Current perspectives on the transmission of Q fever: Highlighting the need for a systematic molecular approach for a neglected disease in Africa

Q Fever in Greece and Factors of Exposure: A Multiregional Seroprevalence Study

INTRODUCTION

The epidemiology of Q fever, caused by Coxiella burnetii, varies significantly worldwide. This study aimed to document the prevalence of Coxiella burnetii in Greece by measuring specific IgG antibody levels in serum samples from the general population and high-risk groups, including farmers, veterinarians, and laboratory workers.

METHODOLOGY

A multiregional, stratified sampling design was employed, with 1,345 participants from Thessaly and Central Macedonia. Serum samples were tested for Coxiella burnetii IgG antibodies, and multivariate analysis was conducted to identify factors associated with seroprevalence.

RESULTS

Overall, 8.1% of participants tested positive for Coxiella burnetii antibodies, with the highest seroprevalence in Larissa (22.2%) and Karditsa (16.1%). High-risk occupational groups, particularly those with direct animal contact, showed a higher seroprevalence (13.6%). Multivariate analysis identified significant associations between seroprevalence and factors such as geographic region, occupation, and gender.

CONCLUSION

The study reveals regional and occupational disparities in Q fever seroprevalence in Greece, particularly in rural areas. These findings underscore the need for targeted public health measures, including heightened surveillance and preventive interventions for high-risk groups.

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

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

Prevalence and risk factors for Q fever, spotted fever group rickettsioses, and typhus group rickettsioses in a pastoralist community of northern Tanzania, 2016-2017

BACKGROUND

In northern Tanzania, Q fever, spotted fever group (SFG) rickettsioses, and typhus group (TG) rickettsioses are common causes of febrile illness. We sought to describe the prevalence and risk factors for these zoonoses in a pastoralist community.

METHODS

Febrile patients ≥2 years old presenting to Endulen Hospital in the Ngorongoro Conservation Area were enrolled from August 2016 through October 2017. Acute and convalescent blood samples were collected, and a questionnaire was administered. Sera were tested by immunofluorescent antibody (IFA) IgG assays using Coxiella burnetii (Phase II), Rickettsia africae, and Rickettsia typhi antigens. Serologic evidence of exposure was defined by an IFA titre ≥1:64; probable cases by an acute IFA titre ≥1:128; and confirmed cases by a ≥4-fold rise in titre between samples. Risk factors for exposure and acute case status were evaluated.

RESULTS

Of 228 participants, 99 (43.4%) were male and the median (interquartile range) age was 27 (16-41) years. Among these, 117 (51.3%) had C. burnetii exposure, 74 (32.5%) had probable Q fever, 176 (77.2%) had SFG Rickettsia exposure, 134 (58.8%) had probable SFG rickettsioses, 11 (4.8%) had TG Rickettsia exposure, and 4 (1.8%) had probable TG rickettsioses. Of 146 participants with paired sera, 1 (0.5%) had confirmed Q fever, 8 (5.5%) had confirmed SFG rickettsioses, and none had confirmed TG rickettsioses. Livestock slaughter was associated with acute Q fever (adjusted odds ratio [OR] 2.54, 95% confidence interval [CI] 1.38-4.76) and sheep slaughter with SFG rickettsioses case (OR 4.63, 95% CI 1.08-23.50).

DISCUSSION

Acute Q fever and SFG rickettsioses were detected in participants with febrile illness. Exposures to C. burnetii and to SFG Rickettsia were highly prevalent, and interactions with livestock were associated with increased odds of illness with both pathogens. Further characterisation of the burden and risks for these diseases is warranted.

Evidence of co-exposure with Brucella spp, Coxiella burnetii, and Rift Valley fever virus among various species of wildlife in Kenya

Background

Co-infection, especially with pathogens of dissimilar genetic makeup, may result in a more devastating impact on the host. Investigations on co-infection with neglected zoonotic pathogens in wildlife are necessary to inform appropriate prevention and control strategies to reduce disease burden in wildlife and the potential transmission of these pathogens between wildlife, livestock and humans. This study assessed co-exposure of various Kenyan wildflife species with Brucella spp, Coxiella burnetii and Rift Valley fever virus (RVFV).

