[A case of Tsutsugamushi disease as an imported infection]

Tsutsugamushi disease is widely spread throughout Japan. A case of tsutsugamushi disease was seen in October, 1996. A 64-year-old male developed typical symptoms of tsutsugamushi disease with Rickettsia tsutsugamushi, after he returned to Japan from Cheju Island, Korea. Not only in Japan but also in other Asian countries including Korea, China, Taiwan, and Thailand, tsutsugamushi disease is one of the most important rickettsial diseases carried by ticks or mites. If a traveller returning from an Asian country has symptoms such as high fever, skin eruption, and lymphadenitis, we should suspect that he is suffering from tsutsugamushi disease and should search if he has an eschar on any area of his body. We should not forget that tsutsugamushi disease is an imported disease. Patients of tsutsugamushi disease often have hematological disorders. They are sometimes referred to the hematological section of the hospital. Hematologists should be familiar with this disease.

[Analysis of clinical severity of tsutsugamushi disease according to the serotype of pathogenic rickettsia]

We compared the severity of clinical symptoms and laboratory test results of tsutsugamushi disease patients in Oita Prefecture according to the serotype of infected R. tsutsugamushi. Of the 45 patients, except one with the Karp-type, who were suffering in Oita Prefecture between 1992 and 1994, 20 were the Irie-type and 24 were the Hirano-type. There was no apparent difference with regard to clinical symptoms between the two groups of patients. Laboratory tests showed that CRP increased almost equally in the two groups. The ESR level was slightly higher in the Irie-type patients than in the Hirano-type, but did not differ significantly between the two groups. Both leukocyte count in the acute stage and platelet count decreased in the Hirano-type, as compared with those of normal ranges in the Irie-type. GPT values elevated in proportion to the day of illness in the acute stage. This trend continued after the initiation of specific chemotherapy in the Hirano-type. The median GOT, GPT and LDH values were 71, 65 and 709 IU/l for the patients in the Hirano-type, as compared with 37, 36.5 and 546.5 for the patients in the Irie-type, respectively. Above results show that the Hirano-type rickettsiae produces a more severe illness than the Irie-type ricketsia. Platelet count had a significant correlation with ESR, suggesting the pathophysiologic changes leading to disseminated intravascular coagulation, a symptom of severe tsutsugamushi disease. There may be common causes in leukopenia and thrombopenia, as being suggested by the significant correlation between leukocyte count and platelet count.

Pregnancy with scrub typhus and vertical transmission: a case report

Scrub typhus is a rickettsian disease which is seldom found in pregnancy. A 31-year-old, 34 weeks pregnant woman presented with fever, chill and cough for 6 weeks. Fetal jeopardy was found then a cesarean section was performed to deliver a 2,200 g male with hepatosplenomegaly. The mother's diagnosis was confirmed by positive Weil-Felix (OXK titer 1:320) and scrub typhus (titer 1:1600) tests. Vertical transmission was also demonstrated by a positive scrub typhus IgM in her child.

Evaluation of an enzyme-linked immunosorbent assay in Thai scrub typhus patients

We report the development of an improved enzyme-linked immunosorbent assay (ELISA) to detect Orientia (formerly Rickettsia) tsutsugamushi antibody in human sera. Results were compared with a standard test, the indirect immunoperoxidase assay (IIP). Control serum samples were collected from 96 American soldiers and 198 Royal Thai Army soldiers with no recent history of clinical illness. Sera were examined from 79 febrile, Thai scrub typhus patients presenting at Chiang Rai (76) and Bangkraui Nontaburi (3) Provincial hospitals (cases confirmed by elevated IIP IgG levels > or = 1:1,600, IgM levels > or = 1:400, or presence of an eschar). The mean + 2 SD, used for the upper limit of normal reactions in the IgG ELISA, was 0.10 for U.S. soldiers and 0.42 for Thai soldiers. Using the 0.10 cutoff value, 29% of the asymptomatic Thai soldiers would be designated as antibody positive. Variability of IgG ELISA values was greater in the Thai soldier group than in American soldiers, possibly reflecting previous exposure to O. tsutsugamushi. In the Thai patients, there was a significant correlation between IIP titers and single serum dilution (1:100) ELISA values (IgG, r = 0.75, n = 104; P < 0.0005; IgM, r = 0.70, n = 75; P < 0.0005) and between IIP titers and ELISA titers (IgG, r = 0.87, n = 103; P < 0.0005; IgM, r = 0.76, n = 75; P < 0.0005). The single serum dilution ELISA was as effective as the titration in determining presence of specific antibodies. The O. tsutsugamushi ELISA is a rapid and objective test amenable to accurately testing the large numbers of sera often obtained in seroepidemiologic investigations.

Diagnosis of scrub typhus in Malaysian aborigines using nested polymerase chain reaction

A rapid diagnostic system for scrub typhus using nested polymerase chain reaction (PCR) was applied to clinical samples from Malaysian Aborigines. Whole blood from twenty-four patients suspected of scrub typhus infection were tested using nested polymerase chain reaction and sera were evaluated by the indirect immunoperoxidase test. Antibody responses towards Rickettsia tsutsugamushi were observed in seventeen patients with the majority having high titers of IgG antibodies. Seven patients were seronegative. The nested PCR amplified R. tsutsugamushi DNA from six patients, of which two were negative serologically and four had high titers of IgG antibodies. Second samples collected seven days after treatment were negative by PCR testing. Nested PCR is highly sensitive and specific and may be used to provide rapid confirmation of scrub typhus cases in endemic region.

