Occurrence of Coxiella burnetii in wild lagomorphs and their ticks in Spanish Mediterranean ecosystems

BACKGROUND

Coxiella burnetii, the causative agent of Q fever, is a zoonotic multi-host vector-borne pathogen of major public health importance. Although the European Food Safety Authority has recently made the monitoring of this bacterium in wildlife a priority, the role of wild lagomorphs in the transmission and maintenance of C. burnetii is poorly understood.

AIMS

The aims of this study were to determine the prevalence and risk factors associated with C. burnetii circulation in European wild rabbits (Oryctolagus cuniculus) and Iberian hares (Lepus granatensis) and to assess the presence of this pathogen in ticks that feed on them in Mediterranean ecosystems in Spain, the country with the highest number of reported cases of Q fever in Europe.

METHODS

A total of 574 spleen samples were collected from 453 wild rabbits and 121 Iberian hares, and 513 ticks (processed in 120 pools) between the 2017/2018 and 2021/2022 hunting seasons.

RESULTS

C. burnetii DNA was detected in 103 (17.9%; 95% CI: 14.8-21.1) of the 574 wild lagomorphs tested. By species, prevalence was 16.3% (74/453; 95% CI: 12.9-19.7) in the European wild rabbit and 24.0% (29/121; 95% CI: 16.4-31.6) in the Iberian hare. At least one positive lagomorph was found on 47.9% of the 96 hunting estates sampled and in every hunting season since 2018/2019. Two risk factors associated with C. burnetii infection were as follows: outbreak of myxomatosis on the hunting estate in the month prior to sampling and high tick abundance observed by gamekeepers on the hunting estate. C. burnetii DNA was also found in 33 of the 120 (27.5%; 95% CI: 19.5-35.5) tick pools tested. The pathogen was detected in 66.7% (4/6), 29.2% (26/89) and 21.4% (3/14) of Haemaphysalis hispanica, Rhipicephalus pusillus and Hyalomma lusitanicum pools respectively.

CONCLUSIONS

This study provides new epidemiological data on C. burnetii in European wild rabbits and is the first survey on this zoonotic pathogen performed in Iberian hares. Our results indicate widespread endemic circulation of C. burnetii and highlight the importance of both wild lagomorph species as natural reservoirs of this zoonotic bacterium in Mediterranean ecosystems in southern Spain, which may be of public and animal health concern. The high prevalence and wide diversity of positive tick species suggest the possible role of ticks in the epidemiological cycle of C. burnetii, with the potential risk of transmission to sympatric species, including humans.

Comparison of test performance of a conventional PCR and two field-friendly tests to detect Coxiella burnetii DNA in ticks using Bayesian latent class analysis

Introduction

Coxiella burnetii (C. burnetii)-infected livestock and wildlife have been epidemiologically linked to human Q fever outbreaks. Despite this growing zoonotic threat, knowledge of coxiellosis in wild animals remains limited, and studies to understand their epidemiologic role are needed. In C. burnetii-endemic areas, ticks have been reported to harbor and spread C. burnetii and may serve as indicators of risk of infection in wild animal habitats. Therefore, the aim of this study was to compare molecular techniques for detecting C. burnetii DNA in ticks.

Methods

In total, 169 ticks from wild animals and cattle in wildlife conservancies in northern Kenya were screened for C. burnetii DNA using a conventional PCR (cPCR) and two field-friendly techniques: Biomeme's C. burnetii qPCR Go-strips (Biomeme) and a new C. burnetii PCR high-resolution melt (PCR-HRM) analysis assay. Results were evaluated, in the absence of a gold standard test, using Bayesian latent class analysis (BLCA) to characterize the proportion of C. burnetii positive ticks and estimate sensitivity (Se) and specificity (Sp) of the three tests.

Results

The final BLCA model included main effects and estimated that PCR-HRM had the highest Se (86%; 95% credible interval: 56-99%), followed by the Biomeme (Se = 57%; 95% credible interval: 34-90%), with the estimated Se of the cPCR being the lowest (24%, 95% credible interval: 10-47%). Specificity estimates for all three assays ranged from 94 to 98%. Based on the model, an estimated 16% of ticks had C. burnetii DNA present.

Discussion

These results reflect the endemicity of C. burnetii in northern Kenya and show the promise of the PCR-HRM assay for C. burnetii surveillance in ticks. Further studies using ticks and wild animal samples will enhance understanding of the epidemiological role of ticks in Q fever.

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.

Epidemiological investigation of Coxiella burnetii in cattle and its association with Ixodid tick infestation in different agro-ecological zones of Southwest Ethiopia

