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The American Journal of Tropical... Jul 2022Murine typhus is an acute undifferentiated febrile illness caused by Rickettsia typhi. In the United States, its reemergence appears to be driven by a shift from the...
Murine typhus is an acute undifferentiated febrile illness caused by Rickettsia typhi. In the United States, its reemergence appears to be driven by a shift from the classic rat-rat flea cycle of transmission to one involving opossums (Didelphis virginiana) and cat fleas. Little is known of the ability of opossums to act as a reservoir and amplifying host for R. typhi. Here, we use Monodelphis domestica (the laboratory opossum) as a surrogate for D. virginiana. Opossums were inoculated via the intraperitoneal (IP) or intradermal (ID) route with 1 × 106 viable R. typhi. Blood and tissues were collected on days 6, 13, 20, and 27 or if moribund. Although one ID-infected opossum died, the remainder did not appear ill, whereas half of the IP-inoculated animals succumbed to infection. Rickettsemia was demonstrated in all animals through week 2 of infection and sporadically in weeks 3 and 4. Rickettsia typhi DNA was detected in all tissues, with most animals demonstrating the presence of bacteria into weeks 3 and 4. Histopathology and immunohistochemistry demonstrated typical findings of rickettsial infection. Akin to infection in rats, the demonstration of disseminated infection, typical inflammation, and prolonged rickettsemia with relatively few clinical effects (especially in the more natural route of ID inoculation) supports the potential of opossums to act as a competent mammalian reservoir and component of the zoonotic maintenance cycle of R. typhi. Understanding the dynamics of infection within opossums may have implications for the prevention and control of murine typhus.
Topics: Animals; Didelphis; Mice; Monodelphis; Rats; Rickettsia; Rickettsia Infections; Rickettsia typhi; Siphonaptera; Typhus, Endemic Flea-Borne
PubMed: 35895366
DOI: 10.4269/ajtmh.21-1076 -
Microorganisms Jul 2022Chiggers are vectors of rickettsial pathogenic bacteria, spp., that cause the human disease, scrub typhus, in the Asian-Pacific area and northern Australia (known as...
Chiggers are vectors of rickettsial pathogenic bacteria, spp., that cause the human disease, scrub typhus, in the Asian-Pacific area and northern Australia (known as the Tsutsugamushi Triangle). More recently, reports of scrub typhus in Africa, southern Chile, and the Middle East have reshaped our understanding of the epidemiology of this disease, indicating it has a broad geographical distribution. Despite the growing number of studies and discoveries of chigger-borne human disease outside of the Tsutsugamushi Triangle, rickettsial pathogens in chigger mites in the US are still undetermined. The aim of our study was to investigate possible DNA in chiggers collected from rodents in North Carolina, USA. Of 46 chiggers tested, 47.8% tested positive for amplicons of the 23S-5S gene, 36.9% tested positive for 17 kDa, and 15.2% tested positive for . Nucleotide sequence analyses of the -specific 23S-5S intergenic spacer (IGS), 17 kDa, and gene fragments indicated that the amplicons from these chiggers were closely related to those in , , , and unidentified species. In this study, we provide the first evidence of infection in chiggers collected from rodents within the continental USA. In North Carolina, a US state with the highest annual cases of spotted fever rickettsioses, these results suggest chigger bites could pose a risk to public health, warranting further study.
PubMed: 35889061
DOI: 10.3390/microorganisms10071342 -
Revista Peruana de Medicina... 2022
Topics: Humans; Mexico; Rickettsia; Rickettsia rickettsii; Rickettsia typhi; Rural Population
PubMed: 35766733
DOI: 10.17843/rpmesp.2022.391.10519 -
Veterinary Parasitology, Regional... Jul 2022The cat flea (Ctenocephalides felis) is a competent vector of numerous bacterial pathogens in the genera Bartonella and Rickettsia. In the United States, free-roaming...
