Rickettsia Orientalis Research Articles

Transmission of Rickettsia Orientalis to Man by Leptotrombidium Akamushi at a Scrub Typhus Endemic Area in Akita Prefecture, Japan

During the summer seasons of 1956 through 1970, 93 larval trombiculid mites were removed from 386 individuals who had been bitten by chiggers in Jumonji, Akita Prefecture. All 87 larvae that were available for examination were identified as Leptotrombidium akamushi. Infestation of man occurred predominantly during July and August, but the period extended from June to November. The duration of attachment was approximately 1 to 3 days. Usually only 1 chigger was found on a victim but on occasion as many as 7 were removed at one time. Scrub typhus developed in 45 (11.7%) of the 386 farmers bitten by chiggers. Although patients with scrub typhus may have sustained multiple bites, only one eschar was found. However, 76% of the patients did not recognize a bite either at the site where an eschar subsequently appeared or elsewhere prior to the onset of disease. If it is assumed that workers who did not subsequently become ill were equally unaware of chigger bites, then the probable incidence of disease in chigger victims was 3.1%. The minimum infectivity rate of L. akamushi larvae in Akita Prefecture was estimated to be 2.3%. Based upon the assumption that infection was transmitted as the result of a single bite, the infective rate of chiggers attacking man was calculated to be 2.5%.

Purification of complement-fixing antigens of Rickettsia orientalis by ether extraction.

Abstract Soluble and particulate antigens of Rickettsia orientalis were obtained by a single preparation of ether extraction of yolk-sac suspension previously treated with Amberlite XE-64. Cross-complement-fixation tests indicated that the soluble antigen has groupor species-specificity and the particulate antigen has type- or strain-specific activity. The soluble antigen was heat-labile, whereas the particulate antigen was heat-stable. Both the soluble and particulate antigens resisted trypsin and phosphatide acyl-hydrolase (phospholipase A). The soluble antigen was partially inactivated by periodic oxidation, but the particulate antigen was resistant to periodate. No change in complement-fixing titers was observed after lyophilization of the antigens. Wassermann-positive serum with high titer showed falsely positive reactions against normal yolk-sac and infected yolk-sac antigens.

Complement-fixation tests of Rickettsia orientalis with sodium deoxycholate treated antigen.

Complement-fixation tests of Rickettsia orientalis were performed by using antigens purified with sodium deoxycholate. Cross complement-fixation tests between antigens of the Gilliam, Ohzeki, Karp and Kato strains and immune mouse sera of these four strains and of the Kaneko strain revealed difference in antigenic structure among the Gilliam, Karp and Kato strains. The Ohzeki strain was identical with the Gilliam strain and the Kaneko strain was identical with the Karp strain. In the homologous system, complement-fixing antibodies of mice infected with R. orientalis began to appear on the 15th day after infection and rose rapidly in a few days, and reached maximum in 4–6 weeks after infection and 8 weeks at latest. Subsequently, the titers declined gradually and showed low titers on the 52nd week in spite of survival of rickettsia in mice. In the heterologous system among which antigenic structures were different, the titers rose somewhat later and declined earlier than those of the homologous system. It was confirmed that the antigen treated with sodium deoxycholate was utilizable in the specific serological diagnosis of scrub typhus, because convalescent sera from all ten patients with the disease showed significant rise of complement-fixing titers against the antigen.

Mmunological Studies of Rickettsia Purification of Complement-fixing Antigens of Rickettsia orientalis by Ether Extraction

mmunological Studies of Rickettsia Purification of Complement-fixing Antigens of <I>Rickettsia orientalis</I> by Ether Extraction

Purification of Complement-Fixing Antigen of Rickettsia Orientalis

Summary A stable complement-fixing antigen of Rickettsia orientalis, free of anti-complementary substance, was obtained by sodium deoxycholate (DCA) sucrose extraction of yolk sac suspensions previously treated with Amberlite XE-64. The optimum concentration of DCA, 1.0% in 0.25 M sucrose solution, yielded an antigen containing approximately one tenth of the nitrogen of the material extracted by sucrose alone without any change in the complement fixation titer of antigen. The DCA-extracted antigen was stable on storage at -70°C for periods of 5 months or more.

Persistent infection of Rickettsia sennetsu in cell culture system.

Persistent infection of Rickettsia sennetsu in cell culture system.

SCRUB TYPHUS IN THE PESCADORES ISLANDS: AN EPIDEMIOLOGIC AND CLINICAL STUDY.

SummaryStudies on scrub typhus conducted during 1962 in the Pescadores Islands revealed that a major mite vector for the disease is Leptotrombidium deliensis. Infected mites were found most often in cover provided by miscanthus and coral walls along field margins. The shrew, Suncus murina, was the host most commonly infested with infected mites. Rattus norvegicus and Rattus rattus rufescens were less important sources. The percentage of infected mites appeared to increase until late summer, then to decline, and to increase again in November. However, the data are insufficient to permit a definite conclusion concerning seasonal cycles.Five of 103 reported cases of scrub typhus in 1962 were studied. Rickettsia orientalis was isolated from whole blood of all five patients. None of them had skin rash, but in other respects their illness was similar to established clinical descriptions of the disease as it occurs in Southeast Asia.

