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Diagnostic Approach to Rash and Fever in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Lee S. Engel, Charles V. Sanders, Fred A. Lopez
Clinical diagnosis is the basis for treatment. Serological testing is sensitive but does not distinguish between infection with R. rickettsii and other rickettsia of the spotted fever group [38,45]. Indirect fluorescent antibody testing is the best serological method available; however, the test has poor sensitivity during the first 710 days of disease onset. Sensitivity increases to greater than 90% when a convalescent serum is available 14–21 days later [43]. Direct immunofluorescence on tissue specimens has a sensitivity of about 70%. Polymerase chain reaction is limited because of poor sensitivity for detecting R. rickettsii DNA in blood [45]. It may be used to amplify DNA from a biopsy of a rash lesion [38]. The Weil-Felix test is no longer recommended because of poor sensitivity and specificity. When SFR is suspected, healthcare providers can send specimens via their state health departments to the Centers for Disease Control and Prevention (CDC) for testing by indirect immunofluorescence antibody, immunohistochemical assay, PCR, and cell culture [45].
Laboratory Diagnostic Tests in the Evaluation of Fever
Published in Benedict Isaac, Serge Kernbaum, Michael Burke, Unexplained Fever, 2019
The Weil-Felix test is included among “febrile agglutinins” for historical reasons, and is rarely helpful in evaluation of patients with obscure fever. The test becomes positive toward the end of the second week of typhus and spotted fever rickettsioses, and is negative in Q-fever, trench fever, and rickettsialpox. False-positive reactions may be encountered in leptospirosis, borreliosis, and Proteus infections.
Rocky Mountain Spotted Fever and Typhus Fever
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
Proteus OX 19, Weil-Felix reactions (WF) — In epidemic typhus and RMSF, agglutinins to Proteus OX 19 develop during the 2nd febrile week and reach their height by the 3rd to 4th weeks. The Proteus reaction does not distinguish between the spotted fever and typhus groups, but it is a dependable screen for their presence. A single titer of 160 to 320 is usually diagnostic, although the demonstration of a rise in titer in a reliable laboratory is more convincing. Proteus OX 19 agglutins fail to appear in 10% or more of patients with typhus or spotted fever. Moreover, when specific antibiotics are given early during the 1st febrile week, the titer will reach diagnostic levels but delayed by a week or more. The Weil-Felix test is nonspecific and false-positive reactions can occur in such conditions as Proteus bacillus urinary tract infections, leptospirosis, brucellosis, tularemia, and enteric, relapsing, and rat bite fevers.
Epidemic Retinitis with Macular Edema –Treatment Outcome with and without Steroids
Published in Ocular Immunology and Inflammation, 2021
Ankush Kawali, Sanjay Srinivasan, Ashwin Mohan, Bharathi Bavaharan, Padmamalini Mahendradas, Bhujang Shetty
Investigations revealed a positive Weil–Felix test (WFT – tube agglutination test used for diagnosis of rickettsial diseases) in eight and in nine patients in Groups 1 and 2, respectively. Few patients had multiple positive tests (Table 1). Six eyes in Group 1 and 7 eyes in Group 2 received topical corticosteroids (prednisolone 1%) six times per day in the tapering dose for anterior uveitis. Twelve eyes in Group 1 and 7 eyes in Group 2 received the topical non-steroidal anti-inflammatory drug (nepafenac 1 mg/ml). Eight patients received doxycycline (100 mg BD for 3 weeks) and six patients received ciprofloxacin (500 mg BD for 10 days) in Group 1. Thirteen patients received doxycycline with oral corticosteroids, one patient received ciprofloxacin followed by doxycycline with oral corticosteroids, and one patient received ciprofloxacin with oral corticosteroids in Group 2. In Group 1, six eyes received topical corticosteroids in tapering dose along with oral doxycycline (n = 3) and ciprofloxacin (n = 3).
Epidemic Retinitis
Published in Ocular Immunology and Inflammation, 2019
Ankush Kawali, Padmamalini Mahendradas, Ashwin Mohan, Madhurya Mallavarapu, Bhujang Shetty
Being a retrospective study, it was not possible to follow standard investigation and treatment protocol. Most of our cases tested positive for Weil–Felix test (WFT) but the gold standard test for rickettsia (immunofluorescence assay – IFA) was positive (spotted fever and typhus fever group at 1:128 dilution) only in 1 out of 3 patients. Scrub typhus IgM by ELISA and PCR was negative in all tested cases (n = 4). WNV serology (IgM ELISA, Sandwich ELISA) and aqueous (RT-LAMP assay) done in nine patients, tested negative (Table 1). Although IgG titers for Mumps, Measles and Rubella are nonspecific, in a pregnant female, rubella IgG titer was found to be significantly high (> 350). Interestingly multiple tests were positive in some individuals (Table 2). Out of 13 cases of thrombocytopenia, only 3 were suspected for dengue fever by their physician. AC Tap for PCR based detection of viruses (HSV n = 5, VZV n = 5, CMV n = 6, chikungunya n = 2, dengue n = 1, WNV n = 9), and PCR for scrub typhus (n = 4) was negative in all tested cases.
Detection of co-infection with Orientia tsutsugamushand and hemorrhagic fever with renal syndrome by next-generation sequencing
Published in International Journal of Neuroscience, 2023
Qianhui Xu, Wenyi Zhang, Qian Wang, Xuejun Fu, Jing Han, Ying Huang
Considering that the positive rate of the Weil-Felix test is significantly correlated with detection time and the specificity of the test is low for the early diagnosis, the NGS is helpful for the confirmation of the diagnosis of scrub typhus. In addition, clinicians need to be reminded to screen for common pathogens that may be co-infected, such as epidemic hemorrhagic fever. Our research supports the role of parasitic mites in the transmission of the Hantaan virus in nature. Lack of knowledge of co-infection may jeopardize the health of affected patients. Our study serves as a reminder of potential coinfection and provides clues for its detection.