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PubMed2002

Virulence of Malaysian isolates of Orientia tsutsugamushi in mice.

The pathogenicity of Malaysian isolates of Orientia tsutsugamushi was investigated by a mouse virulence assay. The isolates could be differentiated as low (4 isolates), moderately (3 isolates) and highly virulent (2 isolates) based on the different responses in infected mice. No direct correlation between severity of human scrub typhus infections and virulence of the O. tsutsugamushi in mice was observed. Mice infected with virulent strains of O. tsutsugamushi showed splenomegaly, ascitis accumulation and enlargement of kidneys and livers whereas avirulent O. tsutsugamushi strains were asymptomatic and exhibited ruffled fur for a short period after infection. There was low antibody response in mice infected with isolates of low pathogenicity as compared with those of highly virulent isolates. Upon dissection of the infected mice, enlargement of mouse organs such as spleen, kidney and liver was noted. Presence of rickettsemia in mice was confirmed by the growth of O. tsutsugamushi in the L929 cells when inoculated with blood from infected mice. O. tsutsugamushi was also cultured from the peritoneal exudates of the infected mice. However, DNA of O. tsutsugamushi was only detected in the peritoneal exudates (by PCR) and blood (by cell culture) and not from other tissue samples.

Animals↗
PubMed1996

Genotypic identification of Rickettsia tsutsugamushi by restriction fragment length polymorphism analysis of DNA amplified by the polymerase chain reaction.

We combined the nested polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) for genotypic identification of Rickettsia tsutsugamushi. Four primers were selected from the DNA sequence of the gene encoding a 56-kD serotype-specific antigen of the Karp strain. Nested PCR produced rickettsia-specific products of approximately 0.6 kb in the amplification of DNA prepared from three reference strains (Gilliam, Karp, and Kato) and two prototype strains (Irie and Hirano) prevalent in the Miyazaki Prefecture of Japan. When the nested PCR products obtained from these five strains were digested with Hha I, profiles specific to each strain were generated. Fourteen of 17 DNA samples of peripheral blood mononuclear cells from patients with scrub typhus tested positive in the nested-PCR, providing a rickettsia-specific band. The serotype of infected rickettsia of 10 patients were diagnosed as Irie and those of four patients were diagnosed as Hirano by indirect immunofluorescence methods. The fragment profiles of the PCR products of these 14 patients after digestion with Hha I corresponded closely with those serotypes. However, the PCR products from two of four samples, which were similar to Hirano strain by a serologic method and by the pattern of digestion with Hha I, produced different RFLP profiles upon further digestion with Hinf I and Alu I. These results may suggest that genetic variation exists within serotypes. Genotypic identification of R. tsutsugamushi by means of PCR-RFLP using three restriction enzymes is apparently useful.

Adult↗
PubMed2005

Chemokine and cytokine production in susceptible C3H/HeN mice and resistant BALB/c mice during Orientia tsutsugamushi infection.

To understand the pathogenesis of scrub typhus, we examined chemokine and cytokine production in susceptible (C3H/HeN) and resistant (BALB/c) mice after infection with O. tsutsugamushi Gilliam. C3H/HeN mice produced high levels of chemokines macrophage inflammatory proteins 1 alpha (MIP-1 alpha ), MIP-2, monocyte chemoattractant protein 1 (MCP-1), and cytokines gamma-interferon (IFN-gamma ), interleukin-12 (IL-12), IL-10, and tumor necrosis factor alpha (TNF-alpha ) in response to O. tsutsugamushi infection, compared to BALB/c mice. Chemokine profiles in infected mice correlated well with the kinetics of inflammatory cell infiltration. Hyperproduction of chemokines and cytokines was observed in another susceptible-infection model (BALB/c-Karp). These results suggest that hyperproduction of chemokines and cytokines are associated with susceptibility during O. tsutsugamushi infection.

Animals↗
PubMed2006

Determination and geographic distribution of Orientia tsutsugamushi serotypes in Thailand by nested polymerase chain reaction.

Clotted blood samples of 240 scrub typhus patients were collected from 8 Regional Medical Sciences Centers in Thailand during 1999 to 2002. The serotypes of Orientia tsutsugamushi and their geographic distribution were determined. A nested polymerase chain reaction (PCR) was used to identify the serotypes of O. tsutsugamushi. The number of patients with positive results for O. tsutsugamushi was 25.0%. Two serotypes, Karp and Kato, were detected in these samples. No Gilliam serotype was detected from any of the study locations. The PCR products were sequenced using an automated DNA sequencer. The nucleotide sequence of gene encoding 56-kDa protein from these samples showed a high sequence homology with the reference sequence of O. tsutsugamushi Karp and Kato serotypes. O. tsutsugamushi Karp serotype was predominant throughout Thailand with the percentage of 96.8% of the total serotype-positive patients, whereas 3.2% for Kato serotype was observed only in the south. The highest number among the region of Karp serotype-positive patients of 31.6% was found in the northeast.

