Detection of Rickettsia tsutsugamushi specific DNA from the lymphocyte of patients by polymerase chain reaction

Polymerase chain reaction was used to detect Rickettsia tsutsugamushi specific DNA from the lymphocytes of patients in the acute phase of the disease. The primers used in the PCR were based on the nucleotide sequences of gene encoding of the 56 kDa antigen of the Gilliam strain. The PCR product is a 78 bp fragment which can be hybridized by the 78 bp DNA probe of the Gilliam strain. Comparison of the results obtained by polymerase chain reaction, immunofluorescent assay and cell culture suggests that the polymerase chain reaction method is the most sensitive one among the three in diagnosis of scrub typhus.

[A case of severe tsutsugamushi disease without eruption]

A 64-year-old male was admitted to our division because of fever. After admission, the patient was given beta-lactam antibiotics intravenously because he had no eruption and eschar. However, the fever continued, and he became unconsciousness and DIC appeared. We diagnosed the patient as Tsutsugamushi disease from indirect fluorescent antibody technique. Minocycline was excellently effective. Several reports of Tsutsugamushi disease without eruption have been given, so we must always be careful of Tsutsugamushi disease.

[Five cases of tsutsugamushi disease]

We experienced 5 cases of tsutusgamushi disease from October to November 1993 at Hokusyo Central Hospital. All patients showed high fever, skin rash and eschar and four patients showed lymph node swelling. All cases were diagnosed serologically by indirect-immunofluorescence technique and treated with minocycline. In a survey of anti-Karp, Kato, Gilliam, Kawasaki, Kuroki antibodies, all patients showed the highest antibody titers against the Kawasaki strain and they were considered Kawasaki type. In Nagasaki Prefecture, the number of patients with tsutsugamushi disease has been increasing since 1982. We carried out immunologic and epidemiologic studies about this disease in Nagasaki Prefecture.

Detection of Rickettsia tsutsugamushi in Experimentally infected mice by PCR

We developed a rapid procedure for the detection of Rickettsia tsutsugamushi DNA by the PCR technique. The primer pair used for the PCR was designed from the DNA sequence of the gene encoding a 120-kDa antigen, which was proven to be group specific by immunoblot analysis with mouse hyperimmune sera against various rickettsial strains. This PCR method was able to detect up to 10 ag of plasmid DNA (pKT12). Specific PCR products were obtained with DNAs from R. tsutsugamushi Kato, Karp, Gilliam, TA716, TA1817, and Boryong, but not with DNAs from other rickettsiae, such as R. prowazekii, R. typhi, R. akari, and strain TT118. In a study with experimentally infected mice, the PCR method could detect rickettsial DNA from 2 days after inoculation (DAI), whereas serum antibody against R. tsutsugamushi could be detected from 6 to 8 DAI by an immunofluorescence test. Although clinical manifestations subsided after 14 DAI, rickettsial DNA in blood samples could be detected by PCR for up to 64 DAI. These results suggest that this PCR method can be applied to the early diagnosis of scrub typhus and can also be used to detect the residual rickettsiae after clinical symptoms subside.

Life-threatening scrub typhus in a traveler returning from Thailand

Scrub typhus is not one of the more commonly encountered diseases in travelers returning from Asia, but it deserves more consideration in view of its severity and the availability of specific chemotherapy and chemoprophylaxis. We describe a case of scrub typhus that was associated with coma and multiorgan failure in a traveler returning to the United States from Thailand. The diagnosis was made only retrospectively despite a travel history and clinical signs that suggested infection with Rickettsia tsutsugamushi. No specific therapy was given, and marked neurological impairment persisted 6 months after the beginning of the illness. An increased awareness of scrub typhus is a prerequisite for recommending prophylaxis and instituting prompt therapy.

Diagnostic tests for Rocky Mountain spotted fever and other rickettsial diseases

Rickettsial diseases continue to confound physicians because of their usually sporadic occurrence and nonspecific clinical presentation. In past years, diagnosis was confirmed only during convalescence; however, newer, more widely available methods, such as antigen detection and improved in vitro cultivation, have enabled a diagnosis at a time when therapeutic decisions are made. Molecular nucleic acid-based techniques have also expanded the spectrum of etiologic agents and illnesses caused by rickettsiae.

A polymerase chain reaction system for rapid diagnosis of scrub typhus within six hours

A rapid diagnostic system for scrub typhus (tsutsugamushi disease) was established using the polymerase chain reaction (PCR) combined with microplate hybridization. With this system, diagnosis can be made within six hours without the need for radioisotopes, electrophoresis, or membrane hybridization. The use of a PCR processor and DNA-precoated enzyme-linked immunosorbent assay plates allows a rapid and precise diagnosis to be easily made even in primary medical care clinics.

