Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SCRUB TYPHUS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2005

Investigation of an outbreak of scrub typhus in the himalayan region of India.

In Indira Gandhi Medical College, Himachal Pradesh, India, during autumn of 2003 (September-November), more than 100 cases of fever of unknown origin (FUO) were reported with 15 ensuing deaths. In addition to all routine investigations and cultures, the Weil-Felix test was incorporated for the investigation of these cases. Antigen was procured from the Central Research Institute, Kasauli. Forty-six percent (45/96) of the cases demonstrated a > or =1:80 titer of agglutinins against OXK antigen. A team from the National Institute of Communicable Diseases, New Delhi, confirmed the antibodies for scrub typhus in some of the serum samples tested for leptospirosis, dengue fever, and rickettsial infections. Twelve blood samples positive for OXK antigen were sent to the Defense Research Development Establishment, Gwalior, for polymerase chain reaction studies, but none of the samples were positive, as all of the patients were already on broad-spectrum antibiotics and had reported to our hospital after 7-10 days of fever. At our institute, the Weil-Felix test has now been rountinely introduced for the investigation of cases of FUO, and the results until April 2004 (150 cases) revealed the presence of other rickettsial infections prevalent in the region. To evaluate the epidemiology and magnitude of the problem, further prospective studies are required.

Agglutination Tests↗
PubMed1975

Serologic classification of scrub typhus isolates from Pakistan.

Detailed serologic characterization of 79 isolates of Rickettsia tsutsugamushi from Pakistan was performed by using complement fixation and direct immunofluorescence techniques for comparison with three prototype strains. Seventy-one were of the Karp serotype and one was of a Gilliam serotype. Seven isolates were multiply-reactive: one with Karp and Gilliam, 3 with Karp and Kato, and 3 with Karp, Gilliam and Kato, No strain failed to react with at least 1 of the 3 prototype antisera. No correlation of antigenic types with local geographic factors, animal hosts, vecotr mites, or specific strain virulence was observed. These findings suggest the possibility that antigenic heterogeneity may be more restricted in areas peripheral to the geographic epicenter of scrub typhus endemicity, that the serotypes are relatively stable genetically and that new geographic variants are probably infrequent. The importance of these findings to the practical problems of immunoprophylaxis and serodiagnosis are discussed.

Animals↗
PubMed1994

Trombiculid fauna and seasonal abundance of Leptotrombidium scutellare (Acari: Trombiculidae) in an endemic area of scrub typhus (Tsutsugamushi disease) in Yamakita Town, Kanagawa Prefecture, Japan.

Using the Tullgren funnel method, we surveyed for trombiculid larvae around dwellings and in mandarin orange groves on the slopes of Sengenyama and Maruyama, Yamakita Town, Kanagawa Prefecture, Japan, during the period between 8 October 1992 and 8 January 1993. In total, 6,690 trombiculid larvae, consisting of 6,669 Leptotrombidium scutellare (Nagayo, Mitamura, Tamiya & Tenjin), 13 L. fuji Kuwata, Berge & Philip, two L. himizu (Sasa, Kumada, Hayashi, Enomoto, Fukuzumi & Obata), two Neotrombicula japonica (Tanaka, Kaiwa, Teramura & Kagaya), one Gahrliepia saduski Womersley, and three Walchia ogatai Sasa & Teramura, were taken from 240 soil samples (40 samples, six times at intervals of 2-4 wk). From the above species composition, L. scutellare is suspected to be the sole vector of scrub typhus in the survey area, where the disease is known to be caused by two serotypic strains of Rickettsia tsutsugamushi Ogata, Kawasaki and Kuroki. L. scutellare larvae rapidly increased in number in late October to form an acuminate peak of abundance in early November, followed by a gradual wane.

Agriculture↗
PubMed1979

Host defenses in experimental scrub typhus: role of normal and activated macrophages.

Resident peritoneal macrophage from BALB/c mice were infected in vitro with Rickettsia tsutsugamushi strain Gilliam, and rickettsial growth was estimated by microscopic examination of Giemsa-stained cells. Both number of infected macrophage per culture and number of intracellular rickettsiae per cell increased with time during culture. Treatment of rickettsiae with immune serum before infection macrophage cultures reduced the number of infected macrophage by 50%. Macrophage treated in vitro with lymphokines were able to suppress rickettsial growth in the absence of detectable antibody and exhibited a 75% reduction in infection compared with normal macrophage. We also obtained activated macrophage from immune mice and found that they were refractory to in vitro rickettsial infection. Macrophage populations activated in vitro or in vivo contained a small percentage of cells which supported unrestrained growth of rickettsiae. These data suggest that an early immunological event in experimental scrub typhus infection may be the development of activated macrophage capable of suppressing rickettsial proliferation before the appearance of circulating antibody.

