Seroprevalence of Coxiella burnetii in Australian dogs

The role of dogs in the transmission of Coxiella burnetii to humans is uncertain, and extensive seroprevalence studies of dogs have not been previously conducted in Australia. This study determined C. burnetii exposure in four diverse canine subpopulations by adapting, verifying and comparing an indirect immunofluoresence assay (IFA) and an enzyme‐linked immunosorbent assay (ELISA) used to detect anti‐C. burnetii antibodies in humans. Canine serum samples (n = 1223) were tested with IFA from four subpopulations [breeding establishments; household pets; free‐roaming dogs in Aboriginal communities; shelter dogs]. The proportions of seropositive dogs were as follows: breeding (7/309, 2.3%), household pets (10/328, 3%), Aboriginal communities (21/321, 6.5%) and shelters (5/265, 1.9%). Dogs from Aboriginal communities were 2.8 times (CI 1.5–5.1; P < 0.001) more likely to be seropositive than dogs from other populations. The ELISA was used on 86 of 1223 sera tested with IFA, and a Cohen's Kappa coefficient of 0.60 (CI 0.43–0.78) indicated good agreement between the two assays. This study has established that Australian dogs within all four subpopulations have been exposed to C. burnetii and that a higher seroprevalence was observed amongst free‐roaming dogs associated with Aboriginal communities. As C. burnetii recrudesces during pregnancy and birth products contain the highest concentration of organism, individuals assisting at the time of parturition, those handling pups shortly after birth as well as those residing in the vicinity of whelping dogs are potentially at risk of developing Q fever. However, the identification of active antigen shed in excreta from seropositive dogs is required in order to accurately define and quantify the public health risk.     

Risk factors for bacterial zoonotic pathogens in acutely febrile patients in Mpumalanga Province,South Africa

Endemic zoonoses, such as Q fever and spotted fever group (SFG) rickettsiosis, are prevalent in South Africa, yet often undiagnosed. In this study, we reviewed the demographics and animal exposure history of patients presenting with acute febrile illness to community health clinics in Mpumalanga Province to identify trends and risk factors associated with exposure to Coxiella burnetii, the causative agent of Q fever, and infection by SFG Rickettsia spp. Clinical and serological data and questionnaires elucidating exposure to animals and their products were obtained from 141 acutely febrile patients between 2012 and 2016. Exposure or infection status to C. burnetii and SFG Rickettsia spp. was determined by presence of IgG or IgM antibodies. Logistic regression models were built for risk factor analysis. Clinical presentation of patients infected by SFG rickettsiosis was described. There were 37/139 (27%) patients with a positive C. burnetii serology, indicative of Q fever exposure. Patients who had reported attending cattle inspection facilities (“dip tanks”) were 9.39 times more likely to be exposed to Q fever (95% CI: 2.9–30.4). Exposure risk also increased with age (OR: 1.03, 95% CI: 1.002–1.06). Twenty‐one per cent of febrile patients (24/118) had evidence of acute infection by SFG Rickettsia spp. Similarly, attending cattle inspection facilities was the most significant risk factor (OR: 8.48, 95% CI: 1.58–45.60). Seropositivity of females showed a significant OR of 8.0 when compared to males (95% CI: 1.49–43.0), and consumption of livestock was associated with a decreased risk (OR: 0.02, 95% CI: 0.001–0.54). A trend between domestic cat contact and SFG rickettsiosis was also noted, albeit borderline non‐significant. In this endemic region of South Africa, an understanding of risk factors for zoonotic pathogens, including exposure to domestic animals, can help clinic staff with diagnosis and appropriate therapeutic management of acutely febrile patients as well as identify target areas for education and prevention strategies.     