Coxiella burnetii is a serious zoonotic disease that causes significant economic losses in cattle production, including abortion, stillbirth, infertility, and reduced milk yield. However, little is known about the epidemiology of C. burnetii in Ethiopia. From November 2020 to November 2021, a cross-sectional study was conducted to estimate the seroprevalence and associated risk factors of C. burnetii in cattle in various agro-ecologies of Southwest Ethiopia. Blood samples were collected from 461 cattle, and the serum samples were tested for the presence of C. burnetii antibodies using an indirect ELISA. To identify potential risk factors for C. burnetii seropositivity, a multivariable mixed-effect logistic regression analysis was used. The study found an overall seroprevalence of 8.68% (95% CI: 6.11-11.25) and 13.57% (95% CI: 9.56-17.58) at the animal and herd levels, respectively, in the study areas. The results of the study indicated that C. burnetii infection was a widespread disease in the study areas. C. burnetii seropositivity at the animal level was significantly associated with age (OR = 4.1, 95%CI: 1.47-10.92), herd size (OR = 3.9, 95%CI: 1.21-12.66), management system (OR = 9.7, 95%CI: 1.27-27.25), cattle access to dogs, cats, and mice (OR = 2.5, 95%CI: 1.21-5.28), accessibility of cattle to wild animals (OR = 4.2, 95%CI: 1.01-17.18), presence of ticks on cattle (OR = 2.3, 95%CI: 1.12-4.83), and history of abortion (OR = 3.8, 95%CI: 1.78-8.23). A herd level analysis identified several risk factors for C. burnetii infection, including the management system (OR = 3.8, 95%CI: 1.59-8.98), agro-ecology (OR = 2.8, 95%CI: 1.43-7.21), herd size (OR = 4.3, 95%CI: 1.69-9.76), and accessibility of cattle to dogs, cats, and mice (OR = 2.6, 95%CI: 1.18-3.96). Therefore, it is important to implement appropriate control methods and raise public awareness about C. burnetii zoonotic transmission. Moreover, further studies should be conducted to isolate and characterize C. burnetii as a cause of reproductive problems and in disease reservoirs such as ticks and wildlife in the study areas.

Occurrence and limited zoonotic potential of Cryptosporidium spp., Giardia duodenalis, and Balantioides coli infections in free-ranging and farmed wild ungulates in Spain

Little information is currently available on the occurrence and molecular diversity of the enteric protozoan parasites Cryptosporidium spp., Giardia duodenalis, and Balantioides coli in wild ungulates and the role of these host species as potential sources of environmental contamination and consequent human infections. The presence of these three pathogens was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were retrospectively collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from the five Spanish bioregions. Overall infection rates were 3.0% (42/1382; 95% CI: 2.1-3.9%) for Cryptosporidium spp., 5.4% (74/1382; 95% CI: 4.2-6.5%) for G. duodenalis, and 0.7% (9/1382; 95% CI: 0.3-1.2%) for B. coli. Cryptosporidium infection was detected in roe deer (7.5%), wild boar (7.0%) and red deer (1.5%), and G. duodenalis in southern chamois (12.9%), mouflon (10.0%), Iberian wild goat (9.0%), roe deer (7.5%), wild boar (5.6%), fallow deer (5.2%) and red deer (3.8%). Balantioides coli was only detected in wild boar (2.5%, 9/359). Sequence analyses revealed the presence of six distinct Cryptosporidium species: C. ryanae in red deer, roe deer, and wild boar; C. parvum in red deer and wild boar; C. ubiquitum in roe deer; C. scrofarum in wild boar; C. canis in roe deer; and C. suis in red deer. Zoonotic assemblages A and B were detected in wild boar and red deer, respectively. Ungulate-adapted assemblage E was identified in mouflon, red deer, and southern chamois. Attempts to genotype samples positive for B. coli failed. Sporadic infections by canine- or swine-adapted species may be indicative of potential cross-species transmission, although spurious infections cannot be ruled out. Molecular evidence gathered is consistent with parasite mild infections and limited environmental contamination with (oo)cysts. Free-ranging wild ungulate species would not presumably play a significant role as source of human infections by these pathogens. Wild ruminants do not seem to be susceptible hosts for B. coli.

Seropositivity for Coxiella burnetii in Wild Boar (Sus scrofa) and Red Deer (Cervus elaphus) in Portugal

Q fever is caused by the pathogen Coxiella burnetii and is a zoonosis that naturally infects goats, sheep, and cats, but can also infect humans, birds, reptiles, or arthropods. A survey was conducted for the detection of antibodies against C. burnetii in a sample of 617 free-ranging wild ruminants, 358 wild boar (Sus scrofa) and 259 red deer (Cervus elaphus), in east–central Portugal during the 2016–2022 hunting seasons. Only adult animals were sampled in this study. Antibodies specific to C. burnetii were detected using a commercial enzyme-linked immunosorbent assay (ELISA; IDVet®, Montpellier, France) according to the manufacturer’s instructions. The seroprevalence of C. burnetii infection was 1.5% (n = 9; 95% confidence interval [CI]: 0.7–2.8%). Antibodies against C. burnetii were detected in 4/358 wild boar (1.1%; 95% CI: CI: 0.3–2.8%) and 5/259 red deer (1.9%; 0.6–4.5%). Results of the present study indicate that antibodies against C. burnetii were present in wild boar and red deer in Portugal. These findings can help local health authorities to focus on the problem of C. burnetii in wildlife and facilitate the application of a One Health approach to its prevention and control.

