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This review evaluates the threat to human health—with the shedding of C. burnetii in dairy animals with reproductive disorders or those without clinical signs. The review also discusses the diagnosis of Q fever in livestock and the possibility of Coxiella-free herds, and it reports the available methods for controlling Q fever. C. burnetii shedding seems to occur frequently in milk taken from asymptomatic dairy cows. The number of Coxiella shed in milk is generally low. The phase I vaccine prevented abortion and greatly decreased the shedding of C. burnetii in milk. [ABSTRACT FROM AUTHOR]

Coxiella burnetii, the agent of Q fever, is an obligate intracellular bacterium that is considered a potential biological weapon of category B. C. burnetii survives within myeloid cells by subverting receptor-mediated phagocytosis and preventing phagosome maturation. The intracellular fate of C. burnetii also depends on the functional state of myeloid cells. This review describes the mechanisms used by C. burnetii to circumvent uptake and trafficking events, and the role of cytokines on C. burnetii survival in myeloid cells. [ABSTRACT FROM AUTHOR]

We are reporting the first known isolation of the Q-fever agent Coxiella burnetii from field-collected cayenne ticks Amblyomma cajennense in North America. Q-fever affects a number of domestic ungulates where it can lead to abortion in sheep and goats. There is far less known about the disease's effects on wild species, primarily because of the tendency of the disease to self resolve and to provide long-term immunity to subsequent infections. The first recovery of C. burnetii in North America was from the tick species Dermacentor andersoni. Since the original isolation C. burnetii has been recovered from five other North American tick species. The currently accepted mode for the majority of human infections is inhalation. The Centers for Disease Control and Prevention, Division of Viral and Rickettsial Diseases, Rickettsial Zoonoses Branch asserts the Q-fever agent as requiring as few as one organism to cause disease via inhalation in susceptible humans. However, with more and more isolations from ticks, evidence linking C. burnetii and ticks is mounting. The true role of tick species as competent vectors is still unconfirmed. Preemptive field collections of possible vector arthropods, hosts, and reservoirs can provide invaluable baseline environmental data that will prove supportive in follow-up studies and abatement efforts. [ABSTRACT FROM AUTHOR]

An immunocompetent animal disease model based on infection with Ehrlichia chaffeensis would facilitate research toward understanding mechanisms responsible for the broad range of clinical signs associated with human monocytic ehrlichiosis (HME). The adaptability of this model for the experimental feeding of tick species and stages and for testing therapies comparable to those for human diseases are additional advantages of large animal models. Herein, we summarize pathology reports for calves that developed fatal disease after experimental inoculation with E. chaffeensis. Elevated liver enzyme levels and lung pathology among these calves corroborated earlier reports of severe HME. Thus, an experimental disease model based on infection of outbred immunocompetent hosts with E. chaffeensis could be within our grasp for the first time. [ABSTRACT FROM AUTHOR]

Mass production of Ehrlichia ruminantium variants from different regions of sub-Saharan Africa is one of the difficulties that must be overcome in producing a heartwater vaccine. Vaccine productivity can be limited by endogenous induction of interferon (IFN), which inhibits the propagation of Ehrlichia ruminantium (ER) in cell culture. Different kinds of endothelial cells, in which ER multiply efficiently, could be grown in a scalable way in VueLife Teflon bags on Cytodex 3 microcarriers where bead-to-bead transfer of cells occurs. The digital holographic microscope designed at the Université Libre de Bruxelles allows detection of the most appropriate time to harvest intracellular microorganisms for vaccine production. [ABSTRACT FROM AUTHOR]

Ehrlichia canis is the etiologic agent of canine monocytic ehrlichiosis (CME) and is a useful model for zoonotic tick-borne pathogens, many of which infect dogs. The purpose of this study was to evaluate rifampin and doxycycline regimens for clearance of E. canis infections in addition to alleviation of CME. Beagles were infected with E. canis by intravenous inoculation with carrier blood and treated with either rifampin or doxycycline after the acute phase of CME. Improved hematological values demonstrated that both treatments effectively relieved signs of the disease. Peripheral blood from all dogs became PCR negative after antibiotic treatment, suggesting that these infections were eliminated and that rifampin is an effective alternative chemotherapeutic agent for treatment of CME. [ABSTRACT FROM AUTHOR]

