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.     

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.     

Human seroprevalence to Coxiella burnetii (Q fever) in Northern Ireland

Despite the widespread prevalence of infection with Coxiella burnetii, there have been few large population-based studies examining the epidemiology of this infection. The aim of this study was to examine the distribution and determinants of C. burnetii past infection in Northern Ireland (NI). Coxiella burnetii phase II specific IgG antibodies were measured by enzyme-linked immunosorbent assay in stored serum from 2,394 randomly selected subjects, aged 12-64, who had participated in population-based surveys of cardiovascular risk factors performed in 1986 and 1987. The overall prevalence of C. burnetii antibody positivity was 12.8%. The prevalence of sero-positivity was slightly higher in males than that in females (14.3% versus 11.2%, P = 0.02). Sero-positivity was low in children (<10%), increasing to 19.5% and 16.4% in males and females, respectively, in the 25-34 age group and subsequently remaining fairly steady with increasing age. Sero-positivity among farmers, at 48.8%, was significantly higher than the general population. More sero-positive than sero-negative women had a history of a miscarriage or still-birth (19.5% versus 9.8%, P < 0.001). In conclusion, this study demonstrated a high prevalence of evidence of past C. burnetii infection in NI. Associations between past C. burnetii infection and age, sex, social class, occupation and reproductive history were seen. We estimate that 20% of Q fever infections in NI occur in farmers.     

DNA microarray-based detection of Coxiella burnetii,the causative agent of Q fever

Background

An easy-to-handle microarray assay based on the cost-effective ArrayTube™ platform has been designed for the rapid and unequivocal identification of Coxiella burnetii, the causative agent of Q fever. The gene targets include the chromosomally coded markers icd, omp/com1, and IS1111 as well as the plasmid coded markers cbbE and cbhE.

Results

A representative panel comprising 50 German C. burnetii isolates and 10 clinical samples was examined to validate the test. All tested isolates harboured plasmid QpH1 and were correctly identified, corresponding to 100% sensitivity. The assay’s limit of detection was 100 genome equivalents (GE) for icd, omp/com1, cbbE and cbhE and 10 GE for IS1111. Assay specificity was 100% as determined by analysing a panel of 37 non-Coxiella strains.

Conclusions

The present array is a rational assembly of established and evaluated targets for the rapid and unequivocal detection of C. burnetii. This array could be applied to the screening of vaginal swabs from small ruminants; screening of environmental samples e.g. on farms or screening of human samples.     

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.     

Q Fever (Coxiella burnetii) Knowledge and Attitudes of Australian Cat Breeders and Their Husbandry Practices

A Q fever outbreak in a small animal veterinary hospital, associated with a cat caesarean section, initiated a cat seroprevalence study (n = 712) that found circulating antibodies to Coxiella burnetii was highest in cattery‐confined breeding cats (9.3%). These findings stimulated interest about potential sources of C. burnetii infection for cats and humans associated with cats. Cat breeders are potentially a group at increased risk of C. burnetii infection, and this study sought to identify potential risk factors. A cross‐sectional online survey was conducted targeting all domestic cat breeders registered with an affiliate member body in Australia in 2015. Responses from 177 cat breeders across Australia were analysed. Forty per cent of responding cat breeders had not heard of Q fever. Raw meat was fed as an integral constituent of the diet by 89% of respondents. Eighty per cent of respondents allowed queens access to the home for parturition, and assistance of queens and resuscitation of kittens at the time of birth were reported by 97% of respondents. Respondents who perceived some level of exposure to Q fever through their breeding activities were three times less likely to perform mouth‐to‐snout resuscitation (OR 0.3 95% CI 0.1–0.9; P = 0.034) than those who did not perceive a risk of exposure. Similarly, respondents who perceived Q fever as a risk through breeding activities were close to eight times more likely to use personal protective equipment during parturition (OR 7.7 95% CI 1.5–39.9; P = 0.015) than those who did not. Husbandry practices of cat breeders that may increase the risk of C. burnetii transmission require further targeted investigations to assess the contribution of these risk factors to the acquisition of disease. Concurrent education forums are recommended to inform Australian cat breeders of the aetiopathogenesis of Q fever.     