Iberian wild leporidae as hosts of zoonotic enteroparasites in Mediterranean ecosystems of Southern Spain

Wild lagomorphs including rabbits and hares can act as natural carriers or reservoirs of bacterial and parasitic zoonotic diseases. However, little is known on the epidemiology and potential public health significance of intestinal eukaryotes in wild leporids. We examined faecal samples from European wild rabbits (Oryctolagus cuniculus, n = 438) and Iberian hares (Lepus granatensis, n = 111) collected in the Autonomous Region of Andalusia in southern Spain during 2012-2021. We searched for the presence of DNA from the main intestinal protist and microsporidial pathogens of veterinary and public health concerns using molecular methods (PCR followed by Sanger and next-generation sequencing). Giardia duodenalis was the most prevalent species found (27.8%, 153/550; 95% CI: 24.1-31.8), followed by Cryptosporidium spp. (1.3%, 7/550; 95% CI: 0.5-2.6), Blastocystis sp. (1.1%, 6/550; 95% CI: 0.4-2.4) and Encephalitozoon intestinalis (0.2%, 1/550; 95% CI: 0.0-10.1). All samples tested negative for Enterocytozoon bieneusi. Sequence analyses revealed the presence of sub-assemblage BIV (n = 1) within G. duodenalis, and Cryptosporidium cuniculus (n = 6) and Cryptosporidium andersoni (n = 1) within Cryptosporidium. The presence of ruminant-adapted C. andersoni is indicative of a potential cross-species transmission event, although a spurious infection (mechanical carriage) cannot be ruled out. Samples assigned to C. cuniculus belonged to the gp60 subtype families Va (n = 3) and Vb (n = 2). The six Blastocystis-positive samples were identified as ST2 (n = 3) and ST1 + ST2 (n = 3). Our molecular results suggest that wild rabbits and hares were primarily infected by leporid-adapted species of eukaryotic pathogens. However, the occasional findings of zoonotic G. duodenalis sub-assemblage BIV, Blastocystis sp. ST1 and ST2, and Encephalitozoon intestinalis could be of public health relevance.

Retrospective Molecular Survey on Bacterial and Protozoan Abortive Agents in Roe Deer (Capreolus capreolus) from Central Italy

Bacterial and protozoan agents can determine abortion and other reproductive disorders in domestic ruminants, but data regarding their occurrence in wild ruminants are scanty worldwide, including in Italy. The aim of this retrospective study was to verify the occurrence of the main bacterial and protozoan abortive agents in 72 spleen samples previously collected from roe deer (Capreolus capreolus) living in mountain areas of Central Italy. All samples were collected and submitted to DNA extraction for other investigations. Molecular analyses were carried out on the DNA samples to detect Brucella spp., Chlamydia abortus, Coxiella burnetii, Salmonella enterica, Listeria monocytogenes, Neospora caninum, and Toxoplasma gondii. Three (4.16%) roe deer resulted PCR positive for C. burnetii and one (1.38%) for T. gondii. These findings suggest that roe deer living in the investigated areas do not act as important reservoirs of the searched agents. However, the tested animals lived in a closed area without contact with domestic animals that are usually involved in the epidemiology of the investigated pathogens. Monitoring of wild ruminants is pivotal to verify changes in the epidemiological scenario from a One Health perspective, too.

The relevance of the wild reservoir in zoonotic multi-host pathogens: The links between Iberian wild mammals and Coxiella burnetii

Q fever is a worldwide zoonosis caused by an obligate intracellular bacterium, Coxiella burnetii, with only anecdotal reports of human-to-human transmission. The cause of human Q fever infections is the circulation of C. burnetii in animal reservoirs. Infected livestock, particularly goats and sheep, may cause Q fever outbreaks in humans. However, wildlife is the origin of several human Q fever cases. Human impacts on habitats, biodiversity and climate are responsible for changes in the patterns of interaction between domestic animals, wildlife and humans, allowing wild animals to play an increasingly relevant role as Q fever reservoirs. In the Iberian Peninsula, human impacts on the environment combined with a high biodiversity, which could maintain high transmission rates of this multi-host pathogen, make wild reservoirs an important piece in Q fever epidemiology. In this study, we review the reporting of C. burnetii infections and exposure in Iberian wild mammals and analyse the link between the diversity of wild mammals and the frequency of C. burnetii notifications in wildlife. For it, the number of wild mammal species per UTM 10 × 10-km grid in mainland Spain and Portugal was estimated as a potential predictor of C. burnetii transmission. The results of non-linear regression analysis showed a quadratic relationship between the number of wild mammal species per grid and the presence of C. burnetii cases reported in the literature both by serology (R²  = 0.86) and polymerase chain reaction (R²  = 0.83). Increasing wild mammal diversity was linked to increasing C. burnetii transmission until an intermediate level when the relationship was inverted. Thus, at high levels of wild mammal diversity, the risk of C. burnetii transmission was lower. These observations show a role of wild mammal biodiversity in C. burnetii ecology that needs to be further explored to better prevent the negative impact of Q fever in livestock and human health in Iberia.

Determinants of Crimean-Congo haemorrhagic fever virus exposure dynamics in Mediterranean environments

Crimean-Congo haemorrhagic fever (CCHF) is an emerging tick-borne human disease in Spain. Understanding the spatiotemporal dynamics and exposure risk determinants of CCHF virus (CCHFV) in animal models is essential to predict the time and areas of highest transmission risk. With this goal, we designed a longitudinal survey of two wild ungulate species, the red deer (Cervus elaphus) and the Eurasian wild boar (Sus scrofa), in Doñana National Park, a protected Mediterranean biodiversity hotspot with high ungulate and CCHFV vector abundance, and which is also one of the main stopover sites for migratory birds between Africa and western Europe. Both ungulates are hosts to the principal CCHFV vector in Spain, Hyalomma lusitanicum. We sampled wild ungulates annually from 2005 to 2020 and analysed the frequency of exposure to CCHFV by a double-antigen ELISA. The annual exposure risk was modelled as a function of environmental traits in an approach to understanding exposure risk determinants that allow us to predict the most likely places and years for CCHFV transmission. The main findings show that H. lusitanicum abundance is a fundamental driver of the fine-scale spatial CCHFV transmission risk, while inter-annual risk variation is conditioned by virus/vector hosts, host community structure and weather variations. The most relevant conclusion of the study is that the emergence of CCHF in Spain might be associated with recent wild ungulate population changes promoting higher vector abundance. This work provides relevant insights into the transmission dynamics of CCHFV in enzootic scenarios that would allow deepening the understanding of the ecology of CCHFV and its major determinants.

