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Early diagnosis of scrub typhus in Thailand from clinical specimens by nested polymerase chain reaction.

The early detection of scrub typhus in Thailand by nested polymerase chain reaction (PCR) is presented. The diagnosis of scrub typhus, from clinical samples obtained from hospitals in the northern part of Thailand, by nested PCR was compared to immunofluorescence (IF) and Weil-Felix (WF) tests. The primer pairs used for the nested PCR were designed on the basis of the nucleotide sequence of the gene that encodes the 56-kDa antigen, and RFLP analysis was used for identification. Clotted blood from 80 patients suspected of scrub typhus infection were tested. With the IF test, antibodies for Orientia tsutsugamushi were observed in 38 patients checking IgM and IgG titers. Only 21 patients showed positive seroconversion while 17 patients were negative. For the WF test, only 13 patients gave a positive seroconversion. In the early stage of infection, 19, 13 and 3 patients were detected with a sensitivity of 90.47% (19/21), 61.90% (13/21) and 14.28% (3/21) by the nested PCR, IF and WF test respectively. Two patients who were negative for seroconvesion by IF and WF were positive by nested PCR. Therefore, this suggests that nested PCR is applicable for specific rapid diagnosis at an early stage of scrub typhus in endemic regions.

Adolescent↗

Scrub typhus: chest radiographic and clinical findings in 130 Thai patients.

OBJECTIVE: To describe chest radiographic findings and their clinical correlation in patients with scrub typhus diagnosed in Thailand and to determine abnormalities that assist in the diagnosis of scrub typhus. MATERIAL AND METHOD: Between July 2001 and December 2002, 130 patients with scrub typhus admitted to three hospitals in the northeastern Thailand were studied. Data of clinical presentations and chest radiographic findings, reviewed by two radiologists who were unaware of the final diagnosis, were analyzed. RESULTS: There were 33 women, 97 men; age range, 11-92 years; median age, 45 years old. Pulmonary symptoms occurred in 61.5% of the patients and eschar was found in 33.1%. Hepatic dysfunction occurred in 58.5% and cardiovascular dysfunction in 33%. Pulmonary involvement was the major presentation in 41.5%. Acute respiratory distress syndrome developed in 7 patients. Overall 5 patients died. The initial radiography showed abnormalities in 64.6% of the patients. Common radiographic abnormalities included bilateral reticular opacities (48.5%), cardiomegaly (28.5%), congestive heart failure (18.5%), air space nodules (13.1%), and pleural effusion (10.8%). Significant association between chest radiographic abnormalities and hepatic and cardiovascular dysfunction were documented. CONCLUSION: Chest radiography should be included in the initial evaluation of patients with suspected scrub typhus. Bilateral reticular infiltration, with or without cardiomegaly or congestive heart failure, was the most frequent radiographic finding of scrub typhus.

Adolescent↗

Passive transfer of scrub typhus plasma to patients with AIDS: a descriptive clinical study.

We examined the HIV-inhibitory effects previously found to be associated with scrub typhus infection. Individual 500 ml units of plasma from donors with mild scrub typhus were safety-tested, subjected to virucidal heat treatment, and administered to 10 HIV-1-infected recipients who were not receiving antiretroviral drugs. HIV-1 copy number fell three-fold or more in two recipients, and virus burden was reduced for 8 weeks in 70% (7/10) of recipients of a single plasma infusion, compared with the mean of three pre-infusion measurements. Scrub typhus donor plasma inhibited HIV-1 in vitro compared with normal human plasma and media controls. In the clearest in vivo response, reduction in viral load was accompanied by clinical improvement, a switchback from the syncytia-inducing to the non-syncytia-inducing phenotype, and decreases in CD8 cells and IL-6 levels. Scrub typhus infections can generate heat-stable, transferable plasma factors that exert prolonged anti-HIV effects. Whether variability in the results is due to different scrub typhus infections, different HIV infections or different individual responses, is unclear.

Acquired Immunodeficiency Syndrome↗

HIV-1 suppression during acute scrub-typhus infection.

