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An initial survey for Wolbachia (Rickettsiales: Rickettsiaceae) infections in selected California mosquitoes (Diptera: Culicidae).

Knowledge of biogeographic variation in Wolbachia infection rates and inferred susceptibility to infection among different mosquito taxa has fundamental implications for the design and successful application of Wolbachia-based vector-borne disease control strategies. Using a Wolbachia-specific polymerase chain reaction assay, we tested 14 North American mosquito species in five genera (Aedes, Anopheles, Culiseta, Culex, and Ochlerotatus) for Wolbachia infection. Wolbachia infections were only detected in members of the Culex pipiens (L.) species complex.

Animals↗

[Rickettsiaceae infections and fluoroquinolones].

Twenty nine patients with Rickettsiosis (Tick born fever, n: 22, Q fever, n: 7) has been treated with fluoroquinolones. These compounds was used alone n: 25 (Pefloxacin, n: 15; Ofloxacin, n: 10) or associated n: 4 (Pefloxacin + Rifampin). The general efficacy was excellent. Common Tick born fever and pulmonary forms of Q fever was fast cured. Severe Tick born fever (neurologic or polyvisceral forms, n: 5) and Q fever with long term hyperthermia, n: 4 cas always cured without complications but the time necessary to obtain apyrexia was often longer (6 cases).

Administration, Oral↗

Detection and characterization of Rickettsia tsutsugamushi (Rickettsiales: Rickettsiaceae) in infected Leptotrombidium (Leptotrombidium) fletcheri chiggers (Acari: Trombiculidae) with the polymerase chain reaction.

We developed a method for detecting and characterizing the DNA of Rickettsia tsutsugamushi in chiggers (larval trombiculid mites) by polymerase chain reaction (PCR). Three procedures for extracting DNA from frozen chiggers were compared by evaluating the yield of PCR amplicand obtained with nine oligonucleotide primer pairs derived from the rickettsial 22 kD, 47 kD, groESL, 56 kD, and 110 kD antigen genes. Although extracts and primer pairs differed in amplification efficiency, R. tsutsugamushi DNA was successfully detected in extracts of colonized infected Leptotrombidium (Leptotrombidium) fletcheri (Wormersley & Heaslip) chiggers and in uninfected chigger extracts seeded with known amounts of Karp-strain rickettsiae. The 22 kD gene restriction fragment length polymorphisms (RFLP) observed in PCR amplicands from five rickettsial isolates obtained from the infected chigger colony over a 26-yr period were identical to those of PCR amplicands derived directly from infected chiggers taken from the same colony. This suggests that stable transmission of R. tsutsugamushi occurs in mites (62 generations), and isolates encompass the full genetic heterogeneity found in the chigger. PCR/RFLP analysis is an important new tool for investigating the complex epidemiology of scrub typhus rickettsiae in their mite vectors.

Animals↗

Epidemiology of rickettsial diseases.

Rickettsial diseases have a diversity of epidemiologic characteristics reflective of the variety of ecologic situations in which the obligate intracellular bacteria are transmitted to humans. For the spotted fever group (SFG) rickettsiae, Rickettsia typhi, R. tsutsugamushi, Coxiella burnetii, and the human ehrlichial agent, humans are a dead-end host who plays no role in the maintenance of the organism in nature. All rickettsioses exist as zoonoses. Moreover, all rickettsiae are found in infected arthopods, which generally serve as the natural hosts and can transmit the infection to the next generation of ticks, mites, chiggers, or fleas. From our anthropocentric viewpoint, Q fever aerosol infection from parturient animals and Brill-Zinsser disease ignited epidemics of louse-borne epidemic typhus are exceptions. However, silent cycles of C. burnetii in ticks and R. prowazekii in the flying squirrel flea may have maintained these agents in transovarial or enzootic cycles for eons before humans and their domestic animals arrived on the scene. Thus, the epidemiology of rickettsial diseases must be recognized as an unfortunate aberration of the rickettsial economy. Several excellent reviews of rickettsial ecology contain a wealth of useful information.

Animals↗

Quinolones in the treatment of lower respiratory tract infections caused by intracellular pathogens.

