Coxiella burnetii (Q fever) in Rattus norvegicus and Rattus rattus at livestock farms and urban locations in the Netherlands; could Rattus spp. represent reservoirs for (re)introduction?

The Q fever outbreak in the Netherlands in 2007-2010 prompted government interventions to reduce the human incidence by reduction of Q fever shedding at dairy goat farms. Mandatory hygiene measures were taken, including the control of animal reservoirs. It has been postulated that brown rats, through their commensal nature, form an important factor in the persistent dissemination of endemic circulating Coxiella burnetii in nature to domestic animals, livestock and humans. Here, the occurrence of C. burnetii in rats captured at different types of location during the Q fever outbreak in the Netherlands, viz. urban areas, nature areas and various types of farm has been determined. This is a first step towards the elucidation of the reservoir status of rats in veterinary and human Q fever epidemiology. C. burnetii DNA was detected in the spleen of 4.9% of the brown rats (Rattus norvegicus) and 3.0% of the black rats (Rattus rattus). Evidence for C. burnetii infection was also found in liver, kidney, lung and intestinal tissue but not in heart, brain and pancreas. C. burnetii IgGs were detected in 15.8% of the brown rats. Positive rats were collected at goat, pig, cattle and poultry farms, and urban locations; including locations outside the designated 5km "increased-risk" zones around bulk milk positive goat farms. The percentage of rat-positive locations was the highest for goat farms (50%) and cattle farms (14.3%). The presence of actively infected rats outside the lambing season and at multiple environmental settings including urban locations might suggest that rats are not merely a spill-over host due to infection by a contaminated environment but might represent true reservoirs, capable of independent maintenance of C. burnetii infection cycles and thereby contributing to spread and transmission of the pathogen. If frequent (re)introduction of C. burnetii to small ruminant farms can be caused by rats as maintenance reservoirs, mandatory wildlife control and lifelong vaccination of herds will be necessary.     

Q fever: an emerging public health concern in Canada.

Q fever in humans and coxiellosis in livestock are on the increase in Canada. The progressive spread of Coxiella burnetii takes place in the animal reservoirs of the rickettsia, mainly domestic ruminants. Human Q fever is a reverberation of the coxiellosis situation on our farms. Increasing animal concentration resulting from the industrialization of agriculture and oversight of the infection in livestock permitted the extension of the zoonotic problem on the farms. Initiative for control of coxiellosis, however, is called for by public health interests at the present time to assure occupational health and safety for workers, and the protection of the general population residing in coxiella threatened environments.     

Emergence and genetic variability of Anaplasma species in small ruminants and ticks from Central Europe

Anaplasmoses are common tick-borne zoonotic bacterial diseases of livestock and free-living ungulates from the genus Anaplasma that are recently emerging in Central Europe. The main aim of this study was to analyze the prevalence and genetic variability of Anaplasma phagocytophilum and Anaplasma ovis in small ruminants and questing ticks from six different sites in Slovakia and the Czech Republic using the PCR of the msp4 gene followed by the sequence analysis. At two farms from southeastern Slovakia, 66.1% small ruminants were infected with A. ovis in contrast to one positive animal from both sites in northern Slovakia. It was represented by two different genotypes. A. phagocytophilum was present in all tested flocks with the infection prevalence ranging from 0.9% to 5.7%. None of the tested questing ticks carried A. ovis. A. phagocytophilum was detected in 1.1% and 7.8% of questing Ixodes ricinus ticks collected around the farms located in southeastern and northern Slovakia, respectively. A. phagocytophilum revealed higher intraspecific diversity than A. ovis.     

Is Q fever an emerging or re-emerging zoonosis?

Q fever is a zoonotic disease considered as emerging or re-emerging in many countries. It is caused by Coxiella burnetii, a bacterium developing spore-like forms that are highly resistant to the environment. The most common animal reservoirs are livestock and the main source of infection is by inhalation of contaminated aerosols. Although the culture process for Coxiella is laborious, advances on the knowledge of the life cycle of the bacterium have been made. New tools have been developed to (i) improve the diagnosis of Q fever in humans and animals, and especially animal shedders, (ii) perform epidemiological studies, and (iii) prevent the disease through the use of vaccines. This review summarizes the state of the knowledge on the bacteriology and clinical manifestations of Q fever as well as its diagnosis, epidemiology, treatment and prevention in order to understand what factors are responsible for its emergence or re-emergence.     