Zoonotic Enterocytozoon bieneusi genotypes in free-ranging and farmed wild ungulates in Spain

Microsporidia comprises a diverse group of obligate, intracellular, and spore-forming parasites that infect a wide range of animals. Among them, Enterocytozoon bieneusi is the most frequently reported species in humans and other mammals and birds. Data on the epidemiology of E. bieneusi in wildlife is limited. Hence, E. bieneusi was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from five Spanish bioregions. The parasite was detected only in red deer (10.4%, 68/653) and wild boar (0.8%, 3/359). Enterocytozoon bieneusi infections were more common in farmed (19.4%, 63/324) than in wild (1.5%, 5/329) red deer. Eleven genotypes were identified in red deer, eight known (BEB6, BEB17, EbCar2, HLJD-V, MWC_d1, S5, Type IV, and Wildboar3) and three novel (DeerSpEb1, DeerSpEb2, and DeerSpEb3) genotypes. Mixed genotype infections were detected in 15.9% of farmed red deer. Two genotypes were identified in wild boar, a known (Wildboar3) and a novel (WildboarSpEb1) genotypes. All genotypes identified belonged to E. bieneusi zoonotic Groups 1 and 2. This study provides the most comprehensive epidemiological study of E. bieneusi in Spanish ungulates to date, representing the first evidence of the parasite in wild red deer populations worldwide. Spanish wild boars and red deer are reservoir of zoonotic genotypes of E. bieneusi and might play an underestimated role in the transmission of this microsporidian species to humans and other animals.

Seasonality of Coxiella burnetii among Wild Rabbits (Oryctolagus cuniculus) and the Hyalomma lusitanicum (Acari: Ixodidae) in a Meso-Mediterranean Ecosystem

(1) Background: Q fever is a worldwide zoonosis caused by Coxiella burnetii that have cases reported in humans and animals almost everywhere. The aim of this study was to describe the seasonality of Coxiella burnetii in the wild rabbit (Oryctolagus cuniculus) and the tick Hyalomma lusitanicum in a meso-Mediterranean ecosystem. (2) Methods: two populations of wild rabbits that differ in whether or not they share habitat with ungulates, mainly red deer (Cervus elaphus) were sampled for a year to collect ticks, blood and vaginal or anal swabs. Presence of C. burnetii DNA in swabs and the tick H. lusitanicum was determined by PCR and serum antibodies by ELISA. (3) Results: C. burnetii DNA was detected in 47.2% of 583 rabbits, in 65.5% of sera, and in more than half of the H. lusitanicum. There were small variations according to sex and age of the rabbits but significant according to the habitat (4) Conclusions: The results indicate that C. burnetii circulates freely between wild rabbits and H. lusitanicum and the sylvatic cycle in meso-Mediterranean environments relies in the presence of wild rabbits and H. lusitanicum above all if sharing habitat with red deer.

Seroepidemiology of Toxoplasma gondii in wild ruminants in Spain

Toxoplasmosis is a parasitic zoonosis caused by Toxoplasma gondii which infects warm-blooded species worldwide. Humans can be infected through ingestion of tissue cysts from raw or undercooked meat, including game meat. A nationwide large-scale cross-sectional study was conducted to assess exposure to T. gondii in seven wild ruminant species in Spain. A total of 2,040 serum samples from 77 sampling sites randomly distributed in the five bioregions (BRs) covering mainland Spain were tested for antibodies against T. gondii using the modified agglutination test. The overall seroprevalence was 22.0% (449/2,040). Seroprevalence by species in decreasing order was as follows: 39.6% (141/356) in roe deer (Capreolus capreolus), 37.1% (138/372) in fallow deer (Dama dama), 16.6% (92/553) in red deer (Cervus elaphus), 14.0% (26/186) in Southern chamois (Rupicapra pyrenaica), 11.5% (24/209) in mouflon (Ovis aries musimon), 7.8% (27/346) in Iberian wild goat (Capra pyrenaica) and 5.6% (1/18) in Barbary sheep (Ammotragus lervia). Seropositivity was detected in 74.0% (57/77) of the sampling sites. Results indicate widespread but not homogeneous exposure to T. gondii in wild ruminant populations in Spain during the last two decades and highlight differences related to animal species and spatial distribution of these species in this country; this implies potential consequences of T. gondii for animal health, conservation and public health.

Epidemiologic and Public Health Significance of Toxoplasma gondii Infections in Venison: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingestion of uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Deer are a popular game. Recently, outbreaks of clinical toxoplasmosis were reported in humans in North America linked to ingestion of undercooked venison. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in deer and other cervids for the past decade. Estimates of worldwide serological prevalence are summarized individually for each species of deer, elk, moose, and caribou. Genetic diversity of 112 viable isolates of T. gondii from cervids is discussed, including its public health significance. Prevalence of T. gondii in deer is very high. Any part of a deer, including liver, spleen, and muscles, should be cooked thoroughly before human consumption.