Q热贝纳柯克斯体TaqMan荧光定量PCR检测方法的建立

根据Q热贝纳柯克斯体(Coxiella burnetii)插入IS1111序列设计引物和探针,建立快速检测Q热的TaqMan实时荧光定量PCR方法。以梯度稀释含有目的扩增片段的重组质粒作为标准品,进行定量PCR反应。结果显示,该方法能够检测出10个拷贝数的阳性质粒;标准曲线相关系数为0.995,扩增效率为103%;结核分枝杆菌(M.tuberculosis)、衣原体(C.psittaci)、布鲁氏菌(Brucella.spp)及牛血液的核酸样本特异性检测结果均为阴性。本研究建立的TaqMan荧光定量PCR法灵敏度高、特异性好,对Q热的检测与鉴定中具有良好的应用前景。     

Pharmacokinetic, metabolism and withdrawal time of orphenadrine in camels (Camelus dromedarius) after intravenous administration

The pharmacokinetics of orphenadrine (ORPH) following a single intravenous (i.v.) dose was investigated in six camels (Camelus dormedarius). Orphenadrine was extracted from the plasma using a simple sensitive liquid–liquid extraction method and determined by gas chromatography/mass spectrometry (GC/MS). Following i.v. administration plasma concentrations of ORPH decline bi-exponentially with distribution half-life (t_1/2α) of 0.50 ± 0.07 h, elimination half-life (t_1/2β) of 3.57 ± 0.55 h, area under the time concentration curve (AUC) of 1.03 ± 0.10 g/h l⁻¹. The volume of distribution at steady state (Vd_ss) 1.92 ± 0.22 l kg⁻¹, volume of the central compartment of the two compartment pharmacokinetic model (V_c) 0.87 ± 0.09 l kg⁻¹, and total body clearance (Cl_T) of 0.60 ± 0.09 l/h kg⁻¹. Three orphenadrine metabolites were identified in urine samples of camels. The first metabolite N-desmethyl-orphenadrine resulted from N-dealkylation of ORPH with molecular ion m/z 255. The second N,N-didesmethyl-orphenadrine, resulted from N-didesmethylation with molecular ion m/z 241. The third metabolite, hydroxyl-orphenadrine, resulted from the hydroxylation of ORPH with molecular ion m/z 285. ORPH and its metabolites in camel were extensively eliminated in conjugated form. ORPH remains detectable in camel urine for three days after i.v. administration of a single dose of 350 mg orphenadrine aspartate.     

Application of the California mastitis test in intramammary Streptococcus agalactiae and Staphylococcus aureus infections of camels (Camelus dromedarius) in Kenya

A study was conducted on 207 lactating camels in six herds in Kenya to evaluate the California mastitis test (CMT) for the detection of intramammary infections (IMIs) caused by Streptococcus agalactiae and Staphylococcus aureus and to investigate the prevalence of both the pathogens in the camel udder. IMI with S. agalactiae was found in 12% of all camels sampled. IMI with S. aureus was present in 11% of all camels sampled. The herd-level prevalence of IMI varied between 0 and 50% for S. agalactiae and between 0 and 13% for S. aureus. Longitudinal observations over 10–12 months confirmed persistent infections for both pathogens. Observations in one herd suggested that camel pox was a contributing factor in spreading and exacerbating S. agalactiae udder infections.

The CMT had quarter-level sensitivities of 77 and 68% for S. agalactiae and S. aureus in camels, respectively. The CMT specificities were 91% for both the pathogens.     

