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 19 recordsLinked to original sources
PubMed1979

Sensitive microplate enzyme-linked immunosorbent assay for detection of antibodies against the scrub typhus rickettsia, Rickettsia tsutsugamushi.

A microtiter enzyme-linked immunosorbent assay (ELISA) has been developed for the titration of antibodies against scrub typhus in human and animal sera. Scrub typhus rickettsiae were grown in monolayers of irradiated mouse LM3 cells and separated from host cell materials by differential centrifugation, filtration through a glass filter (AP-20, Millipore Corp.), and isopycnic banding in Renografin density gradients. The scrub typhus ELISA antigens were obtained from the purified viable rickettsiae by French pressure cell disruption and addition of 0.2% Formalin to the soluble extract. Antisera prepared in rabbits against the prototype Karp, the Kato, and the Gilliam strains of scrub typhus were used to standardize the ELISA and to compare its sensitivity and specificity to that of the indirect fluorescent antibody test (IFA). ELISA titers were measured as the greatest serum dilution showing an optical density 0.25 above controls or by the optical density achieved at a fixed serum dilution. The IFA and ELISA end point titers were quite similar, and all three measures of titer had comparable specificity for the strains of scrub typhus. No cross-reactions between the typhus and scrub typhus wera were observed by ELISA. Both the immunoglobulin M (IgM) and IgG antibody titers of 12 sequential sera from four patients with scrub typhus were obtained by IFA and ELISA. The IFA and ELISA end point titers for IgM and IgG had correlation coefficients of 0.91 and 0.97, respectively, whereas the ELISA optical density values at a serum dilution of 1:100 had slightly lower correlations with IFA titers (0.80 and 0.94). Early rising IgM titers followed by rising IgG titers were demonstrated by ELISA in three patients with primary scrub typhus infections, whereas the IgG response predominated in a patient with a reinfection. It is concluded that the ELISA for scrub typhus is a very satisfactory alternative to the IFA test.

Animals↗
PubMed1977

Electrocardiographic changes in scrub typhus patients.

Ninety-eight cases of scrub typhus were examined electrocardiographically. Various findings beyond the normal range were as follows: In the febrile stage, sinus arrhythmia with some beats below 60 per minute, flat or low T waves in the left precordial leads, sinus tachycardia, ST segment elevation of 4-l mm in V2, prominent u waves measuring 1 mm or more in amplitude, tall and peaked T waves in V2-4, incomplete right bundle branch block, T wave inversion in V3-4, first degree A-V block, Q-Tc interval prolongation, notched T waves in V3, AV junctional escapes, prominent Ta waves or depression of PR segments in V2, and right axis deviation; in the convalescent stage, sinus arrhythmia with some beats below 60 per minute, prominent u waves measuring 1 mm or more in amplitude, tall and peaked T waves in V2-4, flat or low T waves in the left precordial leads, incomplete right bundle branch block, sinus tachycardia, first degree A-V block, Q-Tc interval prolongation, T wave inversion in V3-4, ST segment elevation of 4 mm in amplitude in V2, ventricular premature contractions, atrial premature contractions, and right axis deviation. In comparison with the electrocardiographic findings in 101 asymptomatic normal subjects, flat T waves in the precordial leads, tall and peaked T waves in V2-4 in both acute and convalescent stages, and sinus arrhythmia with some beats below 60 per minute in the convalescent stage were more frequent in cases. Electrocardiographic abnormalities were present most commonly in the acute illness, and our findings support the impression that, with few exceptions, prompt treatment of scrub typhus with antibiotics prevents the serious cardiac complications seen prior to the antibiotic era.

Adult↗
PubMed1977

Epidemiological and serological study of scrub typhus among Chinese military in the Pescadores islands of Taiwan.

