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PLoS Neglected Tropical Diseases May 2022Murine typhus, which is caused by Rickettsia typhi, has a wide range of clinical manifestations. It has a low mortality rate but may result in meningoencephalitis and...
Murine typhus, which is caused by Rickettsia typhi, has a wide range of clinical manifestations. It has a low mortality rate but may result in meningoencephalitis and interstitial pneumonia in severe cases. Comparisons of complete genome sequences of R. typhi isolates from North Carolina, USA (Wilmington), Myanmar (B9991PP), and Thailand (TH1527) identified only 26 single nucleotide polymorphism (SNP) and 7 insertion-deletion (INDEL) sites in these highly syntenic genomes. Assays were developed to further define the distribution of these variant sites among 15 additional isolates of R. typhi with different histories from Asia, the USA, and Africa. Mismatch amplification mutation assays (MAMA) were validated for 22 SNP sites, while the 7 INDEL sites were analyzed directly on agarose gels. Six SNP types, 9 INDEL types, 11 total types were identified among these 18 isolates. Replicate DNA samples as well as comparisons of isolates with different passage and source histories gave consistent genetic typing profiles. Comparison of the SNP and INDEL markers to R. typhi's nearest neighbor Rickettsia prowazekii demonstrated that the majority of the SNPs represent intra-species variation that arose post divergence of these two species while several INDEL sites also exhibited intraspecies variability among the R. prowazekii genomes that have been completely sequenced. The assays for the presence of these SNP and INDEL sites, particularly the latter, comprise a low technology gel method for consistently distinguishing R. typhi and R. prowazekii as well as for differentiating genetic types of R. typhi.
Topics: Animals; Mice; Rickettsia; Rickettsia prowazekii; Rickettsia typhi; Sequence Analysis, DNA; Thailand; Typhus, Endemic Flea-Borne
PubMed: 35639778
DOI: 10.1371/journal.pntd.0010354 -
Research and Reports in Tropical... 2018In this paper, we present a historical review of rickettsiosis in Central America and also the most recent findings of in ectoparasites. All countries of Central... (Review)
Review
In this paper, we present a historical review of rickettsiosis in Central America and also the most recent findings of in ectoparasites. All countries of Central America have records of rickettsiosis. Regarding the typhus group rickettsioses, there is clinical or serological evidence of in Guatemala, in Panama, Guatemala, and Costa Rica and unidentified species of the typhus group in El Salvador. Concerning spotted fever group rickettsiosis, there is serological evidence of infection by in Costa Rica and confirmed cases involving in Panama and Costa Rica. There are also reports of spotted fever group rickettsiosis in acute patients from Guatemala, Honduras, and Nicaragua. Serological studies in Central America show reactivity of , , , , and in domestic and wild mammals. Eight species of have been detected in ectoparasites from Central America: (or very similar), , , , , , , and , in addition to undescribed strains such as Atlantic Rainforest, Colombianensi, IbR/CRC, Barva, Aragaoi, and "Rickettsia nicoyana;" the latter being the only one associated with Argasidae (). is the most common species in Central America, seeing as it has been reported in 10 species of ticks and one of fleas in five of the seven countries of the region. In this study, we demonstrate that the genus is widely distributed in Central America and that rickettsiosis could be an underestimated problem in the absence of greater diagnostic efforts in undetermined febrile cases.
PubMed: 30050361
DOI: 10.2147/RRTM.S160951 -
Vector Borne and Zoonotic Diseases... Apr 2024Flea-borne rickettsioses, collectively referred to as a term for etiological agents , , and RFLOs (-like organisms), has become a public health concern around the...
Flea-borne rickettsioses, collectively referred to as a term for etiological agents , , and RFLOs (-like organisms), has become a public health concern around the world, specifically in the United States. Due to a shared arthropod vector (the cat flea) and clinical signs, discriminating between species has proven difficult. While the effects of microbial coinfections in the vector can result in antagonistic or synergistic interrelationships, subsequently altering potential human exposure and disease, the impact of bacterial interactions within flea populations remains poorly defined. In this study, and systems were utilized to assess rickettsial interactions in arthropods. Coinfection of both and within a tick-derived cell line indicated that the two species could infect the same cell, but distinct growth kinetics led to reduced growth over time, regardless of infection order. Sequential flea coinfections revealed the vector could acquire both spp. and sustain coinfection for up to 2 weeks, but rickettsial loads in coinfected fleas and feces were altered during coinfection. Altered rickettsial loads during coinfection suggest and interactions may enhance the transmission potential of either agent. Thus, this study provides a functional foundation to disentangle transmission events propelled by complex interspecies relationships during vector coinfections.