Seroprevalence and Factors Associated with Coxiella burnetii Infection in Small Ruminants in Baringo County,Kenya

To improve estimates of C. burnetii epidemiology in Kenya, a survey was undertaken in small ruminants in Baringo County, where acute cases of Q fever in humans had been reported in 2014. From 140 household herds selected, 508 (60.5%) goats and 332 (39.5%) sheep were included and an indirect ELISA assay for C. burnetii IgG antibodies performed. In addition, epidemiological information at both herd and animal level was collected. Generalized mixed‐effects multivariable logistic model using herd as the random effect was used to determine variables correlated to the outcome. Overall seroprevalence was 20.5% (95% CI: 17.8%, 23.3%). Goats had 26.0% (95% CI: 22.2%, 30.0%) compared to sheep 12.2% (95% CI: 8.7%, 16.0%). Nomadic pastoralism, goats and older animals (>1 year) were associated with greater risk of C. burnetii seropositivity (P = ≤0.05). Heterogeneity in C. burnetii seropositivity was observed across the sublocations (P = 0.028). Evidence of C. burnetii exposure in small ruminants revealed poses a potential risk of exposure to the people living in close proximity to the animals. We recommended integrated animal–human surveillance and socio‐economic studies for C. burnetii, to aid our understanding of the risk of transmission between the animals and humans, and in the design of prevention and control strategies for the disease in the region.     

Coxiella burnetii seroprevalence in unvaccinated veterinary workers in Australia: Evidence to support Q fever vaccination

Q fever (caused by Coxiella burnetii) is a serious zoonotic disease that occurs almost worldwide. Occupational contact with animals increases the risk of exposure, and Q fever vaccination is recommended for veterinary workers in Australia. This study aimed to investigate C. burnetii seroprevalence among unvaccinated veterinary workers in Australia and determine factors associated with a positive serological result. During 2014 and 2015, convenience sampling at veterinary conferences and workplace vaccination clinics was undertaken. Participants completed a questionnaire and provided a blood sample for C. burnetii serology. Participants were predominantly veterinarians (77%), but veterinary support staff, animal scientists, and administration workers also participated. Blood samples (n = 192) were analysed by an immunofluorescence assay and considered positive where the phase I or phase II IgG titre was ≥1/50. Seroprevalence was 19% (36/192; 95% CI 14%–25%). A positive serological result was significantly associated with (a) working in outer regional/remote areas (odds ratio [OR] 6.2; 95% CI 1.9–20.8; reference = major cities; p = .009) and (b) having spent more than 50% of total career working with ruminants (OR 4.8; 95% CI 1.7–13.5; reference = <15% of career; p = .025). These findings confirm an increased risk of exposure to C. burnetii compared to the general population, providing new evidence to support Q fever vaccination of veterinary workers in Australia.     

Molecular detection of Coxiella burnetii in raw meat intended for pet consumption

The discovery of antibodies against Coxiella burnetii in cattery‐confined breeding cats indicating prior or current exposure (Shapiro et al., 2015) prompted an investigation into possible sources of infection. One hypothesis was that raw meat diets containing reservoir species may provide a source of C. burnetii transmission. The aim of this pilot study was to determine whether C. burnetii DNA was present in raw meat sold exclusively for companion animal consumption. The sample population consisted of raw meat packages (n = 58) of primarily kangaroo origin, with three to four aliquots (50–120 mg) randomly selected from each package. Genomic DNA was extracted from whole tissue in each of these aliquots using a modified protocol. Three quantitative PCR assays were used for the detection of C. burnetii targeting the IS1111 gene, the heat shock operon htpAB and the C. burnetii outer membrane protein‐coding gene, com1. Coxiella burnetii DNA was detected in 25/58 samples (43%) using the IS1111, htpAB and/or com1 PCR assays and confirmed by DNA sequencing. All samples amplifying a product in the com1 assay also amplified a product in the htpAB and IS1111 assays. A total of 17/58 (29%) packets were positive with all three genes, 4/58 (7%) were positive with two genes (IS1111 and htpAB) and 4/58 (7%) were positive with the IS1111 gene only. Coxiella burnetii DNA was five times more likely to be found in offal than skeletal muscle meat samples. All meat samples in which C. burnetii DNA was found were from kangaroo tissues, while samples labelled as non‐kangaroo meat (n = 4) were negative. Multi‐locus variable number of tandem repeat analysis (MLVA) identified three different genotypes of C. burnetii that have all been identified previously from Australian human clinical Q fever cases. Further investigations are required to determine the potential role of certain raw meats in the transmission of C. burnetii to cats and humans.     