Adolescent↗
PubMed1988

Immunoblotting analysis of anti-rickettsial antibodies produced in patients of Tsutsugamushi disease.

The reactivity of sera from patients of Tsutsugamushi disease (scrub typhus) with the antigenic polypeptides of Rickettsia tsutsugamushi was analyzed by the immunoblotting method. The reactivity varied greatly among the sera of individual patients tested. IgG and IgM antibodies of most patients reacted with the 54-56 kilodalton (54-56K) polypeptide located on the rickettsial surface, suggesting that this polypeptide is a predominant antigen in the infection. Other polypeptides of 60K, 50-52K, 46-47K, 35K, and 21-25K were reactive with some but not all sera. From the reactivity of these polypeptides, it was suggested that the 54-56K polypeptide is both strain-specific and group-specific, the 60K polypeptide is group-specific, and the 35K and 21-25K polypeptides are subgroup-specific. IgG antibodies seem to be more cross-reactive with polypeptides of multiple strains than IgM antibodies and have a tendency of increased cross-reactivity that was observed in the sera obtained at the later stage of illness.

Antibodies, Bacterial↗
PubMed2004

Development of a quantitative real-time polymerase chain reaction assay specific for Orientia tsutsugamushi.

Two specific and sensitive polymerase chain reaction (PCR) assays were developed to detect and quantitate Orientia tsutsugamushi, the agent of scrub typhus, using a portion of the 47-kD outer membrane protein antigen/ high temperature requirement A gene as the target. A selected 47-kD protein gene primer pair amplified a 118-basepair fragment from all 26 strains of O. tsutsugamushi evaluated, but it did not produce amplicons when 17 Rickettsia and 18 less-related bacterial nucleic acid extracts were tested. Similar agent specificity for the real-time PCR assay, which used the same primers and a 31-basepair fluorescent probe, was demonstrated. This sensitive and quantitative assay determination of the content of O. tsutsugamushi nucleic acid used a plasmid containing the entire 47-kD gene from the Kato strain as a standard. Enumeration of the copies of O. tsutsugamushi DNA extracted from infected tissues from mice and monkeys following experimental infection with Orientia showed 27-5552 copies/microL of mouse blood, 14448-86012 copies/microL of mouse liver/spleen homogenate, and 3-21 copies/microL of monkey blood.

Animals↗
PubMed1988

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.

Adolescent↗
PubMed2004

Characterization of Orientia tsutsugamushi strains isolated in Shandong Province, China by immunofluorescence and restriction fragment length polymorphism (RFLP) analyses.

In order to identify the characteristics of the Sta56 gene of the 23 isolates of Orientia (O.) tsutsugamushi isolated in Shandong Province, indirect immunofluorescence assay (IFA) was used to identify the gene type of 23 strains O. tsutsugamushi isolated from scrub typhus patients, chigger mites, and rodents. Restriction fragment length polymorphism (RFLP) analysis was also used to analyze the restriction profiles of the Sta56 gene PCR amplification products of the 23 isolated strains of the O. tsutsugamushi; the results were compared with those acquired by nested PCR. By IFA, 21 of the 23 isolates belonged to the Gilliam type, and 2 to the Karp type. Using RFLP analysis, 21 strains had similar restriction profiles to the Japan Kawasaki strain, but they had no restriction site Hha I, and thus had some difference in gene sequence compared with the Japan Kawasaki strain. The other 2 strains had similar restriction profiles to Karp. These results were identical to that acquired by nested-PCR. In Shandong Province, the gene types of epidemic O. tsutsugamushi strains were similar to the Japan Kawasaki type, but had some differences in gene sequence. In addition, Karp also existed.

Animals↗
PubMed2004

[Amplification and typing of Sta56 gene of Orientia tsutsugamushi from Shandong province].

