[The first case of tsutsugamushi disease in Ehime Prefecture]

The first case of tsutsugamushi disease in Ehime Prefecture was experienced in December 1987 with successful isolation of the causative agent. The patient was taken ill twelve days after infection. Immunofluorescent antibody tests using the isolate, Yamazaki strain, and Gilliam, Karp, Kato, Irie and Shimokoshi strains as antigens revealed that the specific antibodies against these antigens appeared and increased in the blood of the patient during the course of the disease. And the antibody titers to the Yamazaki antigen were the highest of these antigens. Agglutinin for Proteus OXK did not appear in the blood of the patient. The immunofluorescent antibody test using type-specific monoclonal antibodies to Gilliam, Karp, Kato, Irie and Shimokoshi strains and these five strains and the Yamazaki strain as antigens revealed that the Yamazaki strain was identified as Karp type of Rickettsia tsutsugamushi.

Application of serologic diagnosis of tsutsugamushi disease (scrub typhus) in Korea where the disease was recently recognized to be endemic

In Korea, tsutsugamushi disease is a recently recognized infection. It has become clear that it is more prevalent than leptospirosis or hemorrhagic fever with renal syndrome. Accurate diagnosis of the disease is necessary for the selection of effective antimicrobial agents which can prevent fatalities and shorten the course. For the diagnosis, various serologic tests are used. Sensitivity and specificity of a test depend on various factors. In this report, microbiological aspects of the infection were briefly described and the Weil-Felix, indirect immunofluorescence and indirect immunoperoxidase tests were compared for their applicability in routine use and usefulness in the diagnosis. Their interpretations were also briefly discussed.

Imported rickettsial disease: clinical and epidemiologic features

PURPOSE AND METHODS

The rickettsioses continue to constitute major health problems in many parts of the world. With increasing international travel, recognition of rickettsial diseases by physicians is becoming more important. The clinical features of four cases of rickettsial disease imported into Canada over a five-year period are presented; two patients with tick typhus (Rickettsia conorii), one patient with scrub typhus (R. tsutsugamushi), and one patient with murine typhus (R. typhi). We also present the North American data over the past 10 years from the Centers for Disease Control (CDC) (Atlanta).

RESULTS

Since 1983 in the United States, three cases of imported scrub typhus, all after travel to India, were confirmed, as well as six cases of murine typhus after travel to southeast Asia. At the CDC, 67 imported cases of tick typhus have been confirmed by indirect fluorescent antibody test since 1976; most illnesses occurred after travel to Africa.

CONCLUSION

Rickettsial diseases are underrecognized by physicians, who should consider these diagnoses in travelers returning from endemic areas. Since effective treatment is available, prompt diagnosis and treatment are important. In all cases, specific serologic confirmation should be obtained.

Rickettsiosis in Japan

The rickettsial diseases of man in Japan include Tsutsugamushi disease (scrub typhus), murine typhus, which occurs sporadically, and one of spotted fever group diseases, recognized as a new entity since 1984. Starting from 1976, there has been a remarkable resurgence in the number of reported cases of Tsutsugamushi disease in Japan after several years of virtual absence, and endemics are still continuing after reaching a prominent outbreak in 1984. Its yearly incidences from 1982 to 1986 were 538, 749, 971, 890 and 738, respectively. This resurgence is most likely related to an increase of vector mite colonies that carry Rickettsia tsutsugamushi. However, it cannot be explained as to how these foci of vector mites developed. The existence of spotted fever group disease had not been recognized until quite recently. This rickettsiosis was first identified in Tokushima and Kochi Prefectures in 1984. To date, the estimated total number of sero-positive cases is over 45 cases. The causative rickettsiae were isolated from the blood of 5 patients using cell culture methods and the identification of these rickettsiae is now being carried out.

Scrub typhus pneumonitis: an entity which is frequently missed

Four cases of scrub typhus pneumonitis are reported. Diagnosis was confirmed by positive Weil-Felix OX-K reaction and immunofluorescent antibody test for Rickettsia tsutsugamushi. Two patients presented with atypical pneumonia and two had overwhelming pneumonia resembling adult respiratory distress syndrome. All patients made a full recovery after appropriate treatment.