Risk factors associated with self-reported Q fever in Australian wildlife rehabilitators: Findings from an online survey

Australian wildlife rehabilitators (AWR) are at increased risk of developing Q fever, a serious zoonotic disease caused by the intracellular bacterium Coxiella burnetii. Previous studies have suggested that Australian wildlife may be a potential C. burnetii infection source for humans. However, a recent serological survey of AWR found no association between C. burnetii exposure and direct contact with any wildlife species. To further explore the potential risk that wildlife may pose, this study aimed to identify associations between self-reported Q fever in AWR and risk factors for exposure to C. burnetii. An online cross-sectional survey was implemented in 2018 targeting AWR nationwide. Risk factors for self-reported Q fever were determined using multivariable logistic regression. Medically diagnosed Q fever was self-reported in 4.5% (13/287) of unvaccinated respondents. Rehabilitators who self-reported medically diagnosed Q fever were significantly more likely to: primarily rehabilitate wildlife at a veterinary clinic (OR 17.87, 95% CI: 3.09–110.92), have domestic ruminants residing on the property where they rehabilitate wildlife (OR 11.75, 95% CI: 2.91–57.42), have been educated at a High School/Technical and Further Education level (OR 10.29, 95% CI: 2.13–84.03) and be aged >50 years (OR 6.61, 95% CI: 1.60–38.35). No association was found between self-reported Q fever and direct contact with wildlife. These findings support previous work suggesting that AWR are at increased risk of C. burnetii infection and may develop Q fever potentially via exposure to traditional infection sources including livestock, other domestic animals, or contaminated environments, in association with their rehabilitation practices and lifestyle. Although Q fever vaccination is recommended for AWR, vaccine uptake is low in this population. Future studies should aim to determine the level of Q fever awareness and identify barriers to Q fever vaccination in this at-risk group. The difficulty in accessing the AWR population also highlights the need for a national centralized AWR database.     

Serosurvey of Coxiella burnetii (Q fever) in Dromedary Camels (Camelus dromedarius) in Laikipia County,Kenya

Dromedary camels (Camelus dromedarius) are an important protein source for people in semi‐arid and arid regions of Africa. In Kenya, camel populations have grown dramatically in the past few decades resulting in the potential for increased disease transmission between humans and camels. An estimated four million Kenyans drink unpasteurized camel milk, which poses a disease risk. We evaluated the seroprevalence of a significant zoonotic pathogen, Coxiella burnetii (Q fever), among 334 camels from nine herds in Laikipia County, Kenya. Serum testing revealed 18.6% positive seroprevalence of Coxiella burnetii (n = 344). Increasing camel age was positively associated with C. burnetii seroprevalence (OR = 5.36). Our study confirmed that camels living in Laikipia County, Kenya, have been exposed to the zoonotic pathogen, C. burnetii. Further research to evaluate the role of camels in disease transmission to other livestock, wildlife and humans in Kenya should be conducted.     

The Effectiveness of Coxiella burnetii Vaccines in Occupationally Exposed Populations: A Systematic Review and Meta‐Analysis

To estimate the effect of vaccination in preventing acute Q fever in individuals occupationally exposed to Coxiella burnetii, a systematic review and meta‐analysis were undertaken in controlled trials and observational studies. Publications were obtained through a scoping study of English and non‐English articles, and those reporting a commercially licensed or licensable vaccine compared with an unvaccinated or placebo control group were included in the review. Two authors performed independent assessment of risk of systematic error and data extraction. One controlled trial and five cohort publications met the inclusion criteria. All trials used a Henzerling phase I vaccine. A random‐effects meta‐analysis estimated significant protection in abattoir workers (RR = 0.07; 95% confidence interval [CI] 0.02–0.22) compared with the control individuals. In individuals with rare or sporadic contact with the abattoir, a significant benefit of vaccination was also found (RR = 0.06; 95% CI 0–0.93). Overall, the vaccine effectively prevented acute Q fever in individuals responsible for handling animals or their products and those working in the abattoir but not directly exposed to animals (RR = 0.06; 95% CI 0.02–0.18). Caution must be taken when interpreting the effect of C. burnetii vaccination as significant heterogeneity amongst publications was observed. A meta‐regression found no significant univariate associations. This may reflect the uncertainty provided by reported data in the cohort publications. Potential systematic biases were present in the publications, and evidence included may not be sufficiently robust to extrapolate the effect of vaccination on occupationally exposed groups beyond the population of abattoir employees in Australia where all included studies occurred.     

