Murine typhus in central Greece: epidemiological, clinical, laboratory, and therapeutic-response features of 90 cases

Clinical and laboratory features of rickettsioses in Yucatan, Mexico

Rickettsia species are obligate intracellular bacteria that can cause mild to severe human disease. Based on phylogeny, clinical symptoms, and antigenic properties, rickettsiae are classified into four groups. Infections by these agents are characterized by clinical symptoms ranging from self-limited to severe and even fatal febrile illnesses, depending on the Rickettsia spp. involved, the patient's predisposition, and timely medical care. The present study aimed to characterize rickettsial diseases in Yucatan according to clinical and laboratory features appearing in medical records corresponding to 427 samples taken between 2015 and 2018. A study was conducted over the period 2015-2018 on 427 samples. Clinical and laboratory features were documented from the patients' medical records. For molecular diagnosis, blood was collected in 3.8 % sodium citrate as anticoagulant, and DNA was extracted. Single-step and nested PCR amplification was performed using genus-specific primers for the rickettsial 17kDa and ompB genes. The amplicons obtained were purified and sequenced. A total of 22.7 % (97/427) positive cases of Rickettsia spp. were identified by PCR from 14.15 % (15/106) of the municipalities in Yucatan. 75.2 % (73/97) of the cases were from the city of Merida during the autumn (September-December). The age groups with the highest frequency of confirmed cases were pediatric (5-14 years) (57.7 %) and adults (25-49 years) (42.2 %). There were six fatal cases in children, one associated with R. typhi and five with R. rickettsii. In non-fatal cases, 32.9 % (32/97) corresponded to the spotted fever group (SFG), and 60.8 % (59/97) to the typhus group (TG). Significant differences in signs, and laboratory data, were observed between the pediatric and adult populations. For the treatment of patients, oral and intravenous doxycycline was used in severe hospitalized cases. Typhus group and spotted fever group Rickettsiae are endemic pathological agents found in urban and rural areas of our region. Molecular identification allows for greater diagnostic accuracy and timely treatment and consequently a better prognosis. It is necessary to implement or reinforce measures focused on the dissemination of knowledge regarding rickettsial diseases and their prevention.

Multisectoral Perspectives on Global Warming and Vector-borne Diseases: a Focus on Southern Europe

Purpose of Review

The climate change (CC) or global warming (GW) modifies environment that favors vectors' abundance, growth, and reproduction, and consequently, the rate of development of pathogens within the vectors. This review highlights the threats of GW-induced vector-borne diseases (VBDs) in Southern Europe (SE) and the need for mitigation efforts to prevent potential global health catastrophe.

Recent Findings

Reports showed astronomical surges in the incidences of CC-induced VBDs in the SE. The recently (2022) reported first cases of African swine fever in Northern Italy and West Nile fever in SE are linked to the CC-modified environmental conditions that support vectors and pathogens' growth and development, and disease transmission.

Summary

VBDs endemic to the tropics are increasingly becoming a major health challenge in the SE, a temperate region, due to the favorable environmental conditions caused by CC/GW that support vectors and pathogens' biology in the previously non-endemic temperate regions.

Vaccine Design and Vaccination Strategies against Rickettsiae

Rickettsioses are febrile, potentially lethal infectious diseases that are a serious health threat, especially in poor income countries. The causative agents are small obligate intracellular bacteria, rickettsiae. Rickettsial infections are emerging worldwide with increasing incidence and geographic distribution. Nonetheless, these infections are clearly underdiagnosed because methods of diagnosis are still limited and often not available. Another problem is that the bacteria respond to only a few antibiotics, so delayed or wrong antibiotic treatment often leads to a more severe outcome of the disease. In addition to that, the development of antibiotic resistance is a serious threat because alternative antibiotics are missing. For these reasons, prophylactic vaccines against rickettsiae are urgently needed. In the past years, knowledge about protective immunity against rickettsiae and immunogenic determinants has been increasing and provides a basis for vaccine development against these bacterial pathogens. This review provides an overview of experimental vaccination approaches against rickettsial infections and perspectives on vaccination strategies.

Murine Typhus in Canary Islands, Spain, 1999-2015

To document the epidemiology, clinical features, and outcomes of murine typhus patients in the Canary Islands (Spain), we analyzed data that were retrospectively collected for 16 years for 221 patients. Murine typhus in the Canary Islands is characterized by a high rate of complications (31.6%), mainly liver, lung, kidney or central nervous system involvement.