Topics: Animals; Humans; Cats; Rickettsia typhi; Rickettsia felis; Ctenocephalides; Coinfection; Rickettsia; Siphonaptera; Flea Infestations; Felis; Cat Diseases
PubMed: 38422214
DOI: 10.1089/vbz.2023.0122 -
Tropical Medicine and Infectious Disease Feb 2022The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (), human monocytic ehrlichiosis (), scrub typhus... (Review)
Review
The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (), human monocytic ehrlichiosis (), scrub typhus (), epidemic typhus (), murine typhus (), Mediterranean spotted fever (), or Rocky Mountain spotted fever (). These diseases are gaining a new momentum given their resurgence patterns and geographical expansion due to the overall rise in temperature and other human-induced pressure, thereby remaining a major public health concern. As obligate intracellular bacteria, Rickettsiales are characterized by their small genome sizes due to reductive evolution. Many pathogens employ moonlighting/multitasking proteins as virulence factors to interfere with multiple cellular processes, in different compartments, at different times during infection, augmenting their virulence. The utilization of this multitasking phenomenon by Rickettsiales as a strategy to maximize the use of their reduced protein repertoire is an emerging theme. Here, we provide an overview of the role of various moonlighting proteins in the pathogenicity of these species. Despite the challenges that lie ahead to determine the multiple potential faces of every single protein in Rickettsiales, the available examples anticipate this multifunctionality as an essential and intrinsic feature of these obligates and should be integrated into available moonlighting repositories.
PubMed: 35202227
DOI: 10.3390/tropicalmed7020032 -
Journal of the Pediatric Infectious... Apr 2021Lipschutz ulcers (LU) present as painful genital ulcers in nonsexually active females. Associated infections include Epstein Barr virus, Mycoplasma pneumoniae,...
Lipschutz ulcers (LU) present as painful genital ulcers in nonsexually active females. Associated infections include Epstein Barr virus, Mycoplasma pneumoniae, Cytomegalovirus, and influenza. To our knowledge, this is the first report of LU occurring with murine typhus. Murine typhus is caused by Rickettsia typhi, a Gram-negative, obligate intracellular organism. Rat fleas (Xenopsylla cheopis) are the classic vector, although cat fleas (Ctenocephalides felis) found on cats, dogs, and opossums have been implicated in maintaining the life cycle of R. typhi in suburban areas. Murine typhus can have a nonspecific presentation making a strong index of suspicion crucial to its diagnosis. The most common presenting signs include fever, poor appetite, malaise, and headache. Laboratory abnormalities may include elevated C-reactive protein, elevated erythrocyte sedimentation rate, hypoalbuminemia, elevated transaminases, elevated neutrophil band count, and thrombocytopenia. The treatment of choice for R. typhi is doxycycline.
Topics: Animals; Dogs; Epstein-Barr Virus Infections; Female; Herpesvirus 4, Human; Humans; Mice; Rats; Rickettsia typhi; Siphonaptera; Typhus, Endemic Flea-Borne
PubMed: 33269795
DOI: 10.1093/jpids/piaa138 -
Veterinary World Aug 2023Scrub typhus and murine typhus are globally distributed zoonoses caused by the intracellular Gram-negative bacteria and , respectively. Numerous studies have been...
BACKGROUND AND AIM
Scrub typhus and murine typhus are globally distributed zoonoses caused by the intracellular Gram-negative bacteria and , respectively. Numerous studies have been undertaken on rickettsial illnesses in humans and animals, including arthropod vectors, in Thailand. However, the reports on the seroprevalence of antibodies to and in buffaloes is extremely rare. Thus, this study aimed to estimate the seroprevalence of both rickettsial infections in water buffaloes () in Phatthalung Province, southern Thailand.
