Evaluation of PCR-based assay in human serum samples for diagnosis of fatal cases of spotted fever group rickettsiosis

Use of eschar swab DNA to diagnose Rickettsia conorii subspecies conorii infection in Crimea: A case report

Mediterranean spotted fever (MSF) has been diagnosed clinically in the Crimean Peninsula since the 1930s. We describe the recent illness of an elderly patient from Crimea who had developed a classic triad of MSF symptoms consisting of fever, maculopapular rash, and eschar. Clinical diagnosis of rickettsiosis was confirmed using real-time PCR and sequencing of 4 Rickettsia protein genes. The strain causing clinical illness was characterized as Rickettsia conorii subspecies conorii Malish 7. This report corroborates the utility of eschar swab material as a source of DNA for PCR-based diagnostics that enables timely patient treatment and management.

History and Current Status of Mediterranean Spotted Fever (MSF) in the Crimean Peninsula and Neighboring Regions along the Black Sea Coast

Mediterranean spotted fever (MSF) is a tick-borne rickettsiosis caused by Rickettsia conorii subspecies conorii and transmitted to humans by Rhipicephalus sanguineus ticks. The disease was first discovered in Tunisia in 1910 and was subsequently reported from other Mediterranean countries. The first cases of MSF in the former Soviet Union were detected in 1936 on the Crimean Peninsula. This review summarizes the historic information and main features of MSF in that region and contemporary surveillance and control efforts for this rickettsiosis. Current data pertinent to the epidemiology of the disease, circulation of the ticks and distribution of animal hosts are discussed and compared for each of the countries in the Black Sea basin where MSF occurs.

An Update on the Laboratory Diagnosis of Rickettsia spp. Infection

Rickettsia species causing human illness are present globally and can cause significant disease. Diagnosis and identification of this intracellular bacteria are challenging with many available diagnostic modalities suffering from several shortcomings. Detection of antibodies directed against Rickettsia spp. via serological methods remains widely used with a broad range of sensitivity and specificity values reported depending on the assay. Molecular methods, including polymerase chain reaction (PCR) testing, enables species-specific identification with a fast turnaround time; however, due to resource requirements, use in some endemic settings is limited. Reports on the use of next-generation sequencing (NGS) and metagenomics to diagnose Rickettsia spp. infection have been increasing. Despite offering several potential advantages in the diagnosis and surveillance of disease, genomic approaches are currently only limited to reference and research laboratories. Continued development of Rickettsia spp. diagnostics is required to improve disease detection and epidemiological surveillance, and to better understand transmission dynamics.

Confirming Rickettsia rickettsii as the etiological agent of lethal spotted fever group rickettsiosis in human patients from Espírito Santo state, Brazil

Although Espírito Santo state is considered an endemic area for Brazilian spotted fever (BSF) with related lethal cases, it also constitutes the only state of southeastern Brazil that currently lacks a specific confirmation of the specific rickettsial agent. In an attempt to a species level confirmation of the etiological agent of fatal rickettsiosis cases in Espírito Santo state, in this study we tested human sera obtained between 2015 to 2017 by means of qPCR and subsequent conventional PCR protocols targeting gltA (citrate synthase) and ompA (190-kDA outer membrane protein) rickettsial genes. All samples were found to contain rickettsial DNA through the citrate synthase qPCR protocol. By conventional PCR, rickettsial gltA and ompA specific DNA fragments were detected in 25% (one sample) and 50% (2 samples) of the screened sera, respectively. Obtained consensuses for each gene partial sequences were 100% identical to Rickettsia rickettsii gltA and ompA genes. The present study confirms for the first time R. rickettsii as the etiological agent of a lethal spotted fever group rickettsiosis in human patients from Espírito Santo state.

MODERN APPROACHES TO LABORATORY DIAGNOSIS OF RICKETTSIAL DISEASES

Abstract. We present a concise review of contemporary laboratory methods for diagnosis of rickettsioses with special emphasis on diseases known in Russian Federation. Classic and emerging rickettsioses are transmitted by a diverse and expanding group of arthropod vectors including ticks, fleas, lice and mites. While epidemiological and clinical clues can provide information important for initial suspicion of rickettsial infection, sensitive and specific laboratory methods are necessary for providing probable or confirmed diagnosis of the rickettsial infection. Accurate and rapid confirmation of rickettsial infection is important for ensuring proper clinical care and prompt initiation of antibiotic therapy. Correct identification of the etiology of rickettsial diseases is also important for early identification of clustered cases, novel foci of infections, and for timely initiation of public health responses to these potentially fatal infections.