Investigating the Role of Micromammals in the Ecology of Coxiella burnetii in Spain

Coxiella burnetii, the causal agent of human Q fever and animal Coxiellosis, is a zoonotic infectious bacterium with a complex ecology that results from its ability to replicate in multiple (in)vertebrate host species. Spain notifies the highest number of Q fever cases to the ECDC annually and wildlife plays a relevant role in C. burnetii ecology in the country. However, the whole picture of C. burnetii hosts is incomplete, so this study seeks to better understand the role of micromammals in C. burnetii ecology in the country. Spleen samples from 816 micromammals of 10 species and 130 vaginal swabs from Microtus arvalis were analysed by qPCR to detect C. burnetii infection and shedding, respectively. The 9.7% of the spleen samples were qPCR positive. The highest infection prevalence (10.8%) was found in Microtus arvalis, in which C. burnetii DNA was also detected in 1 of the 130 vaginal swabs (0.8%) analysed. Positive samples were also found in Apodemus sylvaticus (8.7%), Crocidura russula (7.7%) and Rattus rattus (6.4%). Positive samples were genotyped by coupling PCR with reverse line blotting and a genotype II+ strain was identified for the first time in one of the positive samples from M. arvalis, whereas only partial results could be obtained for the rest of the samples. Acute Q fever was diagnosed in one of the researchers that participated in the study, and it was presumably linked to M. arvalis handling. The results of the study are consistent with previous findings suggesting that micromammals can be infected by C. burnetii. Our findings additionally suggest that micromammals may be potential sources to trace back the origin of human Q fever and animal Coxiellosis cases in Europe.

Transstadial Transmission from Nymph to Adult of Coxiella burnetii by Naturally Infected Hyalomma lusitanicum

Coxiella burnetii (Derrick) Philip, the causative agent of Q fever, is mainly transmitted by aerosols, but ticks can also be a source of infection. Transstadial and transovarial transmission of C. burnetii by Hyalomma lusitanicum (Koch) has been suggested. There is a close relationship between this tick species, wild animals and C. burnetii but the transmission in a natural environment has not been demonstrated. In this study, we collected 80 engorged nymphs of H. lusitanicum from red deer and wild rabbits. They moult to adults under laboratory conditions and we feed them artificially through silicone membranes after a preconditioning period. C. burnetii DNA was tested in ticks, blood and faeces samples using real-time PCR. The pathogen was found in 36.2% of fed adults, demonstrating that transstadial transmission from nymph to adult occurs in nature. The presence of DNA in the 60.0% of blood samples after artificial feeding confirms that adults transmit the bacteria during feeding. Further studies are needed about co-feeding and other possible transmission routes to define the role of this tick species in the cycle of C. burnetii.

Prevalence of Coxiella burnetii (Legionellales: Coxiellaceae) Infection Among Wildlife Species and the Tick Hyalomma lusitanicum (Acari: Ixodidae) in a Meso-Mediterranean Ecosystem

Q fever is a worldwide zoonosis caused by Coxiella burnetii (Derrick) Philip. It is a major cause of abortion among sheep and may be responsible for reproductive losses in red deer in Spain. Airborne transmission is the most widespread; however, some studies suggested that ticks may play a role, but little is known about their actual involvement in the C. burnetii cycle. The aim of this study was to determine the role that Hyalomma lusitanicum (Koch) tick plays in the maintenance of this agent among wildlife in the meso-Mediterranean areas. We processed by PCR 53 swabs from wild rabbits, 21 liver samples from red deer, and 236 ticks collected at different stages. Coxiella burnetii DNA was detected in 43.40% of wild rabbits and 38.09% of red deer, supporting the hypothesis that these animals are quite likely to serve as a reservoir in the field. We also found a high prevalence of C. burnetii in ticks (55.66%). It is worth noting that 50.45% of positive ticks were collected from negative hosts, suggesting that the pathogen probably was acquired at a previous tick stage. Our results suggest transstadial transmission, and the presence of bacterial DNA in the offspring of positive female ticks is the first evidence of the transovarial transmission of C. burnetii by H. lusitanicum. Thus, this tick species seems to play an important role as a bridge of infection in the wildlife cycle, although further studies are needed to confirm vector competence.

The prevalence of Coxiella burnetii in ticks and animals in Slovenia

BACKGROUND

The obligate intracellular bacterium Coxiella burnetii causes globally distributed zoonotic Q fever. Ruminant livestock are common reservoirs of C. burnetii. Coxiella burnetii are shed in large numbers in the waste of infected animals and are transmitted by inhalation of contaminated aerosols. This study was conducted to evaluate the prevalence of C. burnetii infection in domestic animals and ticks in areas of Slovenia associated with a history of Q fever outbreaks.

RESULTS

A total of 701 ticks were collected and identified from vegetation, domestic animals and wild animals. C. burnetii DNA was detected in 17 out of 701 (2.4%) ticks. No C. burnetii DNA was found in male ticks. Ticks that tested positive in the PCR-based assay were most commonly sampled from wild deer (5.09%), followed by ticks collected from domestic animals (1.16%) and ticks collected by flagging vegetation (0.79%). Additionally, 150 animal blood samples were investigated for the presence of C. burnetii-specific antibodies and pathogen DNA. The presence of pathogen DNA was confirmed in 14 out of 150 (9.3%) blood samples, while specific antibodies were detected in sera from 60 out of 150 (40.4%) animals.