Animals↗
PubMed1999

Meningoencephalitis, myocarditis and disseminated intravascular coagulation in a patient with scrub typhus.

A 21-year-old male soldier was admitted due to a sore throat, headache, generalized lymphadenopathy and persistent fever for 12 days. Despite empirical antibiotic treatment for four days at a clinic prior to admission, he continued to have persistent abdominal pain over his right upper quadrant region and progressive jaundice was followed by shock. After admission, he developed an episode of clonic seizures and became delirious and agitated. An electrocardiogram showed first degree atrioventricular (AV) block and non-specific ST-T wave changes. Hematological studies revealed thrombocytopenia, hypofibrinogenemia, abnormal partial thromboplastin time (PTT) and a positive test for D-dimer. The cerebrospinal fluid analysis showed pleocytosis with white cells of 84/mm3 with a lymphocyte predominance, protein of 97 mg/dL and glucose of 79 mg/dL. Indirect immunofluorescence assay showed a fourfold rise in antibodies to Orientia tsutsugamushi in paired serum with IgM antibody titer of 1:640. The patient had a favorable response after parenteral chloramphenicol in addition to oral tetracycline. Early ricognition of scrub typhus and early prescription of anti-rickettsial agents prevent complications of central nervous system involvement and further deterioration of cardiac and hematological function.

Adult↗
PubMed2006

The foci of scrub typhus and strategies of prevention in the Spring in Pingtan Island, Fujian Province.

This study investigates the foci of tsutsugamushi disease on Pingtan Island, China, with emphasis on cases of illness that occur in the spring. The investigation of the physical and medical geography in the endemic area and detection of 141 sera samples in the population of Pingtan Island is described. The serum samples were taken from 102 soldiers and 39 residents and were tested by the indirect immunofluorescence assay. An island resident's history of illness inquiry was also conducted, and the results are discussed. We were able to determine the most prevalent types of rats and mites from the rat bodies. We isolated the DNA from the spleen of 40 rats and from five groups of mites by polymerase chain reaction. Orientia tsutsugamushi was isolated by perctoneally injecting KM mice with the patient's untreated blood along with ground rat viscera (R. losea) and ground mites (L. deliense), respectively. The isolates were typed at the molecular level. This study will then present direct prevention strategies that emphasize personal hygiene, methods of personal protection, keeping living environments clean, and it will provide strategies to eliminate rats and mites. As a result of adopting these strategies, no case of scrub typhus occurred in this region in approximately 2003-2004.

Animals↗
PubMed1998

A new ecology for scrub typhus associated with a focus of antibiotic resistance in rice farmers in Thailand.

Following the documentation of chloramphenicol-resistant and doxycycline-resistant strains of Orientia tsutsugamushi (Hyashi) in northern Thailand, we conducted ecological and epidemiological studies near the houses of patients hospitalized with antibiotic-resistant infections. New associations between chiggers, rodents, and O. tsutsugamushi in active rice agriculture areas, an ecological habitat not described previously, are reported. Rattus rattus (L.) was the most common species (representing 85.8% of the 1,433 rodents processed), followed by Rattus losea (Swinhoe) (9.4%), Bandicota indica (Bechstein) (3.6%), and Rattus argentiventer (Robinson and Kloss) (1.3%). O. tsutsugamushi was isolated from 30% of the R. rattus and R. losea, 29% of the B. indica, and 33% of the R. argentiventer collected. Mean minimum infection rates were 0.03 in Leptotrombidium chiangraiensis Tanskul & Linthicum, a new species of chigger, and 0.002 in Leptotrombidium imphalum (Vercammen-Grandjean & Langston), a chigger species not previously associated with scrub typhus transmission. Efficient vertical and horizontal transmission of O. tsutsugamushi by L. chiangraiensis and L. imphalum was demonstrated. During a 19-mo period from October 1993 to April 1995, the overall prevalence of human IgM and IgG antibody to O. tsutsugamushi was 25.5 and 47.3%, respectively. L. chiangraiensis and L. imphalum are incriminated as vectors of O. tsutsugamushi in a rice field habitat associated with a focus of antibiotic resistance.

Animals↗
PubMed1976

Host defenses in experimental scrub typhus: histopathological correlates.