Prevalence of Coxiella burnetii DNA in vaginal and uterine samples from healthy cats of north-central Colorado

Q fever is a worldwide zoonotic disease caused by Coxiella burnetii. Although traditionally associated with livestock exposure, human infection has also been documented from contact with parturient cats. The goal of this study was to determine the prevalence of C burnetii DNA in uterine and vaginal tissues from healthy client-owned and shelter cats of north-central Colorado using polymerase chain reaction assay. Coxiella burnetii was not amplified from vaginal samples of any cat or uterine biopsies of shelter cats. However, a nucleotide sequence with 99% homology to C burnetii DNA was amplified from four of 47 (8.5%) uterine biopsies of client-owned cats. This study demonstrates that clinically normal cats in north-central Colorado can harbor C burnetii. Care should be taken when attending to parturient cats and contact with parturient secretions should be avoided. Additional studies are indicated to further characterize the role of cats in zoonotic Q fever.     

Diagnosis of Coxiella burnetii-related abortion in Italian domestic ruminants using single-tube nested PCR

Coxiella burnetii, an obligate intracellular parasite with a worldwide distribution, is the causative agent of acute and chronic Q fever in humans. Although infection is often unapparent in cattle, sheep and goats, there is increasing evidence that C. burnetii infection in these species is associated with abortion and stillbirth. This paper describes the introduction of a single-tube nested PCR protocol for the diagnosis of C. burnetii-related abortion in domestic ruminants in Italy. A total of 514 aborted foetuses from cattle (n = 138) and sheep and goat (n = 376), collected from 301 farms, were analyzed from January 2001 to March 2005. Ninety-seven of 514 (18.9%) animals tested PCR-positive, with 16/138 (11.6%) cattle and 81/376 (21.5%) sheep and goat. Eleven of 102 (10.8%) farms with reproductive disorders in cattle and 37/199 (18.6%) farms with reproductive disorders in sheep and goats were infected with C. burnetii. A greater incidence was observed in three of the seven investigated provinces (p < 0.01), with rates of infected farms of up to 23.8%. Data showed that almost all the C. burnetii-related abortions were recorded between October and April (p < 0.01). These findings suggest that Q fever in humans is largely underestimated in Italy, probably because its occurrence is obscured by flu-like symptoms in acute forms.     

Q热血清学检测方法的研究进展

Q热是由贝氏柯克斯体(Coxiella burnetii)引起的急性自然疫源性传染病。本病呈世界性流行,人类和动物普遍易感,已经成为当前分布最广的人兽共患病之一。文章综述了Q热的病原学、流行病学以及血清学检测方法的研究进展,为Q热的进一步研究与防控提供科学依据。     

Seroprevalence of Q fever in naturally infected dairy cattle herds

Coxiella burnetii is the causal agent of Q fever, a worldwide spread zoonosis. Prevention of C. burnetii shedding in cattle is critical to control the spread of the pathogen between animals, and from animals to humans. Vaccination with a phase 1 vaccine has been shown to be effective in preventing shedding when implemented in still susceptible animals, even in infected cattle herds. The identification of these animals (dairy cows and nulliparous females) as targets for vaccination consequently is crucial. Hygiene measures conventionally also are implemented, but their relative impact on C. burnetii diffusion remains unknown. The objectives of this study therefore were to (i) describe the distribution of the within-herd apparent seroprevalence among cows and nulliparous females and (ii) to explore the association between management practices and herd characteristics on the one hand, and these seroprevalences on the other. In a sample of 100 naturally and clinically infected dairy herds, blood samples were taken systematically from all nulliparous females (older than 12 months) and cows, and serologically tested. Information on herd characteristics and management practices were collected through a questionnaire filled in by each farmer. The variation in within-herd seroprevalence among cows and the risk for a herd of having at least one seropositive nulliparous female were investigated using multivariate (linear and logistic respectively) regression models. Median within-herd seroprevalence was 0.32 (Q1=0.22; Q3=0.43). We observed a low to null (median=0.01; Q1=0; Q3=0.10) within-herd seroprevalence in nulliparous females contrary to a high value (median=0.42) and variability (Q1=0.28; Q3=0.56) in cows. Only a few herd characteristics and management practices were found to be related to seroprevalence. Within-herd seroprevalence in cows was found to be significantly (P<0.10) higher in herds (i) with a number of cows<46, (ii) with seasonal calving, and (iii) with grazing or contact through the fence with other ruminant herds. The risk of having at least one seropositive nulliparous female was increased in herds (i) with seasonal calving and (ii) where the foetus and/or the placenta of aborted cows were not systematically removed. Our findings support, in addition to the implementation of high level of hygiene measures, the relevance of vaccination (at least in nulliparous females) as a method to control the spread of C. burnetii within an infected herd, as vaccination is effective in susceptible animals and given that nulliparous females are mostly not infected even in infected herds.     