MATERIALS AND METHODS
From February to March 2023, a total of 156 serum samples were collected from 156 water buffaloes on 29 farms in Phatthalung province. The sera were screened for antibodies against and using an indirect immunofluorescence assay.
RESULTS
The seroprevalence of antibodies against and in individual water buffaloes was 4.49% (95% confidence interval [CI]: 2.19%-8.97%) and 3.85% (95% CI: 1.77%-8.14%), respectively, whereas 31% (9/29) of the herds had buffaloes with antibodies. The number of buffaloes with scrub typhus infection and ectoparasite infestation was statistically significant (p < 0.05; odds ratio = 6.25 [95% CI: 1.19-33.33]). Intriguingly, the prevalence of scrub typhus antibodies in buffaloes that were not infested with ectoparasites was much higher than those that were.
CONCLUSION
This is the first report of and antibodies in water buffalo sera in Southern Thailand. Two serum samples showed a high antibody titer against . Seroprevalence mainly occurred in non-ectoparasite-infested buffaloes, especially for antibodies. At the herd level, one-third of the studied farms showed seroprevalence. Additional research on the occurrence of these pathogens in vectors and in other animal reservoirs is necessary.
PubMed: 37766717
DOI: 10.14202/vetworld.2023.1600-1604 -
Travel Medicine and Infectious Disease 2016To review the current state of knowledge concerning rickettsiae and rickettsioses in Croatia and to discuss their implications for travellers. (Review)
Review
AIM
To review the current state of knowledge concerning rickettsiae and rickettsioses in Croatia and to discuss their implications for travellers.
METHODS
The PubMed database was searched from 1991 to 2015 by combining the words "rickettsia," "rickettsiosis", "travellers" and "Croatia".
RESULTS
Since 1969, Croatia appears to be free of epidemic typhus (ET) caused by Rickettsia prowazekii and the last case of Brill-Zinsser disease was recorded in 2008. Mediterranean spotted fever (MSF) caused by Rickettsia conorii is the most frequent human rickettsial infection in Croatia, followed by murine typhus caused by Rickettsia typhi. Human cases of MSF and murine typhus have been predominantly observed along the eastern Adriatic coast from Zadar to Dubrovnik and between Zadar and Split, respectively. Rickettsia akari, etiologic agent of rickettsialpox, was isolated from blood of a patient diagnosed with MSF in Zadar, but no cases of rickettsialpox were reported. Several species of pathogenic (Rickettsia slovaca, Rickettsia aeschlimannii, Ricketsia helvetica, and Ricketsia raoultii) and species of undetermined pathogenicity (Ricketsia hoogstraalii sp. nov.) rickettsiae were identified in ticks collected in different ecological regions of Croatia. A search of the literature revealed no evidence of rickettsial infection in travellers visiting Croatia. Three imported cases of Rickettsia africae were observed in travellers returning from South Africa.
CONCLUSION
Rickettsiae and rickettsial diseases continue to be present in Croatia. As they can be acquired while travelling, physicians should consider rickettsial infection in the differential diagnosis of patients returning from Croatia and presenting with febrile illness.
Topics: Adult; Animals; Boutonneuse Fever; Croatia; Female; Humans; Male; Mice; Rickettsia; Rickettsia Infections; South Africa; Ticks; Travel; Travel Medicine; Typhus, Endemic Flea-Borne
PubMed: 27404664
DOI: 10.1016/j.tmaid.2016.06.010 -
Emerging Infectious Diseases Jul 2018Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form...
Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus, is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluorescence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.
Topics: Adolescent; Adult; Aged; Animals; Child; Child, Preschool; Exanthema; Female; Germany; Global Health; History, 21st Century; Humans; Male; Mice; Middle Aged; Molecular Diagnostic Techniques; Public Health Surveillance; Rickettsia typhi; Serologic Tests; Siphonaptera; Typhus, Endemic Flea-Borne; Young Adult; Zoonoses
PubMed: 29912688
DOI: 10.3201/eid2407.180093 -
MSphere May 2021Species of (: ) are obligate intracellular parasites of a wide range of eukaryotes, with recognized arthropod-borne human pathogens belonging to the transitional group...
