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At least 1,171 records · Page 65Linked to original sources
PubMed2006

Characterization of Dermacentor variabilis molecules associated with Rickettsial infection.

To ultimately define the virulence factors of rickettsiae, an understanding of the biology of the organism is essential. Comprehension of the pathogen-human interaction is critical to the development of control measures; and, in the case of vector-borne diseases, the role of the vector in maintaining and transmitting pathogens to vertebrate hosts is crucial to ultimate control. Recent studies have identified tick molecules that are likely involved in the tick-rickettsiae interchange, including tick response to infection and possible molecules exploited by rickettsiae during transmission events. We have further characterized several tick-derived molecules, including a histamine release factor, serine proteases, and lysozymes.

Animals↗
PubMed1996

Epidemiological features of Coxiella burnetii infection in England and Wales: 1984 to 1994.

Q fever is an important zoonosis caused by the rickettsial organism Coxiella burnetii, which can result in life threatening illness, especially in those with an underlying cardiac defect. C. burnetii infections in England and Wales reported to the PHLS Communicable Disease Surveillance Centre between 1984 and 1994 were reviewed. A total of 1117 cases were reported, a third of which came from the South Western region. The annual totals fell over this period. The mean age of cases was 45 years, and 74% were men. Reports peaked in the month of May. Contact with animals, mainly cattle and sheep, was reported in 60 cases. Occupationally acquired infection was reported for 24 cases including abattoir workers, farmers, veterinary surgeons, hide handlers, and butchers. Forty-seven per cent of cases presented with respiratory symptoms, 7% with heart disease, and 5% with hepatitis. Seven per cent of cases reported travel abroad before becoming ill. Joint veterinary and medical investigations should be undertaken to establish the natural history of C. burnetii infection in England and Wales and formulate policies to prevent acute and chronic infections.

Adult↗
PubMedDate not supplied

Legionnaires' disease pneumonia: histopathologic features and comparison with microbial and chemical pneumonias.

The histopathologic findings in lung tissue are reported from five cases of Philadelphia Legionnaire's Disease and the results are compared to pneumonias caused by other microbial and chemical agents. Histopathology of lung tissue was similar in all cases, despite the fact that death occurred between the fourth and 14th day of clinical illness. The inflammatory response was almost totally limited to the lower respiratory tract and primarily involved respiratory bronchioles, alveolar ducts and alveoli. Major bronchial branches and pulmonary interstices showed little or no involvement. There was considerable variation in the extent and nature of the consolidation, but the overall reaction pattern was highly characteristic of diffuse alveolar damage. Most involved areas showed intra-alveolar, fibrinocellular mononuclear cell predominant exudates, associated with pneumonocytic hyperplasia and slough. These findings plus the presence of erythroleucophagocytosis by macrophages and paucity of polymorphonuclear leucocytes are commonly associated with psittacine pneumonia, and much less so with classic patterns of bacterial, viral, fungal or rickettsial pneumonias. Of the toxic inhalants, nickel carbonyl, phosgene, nitrous oxide, cadmium oxide and some halogenated hydrocarbons have been associated with this tissue reaction pattern. Bacteria were notably absent in lung tissue stained by methods used to demonstrate the Legionnaires' Disease agent.

Adult↗
PubMed2003

Expression analysis of the T-cell-targeting chemokines CXCL9 and CXCL10 in mice and humans with endothelial infections caused by rickettsiae of the spotted fever group.

Rocky Mountain spotted fever and other related diseases are systemic infections caused by rickettsiae. These obligatory intracellular bacteria target the endothelium, offering an appealing model to study the interactions between endothelial cells and T lymphocytes. We investigated the mRNA expression of chemokines known to target CD8+ T cells and CD4(+) T-helper 1 cells in the lungs of C3H/HeN mice infected with Rickettsia conorii with the purpose of identifying evidence for a role of chemokines in the immune clearance of rickettsiae from the vasculature. The expression of the CXCR3 ligands CXCL9 and CXCL10 was significantly higher than the other chemokines investigated. We validated the relevance of these results in the animal model through the analysis of tissues from humans with Rocky Mountain spotted fever. We then characterized the kinetics and localization of expression of CXCL9 and CXCL10 in lungs, brain, and liver of mice infected with lethal or sublethal doses of R. conorii by a combination of quantitative real-time polymerase chain reaction and immunohistochemistry. Interestingly, the peak of expression of these chemokines occurred 4 days before CD8+ T cells infiltrated the infected tissues. Our results suggest that CXCL9 and CXCL10 may play a role early during the immune response against rickettsial infections.