Methodology

A total of 363 sera from 16 different wildlife species, most of them (92.6%) herbivores, were analysed by Enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against Brucella spp, C. burnetii and RVFV. Further, 280 of these were tested by PCR to identify Brucella species.

Results

Of the 16 wildlife species tested, 15 (93.8%) were seropositive for at least one of the pathogens. Mean seropositivities were 18.9% (95% CI: 15.0–23.3) for RVFV, 13.7% (95% CI: 10.3–17.7) for Brucella spp and 9.1% (95% CI: 6.3–12.5) for C. burnetii. Buffaloes (n = 269) had higher seropositivity for Brucella spp. (17.1%, 95% CI: 13.0–21.7%) and RVFV (23.4%, 95% CI: 18.6–28.6%), while giraffes (n = 36) had the highest seropositivity for C. burnetii (44.4%, 95% CI: 27.9–61.9%). Importantly, 23 of the 93 (24.7%) animals positive for at least one pathogen were co-exposed, with 25.4% (18/71) of the positive buffaloes positive for brucellosis and RVFV. On molecular analysis, Brucella DNA was detected in 46 (19.5%, CI: 14.9–24.7) samples, with 4 (8.6%, 95% CI: 2.2–15.8) being identified as B. melitensis. The Fisher’s Exact test indicated that seropositivity varied significantly within the different animal families, with Brucella (p = 0.013), C. burnetii (p = <0.001) and RVFV (p = 0.007). Location was also significantly associated (p = <0.001) with Brucella spp. and C. burnetii seropositivities.

Conclusion

Of ~20% of Kenyan wildlife that are seropositive for Brucella spp, C. burnetii and RVFV, almost 25% indicate co-infections with the three pathogens, particularly with Brucella spp and RVFV.

Infection of an animal with more than one pathogen may result into a more devastating impact. Only few studies have investigated co-infection with multiple pathogens in wildlife, despite their key role as reservoirs of zoonotic diseases. Therefore, there is need for investigations on co-infection with neglected zoonotic pathogens in wildlife to inform prevention and control approaches and reduce disease impact in wildlife and potential transmission of these pathogens between wildlife, livestock, and humans. This study assessed co-exposure of various Kenyan wildlife species with three zoonotic pathogens, including Brucella spp, Coxiella burnetii and Rift Valley fever virus (RVFV). Results from this study revealed widespread, but varied exposure levels to the three individual pathogens within the several wildlife species. Likewise, the study also found the presence of co-exposure with the three pathogens. The findings from this study points to the need for establishment of surveillance and control programmes that target multiple pathogens in the wildlife populations to reduce the risk of transmission of infectious pathogens in wildlife and their zoonotic transmission.

Longitudinal Study of Selected Bacterial Zoonoses in Small Ruminants in Tana River County, Kenya

Brucellosis, Q fever, and leptospirosis are priority zoonoses worldwide, yet their epidemiology is understudied, and studies investigating multiple pathogens are scarce. Therefore, we selected 316 small ruminants in irrigated, pastoral, and riverine settings in Tana River County and conducted repeated sampling for animals that were initially seronegative between September 2014 and June 2015. We carried out serological and polymerase chain reaction tests and determined risk factors for exposure. The survey-weighted serological incidence rates were 1.8 (95% confidence intervals [CI]: 1.3–2.5) and 1.3 (95% CI: 0.7–2.3) cases per 100 animal-months at risk for Leptospira spp. and C. burnetii, respectively. We observed no seroconversions for Brucella spp. Animals from the irrigated setting had 6.83 (95% CI: 2.58–18.06, p-value = 0.01) higher odds of seropositivity to C. burnetii than those from riverine settings. Considerable co-exposure of animals to more than one zoonosis was also observed, with animals exposed to one zoonosis generally having 2.5 times higher odds of exposure to a second zoonosis. The higher incidence of C. burnetii and Leptospira spp. infections, which are understudied zoonoses in Kenya compared to Brucella spp., demonstrate the need for systematic prioritization of animal diseases to enable the appropriate allocation of resources.