Two-step polymerase chain reaction for diagnosis of scrub typhus and identification of antigenic variants of Rickettsia tsutsugamushi

Two-step polymerase chain reaction (nested PCR) method was examined for the diagnosis of scrub typhus. Primers were derived from the type-specific antigen (TSA) gene DNA sequences of Rickettsia tsutsugamushi, Gilliam strain. These primers served to produce rickettsia-specific products in the amplification of template DNA prepared from all serovariants, Gilliam, Karp, Kato, Kawasaki, Kuroki and Shimokoshi strains, and the fragments of product after digestion with several kinds of restriction endonuclease showed the respective patterns to strain in acrylamide or agarose gel electrophoresis. The rickettsia-specific DNAs were also derived, by this nested PCR, by amplifying DNA from patients' bloods and mites from endemic areas, and the serotype of rickettsiae infected to these hosts could be identified from fragment patterns of the amplified products observed after endonuclease treatment. These results indicate that this PCR is sensitive and specific method not only for detection of rickettsial DNA in patient specimens and in mites, but also for the typing of rickettsiae infected to these hosts.

Rapid diagnosis of scrub typhus by a passive hemagglutination assay using recombinant 56-kilodalton polypeptides

The genes encoding the 56-kDa polypeptides were amplified by polymerase chain reaction from the genomic DNAs of three serotypes of Rickettsia tsutsugamushi, Gilliam, Karp, and Boryong. The amplified products were cloned into expression vector pIH821, and the recombinant antigens were expressed in Escherichia coli as fusion proteins with maltose-binding protein. The recombinant 56-kDa polypeptides were purified by affinity chromatography for the sensitization of sheep erythrocytes. The recombinant 56-kDa polypeptides were evaluated with 89 serum specimens from health blood donors, 94 serum specimens from scrub typhus patients, and 31 serum specimens from patients with other febrile diseases by a passive hemagglutination assay (PHA). Among the scrub typhus patients diagnosed by indirect immunofluorescent-antibody testing, the antibodies to R. tsutsugamushi were detected in 93 patients (99%). One serum specimen from a healthy person showed a false-positive reaction by this method. The recombinant PHA showed no cross-reactions with sera obtained from other febrile patients with diseases such as murine typhus, hemorrhagic fever with renal syndrome, and leptospirosis. In conclusion, this recombinant PHA could be substituted for the conventional indirect immunofluorescent-antibody test and the immunoperoxidase test.

Serotype-specific amplification of Rickettsia tsutsugamushi DNA by nested polymerase chain reaction

Polymerase chain reaction (PCR) with nested primer pairs was used to diagnose scrub typhus and identify the Rickettsia tsutsugamushi serotype. The primer pairs used for PCR were designed on the basis of the nucleotide sequence of the gene that encodes the 56-kDa antigen. Serotype-specific primers were used in the second PCR amplification. Five serovariants, the Gilliam, Karp, Kato, Kawasaki, and Kuroki strains of R. tsutsugamushi, were identified by nested PCR. In addition, the serotype identified by PCR with DNA from blood clots was the same as that of the strain isolated from five patients with scrub typhus. These findings indicate that this method is useful for diagnosis and identification of the rickettsial serotype in infected patients.

Scrub typhus in Korea: importance of early clinical diagnosis in this newly recognized endemic area

Scrub typhus became a well recognized infectious disease threat to military operations in the Pacific Theater during World War II. Early diagnosis and treatment with tetracycline or chloramphenicol dramatically reduces the mortality and morbidity of this disease. Korea is a newly recognized scrub typhus endemic country. We report our experience with 189 scrub typhus patients seen at a civilian outpatient clinic in Chinhae, Republic of Korea, from 1985 through 1990, and verify the accuracy of clinical diagnosis by serologic tests.

High-level expression of a 56-kilodalton protein gene (bor56) of Rickettsia tsutsugamushi Boryong and its application to enzyme-linked immunosorbent assays

The 56-kDa protein of Rickettsia tsutsugamushi, which is located on the rickettsial surface, has been shown to be an immunodominant antigen. The gene that encodes the 56-kDa protein of R. tsutsugamushi Boryong (bor56) was cloned. Sequencing revealed an open reading frame of 1,602 bp encoding 534 amino acids with a molecular weight of 56,803. The 56-kDa protein of R. tsutsugamushi Boryong (Bor56) was expressed as a fusion protein with the maltose-binding protein of Escherichia coli by deleting 252 bp from the 5' end of the open reading frame and subcloning it into the StuI site of pIH821. The recombinant fusion protein was purified by amylose column chromatography for application in an enzyme-linked immunosorbent assay to evaluate the ability of the method to detect the antibody to R. tsutsugamushi in human patient sera. By using sera from 100 patients with scrub typhus and 70 patients with other febrile diseases, a high diagnostic sensitivity (95%) and a high diagnostic specificity (100%) were demonstrated, suggesting the suitability of the recombinant antigen for use as an immunodiagnostic tool.