OBJECTIVE: To clarify the gene type of Orientia tsutsugamushi (Ot) from Shandong province. METHODS: Nested-polymerase chain reaction (nPCR) was used to identify the gene type of 23 isolated Ot strains, 2 pools of homogenized leptotrombidium (L.) scutellare, 10 blood specimens of scrub typhus patients, and at the same time to compare with the international reference strains Gilliam, Karp, Kato. Sequencing analysis of the Sta56 gene was also used to further identify the precise gene types. RESULTS: Of the 35 samples, 33 had the same products in the amplification of template Ot-DNA. They all belonged to Kawasaki strains endemic in Japan while 2 (FXS4 and LHGM2 strain) belonged to Karp strains. The Sta56 gene sequence homologies to Japan Kawasaki strain of the 2 representative strains (B-16 and FXS2 strain) of the 33 samples were 94.22%, 95.21% respectively, but they were less than 75.87% to other prototype strains; The homologies to Karp strain of FXS4 and LHGM2 strain were 83.03%, 96.45% respectively. B-16 and FXS2 strain were designated as of types strain Japan Kawasaki, FXS4 and LHGM2 as Karp strain. CONCLUSION: The results indicated that the dominant Ot strains in Shandong Province were similar to Kawasaki strains, but Karp strains also existed.

Animals↗
PubMed2005

Long-term egg-yolk adaptation of the Orientia tsutsugamushi for preparation of a formalinized immunogen.

To assess the feasibility of preparing a killed rickettsial vaccine against the scrub typhus, the Karp and Gilliam strains of the Orientia tsutsugamushi were adapted through sequential passages in eggs for more than 100 times over 9 years to produce approximately five times more antigen than the unadapted rickettsia. The egg-grown rickettsia was purified by differential centrifugation and batch-type ion-exchange chromatography, and inactivated by formalin treatment. Strong protective immunity was acquired against lethal challenges of the homologous strains and lasted fully for longer than 8 months in the C3H/He mice immunized with either of the single-strain immunogen or in combination of the two strain immuinogens. However, neither immunogen protected animals from the challenges with the two heterologous strains or Boryong, the prevalent strain in Korea, despite that three antigenic proteins of 47, 56, and 110 kDa were eminent in both preparations. IgM, IgG, and neutralizing antibody were induced in the immunized mice in a level and pattern comparable to that in animals infected with live rickettsiae.

Adaptation, Biological↗
PubMed2025

Microbiological Investigations for Chikungunya Virus in Children With Acute Encephalitis Syndrome in a Non-Outbreak Setting in Southern India.

Chikungunya virus (CHIKV) is an emerging cause of acute encephalitis syndrome (AES) in India, with limited data on its role in childhood AES in southern India. We systematically evaluated children with AES in southern India during a non-epidemic period for CHIKV. Serum and cerebrospinal fluid (CSF) samples were tested for CHIKV using IgM ELISA and real-time reverse transcriptase PCR. Amplicon sequencing was performed on PCR-positive samples. Clinical and laboratory features were compared between children with and without CSF CHIKV positivity (PCR/IgM antibodies). Of 376 children with AES, 20 (5.3%) had positive CHIKV tests. Co-infections were common, particularly with scrub typhus. Children presented with diverse symptoms affecting various organ systems. Neurological manifestations included meningism, seizures, cerebellar signs, behavioral abnormalities, cranial nerve involvement, involuntary movements, and hemiparesis/hemiplegia. Children with CSF CHIKV positivity showed more focal neurological deficits and transaminitis, and less musculoskeletal symptoms. Sequencing confirmation of CHIKV was made in all patients with positive CHIKV PCR, revealing a close relationship with 2016 Kenyan and Indian strains, albeit in a different clade within the East/Central/South African genotype. Along with important mutations known to impact CHIKV infectivity, four novel amino acid substitutions were detected in envelope protein coding regions. Our findings underscore the importance of routine and comprehensive CHIKV testing for children with AES, irrespective of season/outbreak. The high rate of co-infections warrants further research. Continued genomic surveillance is essential to monitor emerging mutations with epidemic potential, increased severity and the risk of neurological disease.

Humans↗
PubMed2006

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↗
PubMed1986

Immunological properties of Rickettsia tsutsugamushi, Kawasaki strain, isolated from a patient in Kyushu.