Prospective cohort study reveals unexpected aetiologies of livestock abortion in northern Tanzania

Livestock abortion is an important cause of productivity losses worldwide and many infectious causes of abortion are zoonotic pathogens that impact on human health. Little is known about the relative importance of infectious causes of livestock abortion in Africa, including in subsistence farming communities that are critically dependent on livestock for food, income, and wellbeing. We conducted a prospective cohort study of livestock abortion, supported by cross-sectional serosurveillance, to determine aetiologies of livestock abortions in livestock in Tanzania. This approach generated several important findings including detection of a Rift Valley fever virus outbreak in cattle; high prevalence of C. burnetii infection in livestock; and the first report of Neospora caninum, Toxoplasma gondii, and pestiviruses associated with livestock abortion in Tanzania. Our approach provides a model for abortion surveillance in resource-limited settings. Our findings add substantially to current knowledge in sub-Saharan Africa, providing important evidence from which to prioritise disease interventions.

Exposure of South African Abattoir Workers to Coxiella burnetii

Abattoir workers may contract Q fever by inhalation of Coxiella burnetii bacteria in aerosols generated by slaughtering livestock, or in contaminated dust. We estimated the seroprevalence of C. burnetii and examined the associated factors in a survey of South African abattoir workers. Coxiella burnetii seropositivity was determined by detection of IgG antibodies against C. burnetii phase II antigen. Logistic regression, adjusted for clustering and sampling fraction, was employed to analyze risk factors associated with C. burnetii seropositivity. Among 382 workers from 16 facilities, the overall seroprevalence was 33% (95% confidence interval (CI): 28–38%) and ranged from 8% to 62% at the facility level. Prolonged contact with carcasses or meat products (odds ratio (OR): 4.6, 95% CI: 1.51–14.41) and prior abattoir or butchery work experience (OR: 1.9, 95% CI: 1.13–3.17) were associated with C. burnetii seropositivity. In contrast, increasing age and livestock ownership were inversely associated. Precautions to protect abattoir personnel from Q fever are discussed.

Molecular Detection of Coxiella burnetii, Rickettsia africae and Anaplasma Species in Ticks from Domestic Animals in Lesotho

Tick-borne diseases (TBDs) hamper the growth of the livestock sector and impose major constraints for the health and management of domestic animals in the tropic and subtropical regions globally. Currently, there is no scientific report on the presence of zoonotic pathogens transmitted by tick species in Lesotho. This study aimed to identify zoonotic tick-borne pathogens of economic importance from ticks infesting domestic animals in Lesotho using molecular techniques. A total of 322 tick DNA pools were subjected to PCR screening for the presence of zoonotic pathogens and sequenced. The overall prevalence of Anaplasma spp. was 35% (113/322), with a 100% infection rate in Rhipicephalus microplus, followed by R. evertsi evertsi (92%), Hyalomma rufipes and Otobius megnini sharing 50% and the lowest infection rate was observed in R. decoloratus with 40%. The prevalence of Coxiella burnetii, a gram-negative pleomorphic etiological agent of Query fever (Q fever), was 1% (2/322) for all screened samples, with 20% of R. decoloratus and 1% of R. e. evertsi infected. Rickettsia africae was detected from Hyalomma rufipes with a 70% prevalence. This study provides a baseline knowledge of tick-borne pathogens of medical and veterinary importance in Lesotho and raises awareness of the prevalence of such diseases within the tourism sector as they are mostly affected.

Evidence of exposure to C. burnetii among slaughterhouse workers in western Kenya

Q fever, caused by C. burnetii, has been reported in slaughterhouse workers worldwide. The most reported risk factor for seropositivity is the workers' role in the slaughterhouse. This study examined the seroprevalence and risk factors for antibodies to C. burnetii in slaughterhouse workers in western Kenya to fill a data gap relating to this emerging disease in East Africa.