Intraperitoneal (i.p.) infection of BALB/c mice with 1,000 50% mouse lethal doses of the Karp strain of Rickettsia tsutsugamushi was inevitably lethal, and associated pathological alterations were confined to the peritoneal cavity. These included: (i) continuous proliferation of rickettsial organisms in peritoneal macrophages until death; (ii) hepatic granulomas appearing 6 days after infection and increasing in size and number until death; (iii) splenomegaly, resulting principally from proliferation of lymphoid tissue, and (iv) terminal peritonitis. Under two circumstances, i.p. infections with R. tsutsugamushi were not lethal: (i) infection with 100 50% mouse infectious doses of the Gilliam strain, which, in fact, resulted in immune protection against otherwise lethal Karp challenge; and (ii) Karp infection of animals immunized with the Gilliam strain. In both cases, the associated pathological abnormalities were, as with primary Karp infection, restricted to the peritoneal cavity. Also similar was the striking splenomegaly due to lymphoid proliferation, which was particularly prominent in immunized animals. In contrast to primary and lethal Karp infection, however, these infections were characterized by: (i) minimal and transient proliferation of rickettsial organisms in peritoneal macrophages; (ii) disappearance of hepatic granulomas; and (iii) absence of peritonitis. It was concluded that the survival of an animal bearing an i.p. infection of scrub typhus depended on its ability to concentrate a sufficiently vigorous immune response in the peritoneal cavity, resulting in the evolution of rickettsiacidal macrophages capable of suppressing the infection.

Animals↗
PubMed1982

Host defenses in experimental scrub typhus: delayed-type hypersensitivity responses of inbred mice.

Delayed-type hypersensitivity responses of inbred mice during the course of lethal and chronic infections with strains of Rickettsia tsutsugamushi were evaluated by using the influx of radiolabeled cells into antigen-injected ears. Congenic strains of C3H mice, which previously have been shown to be resistant (C3H/RV) or sensitive (C3H/HeDub) to lethal intraperitoneal infection with the Gilliam strain of rickettsiae, both expressed delayed-type hypersensitivity early in the course of infection (5 to 7 days). The sensitive C3H/HeDub mice, however, exhibited a marked decline in reactivity just before death. In contrast, reactivity of C3H/RV mice remained high through day 9 and declined slowly through day 15 after infection. Similar results were obtained when BALB/c mice were infected with either the Karp or the Gilliam strain of rickettsiae, which produce a lethal or nonlethal infection, respectively, in this strain of mice. Rechallenge of C3H/RV mice elicited a rapid increase in reactivity, suggesting a secondary memory response. To analyze delayed-type hypersensitivity during chronic infection, C3H/HeDub mice were immunized by subcutaneous infection with the Gilliam strain of R. tsutsugamushi, and both delayed-type hypersensitivity reactivity and resistance to intraperitoneal challenge were examined. Delayed-type hypersensitivity reactivity developed slowly and peaked at 21 days postimmunization, which correlated with resistance to intraperitoneal challenge. Delayed-type hypersensitivity reactivity declined thereafter, but resistance to intraperitoneal challenge remained through 28 days postimmunization. Delayed-type hypersensitivity reactivity increased after secondary challenge at 28 days, again suggesting antigen memory generated by primary immunization. Transfer of delayed-type hypersensitivity reactivity was accomplished by using immune thymus-derived splenic lymphocytes isolated with nylon-wool columns. Abrogation of the ability of immune spleen cells to transfer delayed-type hypersensitivity reactivity after treatment with anti-Thy 1.2 alloantiserum and complement further supported the view that delayed-type hypersensitivity responses to scrub typhus rickettsiae were mediated by thymus-derived lymphocytes.

Animals↗
PubMed1991

Efficacy of three pyrethroids against Leptotrombidium fletcheri (Acari: Trombiculidae) infected and noninfected with scrub typhus.

Toxicities of three pyrethroids, d-phenothrin, decamethrin, and permethrin, were evaluated in the laboratory against Leptotrombidium fletcheri (Womersley & Heaslip). The susceptibilities between populations of the species infected and noninfected with scrub typhus were investigated. The three pesticides exhibited different toxicities to the chiggers. D- phenothrin was the most toxic, followed by decamethrin, then permethrin. There were no significant differences between susceptibilities of the infected and noninfected populations. Log-probit regression lines indicated that the species was most sensitive to increasing concentrations of d-phenothrin and least sensitive to permethrin. The results show that the three pesticides are potential candidates for chemical control of L. fletcheri. It may be possible in the future to conduct similar bioassays only with the noninfected population, thus reducing risk of infection to workers conducting the bioassays. Similarly, there may not be a need to separate field-collected chiggers into the two populations before performing the bioassays.

Animals↗