CONCLUSIONS

Our results indicate that ticks, although not the primary source of the bacteria, are infected with C. burnetii and may represent a potential source of infection for humans and animals. Ticks collected from animals were most likely found to harbor C. burnetii DNA, and the infection was not lost during molting. The persistence and distribution of pathogens in cattle and sheep indicates that C. burnetii is constantly present in Slovenia.

Evidence of exposure to Coxiella burnetii in neotropical free-living cervids in South America

Coxiella burnetii (order Legionellales, family Coxiellaceae), the etiological agent of Q fever, is a pleomorphic, obligate Gram-negative intracellular bacillococcus that can infect humans and animals. Among the mammals hosting this agent, both domestic and wild ruminants are of particular economic and public health importance. Ticks and other hematophagous arthropods or aerosols are incriminated in the transmission between reservoirs and susceptible hosts. This study used serological and molecular methods to investigate the C. burnetii occurrence in blood samples from free-living deer (143 Blastocerus dichotomus, 27 Mazama gouazoubira, 4 M. bororo, 3 M. americana, and 11 Ozotocerus bezoarticus) sampled in Mato-Grosso do Sul, São Paulo, Goiás and Paraná states in Brazil. The DNA extracted from the blood samples of 188 cervids was submitted to nested (n) PCR for C. burnetii based on the IS1111 repetitive insertion element of the heat shock protein (htpAB) gene. Additionally, 169 serum samples were submitted to Indirect Immunofluorescence Assay (IFAT) to detect Ig antibodies to C. burnetii. The nPCR results indicated that all blood samples were negative, evidencing the absence of circulating C. burnetii DNA in cervids from the studied regions or, alternatively, the C. burnetii DNA concentration in the deer blood samples was below the threshold of the used PCR technique. On the other hand, 5.32% (9/169) of deer were seropositive for C. burnetii by IFAT, with titers ranging from 256 and 16,384. In conclusion, the present work showed the first evidence of exposure of free-living deer to C. burnetii in Brazil.

Coxiella burnetii in wild mammals: A systematic review

Coxiella burnetii is a multi-host bacterium that causes Q fever in humans, a zoonosis that is emerging worldwide. The ecology of C. burnetii in wildlife is still poorly understood and the influence of host, environmental and pathogen factors is almost unknown. This study gathers current published information on different aspects of C. burnetii infection in wildlife, even in species with high reservoir potential and a high rate of interaction with livestock and humans, in order to partially fill the existing gap and highlight future needs. Exposure and/or infection by C. burnetii has, to date, been reported in 109 wild mammal species. The limited sample size of most of the existing studies could suggest an undervalued prevalence of C. burnetii infection. Knowledge on the clinical outcome of C. burnetii infection in wildlife is also very limited, but currently includes reproductive failure in waterbuck (Kobus ellipsiprymnus), roan antelope (Hippotragus niger), dama gazelle (Nanger dama) and water buffalo (Bubalus bubalis) and placentitis in the Pacific harbor seal (Phoca vitulina richardsi), Steller sea lion (Eumetopias jubatus) and red deer (Cervus elaphus). The currently available serological tests need to be optimised and validated for each wildlife species. Finally, there is a huge gap in the research on C. burnetii control in wildlife, despite of the increasing evidence that wildlife is a source of C. burnetii for both livestock and humans.

Estimating the Efficacy of a Commercial Phase I Inactivated Vaccine in Decreasing the Prevalence of Coxiella burnetii Infection and Shedding in Red Deer (Cervus elaphus)

The red deer (Cervus elaphus) is a relevant reservoir for Coxiella burnetii in Iberia. C. burnetii genotypes that infect red deer also infect humans and domestic animals. Integrated control approaches that target both domestic and wild ruminants are, therefore, required to reduce C. burnetii infection risks in Iberia, especially in wildlife–livestock–human interaction scenarios. The aim of this field experiment was to test the efficacy of an inactivated phase I vaccine [Inactivated phase I vaccine (IPIV); Coxevac^®] when used to control C. burnetii shedding prevalence and burden in red deer as a tool to prevent transmission to livestock and humans. A semi-extensively bred red deer population in which C. burnetii is endemic was used as a model of the Iberian context. Around 75% of the reproductive hinds (>1 year old; N = 441) in the population were first vaccinated early in 2012 and were then revaccinated 3 weeks later; they were subsequently revaccinated biannually until January 2014. 75% of the yearling females left as replacement in 2012 and 2013 were vaccinated in June and revaccinated thereafter following the same protocol. 25% of the population, including the replacement females, was kept as a control group throughout the study. Changes in the humoral immune response after vaccination were estimated by analyzing sera collected at 10 different times between January 2011 and January 2015. The vaccinated and control hinds were surveyed at 2.5, 3.5, and 4.5 months after calving in 2012, 2013, and 2014 to collect vaginal swabs, milk, and feces. The presence and burden of C. burnetii DNA in swabs, milk, and feces was evaluated by means of real-time PCR. Vaccination induced high antibody prevalence and levels. The proportion of animals shedding C. burnetii in vaginal secretions and milk did not change over time in the vaccination group with respect to the control group. In contrast, there was a significant reduction in the proportion of deer shedding C. burnetii in feces in both the vaccinated and control groups. The decrease in the proportion of fecal shedders coincided with a significant reduction in the incidence of infection of non-vaccinated yearling females in the population. This finding suggests that long-term vaccination with IPIV could reduce environmental contamination with C. burnetii and control transmission, perhaps making this a promising tool with which to control C. burnetii in red deer in the future.