Individuals were recruited from all consenting slaughterhouses in the study area between February and November 2012. Information was collected from participating workers regarding demographic data, animals slaughtered and role in the slaughterhouse. Sera samples were screened for antibodies to C. burnetii using a commercial ELISA and risk factors associated with seropositivity were identified using multi-level logistic regression analysis.

Slaughterhouse workers (n = 566) were recruited from 84 ruminant slaughterhouses in western Kenya. The seroprevalence of antibodies to C. burnetii was 37.1% (95% Confidence Interval (CI) 33.2–41.2%). The risk factors identified for C. burnetii seropositivity included: male workers compared to female workers, odds ratio (OR) 5.40 (95% CI 1.38–21.22); slaughtering cattle and small ruminants compared to those who only slaughtered cattle, OR 1.52 (95% CI 1.06–2.19). In addition, specific roles in the slaughterhouse were associated with increased odds of being seropositive, including cleaning the slaughterhouse, OR 3.98 (95% CI 1.39–11.43); cleaning the intestines, OR 3.24 (95% CI 1.36–7.73); and flaying the carcass OR 2.63 (95% CI 1.46–4.75) compared to being the slaughterman or foreman.

We identified that slaughterhouse workers have a higher seroprevalence of antibodies to C. burnetii compared to published values in the general population from the same area. Slaughterhouse workers therefore represent an occupational risk group in this East African setting. Workers with increased contact with the viscera and fluids are at higher risk for exposure to C. burnetii. Education of workers may reduce transmission, but an alternative approach may be to consider the benefits of vaccination in high-risk groups.

Seroprevalence estimate and risk factors for Coxiella burnetii infections among humans in a highly urbanised Brazilian state

BACKGROUND

Q fever is among the top 13 global priority zoonoses, however, it is still neglected and under-reported in most of the world, including Brazil. Thus, we evaluated the seroprevalence of and the risk factors for Coxiella burnetii infections in humans from Minas Gerais, a highly urbanised Brazilian state.

METHODS

Coxiella burnetii was searched for patient samples (n=437), which were suspected of then later confirmed as negative for dengue fever, by the indirect immunofluorescence technique and real-time PCR. Risk factors for infections and spatial clusters for both C. burnetii-seropositive individuals and livestock concentration were evaluated.

RESULTS

We found that 21 samples (4.8%; 95% CI 3.0 to 7.2%) were reactive for at least one class of anti-C. burnetii antibodies (titer of ≥64), with rural residence (p=0.036) being a risk factor. Also, two spatial clusters of seropositivity were found within a significant area by Scan, and a probable relationship between the Scan result and the livestock concentration by area was found.

CONCLUSIONS

Seropositive individuals were associated with rural residence, with a likely relationship with the livestock concentration. Thus, this study establishes baseline figures for C. burnetii seroprevalence in humans in a state of Brazil, allowing the monitoring of trends and setting of control targets, as well as more representative longitudinal and risk analysis studies.

One hundred years of zoonoses research in the Horn of Africa: A scoping review

BACKGROUND

One Health is particularly relevant to the Horn of Africa where many people's livelihoods are highly dependent on livestock and their shared environment. In this context, zoonoses may have a dramatic impact on both human and animal health, but also on country economies. This scoping review aimed to characterise and evaluate the nature of zoonotic disease research in the Horn region. Specifically, it addressed the following questions: (i) what specific zoonotic diseases have been prioritised for research, (ii) what data have been reported (human, animal or environment), (iii) what methods have been applied, and (iv) who has been doing the research?

METHODOLOGY/PRINCIPAL FINDINGS

We used keyword combinations to search online databases for peer-reviewed papers and theses. Screening and data extraction (disease, country, domain and method) was performed using DistillerSR. A total of 2055 studies focusing on seven countries and over 60 zoonoses were included. Brucellosis attracted the highest attention in terms of research while anthrax, Q fever and leptospirosis have been comparatively under-studied. Research efforts did not always align with zoonoses priorities identified at national levels. Despite zoonoses being a clear target for 'One Health' research, a very limited proportion of studies report data on the three domains of human, animal and environment. Descriptive and observational epidemiological studies were dominant and only a low proportion of publications were multidisciplinary. Finally, we found that a minority of international collaborations were between Global South countries with a high proportion of authors having affiliations from outside the Horn of Africa.