Animals↗
PubMed1991

Immunoblot studies to analyze antibody to the Rickettsia typhi group antigen in sera from patients with acute febrile cerebrovasculitis.

In 1986, an unusual syndrome of acute febrile cerebrovasculitis in the Piedmont Region of Virginia was reported. All patients had encephalopathy and prior exposure to both a sylvan environment and flea-infested animals. The initial serological studies suggested a rickettsial origin, corroborating clinical, epidemiological, and histopathological findings. Sera from four of five patients were subsequently studied by immunoblotting. Unabsorbed and absorbed sera were tested with electrophoresed and electroblotted Rickettsia typhi, Legionella bozemanii, and Proteus vulgaris OX19 antigens. The unabsorbed sera reacted with all three antigens. The P. vulgaris- and L. bozemanii-absorbed sera reacted with R. typhi only and without significantly less intensity. In contrast, the reactivity of R. typhi-absorbed sera was significantly lower with all three antigens. These results indicate that these patients had specific antibodies to a typhus group antigen. Although our findings suggest that a rickettsia of the typhus group may have caused this syndrome, no definitive diagnosis could be achieved because a rickettsial organism was not isolated.

Acute Disease↗
PubMed1992

Genetic characterization and transovarial transmission of a typhus-like rickettsia found in cat fleas.

The identification of apparently fastidious microorganisms is often problematic. DNA from a rickettsia-like agent (called the ELB agent) present in cat fleas could be amplified by PCR with conserved primers derived from rickettsial 17-kDa common protein antigen and citrate synthase genes but not spotted fever group 190-kDa antigen gene. Alu I sites in both the 17-kDa and citrate synthase PCR products obtained with the rickettsia-like agent and Rickettsia typhi were different even though both agents reacted with monoclonal antibodies previously thought specific for R. typhi. The DNA sequence of a portion of the 17-kDa PCR product of the rickettsia-like agent differed significantly from all known rickettsial sequences and resembled the 17-kDa sequences of typhus more than spotted fever group rickettsiae. The rare stable transovarial maintenance of this rickettsia in cat fleas has important implications for the disease potential of cat fleas.

Animals↗
PubMed1975

Q fever (Coxiella burnetii) investigations in dairy cattle: persistence of antibodies after vaccination.

The immune response and persistence of antibodies were investigated in dairy cattle vaccinated with formalin-inactivated phase (ph) I Coxiella burnetii vaccine agglutinating antibody geometric mean titer (GMT) of 193.2 at 1 month after vaccination compared to a GMT of 2.0 for nonvaccinated calves. The agglutinating antibodies gradually decreased in vaccinated cattle, but the GMT remained approximately 4 times higher than that for the nonvaccinated group for at least 20 months. Results of serotests at 2 months after revaccination indicated a rapid increase in the GMT to 177.0 with agglutinating titers between 1:64 and 1:512.

Agglutination Tests↗
PubMed2002

Antibiotics for the treatment of onchocerciasis and other filarial infections.

More effective drugs are needed for the treatment of human filarial diseases and the elimination of these infections as a public health problem. The drugs must either kill or sterilize adult worms. The relevant filariae, Onchocerca volvulus, Wuchereria bancofti and Brugia species, harbor rickettsial endoboacteria of the genus Wolbachia as symbionts. Animal experiments have shown that the elimination of these endobacteria causes inhibition of embryogenesis, and with Onchocerca ochengi a macrofilaricidal effect. Trials with human onchocerciasis patients using doxycydine demonstrated a long-term sterilizing activity, opening up a new strategy for the control of filarial infections. Indications of antiwolbachial therapy against onchocerciasis are discussed.

Animals↗
PubMedDate not supplied

Bacillary angiomatosis: microbiology, histopathology, clinical presentation, diagnosis and management.