Coxiella burnetii Genotypes in Iberian Wildlife

To investigate if Coxiella burnetii, the causative agent of Q fever, genotypes circulating in wildlife are associated with those infecting livestock and humans, multiple-locus variable number tandem-repeat analysis (MLVA-6-marker) was carried out over C. burnetii obtained from red deer (Cervus elaphus), Eurasian wild boar (Sus scrofa), European wild rabbit (Oryctolagus cuniculus), black rat (Rattus rattus), and wood mouse (Apodemus sylvaticus). MLVA typing was performed by using six variable loci in C. burnetii: Ms23, Ms24, Ms27, Ms28, Ms33, and Ms34. The C. burnetii cooperative database from MLVABank 5.0 was employed to compare genotypes found in this study with 344 isolates of diverse origin. Twenty-two genotypes from wildlife and two genotypes from domestic goats were identified. Some MLVA genotypes identified in wildlife or in farmed game clustered with genotypes of human Q fever clinical cases, supporting the idea that humans and wildlife share C. burnetii genotypes. The major part of genotypes identified in coexisting red deer and rabbits clustered according to their host of origin, suggesting host specificity for particular C. burnetii genotypes. These findings provide important insights to understand the epidemiology of C. burnetii at the wildlife-livestock-human interface.

Molecular survey on the presence of zoonotic arthropod-borne pathogens in wild red deer (Cervus elaphus)

To estimate the prevalence of some zoonotic tick-borne pathogens in red deer (Cervus elaphus) living in Italian areas with high risk of arthropod exposure, blood samples from 60 red deer were tested by PCR for A. phagocytophilum, Borrelia burgdorferi s.l., Coxiella burnetii, Francisella tularensis, and piroplasms. Thirty-four (56.67%) animals resulted positive for one or more pathogens. In particular, 24 (40%) red deer were positive for A. phagocytophilum, 16 (26.67%) for Babesia divergens, 6 (10%) for C. burnetii, 2 (3.33%) for B. burgdorferi s.l. No positive reaction was observed for F. tularensis. Thirteen (21.67%) animals resulted co-infected by two or three pathogens. Red deer is confirmed as competent reservoir of A. phagocytophilum and B. divergens, but not of B. burgdorferi. This is the first report of C. burnetii-positive red deer in central Italy. Hunters may be at risk of infection both through infected ticks and during the infected cervids carcasses dressing.

Serological survey of Coxiella burnetii at the wildlife-livestock interface in the Eastern Pyrenees, Spain

BACKGROUND

Coxiella burnetii is a zoonotic bacterium that infects a wide range of animal species and causes the disease Q fever. Both wild and domestic ruminants may be relevant in the epidemiology of C. burnetii infection. In order to investigate the significance of the ruminant host community in the alpine and subalpine ecosystems of the Eastern Pyrenees, Northeastern Spain, in the epidemiology of Q fever, a serological survey was performed on samples from 599 wild and 353 sympatric domestic ruminants.

RESULTS

Specific antibodies against C. burnetii were detected with a commercial enzyme-linked immunosorbent assay (ELISA). Domestic sheep showed the highest prevalence (12.7 %, CI 95 % 8.6-16.9), followed by European mouflon (Ovis orientalis musimon) with a 6.8 % prevalence (CI 95 % 1.6-12.1), red deer (Cervus elaphus) with 2.4 % (CI 95 % 0-5.6), and cattle with a prevalence of 1.1 % (CI 95 % 0-3.2). No positive domestic goats, fallow deer (Dama dama), roe deer (Capreolus capreolus) and Southern chamois (Rupicapra pyrenaica) were detected. Sheep flock prevalence was 75 % (nine of the 12 sheep flocks sampled were positive, within-flock prevalence ranging from 11.1 to 25.0 %), whereas cattle herd prevalence was 11.1 % (one out of the nine cattle herds sampled was positive, within-herd prevalence of 10.0 %.

CONCLUSIONS

Both domestic and wild ruminants from the alpine and subalpine ecosystems of the Eastern Pyrenees were exposed to C. burnetii. The higher seroprevalence in sheep and its relative abundance suggest that this species may have a major contribution to the ecology of C. burnetii. Conversely, wild ruminants do not seem to represent a relevant host community for C. burnetii maintenance in the Eastern Pyrenees.

European Rabbits as Reservoir for Coxiella burnetii

We studied the role of European rabbits (Oryctolagus cuniculus) as a reservoir for Coxiella burnetii in the Iberian region. High individual and population seroprevalences observed in wild and farmed rabbits, evidence of systemic infections, and vaginal shedding support the reservoir role of the European rabbit for C. burnetii.