Ultrasonographic Characterization of Follicle Deviation in Follicular Waves with Single Dominant and Codominant Follicles in Dromedary Camels (Camelus dromedarius)

Follicular wave emergence was synchronized by treating camels with GnRH when a dominant follicle (DF) was present in the ovaries. Animals were scanned twice a day from day 0 (day of GnRH treatment) to day 10, to characterize emergence and deviation of follicles during the development of the follicular wave. Follicle deviation in individual animals was determined by graphical method. Single DFs were found in 16, double DFs in 9 and triple DFs in two camels. The incidence of codominant (double and triple DFs) follicles was 41%. The interval from GnRH treatment to wave emergence, wave emergence to deviation, diameter and growth rate of F1 follicle before or after deviation did not differ between the animals with single and double DFs. The size difference between future DF(s) and the largest subordinate follicle (SF) was apparent from the day of wave emergence in single and double DFs. Overall, interval from GnRH treatment to wave emergence and wave emergence to the beginning of follicle deviation was 70.6 ± 1.4 and 58.6 ± 2.7 h, respectively. Mean size of the DF and largest SF at the beginning of deviation was 7.4 ± 0.2 and 6.3 ± 0.1 mm, respectively. In conclusion, the characteristics of follicle deviation are similar between the animals that developed single or double DFs.     

Seroepidemiological study of Q fever,brucellosis and tularemia in butchers and slaughterhouses workers in Lorestan,western of Iran

Most zoonoses are occupational diseases. Q fever, brucellosis and tularemia are major zoonotic diseases for butchers and slaughterhouse workers. However, little information is available about these infectious diseases in such professional populations in western of Iran. The aim of this study was to investigate the seroprevalence and risk factors associated with these three zoonoses among butchers and slaughterhouse workers in the Lorestan province of Iran. In 2017, 289 individuals (144 butchers or slaughterhouse workers, and 145 people from the general population) were enrolled in 11 different counties of this province. Collected serum samples were tested by ELISA for detection of IgG antibodies against Coxiella burnetii, Brucella spp. or Francisella tularensis antigens. The seroprevalence of Q fever, brucellosis and tularemia among all participants were 23.5%, 31.8% and 3.8%, respectively. The seroprevalence of brucellosis and Q fever among butchers and slaughterhouse workers (43.7% and 29.8%, respectively) were significantly higher (p < 0.05) than those of the general population (20% and 17.2%, respectively). A contact history with small ruminants (sheep and goats) was associated with a higher risk of positive serology for all three studied zoonoses. The high seroprevalence for Q fever and brucellosis we found among butchers and slaughterhouse workers suggests that both diseases are common in these populations of the Lorestan province. Since these two infectious diseases are clinically unspecific, they must be systematically included in the etiological diagnosis of infectious diseases occurring in these at-risk populations. In addition, we recommend specific training programs as well as the use of personal protective equipment in these occupational groups to reduce the occurrence of these zoonotic diseases.     

Serum Lipids and Lipoproteins in Clinically Healthy Male Camels (Camelus dromedarius)

Blood samples were collected from the jugular vein of 87 Iranian male dromedary camels of different age groups (<3, 3–5, 5–6 and 6–8 years). Variations in the serum concentrations of cholesterol, triglyceride, total lipid, very low-density lipoprotein (VLDL-cholesterol), low-density lipoprotein (LDL-cholesterol) and high-density lipoprotein (HDL-cholesterol) were investigated. The concentrations of cholesterol, triglyceride, total lipid, HDL-cholesterol, LDL-cholesterol and VLDL-cholesterol in the different age groups were significantly different (p<0.05). With an increase in the age of the animals, there were highly significant increases in the cholesterol, triglyceride, HDL-cholesterol and VLDL-cholesterol concentrations, whereas the concentration of LDL-cholesterol decreased (p<0.001).     

Prenatal Development of the Eye Tunics in the Dromedary Camel (Camelus dromedarius)

Studies of ocular development in the dromedary camel (Camelus dromedarius) have not been reported previously. The aim of the present investigation was therefore to document the major landmarks and the time course in the prenatal development of the eye tunics in dromedary camel and its accommodation with the surrounding hard environment of the desert. Serial histological sections of dromedary camel embryos and foetuses were used. Age estimation was made on the basis of gestational size, crown vertebral‐rump length (CVRL), which ranged 1.2–110 cm. The eye of the dromedary camel developed in a similar manner to that of the human and domestic animals eyes; the principal differences were in the time of occurrence of certain developmental events, pigmented peripheral cornea near the limbus, a remarkably thickened Descemet's membrane and pigmentation in the corneo‐scleral junction, which represent an adaptive modification in relation to a severe environment.     