Intracellular pathogens are inhibited to varying degrees, depending upon the strain of the organism and the quinolone tested. Quinolones achieve levels in the lower respiratory tract that equal or exceed serum concentrations, and they also achieve good intracellular concentrations. Experimental models of intracellular infection have demonstrated the efficacy of ciprofloxacin, difloxacin, fleroxacin, ofloxacin and pefloxacin. Animal models of experimental legionellosis have confirmed in vivo their efficacy in this field. Thus, quinolones appear to be a safe and efficacious alternative treatment in lower respiratory tract infection (LRTI) due to intracellular pathogens. Considering the in vitro and experimental studies, quinolones should play an important role in the treatment of LRTI caused by intracellular pathogens, and prospective controlled studies are strongly recommended.

4-Quinolones↗

Rickettsial skin disease: uncommon presentations.

Rickettsioses occurring worldwide show a significant morbidity and mortality when not properly treated. Early diagnosis is mandatory for better outcome. Clinical symptoms and patient's history are essential, but uncommon presentation of these arthropod-borne diseases may be a challenge.

Anti-Bacterial Agents↗

Rickettsia sennetsu in human blood monocyte cultures: similarities to the growth cycle of Ehrlichia canis.

Microscopic examination of cultured human monocytes infected with Rickettsia sennetsu and stained by the Giemsa method revealed the presence of various organismal growth forms in the cytoplasm of the infected cells. The growth forms were loosely scattered individual organisms, clusters of organisms, various sizes of dense inclusion bodies in intact and vacuolated cytoplasm, and organisms in close proximity to disintegrated monocytes. The appearance and the morphology of these R. sennetsu growth forms were similar to those of Ehrlichia canis propagated in canine monocytes. Specific identification of R. sennetsu was made by staining cultured monocytes with fluorescein-conjugated globulins extracted from the pooled sera of patients recovering from sennetsu rickettsiosis. Mice infected with cultured R. sennetsu developed gross pathological changes indicative of infection, and the organism was demonstrated in their spleens, peritoneal macrophages, and mononuclear blood cells. Human monocyte culture appeared to be more sensitive than the previously used African green monkey kidney cell line (BSC-1) for the isolation of R. sennetsu from samples containing minute infectious quantities of this organism.

Animals↗

Rickettsioses in Japan and the far East.

Three rickettsial diseases are known to exist in Japan currently: Japanese spotted fever (JSF), Tsutsugamushi disease (TD; scrub typhus), and Q fever. Since April 1999, the system for infection control and prevention in Japan has changed drastically. JSF, Q fever, and TD, as emerging infectious diseases, are designated as national notifiable diseases.The geographic distribution of JSF patients is along the coast of central and southwestern Japan, whereas TD and Q fever occur almost all over the country. The number of JSF patients reported was 216 cases during 1984-1998 and 268 cases, under the revised law, in 1999-2004. About 300-1000 cases of TD occur every year, and 7-46 cases of Q fever in 1999-2004. The number of cases of JSF and its endemic area are gradually increasing. There was only one fatality due to JSF until 2003, whereas two patients died of JSF in 2004, so JSF is still a life-threatening disease in Japan. Treatment of fulminant JSF consists of prompt administration of a combination of tetracycline and quinolone. Recent tick surveys revealed that the most probable vectors of JSF are Haemophysalis flava and Haemophysalis hystericis. In addition to R. japonica, two serotypes or species of spotted fever group rickettsiae have been isolated from ticks in Japan; one is closely related to R. helvetica and the other is a new genotype of unknown genotype AT, which is closely related to a Slovakian genotype. These serotypes are of uncertain clinical significance. Epidemiology of rickettsioses in the Far East is mentioned briefly.

Anti-Bacterial Agents↗

Rickettsioses in Australia.

Australia, an island continent in the southern hemisphere, has a range of rickettsial diseases that include typhus group rickettsiae (Rickettsia typhi), spotted fever group rickettsiae (R. australis, R. honei), scrub typhus group rickettsiae (R. tsutsugamushi), and Q fever (C. burnetii). Our knowledge of Australian rickettsiae is expanding with the recognition of an expanded range of R. honei (Flinders Island spotted fever) to Tasmania and southeastern mainland Australia (not just on Flinders Island), and the detection of a new SFG species (or subspecies), tentatively named "R. marmionii" in the eastern half of Australia. This rickettsia causes both acute disease (7 cases, recognized so far) and is also associated (as a "R. marmionii" bacteriaemia) with patients having a chronic illness. The significance of the latter is under investigation. It may be a marker of autoimmune disease or chronic fatigue in some patients.

Animals↗