The cat flea (Ctenocephalides felis) is a competent vector of numerous bacterial pathogens in the genera Bartonella and Rickettsia. In the United States, free-roaming domestic cats (Felis catus) increase the risk of exposure to C. felis for humans and their companion animals. In collaboration with a trap-neuter-return program, we collected fleas from 283 feral/stray cats in southeastern Georgia between May and July of 2020. A total of 3,643 flea specimens were collected, and C. felis was the only flea species recovered from all cats sampled. The mean number of fleas per cat host was highest in the month of June when compared to May and July, and higher in juvenile cats (< 1 year) than the adults (≥ 1 year). Real-time PCR assays were used to test a subset of the collected fleas (n = 468) for the presence of Bartonella spp. and Rickettsia spp. DNA. Among those flea pools tested, 35.2% were positive for genus-specific citrate synthase gene of Bartonella, 16.5% were positive for the genus-specific 17-kDa protein antigen gene of Rickettsia, and none were positive for the species-specific outer membrane protein B gene of Rickettsia typhi. The identification of potential flea-borne pathogens was more frequent from the subset of C. felis collected in May, and female cats had more Bartonella-positive fleas and less Rickettsia-positive fleas than male cats. Overall, the present study provides valuable insights into the frequency of C. felis from outdoor community cats in southeastern Georgia, and highlights the possible risk for human exposure to potential flea-borne pathogens.
Topics: Animals; Bartonella; Cat Diseases; Cats; Chlamydia; Ctenocephalides; Female; Flea Infestations; Georgia; Male; Rickettsia; Siphonaptera
PubMed: 35725106
DOI: 10.1016/j.vprsr.2022.100743 -
Journal of Vector Borne Diseases 2022Fleas (Insecta, Siphonaptera) are important vectors of plague and murine typhus in many parts of the world. Currently, about 2700 flea species were described in the... (Review)
Review
Fleas (Insecta, Siphonaptera) are important vectors of plague and murine typhus in many parts of the world. Currently, about 2700 flea species were described in the world. The most common vector flea Xenopsylla cheopis is found throughout India, but X. astia, and X. brasiliensis are found less and limited in distribution associated with the domestic rats such as Rattus rattus, R. norvegicus, Mus musculus, and Bandicota bengalensis. Bubonic plague is a major flea-borne disease caused by the bacterial pathogen Yersinia pestis, transmitted from rats to humans via the rodent flea, X. cheopis. A major outbreak of plague and high mortality occurred in India. After 1966 with the 3 decadal intervals, plague cases occurred only during the year 1994 reported in 5 different states (Gujarat, Maharashtra, Karnataka, Uttar Pradesh, Madhya Pradesh and New Delhi and subsequently plague cases occurred during 2002 and 2004 after the one-decade interval in Himachal Pradesh (2002). Another outbreak of bubonic plague was reported in Dangud village, Barkhot tehsil, Uttarkashi district, Uttarakhand during October 2004. Ctenocephalides fleas are common in cats and dogs, which are the main vectors of bacteria rickettsiae, such as Rickettsia typhi, R. felis, R. conorii, and Bartonella henselae. Molecular and serological evidence also confirms the presence of R. typhi, R. conorii R. felis and B. henselae pathogens in cats and other fleas in India. Flea bites and flea-borne dermatitis are common in men and pet animals. Because of the re-emergence of the plague, updated information on fleas and flea-borne diseases are essential to control the flea vectors and flea-borne diseases in India. Hence, this comprehensive review updates the available information on fleas and fleas transmitted diseases in India.
Topics: Animals; Cats; Dogs; Flea Infestations; Humans; India; Mice; Plague; Public Health; Rats; Siphonaptera
PubMed: 35708399
DOI: 10.4103/0972-9062.328977 -
La Revue de Medecine Interne Oct 2022Adult-onset Still's disease (AOSD) is a rare multisystemic disorder and a diagnostic challenge for physicians because of the wide range of differential diagnoses. Common...
INTRODUCTION
Adult-onset Still's disease (AOSD) is a rare multisystemic disorder and a diagnostic challenge for physicians because of the wide range of differential diagnoses. Common features of AOSD and secondary hemophagocytic lymphohistiocytosis (sHLH) could favour diagnostic uncertainty, in particular in case of infection-related sHLH.
OBSERVATION
A 61-year-old man was admitted to our internal medicine department for suspected AOSD. He reported a 2-week history of sudden onset fever, headaches, myalgia, sore throat, diarrhoea, and an erythematous macular rash of the trunk as well as petechial purpuric lesions on both legs on return from Reunion Island. Laboratory tests found cytopenia, hepatic cytolysis, hypertriglyceridaemia, and hyperferritinaemia. Hemophagocytosis was diagnosed on bone marrow aspiration in favour of the diagnosis of secondary hemophagocytic lymphohistiocytosis (sHLH). Subcutaneous anakinra (100mg) was initiated to treat sHLH with favourable course. Oral doxycycline was added 3days later because of atypical features for AOSD diagnosis such as diarrhoea, hypergammaglobulinaemia, and doubtful serologies for Rickettsia and Coxiella. Three weeks later, Rickettsia typhi serology was checked again and revealed an increase in IgG titer>4 times that confirmed the diagnosis of murine typhus. A diagnosis of murine typhus complicated by sHLH was retained, successfully treated by anakinra and doxycycline.