Nine isolates of Rickettsia tsutsugamushi were obtained from patients with Tsutsugamushi disease (scrub typhus) in Miyazaki Prefecture in Kyushu. Immunological analyses of these patients' sera and the isolates were performed by indirect immunofluorescence, indirect immunoperoxidase or immunoblotting techniques. In the analysis of reactions of the patients' sera with the prototype strains Gilliam, Karp, and Kato and with the isolates, sera from two patients, including Kawasaki, showed similar profiles and cross-reaction with the two isolates recovered from the corresponding patients, but reacted only weakly with the prototype strains. With guinea pig polyclonal antibodies against the isolate and prototype strains, Kawasaki strain showed some degree of cross-reaction with Gilliam strain but not with either Karp or Kato strain, nor with Shimokoshi strain which is known to be different antigenically from the prototype strains. Additionally, strain-specific murine monoclonal antibodies against Gilliam, Karp, and Kato strains did not react at all with Kawasaki strain. These results suggest that the Kawasaki strain may be different antigenically from the prototype strains and Shimokoshi strain. The finding two strains of the same antigenic type (Kawasaki) among only nine isolates suggests the presence of Kawasaki-type rickettsiae in Miyazaki Prefecture. Shimokoshi strain also did not react with these strain-specific monoclonal antibodies, suggesting that strains of R. tsutsugamushi antigenically distinct from the prototype strains, such as Kawasaki and Shimokoshi strains, may easily be recognized by their nonreactivity with these monoclonal antibodies.

Animals↗
PubMed2003

[Outbreak of hepatitis by Orientia tsutsugamushi in the early years of the new millenium].

BACKGROUND/AIMS: Orientia -tsutsugamushi infection is an acute febrile disease due to the accidental transmission through human skin of forest dwelling vector Leptotrombidium larva. The authors observed liver dysfunctions in patients diagnosed with tsutsugamushi disease (Scrub typhus) in the past 3 years and report the data in the hope of bringing attention to this disease in the differential diagnosis of autumn-season hepatitis, especially of non-A, non-B and non-C hepatitis. METHODS: Medical records of 22 patients diagnosed with tsutsugamushi disease by the hemagglutinin method between October 2000 and November 2002 were reviewed. RESULTS: Female gender was dominant in the ratio of 3.4:1. Mean age was 56.4 +/- 2.6. Admission was between 23rd September and 15th November with the peak between mid October and early November. Fever, being the most common symptom, was observed in 21 cases, myalgia in 13, arthralgia in 12, chills in 6, and skin rash in 6. An incubation period of 7-9 days was most common (10 cases), 13-15 days (4), 10-12 days (3), within 3 days (3), and 4-6 days (2). Average ALT, AST and GGTP were increased to 93.2 +/- 17.3 IU/L (18 +/- 345 IU/L), 92.5 +/- 11.7 IU/L (34-255 IU/L) and 132.2 +/- 14.5 IU/L (19-251 IU/L), respectively, but total bilirubin was normal. All the patients improved with doxycycline therapy. CONCLUSIONS: Since it usually shows liver dysfunction, it is important to take Orientia tsutsugamushi into consideration in differential diagnosis of autumn-season, febrile hepatic disease.

Adult↗
PubMed1990

Aggregated distribution of infective spots composed of Leptotrombidium pallidum, highly prevalent with Rickettsia tsutsugamushi, demonstrated by sentinel voles, Microtus montebelli, on the ground.

In the epidemiological surveys on scrub typhus at Chichibu City near Tokyo, an area, 350 m by 35 m, in the Hitsujiyama Park was found to be heavily infested with Rickettsia tsutsugamushi (Rt). Distribution of trombiculid mites and their infection rates in this area were studied using sentinel animals, 48 Microtus montebelli and 10 ddY mice. The surveys were conducted 6 times in the autumn in 1985 and 1986. At the first 2 surveys, 16 animals were placed at random, and 4 restricted areas were identified as highly populated with trombiculid mites. For the detailed survey, each of 4 areas was divided into 2 m x 2 m quadrats to settle a sentinel animal to each. A total of mites collected by all sentinel animals was 331 Leptotrombidium pallidum, 175 L. fuji and 16 Gahrliepia saduski. Almost all mites were collected by M. montebelli, except only 1 L. fuji in 10 mice. From a M. montebelli in a quadrat, 157 L. pallidum were recovered, whereas the number/vole was 0 to 24 in the others. L. fuji was also highly aggregated at 2 sites. Rt was detected from individual mites by avidin-biotin immunofluorescence or isolated by the mouse passage from individual or pooled mites. Only Karp strain of Rt was detected or isolated from L. pallidum at a ratio of 31/286 (10.8%). No Rt was found from L. fuji or G. saduski. The infection rate in L. pallidum was especially high in 3 voles at ratios of 6/11, 2/5 and 3/5, respectively. Out of 14 sentinel M. montebelli with infected L. pallidum, 12 (85.7%) were infected with Rt. It was concluded that L. pallidum was distributed in aggregated clusters to form the mite islands and was infected heavily at the specific sites to make the infective spots.

Animals↗