Coxiella burnetii: Serological reactions and bacterial shedding in primiparous dairy cows in an endemically infected herd—impact on milk yield and fertility

Coxiella burnetii (C. burnetii) is the causative agent of Q fever both in humans and animals. The objectives of this study were to investigate seropositivity and bacterial shedding in heifers and primiparous cows in an endemically infected herd and to assess the effects on post‐partum diseases, fertility and milk production. At the age of 9 months, 96 Holstein heifers were included. Sampling was performed reproduction‐orientated: at the beginning of the study, at detection of first pregnancy, 3 weeks before expected calving date (blood serum), at parturition and after 21, 42, 100 and 150 days in milk (DIM) (blood serum, vaginal swabs and milk). Serum samples were investigated by a commercial ELISA for the presence of specific antibodies and vaginal swabs and milk samples by PCR to detect C. burnetii DNA. Individual animal data (calving ease, stillbirth, retained foetal membranes, puerperal metritis, endometritis after 42 DIM, presence of corpus luteum after 42 DIM, interval calving‐first service, interval calving‐conception, number of inseminations until 150 DIM, proportion of pregnant cows until 100 and 150 DIM, proportion of pregnant cows after first service and data of the dairy herd improvement test) were documented. All heifers were seronegative at the age of 9 months and 3 weeks before the expected calving date. Subsequently, the proportion of seropositive animals and the antibody score increased significantly towards 42 and 100 DIM, respectively. Vaginal C. burnetii shedding was highest at parturition (30.9%), while the most positive milk samples were detected after 100 DIM (15.3%). Coxiella burnetii seropositivity and shedding had no impact on parameters of reproduction. However, milk fat yield was declined in puerperal vaginal shedders and cows which seroconverted during their first 42 DIM, respectively.     

The sero‐epidemiology of Coxiella burnetii (Q fever) across livestock species and herding contexts in Laikipia County,Kenya

Coxiella burnetii, the causative agent of Query fever (Q fever), is among the most highly infectious zoonotic pathogens transmitted among livestock, with chronic effects challenging to veterinary and medical detection and care systems. Transmission among domestic livestock species can vary regionally due to herd management practices that determine which livestock species are raised, whether or not livestock are in contact with wildlife, and the susceptibility of these livestock to infection. To explore how different livestock management practices are associated with the risk of infection in multispecies environments, we carried out a comparative study of three types of herd management systems in the central Kenyan county of Laikipia: agro‐commercial, mixed conservancy/commercial, and smallholder ranches. We tested C. burnetii antibody seroprevalence in four common livestock species. Across all management types, the highest seroprevalence was in camels (20%), followed by goats (18%), sheep (13%), and cattle (6%). We observed a lower odds of testing seropositive for young compared to adult animals (adjusted OR = 0.44 [95% CI 0.24, 0.76]), and for males compared to females (adjusted OR = 0.52 [95% CI 0.33, 0.80]). Animals from mixed conservancy/commercial and smallholder operations had a higher odds of testing seropositive compared to animals from agro‐commercial ranches (adjusted OR = 5.17 [95% CI 2.71, 10.44] and adjusted OR = 2.21 [95% CI 1.17, 4.43] respectively). These data suggest that herd management practices might affect the transmission dynamics of C. burnetiiin arid African ecosystems like those seen in Kenya where several transmission modes are possible, risk of drought has promoted new livestock species such as camels, and multiple wildlife species may co‐occur with livestock on the landscape. Further longitudinal studies are needed to disentangle the mechanisms underlying these patterns, and further explore transmission patterns between wildlife, domestic animal, and human populations.     