CONCLUSION
Our observation shows that AOSD diagnosis has to be stringent due to the many differential diagnoses, particularly infection complicated by sHLH, which may be rare. It is important to consider murine typhus in patients returning from endemic areas, such as La Reunion or other tropical areas, when they present fever of unknown origin with non-specific clinical features. Moreover, this case illustrates the effectiveness of IL-1 blockers as a treatment for symptomatic sHLH without severity criteria, regardless of the aetiology.
Topics: Adult; Animals; Diarrhea; Doxycycline; Humans; Immunoglobulin G; Interleukin 1 Receptor Antagonist Protein; Interleukin-1; Lymphohistiocytosis, Hemophagocytic; Male; Mice; Middle Aged; Still's Disease, Adult-Onset; Typhus, Endemic Flea-Borne
PubMed: 35697578
DOI: 10.1016/j.revmed.2022.05.011 -
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 -
BMC Medicine May 2022Persistent fever, defined as fever lasting for 7 days or more at first medical evaluation, has been hardly investigated as a separate clinical entity in the tropics....
BACKGROUND
Persistent fever, defined as fever lasting for 7 days or more at first medical evaluation, has been hardly investigated as a separate clinical entity in the tropics. This study aimed at exploring the frequencies and diagnostic predictors of the ubiquitous priority (i.e., severe and treatable) infections causing persistent fever in the tropics.
METHODS
In six different health settings across four countries in Africa and Asia (Sudan, Democratic Republic of Congo [DRC], Nepal, and Cambodia), consecutive patients aged 5 years or older with persistent fever were prospectively recruited from January 2013 to October 2014. Participants underwent a reference diagnostic workup targeting a pre-established list of 12 epidemiologically relevant priority infections (i.e., malaria, tuberculosis, HIV, enteric fever, leptospirosis, rickettsiosis, brucellosis, melioidosis, relapsing fever, visceral leishmaniasis, human African trypanosomiasis, amebic liver abscess). The likelihood ratios (LRs) of clinical and basic laboratory features were determined by pooling all cases of each identified ubiquitous infection (i.e., found in all countries). In addition, we assessed the diagnostic accuracy of five antibody-based rapid diagnostic tests (RDTs): Typhidot Rapid IgM, Test-it Typhoid IgM Lateral Flow Assay, and SD Bioline Salmonella typhi IgG/IgM for Salmonella Typhi infection, and Test-it Leptospira IgM Lateral Flow Assay and SD Bioline Leptospira IgG/IgM for leptospirosis.
RESULTS
A total of 1922 patients (median age: 35 years; female: 51%) were enrolled (Sudan, n = 667; DRC, n = 300; Nepal, n = 577; Cambodia, n = 378). Ubiquitous priority infections were diagnosed in 452 (23.5%) participants and included malaria 8.0% (n = 154), tuberculosis 6.7% (n = 129), leptospirosis 4.0% (n = 77), rickettsiosis 2.3% (n = 44), enteric fever 1.8% (n = 34), and new HIV diagnosis 0.7% (n = 14). The other priority infections were limited to one or two countries. The only features with a positive LR ≥ 3 were diarrhea for enteric fever and elevated alanine aminotransferase level for enteric fever and rickettsiosis. Sensitivities ranged from 29 to 67% for the three RDTs targeting S. Typhi and were 9% and 16% for the two RDTs targeting leptospirosis. Specificities ranged from 86 to 99% for S. Typhi detecting RDTs and were 96% and 97% for leptospirosis RDTs.
CONCLUSIONS
Leptospirosis, rickettsiosis, and enteric fever accounted each for a substantial proportion of the persistent fever caseload across all tropical areas, in addition to malaria, tuberculosis, and HIV. Very few discriminative features were however identified, and RDTs for leptospirosis and Salmonella Typhi infection performed poorly. Improved field diagnostics are urgently needed for these challenging infections.
TRIAL REGISTRATION
NCT01766830 at ClinicalTrials.gov.
Topics: Adult; Antibodies, Bacterial; Female; HIV Infections; Humans; Immunoglobulin G; Immunoglobulin M; Leptospirosis; Malaria; Male; Prospective Studies; Rickettsia Infections; Sensitivity and Specificity; Typhoid Fever
PubMed: 35491421
DOI: 10.1186/s12916-022-02347-8 -
Socio-ecological determinants of rickettsial seroprevalence in a rural community of Yucatán, Mexico.Infection, Genetics and Evolution :... Aug 2022Rickettsial diseases have seen a re-emergence in the Americas in the last few decades, with concerning morbidity, mortality and economic implications that result from...