CONCLUSIONS/SIGNIFICANCE

There is a growing interest in zoonoses research in the Horn of Africa. Recommendations arising from this scoping review include: (i) ensuring zoonoses research aligns with national and global research agendas; (ii) encouraging researchers to adopt a holistic, transdisciplinary One Health approach following high quality reporting standards (COHERE, PRISMA, etc.); and (iii) empowering local researchers supported by regional and international partnerships to engage in zoonoses research.

Detection and distribution of zoonotic pathogens in wild Norway rats (Rattus norvegicus) from Tehran, Iran

This is the first study on the prevalence of vector-borne zoonotic pathogens found in Rattus norvegicus (R. norvegicus) in urban areas of Tehran, Iran. Serological tests were used to detect IgG antibodies against Coxiella burnetii (C. burnetii) and Rickettsia spp. using a commercial qualitative rat ELISA kit. The frequency of Streptobacillus moniliformis (S. moniliformis) and Bartonella spp. was determined using a conventional PCR method. Molecular detection and characterization of Leptospira spp. were conducted using TaqMan real-time PCR based on lipL32 gene and SecY typing methods. A total of 100 R. norvegicus rats were collected from five regions in Tehran, Iran, and investigated to determine their zoonotic pathogens. S. moniliformis and Bartonella spp. were detected in 23 of 100 (23%) and 17 of 100 (17%) R. norvegicus populations, respectively. The highest prevalence of S. moniliformis and Bartonella spp. with similar frequency rates (n = 6/20; 30%) was seen among the R. norvegicus rats captured from the northern and southern parts of Tehran, respectively. Seroreactivity against C. burnetii and Rickettsia spp. was detected in 4% and 1% of R. norvegicus, respectively. C. burnetii. was identified only in one rat captured from the eastern part of Tehran. Results showed that Leptospira spp. was detected only in two rats, collected from the southern part (n = 2/20; 10%) of Tehran. The secY typing method identified two different Leptospira species including L. interrogans and L. kirschneri. The results showed that urban rats might play an important role in transmission of zoonotic pathogens to humans.

High Prevalence and New Genotype of Coxiella burnetii in Ticks Infesting Camels in Somalia

Coxiella burnetii is the causative agent of Q fever. It can infect animals, humans, and birds, as well as ticks, and it has a worldwide geographical distribution. To better understand the epidemiology of C. burnetii in Somalia, ticks infesting camels were collected from five different regions, including Bari, Nugaal, Mudug, Sool, and Sanaag, between January and March 2018. Collected ticks were tested for C. burnetii and Coxiella-like endosymbiont DNA by using IS1111, icd, and Com1-target PCR assays. Moreover, sequencing of the 16S-rRNA was conducted. Molecular characterization and typing were done by adaA-gene analysis and plasmid-type identification. Further typing was carried out by 14-marker Multi-Locus Variable-Number Tandem Repeats (MLVA/VNTR) analysis. The investigated ticks (n = 237) were identified as Hyalomma spp. (n = 227, 95.8%), Amblyomma spp. (n = 8, 3.4%), and Ripicephalus spp. (n = 2, 0.8%), and 59.1% (140/237) of them were positive for Coxiella spp. While Sanger sequencing and plasmid-type identification revealed a C. burnetii that harbours the QpRS-plasmid, MLVA/VNTR genotyping showed a new genotype which was initially named D21. In conclusion, this is the first report of C. burnetii in ticks in Somalia. The findings denote the possibility that C. burnetii is endemic in Somalia. Further epidemiological studies investigating samples from humans, animals, and ticks within the context of "One Health" are warranted.