Potential Animal and Environmental Sources of Q Fever Infection for Humans in Queensland

Q fever is a vaccine‐preventable disease; despite this, high annual notification numbers are still recorded in Australia. We have previously shown seroprevalence in Queensland metropolitan regions is approaching that of rural areas. This study investigated the presence of nucleic acid from Coxiella burnetii, the agent responsible for Q fever, in a number of animal and environmental samples collected throughout Queensland, to identify potential sources of human infection. Samples were collected from 129 geographical locations and included urine, faeces and whole blood from 22 different animal species; 45 ticks were removed from two species, canines and possums; 151 soil samples; 72 atmospheric dust samples collected from two locations and 50 dust swabs collected from domestic vacuum cleaners. PCR testing was performed targeting the IS1111 and COM1 genes for the specific detection of C. burnetii DNA. There were 85 detections from 1318 animal samples, giving a detection rate for each sample type ranging from 2.1 to 6.8%. Equine samples produced a detection rate of 11.9%, whilst feline and canine samples showed detection rates of 7.8% and 5.2%, respectively. Native animals had varying detection rates: pooled urines from flying foxes had 7.8%, whilst koalas had 5.1%, and 6.7% of ticks screened were positive. The soil and dust samples showed the presence of C. burnetii DNA ranging from 2.0 to 6.9%, respectively. These data show that specimens from a variety of animal species and the general environment provide a number of potential sources for C. burnetii infections of humans living in Queensland. These previously unrecognized sources may account for the high seroprevalence rates seen in putative low‐risk communities, including Q fever patients with no direct animal contact and those subjects living in a low‐risk urban environment.     

Disease Risk Surface for Coxiella burnetii Seroprevalence in White‐Tailed Deer

Coxiella burnetii is considered a re‐emerging zoonosis in many countries. The bacterium is enzootic in livestock and wildlife in the United States, and environmental contamination is widespread. Despite the potential for exposure, the estimated prevalence of Q fever in humans and animals is not well elucidated, and reported human infections in the United States are relatively rare. Zoonotic transmission of the bacterium is usually associated with abortions in domestic ruminants, but other modes of transmission, such as contact with infected blood and/or milk during field dressing of infected wildlife, have not been thoroughly investigated. Studies of zoonotic pathogen transmission between animal reservoir hosts and humans are usually established in response to documented emergence or re‐emergence of a zoonosis in a particular locale, and, as such, the prevalence of infection in wildlife is largely unknown for many zoonotic pathogens, including C. burnetii. The objective of this study was to create a disease risk surface for C. burnetii seroprevalence in wild white‐tailed deer (Odocoileus virginianus) in New York State. Blood samples were collected from hunter‐harvested deer from across New York State in 2009 and 2010. The samples were processed and tested for the presence of anti‐C. burnetii antibodies via indirect microimmunofluorescence assays using phase II C. burnetii strain RSA439. Overall, 14.50% of the tested white‐tailed deer were C. burnetii phase II seropositive. The dual Kernel density estimation method was used to create a smoothed disease risk surface, which revealed variation in seroprevalence ranging from 0% to 32.0%. Areas of higher seroprevalence were detected in four discrete areas of Central New York and in one additional area in the southwest corner of the northern part of the state. This suggests certain locales where humans may be at increased risk for exposure to the bacterium secondary to contact with potentially infected deer.     

Q Fever in Alberta,Canada: 1998–2011

Establishing the diagnosis of Q fever (Coxiella burnetii) is important in directing the application of therapy to prevent severe manifestations of the infection. In Alberta, Canada, the presence of high livestock density creates a significant risk of infection, but to date, there has been no comprehensive analysis of local Q fever epidemiological trends and exposure patterns. Between 1998 and 2011, there were 39 cases and an overall adjusted case rate of 0.087 per 100 000 person‐years. Cases were identified most commonly during the May–June season (Figure 2). The median age at date of diagnosis was 49.0 (range: 8.7–71.5) with slightly higher percentage of cases in men (56.4%) than in women (43.6%). There was an apparent geographical clustering of cases. The majority of these cases, with exposure data (n = 31), reported contact with farms and/or livestock, predominantly cattle (6), sheep (5) and goats (5). Cases tended to occur in census divisions with higher density of sheep, goats and cattle. Our findings suggest the need for an increase in targeted messages about Q fever to those in the livestock industry, as more targeted case finding among patients with a high index of suspicion for Q fever. In addition, widespread implementation of a standard questionnaire for cases would enhance surveillance of Q fever in Alberta.     

