Diagnosis Of Rickettsial Diseases Research Articles

Imported rickettsioses in German travelers.

Twenty-two cases of rickettsiosis imported to Germany (13 men, nine women, average age 42 years) in a 5-year period were analyzed retrospectively regarding the travel histories, symptoms and clinical findings, laboratory features and course of the disease. The two primary rickettsial diseases were boutonneuse fever (18 patients) and scrub typhus (three patients). One patient had murine typhus. The main symptom was fever in 91% followed by headache (64%), myalgia (40%), arthralgia (50%) and diarrhea (36%). The most frequent clinical finding was lymphadenopathy in 65%. Eschar was detectable in 55% of patients with Rickettsia conori infection and in one patient with Rickettsia tsutsugamushi infection. All patients with R. tsutsugamushi infection as well as 33% of the patients with R. conori infection had a macular exanthema. One patient with scrub typhus had pleural and pericardial effusions. Seventy-three percent had an increased ESR. Three patients had leucocytosis, three increased transaminases and two normochromic anemia. The incubation period for R. conori infection was 5 to 28 days (average 14 days), for R. tsutsugamushi infection 7 to 21 days (average 16 days). Twenty-one patients were treated with tetracycline or doxycycline, one with erythromycin. All patients were cured. One patient had a relapse. Due to the fact that the symptoms are often not characteristic and that the routine laboratory findings are of only marginal help, the diagnosis of rickettsial diseases is often not easy. A detailed travel history sometimes gives an important hint for diagnosis.

Developments in the diagnosis of rickettsial diseases

Developments in the diagnosis of rickettsial diseases

Serologic diagnosis of rickettsial diseases

Serologic diagnosis of rickettsial diseases

Diagnosis of rickettsial diseases: A perspective

Rickettsioses have nonspecific clinical manifestations, making them difficult to diagnose in a clinical setting. Laboratory testing is usually needed to confirm the diagnosis. Rickettsial isolation is a sensitive and specific diagnostic technique, but the hazards associated with handling pathogenic rickettsiae usually preclude isolation attempts in most laboratories. Rickettsiae can also be detected in infected tissues by fluorescein-labeled antisera or by immunoperoxidase staining, but these techniques lack sensitivity, except when applied to postmortem tissue specimens. However, rickettsial DNA can be detected in acute phase blood specimens by polymerase chain reaction (PCR) technology, and this technique offers the prospect of prompt diagnosis and treatment. Serologic testing remains the most frequently used approach to diagnosis, although antibody tests usually fail to identify rickettsioses early enough to affect the management of individual patients. Available serologic techniques vary considerably in their sensitivity and specificity. Enzyme-linked immunosorbent assays (ELISA) are extremely sensitive, but the general unavailability of specific diagnostic antigens reduces the specificity of this and other serologic techniques. Molecular characterization of rickettsial antigens may soon allow the production of peptide antigens that are specific for each species and could maximize the specificity of test results. No diagnostic technique has any value unless it is applied successfully to the appropriate patient population. Improved surveillance of rickettsial diseases is urgently needed to identify specific areas in which rickettsioses are endemic. Such surveillance data would promote awareness of rickettsioses among local physicians and increase the probability that individual patients with rickettsioses would be identified promptly and receive appropriate therapy early in the course of their illness.

The role of the World Health Organization in the control of rickettsial diseases

The World Health Organization (WHO) pays great attention to the problem of rickettsial diseases. A network exists of Collaborating Centres for Rickettsial Reference and Research, which are designated by WHO. A WHO Consultation on the Laboratory Diagnosis of Rickettsial Diseases was held in 1987. In accordance with the recommendations of this consultative group, WHO first established The Project on Global Surveillance System for Rickettsial Diseases, with the immediate objective of obtaining reliable data on the global prevalence and distribution of rickettsial diseases. This information should contribute directly to the principal objective of reducing morbidity and mortality due to rickettsial diseases. An additional objective is to identify and characterize strains of pathogenic rickettsiae from various localities throughout the world. The final objective of the above study is to transfer the existing diagnostic technology to laboratories in developing countries. Under the auspices of this Project a diagnostic kit was developed for identification of antibodies with antigens of R. prowazekii and R. conorii in the indirect immunofluorescence test. About 20 laboratories in various countries are participating in this Project. Training courses have been organized for participants from countries in Africa and South-East Asia. The first stage of the Project will be evaluated in 1991 and, depending on the outcome of the first stage, a larger programme would be considered for subsequent years.

The Weil-Felix Test Is Archaic and Misleading

To the Editor.— Zuerlein and Smith 1 have appropriately recommended that the Widal group of febrile agglutinin tests should be abandoned because of their dismal predictive value. They unfortunately did not heed their own data or the past recommendations of others 2-4 also to abandon the equally archaic and misleading Weil-Felix reactions. Numerous studies have clearly demonstrated the lack of sensitivity and specificity exhibited by these tests in the diagnosis of rickettsial disease. While mentioning complement fixation as an alternative test along with direct fluorescent antibody testing of biopsy specimens, the authors appear to be unaware of a much more sensitive and specific test now available, the microimmunofluorescent test. 5 This test is available, usually with a 24- to 48-hour turnaround time, from most of the larger commercial reference laboratories. It is an indirect fluorescent antibody test that utilizes either a single dilution (screening test) or multiple dilution (quantitative titer)

The Diagnosis of Rickettsial Diseases: Report of an Unusual Case with Jaundice

The Diagnosis of Rickettsial Diseases: Report of an Unusual Case with Jaundice