Prevalence of Faecal Pathogens in Calves of Racing Camels (Camelus dromedarius) in the United Arab Emirates

Tropical Animal Health and Production -     

First report of Chlamydophila abortus infection in the dromedary camel (Camelus dromedarius) population in eastern Algeria

Chlamydiosis is caused by an obligate intracellular gram-negative bacterium of the genus Chlamydophila which is a zoonotic pathogen. The objectives of the study were to identify the seroprevalence of antibodies against Chlamydophila abortus in dromedary camel herds from four districts in eastern Algeria, as well as to estimate the association between seroprevalence and certain factors present at the animal and herd levels. Blood samples were collected from a random sample of animals within each of 82 camel herds. Serum samples were subjected to a C. abortus ELISA test, and association between the presence of antibodies and potential risk factors was estimated. Animal and herd seroprevalence were 2.5 % and 15.8 %, respectively, indicating substantial exposure of camels to C. abortus in the four districts studied. Age, breed, and sex did not influence seroprevalence in tested animals. Based on the univariate analysis, contact with sheep and goats, contact with other camel herds, and histories of abortion were major risk factors for infection. By using multivariate analysis, contact of camels with sheep and goats and with others camel herds, through shared grazing or watering points, were important factors for transmission of chlamydiosis with an odds ratio of 3.3 and 9.4, respectively. At the herd level the introduction of purchased animals was the major risk factor. This baseline information will be highly useful for launching C. abortus control programs in the region and potentially elsewhere.     

Some Endotoxin-induced Clinical and Biochemical Changes in Plasma of Camels (Camelus dromedarius)

Intravenous administration of endotoxin, prepared from E. coli serotype O55:B5, at a dose of 0.1 microg/kg body weight to calves and adult camels induced fever and increased haematocrit, triiodothyronine and cortisol values. The endotoxin-treated animals showed significantly decreased (p < 0.05) total protein, urea, glucose and creatinine. A significant increase was seen in the activity of aspartate aminotransaminase and creatine kinase. These results demonstrate high sensitivity of camels to endotoxin.     

Serological evidence of Coxiella burnetii infection in beef cattle in Queensland

Background Queensland has the highest incidence of Q fever in Australia. The aim of this study was to undertake a cross‐sectional seroprevalence survey of Coxiella burnetii, the causative agent of Q fever, in beef cattle in Queensland. Methods Serum samples were tested by ELISA for both phase II and phase I antigens of the organism using an Australian isolate. Blood samples were collected at an abattoir that processes beef cattle originating from northern and north‐western Queensland, in addition to blood samples taken from beef cattle across Queensland as part of a second survey. Results Seropositivity was 16.8% (95% confidence interval 16.7–16.8%). Conclusion Evidence of C. burnetii infection in beef cattle has public health implications for occupational exposure of primary producers and veterinarians and for the proximity of beef cattle properties to residential areas in regional Queensland. This study is the first known investigation of C. burnetii seroprevalence in beef cattle in Queensland and the first known use of an Australian C. burnetii isolate for screening using both phase II and phase I antigens.     

The Zinc and Copper Content of the Plasma of Sudanese Camels (Camelus dromedarius)

A study was undertaken to investigate the variations in the content of zinc and copper in the plasma of Sudanese camels (Camelus dromedarius). A total of 993 Arabi camels, aged 0.5-8 years, were used to assess the effect of season, age, sex and physiological status on the plasma concentrations of copper and zinc. There was an increase in the concentration of Cu and a decrease in the concentration of Zn in the plasma with age. The concentrations of both Cu and Zn in the plasma were higher in the rainy season than in the dry season. The plasma copper concentrations in pregnant, low-lactating and high-lactating camels were 81.3 +/- 4.7, 59.7 +/- 6.1 and 61.3 +/- 5.5 microg/100 ml, respectively. The corresponding values for zinc were 51.0 +/- 8.9, 53.4 +/- 6.4 and 67.1 +/- 5.5 microg/100 ml, respectively. However, there was no effect of sex on the content of these minerals in the plasma.