The tick-borne Rickettsiale Ehrlichia ruminantium (E. ruminantium) is the causative agent of heartwater in Africa and the Caribbean. Heartwater, responsible for major losses on livestock in Africa represents also a threat for the American mainland. Three complete genomes corresponding to two different groups of differing phenotypes, Gardel and Welgevonden, have been recently described. One genome (Erga) represents the Gardel group from Guadeloupe Island and two genomes (Erwo and Erwe) belong to the Welgevonden group. Erwo, isolated in South Africa, is the parental strain of Erwe, which was maintained for 18 years in Guadeloupe under different culture conditions than Erwo. The three strains display genomes of differing sizes with 1,499,920 bp, 1,512,977 bp, and 1,516,355 bp for Erga, Erwe, and Erwo, respectively. Gene sequences and order are highly conserved between the three strains, although several gene truncations could be pinpointed, most of them occurring within three regions of accumulated differences (RAD). E. ruminantium displays a strong leading/lagging compositional bias inducing a strand-specific codon usage. Finally, a striking feature of E. ruminantium is the presence of long intergenic regions containing tandem repeats. These repeats are at the origin of an active process, specific to E. ruminantium, of genome expansion/contraction based on the addition or removal of tandem units. [ABSTRACT FROM AUTHOR]

Heartwater is a tick-borne infectious disease caused by the rickettsial organism Cowdria ruminantium, currently Ehrlichia ruminantium. It poses an imminent threat to the Western Hemisphere, where it could cause mortality in cattle and other ruminant livestock in excess of 70%. It has been reported in the Caribbean; and its vector, Amblyomma sparsum, has been found on imported African spurred tortoises ( Geochelone sulcata) and leopard tortoises ( Geochelone pardalis) in southern Florida in the United States, leading to an importation ban on these reptiles. Symptoms have not been previously reported in reptiles. Here, we report peracute and acute deaths in African vipers imported from Africa through Florida. Signs included vomiting mucoid fluid, diarrhea, emaciation, convulsions, and death. Postmortem showed few gross lesions. The most consistent peracute and acute lesions were the pulmonary lesions and pericarditis with considerable bloody fluid in the pericardial sac (hydropericardium). These lesions strongly resembled the lesions of heartwater and a coccobacillus of less than 1-micron diameter was isolated in viper cell culture. The outbreak was brought to a halt by tick control and treatment of all exposed snakes with tetracycline. This isolation, tetracycline sensitivity, clinical signs, preliminary results with polymerase chain reaction of pCS20 ORF, and the viper preference of the disease may indicate a Cowdria-related attenuated species that has adapted to infect reptiles or an emerging new form of this group of microbes. [ABSTRACT FROM AUTHOR]

In this study we have evaluated the in vitro activity of antibiotics against 13 new isolates of Coxiella burnetii using a real-time quantitative PCR assay. MICs against doxycycline ranged from 1 to 8 μg/mL, telithromycin from 0.5 to 2μg/mL , and all strains had MICs ≥ 8 μg/mL for erythromycin. We report that strains resistant to doxycycline exist either in humans or animals. [ABSTRACT FROM AUTHOR]

The article presents information on the PathoSystems Resource Integration Center (PATRIC) established at the Virginia Bioinformatics Institute. It states PATRIC, a bioinformatics research center, helps scientists to develop vaccines, diagnostics, and therapeutics, for several classes of bacteria and viruses, including Rickettsiaceae. It presents a review of the Rickettsiae literature that introduce PATRIC's plan for basic genome annotation, and an analysis of the host-pathogen interactions.

The article focuses on the implications for the government and medical community, to respond and manage a biological attack, with Rickettsial Species, especially Coxiella burnetii. It is stated that the pathogen, place and time of attack, and the method of transmission, would influence the outcome of an attack. It discusses, the importance of a prompt and multifactoral response, aspects of preparedness, and the affect of mass media on the public perception, in case of an attack.

While bacterial transformation has evolved since the early 20th century to allow for the genetic manipulation of a variety of microbial agents, rickettsial organisms have proved resistant to such advances until only recently. The Ehrlichia are small, gram-negative, obligately intracellular bacterial parasites, which belong to the family Anaplasmataceae and cause a variety of infections in human and animal hosts. E. chaffeensis is the causative agent of human monocytotropic ehrlichiosis and is transmitted by Amblyomma americanum, the Lone Star tick. In this work, we describe the first report of successful transformation of a closely related ehrlichial species, the murine monocytotropic species E. muris. Application of these techniques should allow for a wide variety of molecular studies to be performed that were previously impossible. This heralds the beginning of a new era in ehrlichial research. [ABSTRACT FROM AUTHOR]

To address the role of cellular immunity during ehrlichia infection, we have utilized a model of monocytic ehrlichiosis that results from infection of mice by Ixodes ovatus ehrlichia (IOE). Although ehrlichiosis in humans is largely a disease of immunocompromised individuals, the use of the IOE model has allowed us to identify factors required for host defense in normal mice. Using a low-dose infection C57BL/6 mouse model, we have demonstrated that host defense requires immune mechanisms involving CD4 T cell-mediated, TNF-α-, IL-12-, and IFN-γ-dependent, macrophage activation. We have also provided formal evidence that IFN-γ produced by CD4 Th1 cells is sufficient for protective immunity. Our recent studies have demonstrated, in addition, an essential role for IL-10, which is probably important in inhibiting immunopathological responses, and for inducible nitric oxide synthase. The latter observation establishes an important role for reactive nitrogen intermediates in bacterial elimination in vivo. In contrast, evaluation of mice carrying wild-type and mutant alleles of Nramp1 revealed at most a modest role for this gene in resistance to fatal IOE infection. Other studies in low-dose infected mice have indicated that the generation of immunological memory may be impaired during low-dose IOE infection, possibly due to bacterial immune subversion. These studies highlight the utility of the IOE mouse model in identifying important parameters of the immune response during ehrlichiosis. [ABSTRACT FROM AUTHOR]