Rickettsia orientalisの組織培養に関する基礎的研究

In an attempt to isolate Rickettsia orientalis from rodents by means of tissue culture method, a study with a number of growing cell culture in liquid medium was performed to find out the optimal conditions for the support of the growth of R. orientalis from the liver and spleen of the mice previously infected with this infectious agent. The following results are obtained.1) When the suspension of the infected liver and spleen at a concentration of 10% is seeded onto the cells and incubated for 60 minutes at 37°C., it was observed that one-tenth of the particles of the seeded agents was absorved.2) Among the cell cultures used, a noticeable difference is not observed in the growth of R. orientalis, although a slightly lower LD50 titer is estimated in tissue cultures with the culture of DK cells.3) R. orientalis can be easily cultivated and isolated from the specimens from the trapped rodents under the conditions described above.4) For long period cultivation and for the study of the fine morphological structure of R. orientalis, tissue cultures with Descement cells seems to be the most applicable.

Rickettsia orientalis (大関株) 感染マウス臓器よりリケッチアの部分的純化に関する研究

Rickettsia orientalis (大関株) 感染マウス臓器よりリケッチアの部分的純化に関する研究

On the persistence of Rickettsia orientalis in Mice and the Effect of Environmental thermal Condition on the Experimental Infection by Subcutaneous Injection with Rickettsia.

On the persistence of Rickettsia orientalis in Mice and the Effect of Environmental thermal Condition on the Experimental Infection by Subcutaneous Injection with Rickettsia.

The Effect of Saline and Sucrose-Phosphate-glutamate Solution on the Experimental Infection with Rickettsia Orientalis in Mice

The Effect of Saline and Sucrose-Phosphate-glutamate Solution on the Experimental Infection with Rickettsia Orientalis in Mice

恙虫病におけるPAUL-BUNNELL反応について

“Sennetsu” is a well known endemic disease to cause a high fever accompanying enlargement of subcutaneous lymph nodules in Kyushu especially in Kumamoto, Miyazaki and Fukuoka Prefectures. According to the Ohtawara's report the disease would give positive Paul-Bunnel (PB) reaction, might be caused by a filtrable agent and might be the same to the glandular fever described by Pfeiffer. In the past few years a rickettsia-like body agent, however, was isolated from the patients which was nominated by Misao as Rickettsia sennetsu and by Fukuda as Rickettsia todai respectively differentiating from Rickettsia orientalis mainly through the cross challenge test in human volunteers and in animal experiments. Contrary to it the agent was described by another investigators to be Rickettsia orientalis. Furthermore, the disease could be cured by the administration with some antibiotics and it was said that a rise of titer in both Weil-Felix reaction against OXK and PB reaction was given on paired sera from the patient. Consequently it seems unlikely that “Sennetsu” in Kyushu can be the infectious mononucleosis.On the other hand it has been made clear by Dr. Tamiya and his associates that scrub typhus patient might exsist over all Japan in any season especially in summer and the winter. Then it was necessary to elucidate relationship between scrub typhus and “Sennetsu”. Prior to differentiate scrub typhus from “Sennetsu”, attempt was made as to whether or not Rickettsia orientalis might contain a Forssman (F) antigen and whether the scrub typhus patient might give positive PB reaction on sera collected from scrub typhus patients as well as inoculated animals.The results were obtained as follows.1. A rise of titer of PB reaction in 20 rabbits weighing 2.5-3.0kg was seen on 1st to 3rd weeks sera among those collected weekly until the 9th week following intra-ocular, -testicular and -dermal inoculation with mouse organ emulsion infected with 10 field rodent strains and 3 patient strains of Rickettsia orientalis and then fell down. Such positive turned in negative after absorption with guinea pig kidney but the titer did not change in 2 samples and fell down by 1/2 to 3/4 in 7 samples after absorption with cow red cells according to Davidsohn's test.2. The similar results were obtained on sera from 6 rabbits inoculated with normal mouse organ emulsion.3. No rise of titer of PB reaction was obtained in 6 rabbits inoculated with infected rabbit testicular emulsion which was proven not to contain any F antigen. From the foregoing results it was seen that the rise of titer of PB reaction in rabbits 1) and 2) was caused by F antigens contained in mouse organ emulsion and Rickettsia orientalis may not contain any F antigen.4. Low titer of positive PB reaction was seen on sera from 3 rabbits inoculated with infected HeLa cell suspension. Presumably it was caused by calf serum added to the culture media which was known to contain F antigens.5. Sera from 3 guinea pigs containing F antigens did not show any positive PB reaction following intraperitoneal inoculation with normal mouse organ emulsion.6. PB reaction on sera from 3 albino rats not to contain any F antigen resulted in negative following intraperitoneal inoculation of mouse organ emulsion infected with 2 field rodent strains respectively.7. The rise of titer of PB reaction was seen in 4 out of 7 healthy volunteers following intradermal inoculation of normal mouse organ emulsion. The results on sera after Davidsohn's test were obtained similary to 2) in rabbits. No relation was found between a rise of titer of PB reaction and blood types especially Aiv factor.8. The significant rise of titer of Weil-Felix reaction was given on paired sera among 20 serum samples collected from 16 scrub typhus patients in Niigata Prefecture in 1955, while sera gave a low titer O-1: 28 of PB reaction.9. Out of 9 healthy