Rickettsial diseases have seen a re-emergence in the Americas in the last few decades, with concerning morbidity, mortality and economic implications that result from loss of productivity, income, curbs in liberal trade agreements, and reduction in agricultural practices. The aim of this study is to determine the socioecological determinants and seroprevalence for Rickettsia typhi and Rickettsia rickettsii among residents of Teabo, a rural community of Yucatán, Mexico. Sociodemographic data and serum samples were obtained from 180 consenting participants. Antibody titers for R. typhi and R. rickettsii were determined by indirect immunofluorescence assay (IFA). Participants also submitted tick samples collected from their residential area. We conducted logistic regression models to evaluate the association between exposure variables and seroprevalence. Rhipicephalus sanguineus s.l. (37%; n = 65), and Amblyomma cajennense Fabricius (17%; n = 29) were the predominant tick species in peri-domestic areas. Out of the 180 participants, there was significantly higher seroprevalence of R. typhi (n = 77; 46%) compared to R. rickettsii [n = 27, 15%, (p < 0.05)]. Pearson's chi-square test of independence revealed significant differences in R. rickettsii seroprevalence by gender (X [n = 175, df = 4, (p < 0.001)] = 180.26), level of education, (X [n = 180, df = 4, (p < 0.001)] = 44.0), and by tick species found in residential area, (X [n = 180, df = 4, (p = 0.050)] = 9.48). After adjusting for other variables in a logistic regression model, for each unit increase in the number of dogs present in the residential area, there was a 27% increase in the odds of human seroprevalence for R. typhi IgG (AOR = 1.27, 95% CI: 1.01-1.63). Compared to study participants living in residential areas with a 'low' height of vegetation, those living in residential areas with a 'medium' height of vegetation had 2.5 times greater odds of human seroprevalence for R. typhi IgG (AOR = 2.51, 95% CI: 1.19-5.40). Potentially modifiable existing factors in the peri-domestic area may constitute a high-risk source of seroprevalence for rickettsial antibodies among residents of the rural community of Teabo, Yucatán, Mexico.
Topics: Animals; Dog Diseases; Dogs; Humans; Immunoglobulin G; Mexico; Rhipicephalus sanguineus; Rickettsia; Rural Population; Seroepidemiologic Studies
PubMed: 35490957
DOI: 10.1016/j.meegid.2022.105291 -
PLoS Neglected Tropical Diseases Apr 2022Murine typhus is a flea-borne zoonotic disease with acute febrile illness caused by Rickettsia typhi and is distributed widely throughout the world, particularly in port...
Delayed correlation between the incidence rate of indigenous murine typhus in humans and the seropositive rate of Rickettsia typhi infection in small mammals in Taiwan from 2007-2019.
Murine typhus is a flea-borne zoonotic disease with acute febrile illness caused by Rickettsia typhi and is distributed widely throughout the world, particularly in port cities and coastal regions. We observed that murine typhus was an endemic disease (number of annual indigenous cases = 29.23±8.76) with a low incidence rate (0.13±2.03*10-4 per 100,000 person-years) in Taiwan from 2007-2019. Most (45.79%, 174/380) indigenous infections were reported in May, June, and July. The incidence rates in both May and June were statistically higher than those in other months (p<0.05). Correspondingly, sera collected from small mammals (rodents and shrews) trapped in airports and harbors demonstrated anti-R. typhi antibody responses (seropositive rate = 8.24±0.33%). Interestingly, the ports with the highest seropositivity rates in small mammals are all inside/near the areas with the highest incidence rates of indigenous murine typhus. In addition, incidence rates in humans were positively correlated with the 1-month and 2-month prior seropositive rates in small mammals (R = 0.31 and 0.37, respectively). As early treatment with appropriate antibiotics for murine typhus could effectively shorten the duration of illness and reduce the risk of hospitalization and fatality, flea-related exposure experience should be considered in clinics during peak seasons and the months after a rise in seropositivity rates in small mammals. Surveillance in small mammals might be helpful for the development of real-time reporting or even early reminders for physicians of sporadic murine typhus cases based on the delayed correlation observed in this study.
Topics: Animals; Humans; Incidence; Mice; Rickettsia typhi; Shrews; Siphonaptera; Taiwan; Typhus, Endemic Flea-Borne
PubMed: 35468137
DOI: 10.1371/journal.pntd.0010394