BACKGROUND: In HIV-1-infected individuals, viral load has been reported to rise transiently if an acute infection with another organism occurs. Our study was prompted by the unexpected finding that HIV-1 copy number fell during an acute infection with Orientia tsutsugamushi, the causative agent of scrub typhus. METHODS: Serial HIV-1 viral load determinations were made in ten Thai adults with scrub typhus, who were not receiving antiretroviral therapy, and in five HIV-1-infected patients who had other infections (four malaria, one leptospirosis), during and after acute infections. Sera from HIV-1-infected patients with scrub typhus and from mice immunised with O. tsutsugamushi were examined for HIV-1-suppressive activity. FINDINGS: Median viral load 3 days after admission was significantly lower in the scrub-typhus group than in patients with other infections (193% vs 376% of day 28 values, p=0.03). In four O. tsutsugamushi-infected patients HIV-1 RNA copy number fell by three-fold or more compared with day 28 values, and HIV-1 copy numbers were below the assay threshold in two patients with scrub typhus. Five of seven HIV-1 isolates from non-typhus patients with CD4 lymphocytes less than 200 cells/microL were syncytia-inducing variants, whereas all ten isolates from O. tsutsugamushi-infected individuals matched by CD4-cell count were non-syncytia inducing (p=0.03). Sera from an HIV-1-negative patient with scrub typhus had potent HIV-1-suppressive activity in vitro. Sera from typhus-infected mice inhibited HIV-1 syncytia formation and bound by immunofluorescence to HIV-1-infected lymphocytes. INTERPRETATION: HIV-1-suppressive factors are produced during some scrub-typhus infection and should be investigated further in the search for novel strategies for the treatment and prevention of AIDS.

Acute Disease↗

Scrub typhus during pregnancy: a case report and review of the literature.

Scrub typhus is a rickettsial disease that is uncommon during pregnancy. We report a case of a 33-year-old woman, G1P0, 29 weeks pregnancy who presented to hospital with high fever, chill and headache for two weeks. Her diagnosis of scrub typhus was confirmed by serum immunofluorescent assay. She was successfully treated with chloramphenicol, but preterm delivery occurred. Her infant died from respiratory distress syndrome. No vertical transmission was demonstrated in this case. Scrub typhus should be listed in the differential diagnosis of acute febrile illness in pregnant women, who either live in, or return from, endemic areas. Chloramphenicol can be used safely during pregnancy if it is not circulating at the time of delivery.

Adult↗

Scrub typhus complicating acute respiratory distress syndrome: a report of two cases.

Scrub typhus is a zoonotic disease, caused by Rickettsia tsutsugamushi, in which humans are accidental hosts. Although it is an acute febrile illness, severe complications of this disease are very rare since the introduction of specific antibiotic therapy. The authors report two cases of scrub typhus complicating acute respiratory distress syndrome. The first case progressed to multiple organ failure, and the patient expired. In the second case, the patient recovered and was discharged. These two cases were proved to be scrub typhus by their travel history or their having lived in endemic area, clinical manifestations, an eschar and indirect immunofluorescent antibody test. For a good prognosis, early diagnosis and early treatment of this disease are important.

Female↗

Roxithromycin treatment of scrub typhus (tsutsugamushi disease) in children.

BACKGROUND: Although chloramphenicol and doxycycline have been used for the treatment of scrub typhus, a difficulty exists in determining which drug to use in treating children because of such potential complications as aplastic anemia or tooth discoloration. We evaluated the effect of roxithromycin, a macrolide antibiotic, on scrub typhus in children. METHODS: A retrospective analysis was conducted on 39 children with scrub typhus who were treated with doxycycline (DC), chloramphenicol (CM) or roxithromycin (RM) between 1991 and 2000. We divided the patients into the DC-treated group (DC group; 16 children), CM-treated group (CM group; 14 children) and RM- treated group (RM group; 9 children) and compared these groups. RESULTS: Most cases (97%) occurred in October and November. Fever and rash were observed in all 39 cases, and an eschar was noted in 36 cases (92%). No statistical differences could be found between the 3 groups in mean age, duration of fever before admission, white blood cell (WBC) count and complications including abnormal liver enzymes. In most cases defervescence after treatment was within 24 h (34 cases, 87%) and during 24 to 48 h in 2 cases in the DC group, 1 case in the CM group and 2 cases in the RM group (no statistical difference). CONCLUSION: Roxithromycin was as effective as conventional doxycycline or chloramphenicol in children with scrub typhus and may be safer to use.