Q热贝氏柯克斯体间接ELISA检测方法的建立

本研究以Q热贝氏柯克斯体弱毒株Ⅱ相全菌为包被抗原建立Q热贝氏柯克斯体间接ELISA检测方法,通过方阵滴定法对抗原包被浓度和二抗反应浓度的确定及各项反应条件的优化,确定其阴阳性临界值为0.44。用本方法与IDEXX Q热抗体检测试剂盒对393份牛临床血清进行检测,检出的血清阳性率分别为11.45%和6.10%,符合率为94.66%。结果表明,本试验建立的检测Q热贝氏柯克斯体的间接ELISA法具有较好的特异性及较强的敏感性,可初步应用于Q热贝氏柯克斯体抗体的临床检测。     

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.     

Q fever: an overview

Q fever, a zoonosis caused by the gram-negative bacterium Coxiella burnetii, occurs worldwide and affects both humans and animals. Ruminants are considered to be the main source of infection of humans, with the main route of infection being through inhalation of the organism of fine-particle aerosols. Abortion is the main clinical sign in ruminants. During and after abortion, large quantities of the bacterium are shed via the placenta and other vaginal secretions. The bacterium may also be present in faeces and milk. The bacterium can survive for a long time in the environment after shedding and can be spread over long distances. Seroprevalence among cattle is rather high in the Netherlands and in many other countries. Infection is diagnosed by detecting antibodies against the bacterium or the bacterium itself by means of a PCR method. The efficacy of using antibiotics or vaccines for treatment or prevention of the disease in cattle is still unclear and there are currently no effective disease control programmes.     

Shedding routes of Coxiella burnetii in dairy cows: implications for detection and control

Reliable detection of Coxiella burnetii shedders is a critical point for the control of the spread of this bacterium among animals and from animals to humans. Coxiella burnetii is shed by ruminants mainly by birth products (placenta, birth fluids), but may also be shed by vaginal mucus, milk, and faeces, urine and semen. However, the informative value of these types of samples to identify shedders under field conditions is unknown. Our aim was then to describe the responses obtained using a real-time PCR technique applied to milk, vaginal mucus and faeces samples taken from 242 dairy cows in commercial dairy herds known to be naturally infected with Coxiella burnetii, and to assess their putative associations. Positive results were found in all types of tested samples even in faeces. No predominant shedding route was identified. Among the shedder cows, 65.4% were detected as shedders by only one route. By contrast, cows with positive results for all three samples were scarce (less than 7%). Testing a cow based on only one type of biological sample may lead to misclassify it with regards to its shedding of Coxiella burnetii and thereby underestimate the risk of bacterial spread within a herd.     

Q fever antibody titer--follow-up study in cattle with special reference to pregnancy]

In 290 Q fever positive cattle from three 2000 head dairy farms in the former district of Erfurt (Thüringen) the course of titers was examined serologically over several months by means of the complement fixation test (CFT). In 47.2% of the cows serologically observed for 2 up to 28 months complement fixing antibodies against Coxiella burnetii could be demonstrated til the end of the investigation period. Repeated tests during pregnancy showed increase of antibody titers in the first 4 months and after a short decrease again from the 5. til the 7. month. By observing the antibody titers during several pregnancies each time a new increase comparable to a booster immunisation could be found. This may explain the persistence of Q fever antibodies in cows for several years. The results of this investigation suggest that from a high antibody titer it can not be concluded an abortion in a positive cow being caused by a Coxiella burnetii infection.     

Q fever (coxiellosis): epidemiology and pathogenesis

Q fever is a widespread zoonosis caused by the Gram-negative bacterium Coxiella burnetii. Aborting domestic ruminants are the main sources of human infection but the reservoir of infection is extremely wide. In humans, Q fever may occur as acute pneumonia, hepatitis or flu-like illness or may take a severe chronic form, characterized by endocarditis, chronic hepatitis and chronic fatigue syndrome. In animals, the main clinical manifestation is late abortion. Infection with C. burnetii can be diagnosed using cultural, serological and genetic methods but because the organism is potentially dangerous and requires specialized skills only specialist laboratories are capable of undertaking diagnostic tests. This paper provides a brief overview of the epidemiology and pathogenesis of Q fever (coxiellosis).     

Abortion and stillbirth among dairy goats as a consequence of Coxiella burnetii

The clinical signs and pathological findings of clinical Q fever in dairy goats in the Netherlands are described. The disease is characterized by endemic or epidemic abortion in late pregnancy, stillbirth, or the birth of weak kids. These consequences of Coxiella burnetii infection appear to have increased during recent years in the Dutch dairy goat population. Detection of the agent in placental tissue by immunohistochemistry has proven diagnostically useful.     