An outbreak of 69 cases of scrub typhus occurred among Chinese military personnel stationed in the Pescadores Islands, Taiwan Province, Republic of China between May and November 1975. A retrospective epidemiological study of this outbreak indicated that military personnel over 40 were more likely to have scrub typhus than those under 40. High risk groups included the Garrison Force (home guard), anti-aircraft gunners and infantry and armoured units stationed at Hsing-jen. The onset of symptoms in 69% occurred within one year of residence in the Pescadores. The clinical course of scrub typhus and the serological response to infection were also studied. Eschar formation, fever, headache chills and lymph node enlargement were the predominant clinical manifestations noted. The indirect immunofluorescent antibody test (IFAT) demonstrated diagnostic (four-fold) rises in antibody titres to Rickettsia tsutsugamushi reference strains in 36 of 41 paired sera tested. 11 of 19 patients from whom only single sera were obtained had IFA titres presumptive of scrub typhus (greater than or equal to 1:160). Of 19 patients experiencing possible primary infections, 13 (68%) responded with antibodies directed against more than one reference strain of R. tsutsugamushi. These results suggest that several antigenically diverse strains of R. tsutsugamushi may be active in the Pescadores.

Animals↗
PubMed1977

Experimental scrub typhus immunogens: gamma-irradiated and formalinized rickettsiae.

Scrub typhus immunogens were prepared by exposing infected yolk sac suspensions of Rickettsia tsutsugamushi to various doses of gamma radiation. Mouse lethality was abolished at doses greater than 200 krads, whereas immunogenicity of the suspensions, as shown by mouse protection tests, was diminished relatively little by radiation doses in the 200- to 400-krad range. Using a 300-krad gamma dose to provide a safety factor, immunogens were prepared and their protective capacity was contrasted with formalinized scrub typhus immunogens prepared by conventional techniques. Formalinized suspensions afforded mice only partial protection against intraperitoneal challenge with 1,000 50% mouse lethal doses of the virulent homologous strain and no significant protection against similar challenge with an equally virulent heterologous strain. Using the same strains, radiation-inactivated preparations provided 100% protection against 10,000 50% mouse lethal doses of the homologous strain and 70% protection against challenge with the same doses of a heterologous strain. Neither immunogen was a potent stimulator of antibody production as measured by the complement-fixation test. Cell-transfer studies using inbred mice indicated a role for cell-mediated immunity after vaccination with gamma-irradiated immunogens, but no cell-mediated protection could be demonstrated after vaccination with formalin-inactivated rickettsiae.

Animals↗
PubMed2025

Proteome Profiling in Cerebrospinal Fluid Reveals Increased Levels of Peroxiredoxin 2 Discriminating Japanese Encephalitis Virus and Scrub Typhus Infection.

Japanese encephalitis virus (JEV) and scrub typhus (ST) are major etiological agents of acute encephalitis syndrome (AES) in India and South Asia. The pathophysiological changes at the molecular level caused by JEV and ST have yet to be studied in detail. The cerebrospinal fluid (CSF) proteomic landscape is a critical indicator of CNS pathology. Here, we conducted label-free quantitative proteomics on CSF from AES patients (n = 15) to identify etiology-specific differentially expressed proteins (DEPs) linked to encephalitis. The key DEPs were validated via ELISA in CSF (n = 49) and serum (n = 33). Our findings revealed 50 proteins exhibited differential expression across JEV and ST groups, with a notable subset of three proteins, PRDX2, KLK6, and TTR. PRDX2 and KLK6 were markedly elevated in JEV CSF (AUC: 0.8933 and 0.9689) but not in ST or non-JEV AES, while TTR was reduced in JEV yet elevated in ST (AUC: 0.5619 vs. 0.8238). Further, PRDX2 upregulation was validated in JEV-infected mouse brains and cortical neurons. Overexpression of PRDX2 in human neuroblastoma cells correlated with enhanced antiviral gene expression, p-STAT1, p-AKT (ser473), and viral replication. Thus, our comprehensive proteomic analysis of CSF identifies PRDX2 as an important circulatory protein, differentially expressed between JEV and ST, with high specificity and enhancing viral propagation, underscoring its role in viral propagation and pathogenesis.

Humans↗
PubMed1979

Vectors of scrub typhus and their hosts on a mature oil palm estate.