Bacillary angiomatosis is known to be caused by a rickettsial organism; Rochalimaea henselae. This causative agent has been compared with different microorganisms and clinical conditions that appear in similar settings buy have been clearly differentiated from them; e.i. Cat-scratch disease (Afipia felis), Bartonella bacilliformis, other Rochalimaea sp., Kaposi's sarcoma, Lobular capillary hemangioma, Angiosarcoma, and Epithelioid hemangioma. Clinically the bacillary angiomatosis (BA) skin lesions vary from a single lesion to thousands. The cutaneous lesion appears as a bright-red round papule, subcutaneous nodule, or as a cellulitic plaque. When the lesion is biopsied it tends to blanch-out, bleed, and cause pain. The patient might present with signs and symptoms of chills, headaches, fever, malaise, and anorexia with or without weight loss. The extracutaneous lesions found in BA tend to be from multiple organs affecting from the oral lesions to anal mucosal lesions to widespread visceral lesions. The sites of preference for BA lesion manifestation tend to be the liver, spleen, lymph nodes, and bone. To diagnose bacillary angiomatosis the physician should prepare a differential diagnosis based primarily on its histopathological and clinical characteristics. To confirm the results from the stain, electron microscopy can identify the bacillus and pin-point the diagnosis of bacillary angiomatosis. The lesions presented by BA respond well to therapy with erythromycin 500 mg four times daily for a duration of 2 weeks to 2 months. In case of intolerance to erythromycin the second line of drug that successfully treats the BA bacillus is doxycyline. If relapses of the BA lesion recur, then a prolonged antibiotic therapy is necessary and in AIDS patients the duration may be extended as life-long suppressive therapy.

Angiomatosis, Bacillary↗
PubMed2006

Molecular characterization of Rickettsia rickettsii infecting dogs and people in North Carolina.

Rocky Mountain spotted fever (RMST) is an important cause of morbidity and mortality in people and dogs in the United States. Disease manifestations are strikingly similar in both species, and illness in dogs can precede illness in people. R. rickettsii has been identified as a Select Agent by the CDC as a Category C priority pathogen by the National Institute of Allergic and Infectious Diseases because it is amenable to use as a bioterror agent. The clinical and temporal relationship of naturally occurring diseases in dogs and people suggests that dogs could serve as sentinels for natural infection and bioterrorist attacks using this organism. Recognizing genetic modifications in naturally occurring disease agents in order to distinguish them from intentionally released agents are priorities put forth by the NIAID. To determine whether the rickettsiae naturally infecting dogs is the same as those that infect persons in a given geographical region, we characterized rickettsial isolates obtained from three dogs and two persons diagnosed with RMSF in North Carolina. Portions of three genes (ompA, rrs, and gltA) amplified by PCR were cloned and sequenced or directly sequenced. Reactions were run in duplicate in forward and reverse directions. Gene sequences were aligned with known sequences deposited in GenBank and with each other. Sequences of the 5' region of the ompA gene were 100% homologous with a tick strain (Bitterroot) of R. rickettsii for all five isolates. Sequences of the rrs gene were 99.8 99.9% homologous with a tick strain (Sawtooth) of R. rickettsii. rrs gene sequences from one dog and the two persons was identical. Sequences of one dog isolate differed from these by one base pair. Sequences from another dog isolate differed by two base pairs. Sequences of the gltA gene are pending. This confirms on a molecular level that R. rickettsii causing naturally occurring RMSF in dogs in North Carolina is highly homologous to R. rickettsii that causes the disease in people in the same region. Sequence data will be deposited in GenBank, thereby providing genetic information regarding naturally occurring R. rickettsii.

Animals↗
PubMed2001

Ticks (Acari: Ixodidae) associated with domestic dogs in Franca region, São Paulo, Brazil.

Ticks on 140 domestic dogs from both urban and rural areas of Franca region in São Paulo state were identified with 102 dogs from urban areas and 38 from rural areas. Of urban dogs, 27.5% were infested exclusively by Rhipicephalus sanguineus ticks. Of the rural dogs, 36.8% were infested with the following tick species: R. sanguineus, Boophilus microplus, Amblyomma ovale and A. cajennense. Mixed infestations included a dog hosting A. cajennense and A. ovale and another with B. microplus and R. sanguineus. The most intense infestations were detected on urban dogs. Hemolymph tests of these ticks performed to detect rickettsial or Borrelia bacteria yielded negative results.

Animals↗
PubMed2004

Acute tick-borne rickettsiosis caused by Rickettsia heilongjiangensis in Russian Far East.

An acute tick-borne rickettsiosis caused by Rickettsia heilongjiangensis was diagnosed in 13 patients from the Russian Far East in 2002. We amplified and sequenced four portions of three rickettsial genes from the patients' skin biopsy results and blood samples and showed that the amplified rickettsial genes belong to R. heilongjiangensis, which was recently isolated from Dermacentor sylvarum ticks in nearby regions of China. This rickettsia, belonging to subgroup of R. japonica, was previously suggested to be pathogenic for humans on the basis of serologic findings. We tested serum samples with different rickettsial antigens from 11 patients and confirmed increasing titers of immunoglobulin (Ig) G and IgM to spotted fever group rickettsiae, including R. heilongjiangensis. Clinical and epidemiologic data on these patients show that this disease is similar to other tick-borne rickettsioses.

Acute Disease↗