Species of (: ) are obligate intracellular parasites of a wide range of eukaryotes, with recognized arthropod-borne human pathogens belonging to the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae. Growing in the host cytosol, rickettsiae pilfer numerous metabolites to make a typical Gram-negative bacterial cell envelope. The O-antigen of rickettsial lipopolysaccharide (LPS) is immunogenic and has been shown to tether the S-layer to the rickettsial surface; however, little is known about the structure and immunogenicity of the lipid A moiety. The structure of lipid A, the membrane anchor of LPS, affects the ability of this molecule to interact with components of the host innate immune system, specifically the MD-2/TLR4 receptor complex. To dissect the host responses that can occur during and infection, structural analysis of lipid A is needed. Lipid A was extracted from four species and structurally analyzed. (TRG), (TG), and (SFG) produced a similar structure, whereas (SFG) altered the length of a secondary acyl group. While all structures have longer acyl chains than known highly inflammatory hexa-acylated lipid A structures, the modification should differentially alter interactions with the hydrophobic internal pocket in MD2. The significance of these characteristics toward inflammatory potential as well as membrane dynamics between arthropod and vertebrate cellular environments warrants further investigation. Our work adds lipid A to the secretome and O-antigen as variable factors possibly correlating with phenotypically diverse rickettsioses. Spikes in rickettsioses occur as deforestation, urbanization, and homelessness increase human exposure to blood-feeding arthropods. Still, effective vaccines remain elusive. Recent studies have determined that lipopolysaccharide anchors the protective S-layer to the bacterial surface and elicits bactericidal antibodies. Furthermore, growing immunological evidence suggests vertebrate sensors (MD-2/TLR4 and noncanonical inflammasome) typically triggered by the lipid A portion of lipopolysaccharide are activated during infection. However, the immunopotency of lipid A is unknown due to poor appreciation for its structure. We determined lipid A structures for four distinct rickettsiae, revealing longer acyl chains relative to highly inflammatory bacterial lipid A. Surprisingly, lipid A of the Rocky Mountain spotted fever agent deviates in structure from other rickettsiae. Thus, lipid A divergence may contribute to variable disease phenotypes, sounding an alarm for determining its immunopotency and possible utility (i.e., as an adjuvant or anti-inflammatory) for development of more prudent rickettsiacidal therapies.
Topics: Humans; Lipid A; Rickettsia; Rickettsia Infections
PubMed: 33952661
DOI: 10.1128/mSphere.00184-21 -
Journal of Global Infectious Diseases 2022Co-infection with different agents such as bacterial, viral, and Rickettsia is being increasingly recognized due to greater availability and utilization of the...
INTRODUCTION
Co-infection with different agents such as bacterial, viral, and Rickettsia is being increasingly recognized due to greater availability and utilization of the diagnostic tests among malaria patients.
METHODS
Consecutive admitted malarial cases were included and were subjected to test for general investigations, bacteria, typhoid, dengue, chikungunya, and rest for specific diagnosis. All patients were followed up till discharge or death and appropriate statistical tests were performed.
RESULTS
A total of 152 malaria patients were recruited and 27 (18.8%) had concurrent infections. It included 40.7% dengue only, 18.7% pneumonia, 11.1% urinary tract infection (UTI), 7.4% enteric fever, 3.7% leptospirosis, chikungunya, and tuberculous meningitis each, and 3.7% each of dengue with pneumonia and UTI. The organisms isolated were and The mean duration of fever was 6.33 ± 3.63 days with a range of 3-20 days. Blood culture grew in 2 cases and Dengue co-infections had significantly higher clinical and laboratory features of dengue and complications such as bleeding, jaundice, and cholecystitis, whereas rest concurrent infections had a significantly higher proportion of nausea and vomiting, convulsion, altered sensorium, productive cough, urinary symptoms, shock, acute kidney injury, anemia, and mean neutrophil count. There was significantly higher mortality among malaria-dengue concurrent infection group with 2 (15.4%) than malaria mono-infection group 3 (2.4%).
CONCLUSION
Co-infections with malaria are not uncommon, especially dengue fever and other bacterial infections. The dominant clinical picture is of the superimposed infection. Decision should be clinically guided adjunct with specific diagnostic tests, and timely treatment has favorable outcome.
PubMed: 35910822
DOI: 10.4103/jgid.jgid_279_21