L. (L.) deliense was the predominant vector of scrub typhus in a mature oil palm estate, but a small number of L. (L.) fletcheri (0.1% from rodents) and L. (L.) vivericola (0.02% from rodents and 8.0% from black plates) was also collected. Although good correlation between L. (L.) deliense collected from rodents and from black plates was not established, either method may serve as a general indicator of population fluctuations over a period of time. For the most part, the vectors of scrub typhus were limited to litter piles, and thus, the possibility of contracting scrub typhus within this type of habitat was minimal.

Animals↗
PubMed1977

Rickettsia tsutsugamushi infection and scrub typhus incidence among Chinese military personnel in the Pescadores Islands.

Personnel assigned to infantry units of the army of the Republic of China (Taiwan) stationed in the Pescadores Islands experienced the highest incidence rate of scrub typhus (4%) and the highest rate of Rickettsia tsutsugamushi infection (12%) of the units studied during 1976. The ratio of scrub typhus to infection with R. tsutsugamushi was 30%. Non-immune personnel, when infected, were more likely to develop scrub typhus than were those who had previously been infected. There was a correlation between clinical illness and high antibody titers developed in response to the infection.

Humans↗
PubMed1979

Changing risk of scrub typhus in relation to socioeconomic development in the Pescadores islands of Taiwan.

Long term changes in risk of Rickettsia tsutsugamushi infection among civilian residents of the Pescadores Islands of Taiwan were associated with changing social conditions. Age specific incidence rates of scrub typhus in the Pescadores before 1940 were highest among children under 5 years of age. Rickettsiae can be demonstrated in vectors, wild animals continue to be infected and scrub typhus occurs in military personnel. A serologic survey for antibody to R. tsutsugamushi was conducted during 1975 and 1977 and failed to show evidence of previous infection among children. Two events appear to be associated with the decreased incidence of rickettsial infection in the young: increased urbanization and increased enrollment in schools. Both changes accompanied socioeconomic development which took place in the islands during the past 50 years. Prevalence of antibody to R. tsutsugamushi continues to be equal in the sexes and is undoubtedly due to similar occupational exposure of both sexes in fields and farms where vectors are numerous. The absence of apparent morbidity due to scrub typhus among the civilian populace was attributed to the mild nature of the disease caused by Pescadores strains, misdiagnosis and a lack of obligatory reporting.

Adolescent↗
PubMed1976

Scrub typhus: a common cause of illness in indigenous populations.

An explanation was sought for the disparity between the low reported incidence of scrub typhus and the high prevalence of antibody to Rickettsia tsutsugamushi in the rural population of Malaysia. A combination of isolation of the organism, titration of antibody by indirect immunofluorescence, and the Weil-Felix test was used to confirm infections. Scrub typhus was found to be very common, causing 23% of all febrile illnesses at one hospital. The infection was particularly prevalent in oil-palm workers, causing an estimated 400 cases annually in a population of 10,000 people living on one plantation. The clinical syndrome, whether mild or severe, was difficult to distinguish from that due to other infections. Eschars, rashes and adenopathy were uncommon. When used to examine early sera, the Weil-Felix test failed to confirm the diagnosis in most infections.20

Adolescent↗
PubMed1978

Single dose doxycycline therapy for scrub typhus.

A single dose of 200 mg of doxycycline was shown to be as effective as a seven day course of tetracycline, in patients suspected of having scrub typhus. 65 (44%) of the 149 patients studied fulfilled the criteria for definite diagnosis of scrub typhus; 10 had an additional diagnosis. Rickettsia tsutsugamushi was isolated from 49 (75%) patients. There was no difference between the two treatment groups in time to defervescence, abolition of cough and headache, or in the time taken to recover well-being. There were no relapses in either group. Of the remaining 84 patients, a causal diagnosis was achieved in 52. Irrespective of a diagnosis there was no difference in apparent response to either doxycycline or tetracycline.

Adolescent↗
PubMed1979

Forecasting the onset of a scrub typhus epidemic in the Pescadores Islands of Taiwan using daily maximum temperatures.