Coxiella burnetii Shedding During the Peripartum Period and Subsequent Fertility in Dairy Cattle

The objective of this study was to assess the effects of Coxiella burnetii shedding or seropositivity on post‐partum recovery and subsequent fertility in high‐producing dairy cows. Given the difficulty in diagnosing C. burnetii infection at the farm level, an exhaustive series of tests in 43 pregnant animals that delivered at least one live calf were conducted, including blood serology and PCR of milk or colostrum, cotyledons (only at parturition), faeces, vaginal fluid against C. burnetii on gestation Day 171–177, at parturition and on Days 1–7, 8–14, 15–21, 22–28, 29–35 and 90–97 post‐partum. During scheduled herd visits, ultrasonography (US) of the genital tract and examination of vaginal fluid were performed on Days 15–21 (V1), 22–28 (V2), 29–35 (V3) and 51–57 (V4) post‐partum by the same veterinarian. Logistic regression analysis revealed that the likelihood of suffering endometritis (the presence of echogenic intrauterine fluid (IUF), cervical diameter of ≥4 cm or endometrial thickness ≥0.75 cm) was lower in C. burnetii‐seropositive animals (OR = 0.10), compared with C. burnetii‐seronegative animals. According to Kaplan–Meier survival analysis, C. burnetii‐seronegative and non‐shedding cows showed a delayed return to luteal activity and conception was delayed in non‐shedding animals, compared with the remaining animals. Overall, the results of our study provide useful insight into the effects of C. burnetii infection on post‐partum recovery and subsequent fertility. In particular, animals not infected with Coxiella seem to be susceptible to infection and not protected against the bacterium in dairy herds. The elevated costs of determining an infection at the farm level, make monitoring of cows virtually impossible from a clinical point of view.     

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.     

Identification of a nonsense mutation in feline ABCB1

The aim of this study was to sequence all exons of the ABCB1 (MDR1) gene in cats that had experienced adverse reactions to P‐glycoprotein substrate drugs (phenotyped cats). Eight phenotyped cats were included in the study consisting of eight cats that experienced central nervous system toxicosis after receiving ivermectin (n = 2), a combination product containing moxidectin and imidacloprid (n = 3), a combination product containing praziquantel and emodepside (n = 1) or selamectin (n = 2), and 1 cat that received the product containing praziquantel and emodepside but did not experience toxicity (n = 1). Fifteen exons contained polymorphisms and twelve exons showed no variation from the reference sequence. The most significant finding was a nonsense mutation (ABCB11930_1931del TC) in one of the ivermectin‐treated cats. This cat was homozygous for the deletion mutation. All of the other phenotyped cats were homozygous for the wild‐type allele. However, 14 missense mutations were identified in one or more phenotyped cats. ABCB11930_1931del TC was also identified in four nonphenotyped cats (one homozygous and three heterozygous for the mutant allele). Cats affected by ABCB11930_1931del TC would be expected to have a similar phenotype as dogs with the previously characterized ABCB1‐1Δ mutation.     

Serosurvey and Observational Study of US Army Veterinary Corps Officers for Q Fever Antibodies from 1989 to 2008

Since World War II, the military has experienced outbreaks of Q fever among deploying units including recent case reports of Q fever in US military personnel returning from serving in the Middle East during Operation Iraqi Freedom and Operation Enduring Freedom. Occupational exposure and prevalence of Q fever among US Army Veterinary Corps officers have not been examined. A retrospective serosurvey and observational study of 500 military veterinarians were conducted using archived serum specimens from military veterinarians who entered and served between 1989 and 2008 and were tested for exposure to Coxiella burnetii. Corresponding longitudinal health‐related, demographic, medical and deployment data were examined. A total of 69 (13.8%) individuals at military entry and 85 (17%) had late career positive titres. A total of 18 (3.6%) individuals showed seroconversion. Women were more likely to be seropositive after military service [prevalence ratio (PR) 1.96; 95% confidence interval (CI) 1.15–3.35] and were also more likely to seroconvert (incidence rate ratio 3.55; 95% CI 1.19–12.7). Women who deployed to Operation Iraqi Freedom were more likely to be seropositive (PR 3.17; 95% CI 1.03–9.71). Veterinarians with field service and pathology specialties had the highest incidence rates (7.0/1000 PY; 95% CI 4–12 and 3–19, respectively). This is the first report documenting US military veterinarians' exposure to C. burnetii. Military veterinarians are at risk prior to service, with moderate number of new cases developing during service and most maintaining titres for long periods of time. Women consistently demonstrated higher seroprevalence and incidence levels. As increasing numbers of women enter the veterinary profession and subsequently the US Army, this may warrant close monitoring. This study likely underestimates exposure and risk and does not address chronic health effects, which may be valuable to explore in future health studies.     

