Diagnosis of Queensland tick typhus and African tick bite fever by PCR of lesion swabs.
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ABSTRACT:
SUBMITTER: Wang JM
PROVIDER: S-EPMC2727311 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:African tick bite fever is an emerging infectious disease among travellers caused by the pathogen Rickettsia africae. Most travel-associated cases have been reported from countries in southern Africa. So far it has rarely been reported among travellers to eastern Africa and our patient is one of the first described cases imported from Tanzania. A woman presented with fever, chills, headache, myalgia and a rickettsial eschar on her ankle after returning from Tanzania. The diagnosis of African tick bite fever is often based on clinical grounds due to a lack of reliable diagnostic tests at commencement of symptoms. In this patient direct molecular detection of R. africae was performed by PCR from a sample obtained non-invasively with a swab from the rickettsial eschar. A positive PCR result was achieved although the patient had already started antibiotic treatment with doxycycline. In conclusion, this non-invasive method enables early diagnosis of African tick bite fever by direct molecular detection of R. africae and might improve the management of undifferentiated fever in travellers from Africa.
| S-EPMC5010599 | biostudies-literature
Project description:In testing paired serum samples from 40 consecutive cases of African tick bite fever, we detected diagnostic antibodies against spotted fever group rickettsiae in 45% of the patients by immunofluorescence assay (IFA) and in 100% of the patients by Western blotting (WB) (P < 0.01). A specific diagnosis of Rickettsia africae infection could be established in 15% of the patients by IFA and in 73% of the patients by a combination of WB and cross-adsorption assays (P < 0.01).
| S-EPMC440600 | biostudies-other
Project description:A confirmed case of rickettsiosis acquired in South Africa and recognized in Poland was described. The patient fulfilled clinical criteria highly suggestive of African tick bite fever, such as eschars, regional lymphadenitis, cutaneous rash within 10 days after his return from sub-Saharan Africa. Infection with Rickettsia africae was confirmed by polymerase chain reaction and sequencing.
| S-EPMC3907904 | biostudies-literature
Project description:We report a clinical case of African tick-bite fever in a Brazilian traveler right after his return from South Africa. Definitive diagnosis was supported by seroconversion between acute-phase and convalescent-phase serum samples, detection of rickettsial DNA in skin lesions, and in vitro culture of Rickettsia africae from the patient's skin. Most of the previous reported cases of African tick-bite fever were confirmed solely by serological or/and molecular methods. Through this first confirmed case of African tick-bite fever in Brazil, it is quite possible that other cases are occurring unnoticed by the health authorities, requiring a greater vigilance in traveler's medicine in South America.
| S-EPMC5956635 | biostudies-literature
Project description:Introduction: African tick-bite fever, caused by Rickettsia africae, is endemic in rural areas of sub-Saharan Africa and a possible cause of fever in returning Swedish travellers. Two patients are presented, and the advantages and disadvantages of different diagnostic methods are discussed. Patients and methods: Two middle-aged men fell ill with fever after returning home from South Africa. Both had single eschars and one also presented with a lymph node swelling. Samples were taken for serology, general bacterial culture from the wound (Patient 1) using a swab and additionally for Patient 2 PCR of a skin biopsy from the eschar. Results and discussion: Both patients seroconverted one month after onset. Real-time PCR of the biopsy was positive, where sequencing of the gltA gene was 99-100% consistent with R. africae. A drop of fluid from the biopsy contained a sufficient number of bacteria to also allow for isolation of rickettsiae in Vero cell culture. Direct molecular detection by PCR from a swab used for bacteria culture from the eschar from Patient 1 also yielded a positive result. In conclusion, the findings highlight the usefulness of swabs for early non-invasive diagnosis of African tick-bite fever in febrile travellers.