Evaluation of the whole blood lymphocyte transformation assay for scrub typhus exposure: adaptability to field sample collection

The optimal conditions for the determination of exposure to scrub typhus by the whole blood lymphocyte transformation assay was 7 days culture of 10% blood in RPMI 1640 medium supplemented with 10% human AB-negative serum and L-glutamine with 50-200 micrograms protein/ml of Karp, Kato, or Gilliam strain membrane antigen. A simple exponentially decaying linear model shows the decrease in lymphocyte viability, the ability of sensitized cells to be stimulated with PHA mitogen, and the corresponding decrease in stimulation by scrub typhus antigens with increasing time of preincubation on ice. The lower limit of stimulation index for the detection of scrub typhus by whole blood lymphocyte transformation assay was 4.0 with a type I error of 1%.

Comparative evaluation of the indirect immunoperoxidase test for the serodiagnosis of rickettsial disease

An indirect immunoperoxidase test was compared with an indirect fluorescent antibody test and the Weil-Felix OXK test for serodiagnosis of scrub typhus by measuring the rickettsial antigen specific activity of IgG, IgM, and whole globulin. Acute and convalescent sera from 50 Rickettsia tsutsugamushi isolate-positive scrub typhus patients and from 45 febrile patients diagnosed as having diseases other than scrub typhus were tested. The receiver operating characteristic for each test showed that the indirect immunoperoxidase and indirect fluorescent antibody tests were more sensitive and specific than the Weil-Felix test using convalescent and acute as well as paired sera. The indirect immunoperoxidase test showed no cross-reactivity when R. tsutsugamushi antigen was tested against sera collected from patients living outside the scrub typhus-endemic area with diseases other than scrub typhus. The indirect immunoperoxidase and indirect fluorescent antibody tests were comparable in measured response to R. tsutsugamushi, R. typhi, and TT-118 (spotted fever group) antigen. Thus the indirect immunoperoxidase test represents a sensitive, specific, reproducible, and practical semiquantitative test for rickettsial disease diagnosis.

A serological survey of scrub, tick, and endemic typhus in Sabah, East Malaysia

A seroepidemiological survey of 837 people and 383 febrile patients was performed in rural areas of Sabah. We determined that the rickettsial diseases scrub typhus and endemic typhus were uncommon causes of febrile illness, as was tick typhus, except in forest dwelling peoples. The rate of occurrence of SFGR specific antibody was 16.5% among 412 forest dwellers, indicating that tick typhus may be a frequent cause of illness in this population.

Detection of surface antigen in Rickettsia tsutsugamushi infected mouse reticuloendothelial cells

Antibody produced by immunizing CBA/CaJ mice with RE cells from C57B1/6J mice infected 14 days earlier with R. tsutsugamushi Gilliam strain bound readily to Gilliam strain non-cell associated rickettsiae and less readily to the periphery of infected RE cells. Conversely, antibody produced by immunizing with RE cells infected 21 days earlier did not bind to Gilliam rickettsiae but bound to the surface of RE cells from mice infected 21 days earlier. This binding was not related to alloantibodies because these were absorbed prior to testing. The demonstration of rickettsial antibody staining of infected cell associated antigen(s) in this assay system provides a new method for the detection of R. tsutsugamushi infection.

Febrile illness in Malaysia--an analysis of 1,629 hospitalized patients

We studied 1,629 febrile patients from a rural area of Malaysia, and made a laboratory diagnosis in 1,025 (62.9%) cases. Scrub typhus was the most frequent diagnosis (19.3% of all illnesses) followed by typhoid and paratyphoid (7.4%); flavivirus infection (7.0%); leptospirosis (6.8%); and malaria (6.2%). The hospital mortality was very low (0.5% of all febrile patients). The high prevalence of scrub typhus in oil palm laborers (46.8% of all febrile illnesses in that group) was confirmed. In rural Malaysia, therapy with chloramphenicol or a tetracycline would be appropriate for undiagnosed patients in whom malaria has been excluded. Failure to respond to tetracycline within 48 hours would usually suggest a diagnosis of typhoid, and indicate the need for a change in therapy.