The occurrence of Coxiella burnetii in sheep and ticks of the genus Dermacentor in Baden-Wuerttemberg

This study examined the occurrence of Coxiella burnetii (C. burnetii), the infectious agent of Q-fever, in sheep and sheep-ticks in Baden-Wuerttemberg, Germany, as a possible source of infection in Q-fever outbreaks. Using PCR, we examined a total of 1066 Dermacentor ticks from 23 herds and 49 samples of tick excrement from 18 herds for C. burnetii. We found the infectious agent in one non-engorged tick and in one sample of tick excrement from the same herd, in Efringen-Kirchen (district Loerrach). Sequencing the PCR-products confirmed the amplifications as specific for C. burnetii. Further serological tests of random samples of the four districts of Baden-Wuerttemberg showed a seroprevalence from 0 to 1.4% using complement fixation test (CFT), as well as a 0.9 to 10.2% seroprevalence, using ELISA test. Serum samples from a Q-fever-suspicious herd resulted, however, in 6% (CFT) and 53% (ELISA) positive reactions. A comparison between CFT and ELISA showed both a correlation of the two test methods that increased with higher CFT titration levels and positive reactions using ELISA for 9.4% of the serums that had tested negative using CFT. The results of the present study reveal that ticks and their excrements are important vectors of transmission of Q-fever in Baden-Wuerttemberg. Investigations on C. burnetii using PCR as well as serological surveys of sheep are important instruments for diagnosis and disease control of Q-fever.     

Development of a method for detecting Coxiella burnetii in cheese samples

Coxiella burnetii is the causative agent of Q fever, and the main route of infection in humans is inhalation of contaminated aerosols. Although oral transmission by contaminated raw milk or dairy products is also a possible route of human infection, there have been few studies investigating the presence of C. burnetii in dairy products. We developed a new method of extracting DNA from cheese and detecting C. burnetii DNA in cheese samples with a nested PCR assay. The limit of detection was 6.0 × 10(2) C. burnetii particles per gram. We subsequently used this method to examine the presence of C. burnetii in cheese at commercial markets in Tokyo from June 2005 to December 2008. Twenty-eight of 147 cheese samples were found to be positive for C. burnetii DNA. However, when we assessed the viability of C. burnetii by inoculating mice with DNA-positive samples, all of the samples were found to be negative. Thus, the viability of C. burnetii appears to have been lost in these cheese samples.     

Relevance of the positron emission tomography in the diagnosis of vascular graft infection with Coxiella burnetii

Coxiella burnetii, the causative agent of Q fever, may cause culture-negative vascular graft infections that can be diagnosed by serology and molecular biology. We present a case of vascular graft infection detected by positron emission tomography (PET) scanner. The presence of C. burnetii was confirmed by high antibody titers and positive polymerase chain reaction specific for C. burnetii. This report emphasizes the relevance of the PET scanner in the diagnosis of infection when used in association with Q fever serology and molecular biology for the etiological identification of C. burnetii.     

Occurrence and risk factors of Coxiella burnetii in domestic ruminants in Lebanon

Coxiella burnetii causes diseases in humans (Q fever) and animals, domestic ruminants playing a major role in the epidemiology of the infection. Information on C. burnetii infection in Lebanon is scanty. In order to assess the prevalence of C. burnetii infection in ruminants, a cross-sectional study was undertaken in 2014. A total of 1633 sera from ruminants (865 cattle, 384 sheep and 384 goats) from 429 farms (173 cattle, 128 sheep and 128 goats), in seven provinces of Lebanon were randomly selected and assayed for the presence of antibodies.39.86% of farms (95% CI: 35.23–44.56) resulted positive. The seroprevalence was 30.63% in Cattle-farms, 46.88% in sheep-farms and 45.31% in goat-farms.Milk samples collected from 282 seropositive animals (86 cows, 93 sheep and 103 goats) from 171 positive farms were tested by a high sensitive Real-Time PCR targeted to the IS1111 transposon of C. burnetii. The overall prevalence in farms was estimated to be 14.04%. Cattle-, sheep- and goat farm prevalence rates were 15.09%, 10% and 17.24%, respectively.The findings of the study show that C. burnetii prevalence in Lebanese domestic ruminants is related to animal species and farming practices. Indeed, the mixed herds with sheep (p < 0.01), the presence of common lambing/kidding areas (p < 0.001) in farms where the use of disinfectants was not a routine practice (p < 0.05) were identified as important risk factors.The results of the study provide baseline information for setting up herd management and public health measures for the prevention and control of Q fever in Lebanon.