Molecular detection of Coxiella burnetii infection in small mammals from Moshi Rural and Urban Districts, northern Tanzania

Coxiella burnetii is an obligate intracellular bacterium that causes Q fever, a zoonotic disease of public health importance. In northern Tanzania, Q fever is a known cause of human febrile illness, but little is known about its distribution in animal hosts. We used a quantitative real-time PCR (qPCR) targeting the insertion element IS1111 to determine the presence and prevalence of C. burnetii infections in small mammals trapped in 12 villages around Moshi Rural and Moshi Urban Districts, northern Tanzania. A total of 382 trapped small mammals of seven species were included in the study; Rattus rattus (n = 317), Mus musculus (n = 44), Mastomys natalensis (n = 8), Acomys wilson (n = 6), Mus minutoides (n = 3), Paraxerus flavovottis (n = 3) and Atelerix albiventris (n = 1). Overall, 12 (3.1%) of 382 (95% CI: 1.6-5.4) small mammal spleens were positive for C. burnetii DNA. Coxiella burnetii DNA was detected in five of seven of the small mammal species trapped; R. rattus (n = 7), M. musculus (n = 1), A. wilson (n = 2), P. flavovottis (n = 1) and A. albiventris (n = 1). Eleven (91.7%) of twelve (95% CI: 61.5-99.8) C. burnetii DNA positive small mammals were trapped within Moshi Urban District. These findings demonstrate that small mammals in Moshi, northern Tanzania are hosts of C. burnetii and may act as a source of C. burnetii infection to humans and other animals. This detection of C. burnetii infections in small mammals should motivate further studies into the contribution of small mammals to the transmission of C. burnetii to humans and animals in this region.

Vector competence of the African argasid tick Ornithodoros moubata for the Q fever agent Coxiella burnetii

Q fever is a widespread zoonotic disease caused by the intracellular bacterium Coxiella burnetii. While transmission is primarily but not exclusively airborne, ticks are usually thought to act as vectors on the basis of early microscopy studies. However, recent observations revealed that endosymbionts of ticks have been commonly misidentified as C. burnetii, calling the importance of tick-borne transmission into question. In this study, we re-evaluated the vector competence of the African soft tick Ornithodoros moubata for an avirulent strain of C. burnetii. To this end, we used an artificial feeding system to initiate infection of ticks, specific molecular tools to monitor further infections, and culture assays in axenic and cell media to check for the viability of C. burnetii excreted by ticks. We observed typical traits associated with vector competence: The exposure to an infected blood meal resulted in viable and persistent infections in ticks, trans-stadial transmissions of infection from nymphs to adults and the ability of adult ticks to transmit infectious C. burnetii. However, in contrast to early studies, we found that infection differed substantially between tick organs. In addition, while adult female ticks were infected, we did not observe C. burnetii in eggs, suggesting that transovarial transmission is not effective. Finally, we detected only a sporadic presence of C. burnetii DNA in tick faeces, but no living bacterium was further isolated in culture assays, suggesting that excretion in faeces is not a common mode of transmission in O. moubata.

The intracellular bacterium Coxiella burnetii is the agent of Q fever, a widespread zoonotic disease. Some early detection reports and microscopy studies identified ticks as vectors of Q fever but more recent studies and molecular analyses revealed that endosymbionts of ticks have been commonly misidentified as C. burnetii: It raises questions of whether ticks play an important role in Q fever transmission. In our study, we therefore experimentally re-evaluate the vector competence of the African soft tick Ornithodoros moubata for C. burnetii. We found that O. moubata can be infected by C. burnetii after the exposure to an infected blood meal. It resulted in viable and persistent infections in ticks, a trans-stadial transmission and the ability of adult ticks to transmit infection when feeding. Infection was however not transmitted transovarially or by faeces as early reported. Overall, we conclude that O. moubata may act as a driver of the transmission and of the spatial dispersal of Q fever among vertebrates where this tick is present in Africa.