Daily maximum atmospheric temperatures were used to forecast the seasonal onset of scrub typhus in the Pescadores Islands of Taiwan. The day of the year on which the temperature first reached 30 degrees C was selected as the predictive base. Predictions for 1977 closely matched observed events. The model provides an easy and effective means to forecast the start of scrub typhus epidemics in the Pescadores Islands and could be used for such practical purposes as determining when prophylactic antibiotics should be administered to subjects whose risk of infection with Rickettsia tsutsugamushi is high.

Disease Outbreaks↗
PubMed1977

Plaque assay and cloning of scrub typhus rickettsiae in irradiated L-929 cells.

It was demonstrated that gamma-irradiated L-929 cells support plaque formation by three strains of Rickettsia tsutsugamushi and representative species of the spotted fever and typhus group rickettsiae. Sensitivity of the plaque assay for detection of viable scrub typhus rickettsiae was similar to that achieved with intraperitoneal inoculation of random-bred mice. The concentration of irradiated cells and the temperature and length of incubation were all found to affect plaque size. A technique combining terminal dilution and plaque purification was used to obtain clones of three strains of scrub typhus rickettsiae.

Gamma Rays↗
PubMed1976

Experiments on chickens placed on ground endemic of classical scrub typhus in Akita prefecture, Japan.

The chicken is available as a bait animal for the study of vector mites and has been found to be infected by chigger mite bite in an area endemic of scrub typhus. L. pallidum and L. palpale were reconfirmed to be zoophilic for the chicken. It is suggested a walking bird can serve as a vector--carrying mites from one place to another. R. orientalis can persist subclinically for a certain period in the spleen and liver of chickens placed on the ground endemic of scrub typhus. Specimens of L. pallidum, 22 in number, collected from chickens placed on the ground of an endemic area in Akita Prefecture were found rickettsia-positive. Both strains isolated from bait chickens and L.pallidum collected from host chickens were identified as a Kato type of R. orientalis.

Animals↗
PubMed1976

Experiments on chickens placed on ground endemic of classical scrub typhus in Akita Prefecture, Japan.

The chicken is available as a bait animal for the study of vector mites and has been found to be infected by chigger mite bite in an area endemic of scrub typhus. L. pallidum and L. palpale were reconfirmed to be zoophilic for the chicken. It is suggested a walking bird can serve as a vector--carrying mites from one place to another. R. orientalis can persist subclinically for a certain period in the spleen and liver of chickens placed on the gound endemic of scrub typhus. Specimens of L. pallidum, 22 in number, collected from chickens placed on the ground of an endemic area in Akita Prefecture were found rickettsia-positive. Both strains isolated from bait chickens and L.pallidum collected from host chickens were identified as a Kato type of R. orientalis.

Animals↗
PubMed1979

Gamma-irradiated scrub typhus immunogens: broad-spectrum immunity with combinations of rickettsial strains.

Scrub typhus immunogens were prepared from Rickettsia tsutsugamushi strains Karp, Kato, Gilliam, Kostival, and Buie by exposing frozen infected yolk sac suspensions to 300 krad of gamma radiation. Mouse protection tests showed that each of the irradiated immunogens protected C3H/HeDub mice against high challenge levels of Karp and Gilliam, but that none of these single-strain immunogens were capable of protecting against all five of the challenge strains. Broad-spectrum protection was achieved by using combinations of three strains of irradiated rickettsiae in a vaccination regimen of three injections at 5-day intervals. A comparison of vaccination efficacy employing three such combinations (Karp-Gilliam-Kato, Karp-Kostival-Kato, and Buie-Kostival-Kato) indicated that both sequential administration of strains on successive vaccination days and multiple injections of trivalent mixtures produced protective responses superior to those obtained with single-strain immunogens. Trivalent mixtures of rickettsiae exhibited a striking synergistic effect on the immune response of C3H/HeDub mice and elicited a protective response against Kato challenge that could not be obtained with any single-strain immunogen. Mice vaccinated with the trivalent Karp-Gilliam-Kato immunogen resisted challenge with more than 10(3) 50% mouse lethal doses of Karp and Gilliam for 12 months, and were resistant to similar levels of challenge with Kato and Buie for 6 months.