Prevalence of Coxiella burnetii antibodies in Portuguese dairy cattle herds

Q fever is an important zoonotic disease which has been recently diagnosed, mainly in sheep and goats, in Portugal. The aim of the present study was to determine the prevalence of bovine Coxiella burnetii antibodies in dairy farms from the northwest of Portugal. Bulk tank milk samples were randomly obtained, on November 2013, from 90 dairy farms and assayed using an ELISA kit. The apparent prevalence was 61.1 % (95 % C.I. from 50.8 to 70.5 %). The proportion of negative and intermediate (inconclusive) herds was 34.5 % (25.5 to 44.7 %) and 4.4 % (1.7 to 10.9 %), respectively. In conclusion, a high level of exposure to Coxiella burnetii was observed in Portuguese dairy cattle herds, highlighting the needs to better understand the epidemiology of Q fever in Portugal by the implementation of a monitoring program based on harmonized serologic and molecular methodologies and elucidation of the infection status of the herds.

     

A systematic knowledge synthesis on the spatial dimensions of Q fever epidemics

From 2007 through 2010, the Netherlands experienced the largest Q fever epidemic ever reported. This study integrates the outcomes of a multidisciplinary research programme on spatial airborne transmission of Coxiella burnetii and reflects these outcomes in relation to other scientific Q fever studies worldwide. We have identified lessons learned and remaining knowledge gaps. This synthesis was structured according to the four steps of quantitative microbial risk assessment (QMRA): (a) Rapid source identification was improved by newly developed techniques using mathematical disease modelling; (b) source characterization efforts improved knowledge but did not provide accurate C. burnetii emission patterns; (c) ambient air sampling, dispersion and spatial modelling promoted exposure assessment; and (d) risk characterization was enabled by applying refined dose–response analyses. The results may support proper and timely risk assessment and risk management during future outbreaks, provided that accurate and structured data are available and exchanged readily between responsible actors.     

Knowledge and prevention of tickborne diseases among Hispanic and non‐Hispanic residents of Maryland and Virginia

Tickborne diseases (TBDs) such as Lyme disease (LD), babesiosis, ehrlichiosis and Rocky Mountain spotted fever cause substantial morbidity and even mortality in the USA. Data indicate that Hispanic populations may be at greater risk for occupational exposure to ticks and disseminated LD; however, information on knowledge and practices of Hispanic populations regarding TBDs is limited. We surveyed 153 Hispanic and 153 non‐Hispanic residents of Maryland and Virginia to assess awareness of TBDs, prevention practices and risk of tick encounters. Hispanic respondents were less likely than non‐Hispanics to report familiarity with LD symptoms (21% vs. 53%, p < 0.001) and correctly identify ticks as vectors of LD (40% vs. 85%, p < 0.001). Although there was no significant difference in overall proportion of respondents who routinely take one or more preventive measures to prevent tick bites (59% vs. 61%, p = 0.65), Hispanics were more likely to report showering after coming indoors (36% vs. 25%, p = 0.04) but less likely to conduct daily tick checks compared with non‐Hispanics (17% vs. 35%, p < 0.001). History of tick bite or finding a tick crawling on oneself or a household member in the past year did not significantly differ between Hispanics and non‐Hispanics (19% vs. 24%, p = 0.26). Notably, after controlling for Hispanic/non‐Hispanic ethnicity, primary language (English vs. Spanish) was a significant predictor of whether an individual had knowledge of LD symptoms, correctly identified ticks as vectors for LD and performed daily tick checks. These results provide guidance for future development of more targeted and effective TBD prevention education for both Hispanic and non‐Hispanic communities.