A Deterministic Model for Q Fever Transmission Dynamics within Dairy Cattle Herds: Using Sensitivity Analysis and Optimal Controls

This paper presents a differential equation model which describes a possible transmission route for Q fever dynamics in cattle herds. The model seeks to ascertain epidemiological and theoretical inferences in understanding how to avert an outbreak of Q fever in dairy cattle herds (livestock). To prove the stability of the model's equilibria, we use a matrix-theoretic method and a Lyapunov function which establishes the local and global asymptotic behaviour of the model. We introduce time-dependent vaccination, environmental hygiene, and culling and then solve for optimal strategies. The optimal control strategies are necessary management practices that may increase animal health in a Coxiella burnetii-induced environment and may also reduce the transmission of the disease from livestock into the human population. The sensitivity analysis presents the relative importance of the various generic parameters in the model. We hope that the description of the results and the optimality trajectories provides some guidelines for animal owners and veterinary officers on how to effectively minimize the bacteria and control cost before/during an outbreak.

Sero-Epidemiological Study of Selected Zoonotic and Abortifacient Pathogens in Cattle at a Wildlife-Livestock Interface in South Africa

A cross sectional sero-epidemiological study was conducted on cattle in a communal farming area adjacent to Kruger National Park at a wildlife-livestock interface in South Africa. A total of 184 cattle were screened for exposure to 5 abortifacient or zoonotic pathogens, namely Coxiella burnetii, Toxoplasma gondii, Chlamydophila abortus, Neospora caninum, and Rift Valley fever virus (RVFV) using enzyme-linked immunosorbent assays. In addition, the virus neutralization test was used to confirm the presence of antibodies to RVFV. The seroprevalence of C. burnetii, T. gondii, C. abortus, N. caninum, and RVFV antibodies was 38.0%, 32.6%, 20.7%, 1.6%, and 0.5%, respectively, and varied between locations (p < 0.001). Seroprevalence of C. burnetii and T. gondii was highly clustered by location (intraclass correlation coefficient [ICC] = 0.57), and that of C. abortus moderately so (ICC = 0.11). Seroprevalence was not associated with sex or age for any pathogen, except for C. abortus, for which seroprevalence was positively associated with age (p = 0.01). The predominant mixed infections were C. burnetii and T. gondii (15.2%) and C. burnetii, T. gondii, and C. abortus (13.0%). The serological detection of the five abortifacient pathogens in cattle indicates the potential for economic losses to livestock farmers, health impacts to domestic animals, transmission across the livestock-wildlife interface, and the risk of zoonotic transmission. This is the first documentation of T. gondii infection in cattle in South Africa, while exposure to C. burnetii, C. abortus, and N. caninum infections is being reported for the first time in cattle in a wildlife-livestock interface in the country.

Q fever: A neglected disease of camels in Giza and Cairo Provinces, Egypt

Background and Aim

Q fever is a zoonotic disease caused by Coxiella burnetii. Cattle, sheep, and goat are the main reservoir of C. burnetii. In Egypt, the epidemiological data about C. burnetii in camels are limited. Therefore, the current study was conducted to identify C. burnetii infection in camels by different molecular tools and to estimate its seropositivity through the detection of anti-C. burnetii antibodies in camel sera.

Materials and Methods

Blood samples were collected 112 from camels in Giza and Cairo Provinces, Egypt. All blood samples were screened by trans-quantitative polymerase chain reaction (trans-qPCR) for C. burnetii and positive samples subjected to standard PCR using the superoxide dismutase enzyme coding gene of C. burnetii. Sera of studied camels were examined for the presence of antibodies against C. burnetii using enzyme-linked immunosorbent assay.

Results

Out of 112 camels, 19 were positive for C. burnetii by qPCR with an overall prevalence of 16.9% (18.6% in Giza and 15.1% in Cairo Provinces, respectively). The seroprevalence of anti-C. burnetii IgG antibodies in the examined camels was 4.5% (5/112).

Conclusions

Trans-qPCR assay is a rapid and sensitive tool for the detection of C. burnetii in acute stage. Camels should be considered one of the major reservoirs for C. burnetii in Egypt.