The nature of immunity against scrub typhus in mice. II. The cross-protection test with mice for identification and differentiation of several strains of Rickettsia orientalis newly isolated in Japan.

The antigenical differences among several strains of Rickettsia orientalis have already been reported by many workers. At first, Bengtson (1945, 1946) differentiated Karp (New Guinea), Seerangayee (Malaya), and Gilliam (Burma) strains of Rickettsia orientalis by complement fixation, and later Philip (1947) observed that sera of patients of tsutsugamushi disease in Japan could be divided into two different types (Karp and Gilliam types) by complement fixation reaction. On the other hand, Bell et al. (1946), Bennett et al. (1949), and Fox (1949) demonstrated independently the heterogeneity of several strains by cross-neutralization test, and similar results were obtained by Right et al. (1948) in their cross-vaccination studies. By these findings, the causative agent is usually identified by demonstrating resistance of convalescent animals to approximately 100 LD50 of a known strain of scrub typhus, because subcutaneous inoculation of the agent into animals induces an inapparent infection which is followed by immunity, and the resistance of convalescent animals to reinfection is found to be almost common among all strains so far tested.But in the protection test, there has been left a criticism that the resistance of convalescent animals might be explained just as reasonably as a manifestation of interference phenomenon (Fox, 1949) .In the previous report (Shishido et al., 1958), it was analysed that the resistance of mice surviving subcutaneous infection of Rickettsia orientalis (Kato strain) to reinfection of the same agent was caused by immunity acquired by the initial infection, although such immunized mice could maintain a nonspecific resistance (interference) to superinfection of a heterologous rickettsia (Rickettsia mooseri) and a virus (Meningopneumonitis virus) .The present paper deals with the results of cross-protection tests among many strains suspected by us as Rickettsia orientalis on the criteria of morphological characters and general properties of the agents. Most of these strains were recently isolated from field rodents trapped at many different areas of Japan for the epidemiological studies of scrub typhus in Japan designed by Dr. Tamiya et al. (1955, 1956, 1957, 1958) . At the same time, a strain, which was isolated from a rodent trapped in Hokkaido, an island located in the north-eastern part of Japan and to which the name of Rickettsia tamiyai was proposed by Kawamura (1954a, 1954b), was tested in comparsion with those newly isolated strains. From the present results, the authors concluded that all strains including Rickettsia tamiyai were to be identified as Rickettsia orientalis, although a minor difference was observed in some strains.

Morphological Changes in Various Organs of Mice sacrificed daily after Inoculation with &lt;i&gt;Rickettsia orientalis&lt;/i&gt;

Morphological Changes in Various Organs of Mice sacrificed daily after Inoculation with &lt;i&gt;Rickettsia orientalis&lt;/i&gt;

新潟県下の恙虫病汚染地において恙虫寄生をうけたラットから Rickettsia orientalis を分離した 1 例

新潟県下の恙虫病汚染地において恙虫寄生をうけたラットから Rickettsia orientalis を分離した 1 例

Experimental Studies of Immunity Following Induced Inapparent Infection with &lt;i&gt;Rickettsia orientalis&lt;/i&gt; in Mice

Experimental Studies of Immunity Following Induced Inapparent Infection with &lt;i&gt;Rickettsia orientalis&lt;/i&gt; in Mice

Studies on the Effects of X Rays Radiation upon the Growth of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; and Neutralization Tests in Yolk Sacs of Developing Chick Embryos

Studies on the Effects of X Rays Radiation upon the Growth of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; and Neutralization Tests in Yolk Sacs of Developing Chick Embryos

Studies on the Preservation of Strains of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; by Freezing

Studies on the Preservation of Strains of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; by Freezing

Intradermal Inoculation with &lt;i&gt;Rickettsia orientalis&lt;/i&gt; in Goats, Especially on Dermal Reaction

Intradermal Inoculation with &lt;i&gt;Rickettsia orientalis&lt;/i&gt; in Goats, Especially on Dermal Reaction

Experimental Studies of Seasonal Influence on Host-Parasite-Relationship by Using of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; and Mice

Experimental Studies of Seasonal Influence on Host-Parasite-Relationship by Using of &lt;i&gt;Rickettsia orientalis&lt;/i&gt; and Mice