| S-EPMC5549825 | biostudies-literature
Project description:Background: Ticks transmit a plethora of pathogens of zoonotic implications. Their distribution, diversity and the pathogens they transmit differ from one ecological location to another. Rickettsia africae is the agent of African tick bite fever found in South Africa, a zoonotic infection that is frequently reported among travelers who have visited many sub-Saharan African countries where the pathogen is prevalent. Methods: Ticks were collected from domestic animals in Raymond Nkandla Municipality, Eastern Cape, South Africa. The ticks were identified morphologically prior to DNA extraction followed by molecular identification of randomly selected ticks from the morphologically delineated groups. To assess for the presence of tick-borne pathogens belonging to Rickettsia spp. by PCR (polymerase chain reaction), we used specific primer pairs targeting the gltA, ompA and ompB genes. The selected amplified ticks, all positive ompB and forty three ompA amplicons were sequenced in a commercial sequencing facility. The obtained nucleotide sequences were edited and subjected to BLASTn for homology search and phylogenetic analyses were performed with MEGA 7 Version for genetic relationships with curated reference sequences in GenBank. Results: A total of 953 ticks collected in the study were delineated into three genera consisting of Amblyomma, Rhipicephalus and Hyalomma in decreasing order of abundance. The presence of rickettsial DNA was detected in 60/953 (6.3%) from the three genera of ticks screened. Genetic analyses of the DNA sequences obtained showed that they have phylogenetic relationship to members of the spotted fever group rickettsiae with R. africae, being the predominant SFGR (spotted fever group rickettsiae) detected in the screened ticks. Conclusion: This report shows that R. africae is the predominant spotted fever group rickettsiae in ticks collected from domestic animals in the study area and the human health impacts are not known.
| S-EPMC7459594 | biostudies-literature
Project description:Colorado tick fever (CTF) virus elicits an acute illness in humans, producing nonspecific flu-like symptoms and a biphasic fever in approximately 50% of patients. The disease is transmitted by the adult Rocky Mountain wood tick (Dermacentor andersoni), and therefore incidence is limited by the habitat and life cycle of that vector. The early symptoms of infection are difficult to distinguish from those of several other agents, especially Rickettsia rickettsii. Serologic testing is usually unable to provide evidence of CTF viral infection during the acute phase because of the late appearance of the various antibodies. Here we report the development and clinical application of a test to diagnose this disease during the acute stages. Oligonucleotide primers to the S2 segment of CTF (Florio) virus were made, and these were used in the amplification of a 528-bp fragment of DNA, transcribed from the double-stranded CTF virus RNA template by reverse transcriptase PCR. RNAs processed from 16 CTF virus isolates yielded similar results when analyzed on agarose gels. These were distinguishable from their antigenic relatives Eyach, S6-14-03, and T5-2092 and from other coltiviruses and an orbivirus but not from the antigenically distinct CTF virus-related isolate 720896. A mouse model demonstrated the utility of this method with whole-blood specimens, and CTF virus was successfully detected in human sera from the initial day of the onset of symptoms to 8 days later. The reverse transcriptase PCR method is a promising tool for the early diagnosis of CTF viral infection, or for ruling out CTF virus as the etiologic agent, in order to facilitate appropriate medical support.
| S-EPMC232730 | biostudies-other
Project description:Alpha-gal syndrome (AGS) is a delayed allergic response to red meat caused by the production of alpha-gal-specific IgE following certain tick bites. We designed this study to characterize the underlying immune response to tick bites associated with AGS. Our results suggest that Amblyomma americanum bites direct mouse immunity toward Th2 following the initial burst of proinflammatory response and facilitate host sensitization to the α-gal antigen.
2024-01-09 | GSE249650 | GEO
Project description:A fluorogenic probe hydrolysis (TaqMan) PCR assay for African swine fever virus (ASFV) was developed and evaluated in experimentally infected swine. This sensitive and specific one-step single-tube assay, which can be performed in 2 h or less, detected viral DNA in tonsil scraping samples 2 to 4 days prior to onset of clinical disease. Thus, the assay would have application for preclinical diagnosis of African swine fever and surveillance and/or emergency management of a disease outbreak.
| S-EPMC540100 | biostudies-literature
Project description:BackgroundIncreasing numbers of tick-borne pathogens are being discovered, including those that infect humans. However, reports on co-infections caused by two or more tick-borne pathogens are scarce.Case presentationA 38-year-old male farmer was bitten by a hard tick, presented with fever (37.7 °C), severe headache and ejection vomiting. Lumbar puncture was performed in the lateral decubitus. The cerebrospinal fluid (CSF) was clear, and analysis showed severe increased pressure (320 mm H2O), mild leukocytosis (126.0 × 106/L, mononuclear cells accounting for 73%) and elevated total protein concentration (0.92 g/L). Bacterial cultures of CSF and blood were negative. The diagnosis of Rickettsia raoultii and Tacheng tick virus 1 (TcTV-1) co-infection was confirmed by amplifying four rickettsial genetic markers and the partial small (S) RNA segment of TcTV-1 from the patient's blood. The patient gradually recovered after treatment with levofloxacin and ribavirin.ConclusionsThis is the first reported co-infection case with fever and meningitis caused by R. raoultii and TcTV-1. It is vital to screen for multiple pathogens in tick-bitten patients, especially in those with severe complex symptoms.
| S-EPMC8620164 | biostudies-literature