Adolescent↗

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↗

Clinical usefulness of eschar polymerase chain reaction for the diagnosis of scrub typhus: a prospective study.

BACKGROUND: The aim of this study was to determine the diagnostic utility of performing eschar polymerase chain reaction (PCR) for the diagnosis of scrub typhus through a prospective comparison of eschar PCR results with indirect immunofluorescent antibody assay (IFA) results. METHODS: We conducted a multicenter prospective study involving patients with possible scrub typhus. Whole-blood samples and eschars were obtained for serological evaluation and PCR. A new crust was formed several days later at the site of the removed eschar. The newly formed crust was taken for performance of the second eschar PCR. Additional blood samples and eschars were collected, if possible, at 1-week intervals for 1 month after antibiotic treatment. RESULTS: We prospectively studied 135 patients with possible scrub typhus. Of these patients, 118 had scrub typhus confirmed on the basis of either a single indirect immunofluorescent specific immunoglobulin M titer against Orientia tsutsugamushi of > or = 1:10 or a > or = 4-fold increase in the follow-up titer. The results of nested PCR assay of the eschars demonstrated a sensitivity of 0.86 (95% confidence interval, 0.78-0.92) and a specificity of 1 (95% confidence interval, 0.05-1). Among the 50 patients who showed positive results of eschar PCR at admission, 46 (92%) also showed positive results for the follow-up PCR test of the newly formed eschar after the treatment with antibiotics. CONCLUSIONS: The eschar PCR assay was useful as a rapid and reliable test to confirm the diagnosis of scrub typhus, even though the patients received treatment with appropriate antibiotics, such as macrolides, quinolones, and tetracycline, which are all active against Orientia and Rickettsia species.

Adult↗

Identification of the target cells of Orientia tsutsugamushi in human cases of scrub typhus.

Orientia tsutsugamushi is the etiologic agent of scrub typhus, a chigger-borne zoonosis that is a highly prevalent, life-threatening illness of greatest public health importance in tropical Asia and the islands of the western Pacific Ocean. The target cell of this bacterium is poorly defined in humans. In this study, O. tsutsugamushi were identified by immunohistochemistry using a rabbit polyclonal antibody raised against O. tsutsugamushi Karp strain in paraffin-embedded archived autopsy tissues of three patients with clinical suspicion of scrub typhus who died during World War II and the Vietnam War. Rickettsiae were located in endothelial cells in all of the organs evaluated, namely heart, lung, brain, kidney, pancreas, and skin, and within cardiac muscle cells and in macrophages located in liver and spleen. Electron microscopy confirmed the location of rickettsiae in endothelium and cardiac myocytes.

Adult↗

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↗

Acute hearing loss due to scrub typhus: a forgotten complication of a reemerging disease.

We describe 6 patients with scrub typhus who presented with acute hearing loss, a forgotten complication of this reemerging disease. They were admitted with fever of 10-14 days' duration and had clinical evidence of deafness and pneumonitis. Five patients had eschars, which prompted the diagnosis of typhus fever and led to early institution of treatment. Deafness has been described as a clue to the diagnosis of scrub typhus; awareness of this symptom facilitated early diagnosis in 4 of 5 patients who recovered. Acute hearing loss or hearing impairment in a febrile patient should arouse strong suspicion of scrub typhus.

Acute Disease↗

Acute myocardial infarction following scrub typhus infection.

Up to recently, a few cases of myocarditis in the cardiac manifestations of scrub typhus have been reported. However, acute myocardial infarction (AMI) associated with scrub typhus has not been previously reported. We presented a case of AMI ensued on scrub typhus, which were successfully treated by percutaneous coronary intervention (PCI).

