhalation of aerosols. A survey of 1622 environmental samples taken across the United States in 2006-2008 found that 23.8% of the samples contained C. burnetii DNA. To identify the strains circulating in the U.S. environment, DNA from these environmental samples was genotyped using an SNP-based approach to derive sequence types (ST) that are also compatible with multispacer sequence typing methods. Three different sequence types were observed in 31 samples taken from 19 locations. ST8 was associated with goats and ST20 with dairy cattle. ST16/26 was detected in locations with exposure to various animals and also in locations with no direct animal contact. Viable isolates were obtained for all three sequence types, but only the ST20 and ST16/26 isolates grew in acidified citrate cysteine medium (ACCM)-2 axenic media. Examination of a variety of isolates with different sequence types showed that ST8 and closely related isolates did not grow in ACCM-2. These results suggest that a limited number of C. burnetii sequence types are circulating in the U.S. environment and these strains have close associations with specific reservoir species. Growth in ACCM-2 may not be suitable for isolation of many C. burnetii strains.