Animals↗
PubMed1977

Host defenses in experimental scrub typhus: role of spleen and peritoneal exudate lymphocytes in cellular immunity.

Lymphocytes obtained from spleens or peritoneal exudates of immune donor mice were evaluated for their ability to passively confer protection on recipients subsequently challenged with virulent scrub typhus rickettsiae. Peritoneal exudate lymphocytes (PELs) injected intraperitoneally were able to transfer complete protection against rickettsial challenge by 5 days after immunization, whereas splenic lymphocytes (SpL's) required 15 days to exhibit similar resistance. When immune lymphocytes were transferred intravenously, cells from both anatomical compartments required 15 days after immunization before they were able to completely protect recipients. PELs maintained this protective capacity for 2 weeks, but the passive immunity induced by intravenously transferred SpL's rapidly diminished to insignificant levels. It was particularly interesting that the protective effect of SpL's could be dramatically reduced by the concomitant presence of a mineral oil-induced peritoneal exudate. Almost total abrogation of resistance was observed when SpL's obtained from exudate-bearing mice were transferred intravenously. The protective capacity of both PELs and SpL's was resistant to 1,200 rads of gamma radiation at 7 to 10 days after immunization, but resistance was transient and by 3 weeks was undetectable. It was not possible to determine from this study whether the transferred lymphocytes were proximate mediators of protection in scrub typhus infection of mice or whether they served to recruit the host's own defenses, or both. However, it was possible to conclude that PEL's and SpLs exhibited functional heterogeneity and that PELs were more efficient mediators of protection.

Animals↗
PubMed1977

Host defenses in experimental scrub typhus: effect of chloramphenicol.

The effect of chloramphenicol treatment on the development of immunity to scrub typhus in mice was studied. Chemotherapy was administered either shortly before infection and for 14 days thereafter (group I), or from 7 to 21 days postinfection (group II). Although the full course of either regimen resulted in complete protection of the mice against subsequent challenge with the homologous strain of Rickettsia tsutsugamushi, initiation of chemotherapy at 7 days postinfection resulted in more rapid development of immunity against both the original infection and subsequent challenge. In both treatment groups, a 1- to 2- day hiatus was observed between immunity to challenge in the treated animal and the ability to transfer this immunity to syngeneic recipients with lymphocyte-enriched spleen cells. Similarly, complement-fixing antibodies were not detectable until shortly after the animals were able to resist challenge. These data supported the conclusion that the rickettsiostatic effect of chloramphenicol allows the infected animal time to mount an effective immune response and, further, that initiation of chemotherapy early in the infection may delay development of this response.

Animals↗
PubMed1978

Gamma-irradiated scrub typhus immunogens: development and duration of immunity.

The development and duration of immunity to lethal scrub typhus infection was studied in BALB/c mice vaccinated with gamma-irradiated Rickettsia tsutsugamushi, strain Karp. One intraperitoneal injection containing approximately 10(8) 50% mouse lethal doses (MLD(50)) of irradiated organisms elicited an immune response protective against challenge with 10(5) MLD(50) of viable Karp. The same mass of immunogen given in three injections at 5-day intervals increased homologous (Karp strain) protection 25-fold and heterologous (Kato strain) protection 60-fold. Further temporal expansion of the immunization regimen did not increase protection. Subcutaneous vaccination provided significant, but lower, levels of protection than were achieved by intraperitoneal immunization, but the levels of cell-transferable immunity elicited by the two routes were approximately the same. Immunologically specific protection after intraperitoneal vaccination developed rapidly enough to provide resistance against simultaneous challenge with 200 MLD(50) of Karp. Homologous immunity was protective against a 10(6)-MLD(50) challenge 7 days after completion of the three-injection regimen, remained at that level for 3 months, dropped to 10(4) MLD(50) by 9 months, and was effective against a 50-MLD(50) Karp challenge at 12 months. Protection against heterologous challenge was first observed on day 17 and peaked on day 38, when the mice resisted a 10(5)-MLD(50) Kato challenge. Thereafter, heterologous protection waned rapidly and was not significant at 6 months.

Animals↗