Humans↗

Usefulness of nested PCR for the diagnosis of scrub typhus in clinical practice: A prospective study.

The aims of this study were to determine the diagnostic accuracy and clinical usefulness of using nested polymerase chain reaction (PCR) for the diagnosis of scrub typhus through a prospective comparison of nested PCR and indirect immunofluorescent antibody assay (IFA). We conducted a multi-center prospective study of patients who were suffering with possible scrub typhus infection. Whole blood samples were collected for PCR testing, and sera were obtained for serology evaluation using the indirect IFA and the passive hemagglutination assay (PHA). We prospectively studied 135 patients with possible scrub typhus. One hundred eighteen patients were confirmed as having scrub typhus, 7 patients were undetermined, and 10 patients were confirmed as having other diseases. The results of nested PCR assay showed a sensitivity of 82.2% and a specificity of 100%. Ninety-six of the 118 patients were positive for IgM on their admission day. Of the 22 patients who were negative for IgM antibody at admission, 19 had positive results for nested PCR of the buffy coat. The nested PCR assay of the buffy coat is useful as a rapid and reliable test for confirming the diagnosis of scrub typhus.

Adolescent↗

Scrub typhus in Korea: importance of early clinical diagnosis in this newly recognized endemic area.

Scrub typhus became a well recognized infectious disease threat to military operations in the Pacific Theater during World War II. Early diagnosis and treatment with tetracycline or chloramphenicol dramatically reduces the mortality and morbidity of this disease. Korea is a newly recognized scrub typhus endemic country. We report our experience with 189 scrub typhus patients seen at a civilian outpatient clinic in Chinhae, Republic of Korea, from 1985 through 1990, and verify the accuracy of clinical diagnosis by serologic tests.

Adolescent↗

Scrub typhus in Japan: epidemiology and clinical features of cases reported in 1998.

Surveillance for scrub typhus was conducted in Japan in 1998 using a questionnaire. A total of 462 cases were reported. Scrub typhus occurred in both the fall and spring in the northern part of Honshu (the main island), and in the fall in the central part of Honshu and on the island of Kyushu. The occurrence of the disease varied with age, gender, and activity. Seventy-six percent of the patients were more than 51 years old, and 36% and 16% of the patients were engaged in farm work and forestry, respectively. Fever, rash, and eschar were detected in 98%, 93%, and 97% of the patients, respectively. Elevated levels of C-reactive protein, aspartate transaminase, and alanine transaminase were detected in 96%, 87%, and 77% of the patients, respectively. Disseminated intravascular coagulation developed in 34 cases and had a unique regional distribution. This study shows the status of scrub typhus in Japan in 1998 and provides important information for diagnosis and prevention.

Adolescent↗

Diagnosis of scrub typhus in Malaysian aborigines using nested polymerase chain reaction.

A rapid diagnostic system for scrub typhus using nested polymerase chain reaction (PCR) was applied to clinical samples from Malaysian Aborigines. Whole blood from twenty-four patients suspected of scrub typhus infection were tested using nested polymerase chain reaction and sera were evaluated by the indirect immunoperoxidase test. Antibody responses towards Rickettsia tsutsugamushi were observed in seventeen patients with the majority having high titers of IgG antibodies. Seven patients were seronegative. The nested PCR amplified R. tsutsugamushi DNA from six patients, of which two were negative serologically and four had high titers of IgG antibodies. Second samples collected seven days after treatment were negative by PCR testing. Nested PCR is highly sensitive and specific and may be used to provide rapid confirmation of scrub typhus cases in endemic region.

Adolescent↗

Usefulness of eschar PCR for diagnosis of scrub typhus.

We report here on the case of a child who was infected with scrub typhus, and we made the diagnosis according to the serology and by performing PCRs on the child's eschar. The patient was treated with azithromycin, and he did not experience any complications. Performing nested PCR on the eschar might be both a rapid diagnostic test for scrub typhus in the early acute stage and a differential test as to whether or not a scab is a scrub typhus eschar.

Antigens, Bacterial↗