Diagnosis of typhus infection with Rickettsia tsutsugamushi by polymerase chain reaction

Two sets of oligonucleotide primers were used to amplify the genomic DNA of Rickettsia tsutsugamushi, the causative agent of scrub typhus (tsutsugamushi disease), by the polymerase chain reaction. Each set of primers amplified 538-bp and 109-bp products, representing part of a gene encoding a possible major 58-kDa immunogenic protein, from whole genomic DNA extracted from R. tsutsugamushi strains Karp, Kato, Gilliam, Kuroki and Kawasaki. No amplification was observed from R. sibirica, R. rickettsii, mouse and human genomic DNA. DNA amplification was observed from crude lysates of peripheral whole blood, tissue homogenates and paraffin-embedded skin biopsy sections obtained from patients with scrub typhus disease. Southern blot analysis demonstrated the specificity of the amplified DNA fragments following hybridisation with a DNA probe generated from R. tsutsugamushi strain Karp. By means of this procedure, a rapid and sensitive diagnosis of scrub typhus disease can be made during the acute stage of this infection.

Sensitivity of polymerase chain reaction assay for Rickettsia tsutsugamushi in patients' blood samples

We developed a nested polymerase chain reaction (PCR) method to detect Rickettsia tsutsugamushi (R. tsutsugamushi) DNA and determined its sensitivity. Primers were selected from the DNA sequence of the 58-kDa group-specific antigen gene of the Karp strain. The target sequence of rickettsial DNA was detectable as the band corresponding to 88 bp in 1.0 microgram of the DNA extracted from BS-C-1 cells infected with R. tsutsugamushi. Rickettsia-specific bands were observed not only for the homologous Karp strain, but also for four heterologous strains: two other reference strains (Gilliam and Kato) and two prototype strains prevalent in Miyazaki district (Irie and Hirano). The minimum copy number detectable by this method was estimated to be five rickettsiae. All of nine peripheral blood mononuclear cell samples from patients with tsutsugamushi disease who were seen 2-11 days after disease onset tested positive for rickettsial DNA. The PCR assay method presented here could be a specific diagnostic tool for tsutsugamushi disease, especially in its early acute stage.

Tsutsugamushi disease in the central part of Japan

Two cases of tsutsugamushi disease misdiagnosed initially as drug eruption were reported. Clinical symptoms of both cases disappeared dramatically after starting minocycline. Statistical examinations were performed on 29 cases of tsutsugamushi disease, including those observed in Mie Prefecture since 1982. Half of them were seen in the last 2 years. The onset was predominantly recorded in November (59%). Presumptive sites of infection were forests (63%) and fields (21%). No patients were infected along river-banks.

Gelatin particle agglutination test for early serodiagnosis of Japanese spotted fever

A gelatin particle agglutination (PA) test for Japanese spotted fever has been developed. Gelatin particles were sensitized with a sonicated causative rickettsia and used as antigens. The antibodies by PA test were detected as early as days 4-7 after the onset, whereas those by indirect immunoperoxidase (IP) test were detected after days 8-11. In addition, PA titers were higher than IP titers before days 20-23. The agglutinins detected by PA test were proven to be IgM because they were all sensitive to dithiothreitol. PA test was, however, less specific than IP test, giving a little nonspecific reaction to the sera from patients with scrub typhus and from individuals unrelated to those two rickettsioses. Nevertheless, PA test, which is simple, rapid, and easy to interpret the results, is useful for the early serodiagnosis of Japanese spotted fever.

[A case of new type scrub typhus (tsutsugamushi disease) presenting with acute respiratory failure and hemophagocytic syndrome]

A 47-year-old male was referred to our hospital with persistent high fever. He had received antibiotics (ASPC) for the diagnosis of acute infectious disease, which failed to respond, and subsequently developed marked lymphocytopenia and thrombocytopenia. During his hospitalization, hypoxic respiratory failure rapidly developed. A bone marrow aspiration revealed marked hemophagocytosis, leading to the tentative diagnosis of opportunistic respiratory infection associated with malignant histiocytosis. Treatment for suspected malignancy and Pneumocystis carinii pneumonia was commenced. However, because of the initial lack of response to ASPC, generalized skin rashes without an ordinary stick wound which had diminished before the hospitalization, and a history of working outdoors in a nearby mountain area, the possibility of new type tsutsugamushi disease was strongly suggested. Intravenous administration of minocycline promptly improved his symptoms and laboratory data. The diagnosis was confirmed by a significant increase in the titer of antibody to Rickettsia tsutsugamushi. The thrombocytopenia was considered to have been caused by co-existent hemophagocytic syndrome.