Long-Term Dynamics of Coxiella burnetii in Farmed Red Deer (Cervus elaphus)

Several aspects of the dynamics of Coxiella burnetii that are relevant for the implementation of control strategies in ruminant herds with endemic Q fever are unknown. We designed a longitudinal study to monitor the dynamics of exposure to C. burnetii in a red deer herd with endemic infection in order to allow the design of Q fever-specific control approaches. Other relevant aspects of the dynamics of C. burnetii – the effect of herd immune status, age, season, and early infection on exposure, the average half-life of antibodies, the presence and duration of maternal humoral immunity, and the age of first exposure – were analyzed. The dynamics of C. burnetii in deer herds seems to be modulated by host herd and host individual factors and by particular host life-history traits. Red deer females become exposed to C. burnetii at the beginning of their second year since maternal antibodies protect them after birth and during the main pathogen shedding season – at the end of spring-early summer. Infection pressure varies between years, probably associated with herd immunity effects, determining inter-annual variation in the risk of exposure. These results suggest that any strategy applied to control C. burnetii in deer herds should be designed to induce immunity in their first year of life immediately after losing maternal antibodies. The short average life of C. burnetii antibodies suggests that any protection based on humoral immunity would require re-vaccination every 6 months.

Acute Q fever infection in Thuringia, Germany, after burial of roe deer fawn cadavers (Capreolus capreolus): a case report

We report on a case of a 48-year-old man who presented with acute Q fever infection after burying two fawn cadavers (Capreolus capreolus). Recent outbreaks of Q fever in Europe have been traced back to intensive goat breeding units, sheep flocks in the proximity of highly populated urban areas or to farmed deer. To our knowledge, this is the first case report describing Q fever infection in a human linked to roe deer as a source of infection.

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Q fever is a zoonosis of worldwide distribution with the exception of New Zealand. It is caused by an intracellular bacterium, Coxiella burnetii. The disease often goes underdiagnosed because the main manifestation of its acute form is a general self-limiting flu-like syndrome. The Dutch epidemics renewed attention to this disease, which was less considered before. This review summarizes the description of C. burnetii (taxonomy, intracellular cycle, and genome) and Q fever disease (description, diagnosis, epidemiology, and pathogenesis). Finally, vaccination in humans and animals is also considered.

Host and Environmental Factors Modulate the Exposure of Free-Ranging and Farmed Red Deer (Cervus elaphus) to Coxiella burnetii

The control of multihost pathogens, such as Coxiella burnetii, should rely on accurate information about the roles played by the main hosts. We aimed to determine the involvement of the red deer (Cervus elaphus) in the ecology of C. burnetii. We predicted that red deer populations from broad geographic areas within a European context would be exposed to C. burnetii, and therefore, we hypothesized that a series of factors would modulate the exposure of red deer to C. burnetii. To test this hypothesis, we designed a retrospective survey of 47 Iberian red deer populations from which 1,751 serum samples and 489 spleen samples were collected. Sera were analyzed by enzyme-linked immunosorbent assays (ELISA) in order to estimate exposure to C. burnetii, and spleen samples were analyzed by PCR in order to estimate the prevalence of systemic infections. Thereafter, we gathered 23 variables-within environmental, host, and management factors-potentially modulating the risk of exposure of deer to C. burnetii, and we performed multivariate statistical analyses to identify the main risk factors. Twenty-three populations were seropositive (48.9%), and C. burnetii DNA in the spleen was detected in 50% of the populations analyzed. The statistical analyses reflect the complexity of C. burnetii ecology and suggest that although red deer may maintain the circulation of C. burnetii without third species, the most frequent scenario probably includes other wild and domestic host species. These findings, taken together with previous evidence of C. burnetii shedding by naturally infected red deer, point at this wild ungulate as a true reservoir for C. burnetii and an important node in the life cycle of C. burnetii, at least in the Iberian Peninsula.

A Review of the Current Status of Relevant Zoonotic Pathogens in Wild Swine (Sus scrofa) Populations: Changes Modulating the Risk of Transmission to Humans

Many wild swine populations in different parts of the World have experienced an unprecedented demographic explosion that may result in increased exposure of humans to wild swine zoonotic pathogens. Interactions between humans and wild swine leading to pathogen transmission could come from different ways, being hunters and game professionals the most exposed to acquiring infections from wild swine. However, increasing human settlements in semi-natural areas, outdoor activities, socio-economic changes and food habits may increase the rate of exposure to wild swine zoonotic pathogens and to potentially emerging pathogens from wild swine. Frequent and increasing contact rate between humans and wild swine points to an increasing chance of zoonotic pathogens arising from wild swine to be transmitted to humans. Whether this frequent contact could lead to new zoonotic pathogens emerging from wild swine to cause human epidemics or emerging disease outbreaks is difficult to predict, and assessment should be based on thorough epidemiologic surveillance. Additionally, several gaps in knowledge on wild swine global population dynamics trends and wild swine-zoonotic pathogen interactions should be addressed to correctly assess the potential role of wild swine in the emergence of diseases in humans. In this work, viruses such as hepatitis E virus, Japanese encephalitis virus, Influenza virus and Nipah virus, and bacteria such as Salmonella spp., Shiga toxin-producing Escherichia coli, Campylobacter spp. and Leptospira spp. have been identified as the most prone to be transmitted from wild swine to humans on the basis of geographic spread in wild swine populations worldwide, pathogen circulation rates in wild swine populations, wild swine population trends in endemic areas, susceptibility of humans to infection, transmissibility from wild swine to humans and existing evidence of wild swine-human transmission events.