ELISA-based colorimetric detection of Rickettsia tsutsugamushi DNA from patient sera by nested polymerase chain reaction

A rapid diagnostic system for scrub typhus was established using colorimetric detection of nested polymerase chain reaction (PCR). This system relied on binding the amplified DNA via a sequence in one of oligodeoxyribonucleotide to the DNA-binding protein GCN4 coated on the well of a micotiter dish. The primer pairs used for the nested PCR were designed on the basis of the homologous nucleotide sequence of the gene that encodes the 56 kDa antigen of serovariants. With this colorimetric PCR, diagnosis can be performed easily from serum samples of patients before the antibody titer increases or in the early stage of the disease. Furthermore, these positive results are able to be confirmed by pathogenic isolation.

[A case of tsutsugamushi disease which occurred in south western Shikoku]

We report a case of tsutsugamushi disease found in south western Shikoku. A 64-year-old male who lived in Towa Village in Kochi, developed a fever and headache on April 6, 1994, and was admitted to Uwajima City Hospital on April 15, with a ten-day history of illness. He had an eschar on the right anterior side of the breast and an enlargement of the right axillary lymph node, without a rash. Laboratory data showed mild liver injury and atypical lymphocytes with 6% in peripheral blood. After his blood was drawn for rickettsial isolation, the minocycline was administered. His symptoms improved rapidly and was discharged in good condition. We successfully isolated the causative agent, Rickettsia tsutugamushi, and designated it as the Shiba strain. High antibody titer against the Kato, Karp and Gilliam strains was detected in serum on admission and increased during the course of the disease. In Shikoku, tsutsugamushi disease is rare and only 13 cases were reported during last ten years. Especially in south western district of Shikoku, there have been no case reported since 1960. This case is important epidemiologically and suggests that we should pay attention to this disease.

Effectiveness of a dot-blot immunoassay of anti-Rickettsia tsutsugamushi antibodies for serologic analysis of scrub typhus

We compared a commercially available dot-blot immunoassay system with the indirect immunofluorescence assay (IFA) in tests of known negative and known positive sera from scrub typhus cases. Using a panel of 100 sera from patients with various rickettsial and nonrickettsial infections, we observed that the IFA was 99% specific and the dipstick assay was 98% specific. In tests of 91 sera (30 negative and 61 positive for scrub typhus antibodies) from a study of febrile patients in Malaysia, using the standard of an IFA titer < 1:64 as negative, an IFA titer > 1:128 as positive, and an IFA titer = 1:64 as either positive or negative (supported by clinical records), dipsticks were 83% specific and 90% sensitive. The quantitative correlation of the dipsticks to IFA titers was confirmed by significant differences in geometric means of inverse IFA titers corresponding to the number of positive dipstick spots (no dots = 8.5, one dot = 43.3, two dots = 206.7, and three dots = 676.9). The assay would enable physicians and public health workers who deal with patients to quickly diagnose and appropriately treat most cases of the disease, especially in areas of high prevalence where the proportion of false-positive results to true-positive results would be low.

Granulomatous hepatitis associated with scrub typhus

A 56 year old patient with scrub typhus infection having unusual presentation of hepatic injury resembling acute hepatitis is described. The clinical features of fever, headache, eschar, lymphadenopathy, lymphocytosis and high Rickettsia tsutsugamushi immunofluorescence titres confirmed the diagnosis of scrub typhus. Acute hepatitis was proven by hepatic biochemical tests and liver biopsy. The patient had a complete recovery soon after antibiotic treatment. The presentation of this case suggests that scrub typhus infection should be included in the list of differential diagnosis of acute hepatitis or granulomatous hepatitis, at least in the Asian Pacific region where scrub typhus still prevails.

Development and preliminary evaluation of an IgM dot-immunobinding assay (IgM-DIA) for rapid serodiagnosis of scrub typhus infection

An IgM dot-immunobinding assay (IgM-DIA) was developed for the diagnosis of scrub typhus infection. The whole cell antigens of Karp, Kato and Gilliam strains of Rickettsia tsutsugamushi were immobilized onto nitrocellulose paper and reacted with patients sera. The presence of IgM R. tsutsugamushi specific antibody in the patient sera could be detected by the observation of a visible brown dot on the nitrocellulose paper. The IgM-DIA has a sensitivity of 90.4% and specificity of 81.4% as compared to the indirect immunoperoxidase test. The IgM-DIA is rapid, simple, cost-effective, does not require microscope or incubator. It is recommended as a rapid screening test for the diagnosis of scrub typhus infection in the field or rural area within the hyperendemic region.

Imported rickettsioses in German travelers

Twenty-two cases of rickettsiosis imported to Germany (13 men, nine women, average age 42 years) in a 5-year period were analyzed retrospectively regarding the travel histories, symptoms and clinical findings, laboratory features and course of the disease. The two primary rickettsial diseases were boutonneuse fever (18 patients) and scrub typhus (three patients). One patient had murine typhus. The main symptom was fever in 91% followed by headache (64%), myalgia (40%), arthralgia (50%) and diarrhea (36%). The most frequent clinical finding was lymphadenopathy in 65%. Eschar was detectable in 55% of patients with Rickettsia conori infection and in one patient with Rickettsia tsutsugamushi infection. All patients with R. tsutsugamushi infection as well as 33% of the patients with R. conori infection had a macular exanthema. One patient with scrub typhus had pleural and pericardial effusions. Seventy-three percent had an increased ESR. Three patients had leucocytosis, three increased transaminases and two normochromic anemia. The incubation period for R. conori infection was 5 to 28 days (average 14 days), for R. tsutsugamushi infection 7 to 21 days (average 16 days). Twenty-one patients were treated with tetracycline or doxycycline, one with erythromycin. All patients were cured. One patient had a relapse. Due to the fact that the symptoms are often not characteristic and that the routine laboratory findings are of only marginal help, the diagnosis of rickettsial diseases is often not easy. A detailed travel history sometimes gives an important hint for diagnosis.

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.