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Proceedings (Baylor University. Medical... 2022Murine typhus is a rare condition caused by the gram-negative bacterium which classically presents with the triad of fever, rash, and headache. Herein we report a rare...
Murine typhus is a rare condition caused by the gram-negative bacterium which classically presents with the triad of fever, rash, and headache. Herein we report a rare presentation of murine typhus in an adult who presented predominantly with fever and gastrointestinal symptoms. Initial imaging showed cardiomegaly and hepatosplenomegaly, which led to further workup revealing rickettsial disease. Although this illness is considered a rare diagnosis in the emergency department, every person with a pet that might have fleas is susceptible to it.
PubMed: 35991722
DOI: 10.1080/08998280.2022.2078640 -
Developmental and Comparative Immunology Sep 2019The immune response of arthropod vectors plays a key role in the spread and transmission of vector-borne diseases. Although fleas transmit several human pathogens (e.g.,... (Review)
Review
The immune response of arthropod vectors plays a key role in the spread and transmission of vector-borne diseases. Although fleas transmit several human pathogens (e.g., Bartonella henselae, Rickettsia felis, R. typhi, and Yersinia pestis), few studies have examined how these vectors respond to infection. In hematophagous arthropods, imbibed pathogens must survive the hostile environment of blood meal digestion, which includes proteolytic digestive enzymes, protease inhibitors and expression of genes associated with protection of epithelial linings. Additionally, insect epithelial cells exhibit local immune defense against ingested pathogens by producing antimicrobial peptides and reactive oxygen species. This review details these and other aspects of insect immunity as it relates to fleas, with an emphasis on the gut immune response to two blood-borne pathogens, R. typhi and Y. pestis.
Topics: Animals; Antimicrobial Cationic Peptides; Bartonella henselae; Epithelial Cells; Flea Infestations; Humans; Insect Vectors; Rickettsia felis; Siphonaptera; Yersinia pestis
PubMed: 31002845
DOI: 10.1016/j.dci.2019.03.019 -
Research and Reports in Tropical... 2021Murine typhus and flea-borne spotted fever are undifferentiated febrile illnesses caused by and , respectively. These organisms are small obligately intracellular... (Review)
Review
Murine typhus and flea-borne spotted fever are undifferentiated febrile illnesses caused by and , respectively. These organisms are small obligately intracellular bacteria and are transmitted to humans by fleas. Murine typhus is endemic to coastal areas of the tropics and subtropics (especially port cities), where rats are the primary mammalian host and rat fleas () are the vector. In the United States, a cycle of transmission involving opossums and cat fleas () are the presumed reservoir and vector, respectively. The incidence and distribution of murine typhus appear to be increasing in endemic areas of the US. has also been reported throughout the world and is found within the ubiquitous cat flea. Flea-borne rickettsioses manifest as an undifferentiated febrile illness. Headache, malaise, and myalgia are frequent symptoms that accompany fever. The incidence of rash is variable, so its absence should not dissuade the clinician to consider a rickettsial illness as part of the differential diagnosis. When present, the rash is usually macular or papular. Although not a feature of murine typhus, eschar has been found in 12% of those with flea-borne spotted fever. Confirmatory laboratory diagnosis is usually obtained by serology; the indirect immunofluorescence assay is the serologic test of choice. Antibodies are seldom present during the first few days of illness. Thus, the diagnosis requires acute- and convalescent-phase specimens to document seroconversion or a four-fold increase in antibody titer. Since laboratory diagnosis is usually retrospective, when a flea-borne rickettsiosis is considered, empiric treatment should be initiated. The treatment of choice for both children and adults is doxycycline, which results in a swift and effective response. The following review is aimed to summarize the key clinical, epidemiological, ecological, diagnostic, and treatment aspects of flea-borne rickettsioses.
PubMed: 33574726
DOI: 10.2147/RRTM.S274724 -
Emerging Infectious Diseases Nov 2023Murine typhus is a febrile, fleaborne disease caused by infection with Rickettsia typhi bacteria. Cases can range from mild and nonspecific to fatal. We report 2 cases...
Murine typhus is a febrile, fleaborne disease caused by infection with Rickettsia typhi bacteria. Cases can range from mild and nonspecific to fatal. We report 2 cases of murine typhus in Costa Rica, confirming the presence and circulation of R. typhi causing severe disease in the country.
Topics: Animals; Mice; Humans; Typhus, Endemic Flea-Borne; Costa Rica; Rickettsia typhi; Rickettsia
PubMed: 37877575
DOI: 10.3201/eid2911.221561 -
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 -
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 -
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 -
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 -
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