A ten years experience on diagnosis of rickettsial diseases using the indirect immunoperoxidase methods

An accurate diagnosis of Tsutsugamushi disease (TD) can be made within a few hours after receiving serum specimens by detecting the specific IgG and IgM antibodies in the patient's serum. Using the indirect immunoperoxidase test we found a total of 730 cases of TD in 32 out of 47 prefectures when serum samples from 2,224 cases of suspected disease or fever of unknown origin or from patients with febrile exanthema of unknown cause were examined during a 10 years period (from May 1980 till December 1989). In addition, 27 cases of spotted fever group rickettsial infection were confirmed and one case of African spotted fever group infection was also detected in 1988. Furthermore, possibly the first case of TD was found in People's Republic of Congo (Africa) in 1989.

Specific amplification of Rickettsia tsutsugamushi DNA from clinical specimens by polymerase chain reaction

Polymerase chain reaction (PCR) was used to detect Rickettsia tsutsugamushi-specific DNA in clinical specimens. The primer pair used for PCR was designed from the nucleotide sequence of the gene encoding the 56-kDa antigen of the Gilliam strain. Theses primers led to a 78-bp fragment by amplifying the genomic DNAs from five serovariants, i.e., the Gilliam, Karp, Kato, Kawasaki, and Kuroki strains of R. tsutsugamushi, and also the DNA from blood clots of patients with scrub typhus, even at the early stage of onset of the disease. This indicates that this method is suitable for the diagnosis of scrub typhus.

Murine and scrub typhus at Thai-Kampuchean border displaced persons camps

Rickettsial infections are considered a major cause of illness among inmates of Thai-Kampuchean border displaced persons camps. In the absence of sophisticated laboratory support, it had become common practice to treat patients with obscure fevers with tetracycline as a 'diagnostic' test for typhus. This study evaluated a group of 67 randomly selected camp inmates who presented with fever and had findings that indicated a specific diagnosis. Differential blood counts, malaria smears, hemoglobin determinations, blood cultures, dengue and Japanese encephalitis virus and rickettsial IgM and IgG antibody titers were determined. Patients were then treated with tetracycline and followed. They could be divided into six groups after data were analyzed. Those with no final diagnosis comprised 14 cases (21%), 4 patients (6%) were found to have dengue fever, 6 (9%) scrub typhus and 39 (58%) had murine (endemic) typhus. None of the bacterial blood cultures drawn from this group grew any organisms and no tick typhus or Japanese encephalitis was diagnosed. Analysis of symptoms and signs did not allow clinical differentiation between groups. All patients became afebrile and well within 1-5 days of starting tetracycline therapy. We conclude that rickettsial disease is a major health problem in the Thai-Kampuchean border camps. The incidence of murine typhus increased during the dry season and was more prevalent among males. The use of tetracycline as a 'therapeutic test' did not distinguish between rickettsial, viral and undiagnosed febrile diseases.

Rickettsial meningitis and encephalitis

Nine of 72 patients with scrub typhus and three of 137 with murine typhus presented with meningitis and/or encephalitis syndromes. Focal neurologic signs were rare, and cerebrospinal fluid profiles were similar to those of leptospirosis and viral and tuberculous meningitis. One patient had papilledema, and another had cerebellitis. Other major organ involvement (renal, liver, or lungs) occurred in five patients. One patient died and four spontaneously recovered, while the conditions of the rest responded well to either chloramphenicol or doxycycline. Scrub and murine typhus should be included in the differential diagnoses of aseptic meningitis and encephalitis in patients exposed to endemic areas, especially when accompanied by renal insufficiency and/or jaundice. They are treatable forms of virallike meningoencephalitis.

[Polymerase chain reaction for the diagnosis of tsutsugamushi disease]

A polymerase chain reaction (PCR) using specific oligonucleotide primers and Taq polymerase was developed for the detection of Rickettsia tsutsugamushi, the causative agent of tsutsugamushi disease. Oligonucleotide primers were synthesized on the basis of DNA sequences encoding 58 kD antigen of R. tsutsugamushi. Specific DNA amplification of 358 bp and 109 bp DNA fragments were demonstrated using patient's blood. This PCR method would enable to make a rapid and sensitive diagnosis of tsutsugamushi disease.