Project description:We report a series of 5 case-patients who had Israeli spotted fever, of whom 2 had purpura fulminans and died. Four case-patients were given a diagnosis on the basis of PCR of skin biopsy specimens 3-4 days after treatment with doxycycline; 1 case-patient was given a diagnosis on the basis of seroconversion. Rickettsia spp. from the 2 case-patients who died were sequenced and identified as Rickettsia conorii subsp. israelensis. Purpura fulminans has been described in association with R. rickettsii and R. indica, but rarely with R. conorii subsp. israelensis.
Project description:Rickettsia microorganisms are causative agents of several neglected emerging infectious diseases in humans transmitted by arthropods including ticks. In this study, ticks were collected from four geographical regions of Uganda and pooled in sizes of 1-179 ticks based on location, tick species, life stage, host, and time of collection. Then, they were tested by real-time PCR for Rickettsia species with primers targeting gltA, 17kDa and ompA genes, followed by Sanger sequencing of the 17kDa and ompA genes. Of the 471 tick pools tested, 116 (24.6%) were positive for Rickettsia spp. by the gltA primers. The prevalence of Rickettsia varied by district with Gulu recording the highest (30.1%) followed by Luwero (28.1%) and Kasese had the lowest (14%). Tick pools from livestock (cattle, goats, sheep, and pigs) had the highest positivity rate, 26.9%, followed by vegetation, 23.1%, and pets (dogs and cats), 19.7%. Of 116 gltA-positive tick pools, 86 pools were positive using 17kDa primers of which 48 purified PCR products were successfully sequenced. The predominant Rickettsia spp. identified was R. africae (n = 15) in four tick species, followed by R. conorii (n = 5) in three tick species (Haemaphysalis elliptica, Rhipicephalus appendiculatus, and Rh. decoloratus). Rickettsia conorii subsp. israelensis was detected in one tick pool. These findings indicate that multiple Rickettsia spp. capable of causing human illness are circulating in the four diverse geographical regions of Uganda including new strains previously known to occur in the Mediterranean region. Physicians should be informed about Rickettsia spp. as potential causes of acute febrile illnesses in these regions. Continued and expanded surveillance is essential to further identify and locate potential hotspots with Rickettsia spp. of concern.
Project description:A retrospective analysis by molecular-sequence-based techniques was performed to correctly identify the etiological agent of 24 Mediterranean spotted fever cases occurring in Western Sicily, Italy, from 1987 to 2001. Restriction analysis of a 632-bp PCR-amplified portion of the ompA gene allowed presumptive identification of five clinical isolates as belonging to Rickettsia conorii subsp. israelensis, the etiological agent of Israeli spotted fever (ISF). The remaining 19 rickettsial isolates were Rickettsia conorii subsp. conorii, the only pathogenic rickettsia of the spotted fever group reported in Italy until the present. Sequence analysis of the ompA gene confirmed the identification of all the R. conorii subsp. israelensis isolates and demonstrated that rickettsiosis caused by R. conorii subsp. israelensis can be traced back to 1991 in Sicily. The recorded clinical data of the five ISF patients support the idea that these strains could correlate to more-severe forms of human disease. Three of five patients experienced severe disease, and one of them died.
Project description:We investigated 2 fatal cases of Rocky Mountain spotted fever that occurred in 2003 and 2004 near the same locality in Colombia where the disease was first reported in the 1930s. A retrospective serosurvey of febrile patients showed that > 21% of the serum samples had antibodies aaainst spotted fever group rickettsiae.
Project description:We describe a fatal pediatric case of Rocky Mountain spotted fever in Panama, the first, to our knowledge, since the 1950s. Diagnosis was established by immunohistochemistry, PCR, and isolation of Rickettsia rickettsii from postmortem tissues. Molecular typing demonstrated strong relatedness of the isolate to strains of R. rickettsii from Central and South America.
Project description:We describe the first case of Japanese spotted fever and the first isolate of spotted fever group rickettsia from a patient in South Korea. The isolated rickettsia from the patient was identified as Rickettsia japonica by analysis of the nucleotide sequences of 16S rRNA, gltA, ompA, ompB, and sca4 genes.
Project description:Spotted Fever Group Rickettsiae (SFGR) can cause mild to fatal illness. The early interaction between the host and rickettsia in skin is largely unknown, and the pathogenesis of severe rickettsiosis remains an important topic. A surveillance of SFGR infection by PCR of blood and skin biopsies followed by sequencing, and immunohistochemical detection was performed on patients with a recent tick bite from 2013–2016. Humoral and cutaneous immune profiles were evaluated for different SFGR cases by serum cytokine and chemokine detection, skin immunohistochemical (IHC) staining, and transcriptome sequencing (RNA-seq). A total of 111 SFGR cases were identified, including 79 Candidatus Rickettsia tarasevichiae (CRT), 22 R. raoultii, 8 R. sibirica, and 2 R. heilongjiangensis. The sensitivity to detect SFGR in skin biopsies (9/24, 37.5 %) was significantly higher than in blood samples (105/2671, 3.9 %) (p<0.05). As early as one day after the tick bite, rickettsia could be detected in the skin. R. sibirica infection was more severe than CRT and R. raoultii. Increased levels of serum IL18, IP10, and MIG, and decreased IL2 in R. sibirica febrile patients were observed compared to CRT febrile infections. RNA-seq and IHC staining could not discriminate SFGR infected and uninfected tick-fed skin lesions. The type I interferon (IFN) response was differently expressed between R. sibirica and R. raoultii infection at the cutaneous interface. Severe rickettsiosis might be inclined to induce an increased type I IFN response on the infected skin but which were complicated by the bite of a tick eliciting immune cell infiltration.
Project description:Rickettsiae were isolated by cell culture of buffy coat blood from six patients with spotted fever from southeastern Australia and Flinders Island in Bass Strait. The isolates were genetically compared with two previous Rickettsia australis patient isolates. The genus-specific 17-kDA genes from the isolates were compared after DNA amplification and restriction fragment analysis of the amplified DNA. This comparison revealed that mainland rickettsial isolates from southeastern Australia were identical to two previous isolates of R. australis from northeastern Australia. Rickettsial isolates from Flinders Island were distinct from the mainland isolates. The 16S rRNA gene sequences from the isolates were determined and compared. The Flinders Island rickettsial agent was most closely related (0.3% structural divergence) to Rickettsia rickettsii, Rickettsia conorii, and Rickettsia slovaca. The Flinders Island rickettsial agent was 1.3 and 2.1% structurally divergent from R. australis and Rickettsia akari, respectively. The 16S rRNA gene sequence from the Flinders Island agent shows that this rickettsia is more closely related to the rickettsial spotted fever group than is R. australis. We conclude that there are two populations of spotted fever group rickettsiae in Australia and propose that the genetically distinct causative organism of Flinders Island spotted fever be designated Rickettsia honei. The extent of distribution and animal host reservoirs remain to be elucidated.