Phylogenetic analysis of five rickettsial genes (17-kDa gene, gltA, ompB, ompA, and sca4) from two molecular isolates of Candidatus Rickettsia andeanae from two ticks (Amblyomma maculatum and Ixodes boliviensis) collected from two domestic horses living in two separate locations in northern Peru (Coletas and Naranjo) was conducted to more clearly characterize this recently reported novel spotted fever group (SFG) rickettsia. Following nested polymerase chain reaction (PCR) amplification of the17-kDa gene, gltA, ompB, ompA, and sca4, amplicons were purified, sequenced, and compared to those downloaded from GenBank. Phylogenetic analyses of the Candidatus Rickettsia andeanae sequences generated from17-kDa gene (483 bp), gltA (1185 bp), ompA (1598 bp), ompB (4839 bp), and sca4 (2634 bp) demonstrated that they aligned strongly with those of SFG rickettsiae. Moreover, the sequences of these five genes most closely aligned with the following rickettsiae: ompA: Rickettsia sp RpA4 (98.03%), R. sp DnS28 (97.90%), and R. rhipicephali and R. massiliae (97.11%); ompB: R. aeschlimannii (97.22%), R. rhipicephali (97.20%), and R. sp Bar 29 (97.10%); and sca4: R. massiliae (97.8%), R. rhipicephali, and R. slovaca (97.7%). These results from the additional phylogenetic analyses of Candidatus Rickettsia andeanae confirm its inclusion within, and distance and uniqueness from, other known SFG rickettsiae. [ABSTRACT FROM AUTHOR]

In this paper, we describe the identification of an iron-acquisition gene homologue, ferrous iron transporter (feoB) in C. burnetii. The results of a genomic screen for putative Fur-regulated genes and Fur boxes and the development of a two-plasmid system to analyze these Fur boxes will also be illustrated. [ABSTRACT FROM AUTHOR]

Coxiella burnetii has two phase variants: highly virulent phase I and avirulent phase II. To examine the differences between the two phase variants in interaction with host response to infection, we performed experimental infection in immunodeficient mice. Experimental C. burnetii phase I infection in SCID mice suggested that innate immunity cannot control replication of the bacteria and that acquired immunity is essential for mice to survive infection. In this study, we used SCID and SCIDbg mice to determine whether phase II bacterial infection can be controlled in vivo. [ABSTRACT FROM AUTHOR]

Over the last 20 years, advances in molecular techniques have greatly facilitated the identification of the members of the Rickettsiales, and numerous new species and diseases have been described. In this paper, we review taxonomic rules and appropriate approaches to valid naming of rickettsial species and the diseases they cause. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare different polymerase chain reaction (PCR) methods for the detection of Ehrlichia canis in blood samples and to relate these results to clinical findings and serology to E. canis using the indirect fluorescent antibody (IFA) test. Nine seropositive and nine seronegative dogs were included in this study. DNA was extracted once and used in one simple PCR and five nested PCR protocols previously described. In selected dogs (three seropositive and one seronegative) blood samples were aseptically collected in order to attempt the isolation of E. canis in the DH82 cell line. Results show that nested PCR protocols seem to be more sensitive than the simple PCR. Considering only nested PCR protocols, 33% of the IFA-positive samples were PCR positive using the five different protocols. The rest of the IFA-positive samples were PCR positive or negative depending on the protocol used. Clinical signs and laboratory findings compatible with canine monocytic ehrlichiosis (CME) were found in 67% of dogs positive by the IFA test. All samples positive by both techniques (IFA test and PCR) were from dogs suffering from clinical CME. IFA-negative samples were PCR negative, except 22% that were PCR positive when using only one of the nested PCR protocols. Isolation of the agent was exclusively achieved in the only case in which the IFA test and all the PCR protocols were also positive. [ABSTRACT FROM AUTHOR]

The article presents information on three medical cases of patients suffering from ehrlichia ruminantium. One of the cases is of a six year old child who died a week after hospital admission with complaints of severe headache and sleepiness. Another case is of a six year old patient who died a week after hospital admission.

The article presents information on a study that investigates the presence of rickettsia slovaca in dermacentor marginatus ticks attached to symptomatic and asymptomatic people. Researchers in the study examines the presence of spotted fever group rickettsia. According to the study, rickettsia strains are less pathogenic than rickettsia slovaca.