GroEL is an immunodominant surface-exposed antigen of Rickettsia typhi

Rickettsioses are neglected and emerging potentially fatal febrile diseases that are caused by obligate intracellular bacteria, rickettsiae. Rickettsia (R.) typhi and R. prowazekii constitute the typhus group (TG) of rickettsiae and are the causative agents of endemic and epidemic typhus, respectively. We recently generated a monoclonal antibody (BNI52) against R. typhi. Characterization of BNI52 revealed that it specifically recognizes TG rickettsiae but not the members of the spotted fever group (SFG) rickettsiae. We further show that BNI52 binds to protein fragments of ±30 kDa that are exposed on the bacterial surface and also present in the periplasmic space. These protein fragments apparently derive from the cytosolic GroEL protein of R. typhi and are also recognized by antibodies in the sera from patients and infected mice. Furthermore, BNI52 opsonizes the bacteria for the uptake by antigen presenting cells (APC), indicating a contribution of GroEL-specific antibodies to protective immunity. Finally, it is interesting that the GroEL protein belongs to 32 proteins that are differentially downregulated by R. typhi after passage through immunodeficient BALB/c CB17 SCID mice. This could be a hint that the rickettsia GroEL protein may have immunomodulatory properties as shown for the homologous protein from several other bacteria, too. Overall, the results of this study provide evidence that GroEL represents an immunodominant antigen of TG rickettsiae that is recognized by the humoral immune response against these pathogens and that may be interesting as a vaccine candidate. Apart from that, the BNI52 antibody represents a new tool for specific detection of TG rickettsiae in various diagnostic and experimental setups.

Sunbathing, a possible risk factor of murine typhus infection in Greece

BACKGROUND

There are few studies about the presence of murine typhus in Greece. Our objective was to conduct a large scale retrospective investigation to determine the clinical and epidemiological features of patients diagnosed with murine typhus in Greece.

METHODOLOGY/PRINCIPAL FINDINGS

From 2012 to 2019 serum samples from hospitalized patients and outpatients throughout Greece suspected for murine typhus infection were tested by immunofluorescence assay for Rickettsia typhi. Immunofluorescence positive samples obtained since 2016 were also tested by qPCR targeting R. typhi. Clinical and epidemiological data were retrospectively collected for the patients with confirmed murine typhus. Overall, we tested 5,365 different patients and, in total, 174 patients from all geographic regions of Greece were diagnosed with murine typhus. The most frequently reported sign or symptom was fever (89%), followed by headache (84%) and rash (81%). The classical triad of fever, headache, and rash was present in 72% of patients during their illness. Severe infections with complications including acute renal failure or septic shock were not recorded. The majority of cases (81%) occurred during May-October and peaked in June and September. Most of patients (81%) infected in Athens, recalled that their only activity the last weeks before symptoms onset was swimming on the beach and 59% of them also reported an insect bite while sunbathing.

CONCLUSIONS/SIGNIFICANCE

Our results may reflect the reemergence of murine typhus in Greece and we highlight the importance of awareness of this difficult-to-recognize undifferentiated febrile illness.

Selection of Diagnostic Cutoffs for Murine Typhus IgM and IgG Immunofluorescence Assay: A Systematic Review

Murine typhus is a neglected but widespread infectious disease that results in acute fever. The immunofluorescence assay (IFA) is the "gold standard" to identify IgM or IgG antibodies, although there is a lack of standardization in methodologies. The objective of this review is to summarize 1) the differences in published methodologies, 2) the diagnostic cutoff titers, and 3) the justification of diagnostic cutoffs. Searches were performed by combining the following search terms: "murine typhus," "rickettsia typhi," "immunofluorescence," "IFA," and "serologic" with restrictions (i.e., "rickettsia typhi" or "murine typhus," and "IFA" or "immunofluorescence," or "serologic*"). The search identified 78 studies that used IFA or immunoperoxidase assay (IIP) antibody cutoffs to diagnose murine typhus, 39 of which were case series. Overall, 45 studies (57.7%) provided little to no rationale as to how the cutoff was derived. Variation was seen locally in the cutoff titers used, but a 4-fold or greater increase was often applied. The cutoffs varied depending on the antibody target. No consensus was observed in establishing a cutoff, or for a single-value diagnostic cutoff. In conclusion, there is a lack of consensus in the establishment of a single-value cutoff. Further studies will need to be executed at each distinct geographic location to identify region-specific cutoffs, while also considering background antibody levels to distinguish between healthy and infected patients.

Underdiagnoses of Rickettsia in patients hospitalized with acute fever in Indonesia: observational study results

Background

Reports of human rickettsial infection in Indonesia are limited. This study sought to characterize the epidemiology of human rickettsioses amongst patients hospitalized with fever at 8 tertiary hospitals in Indonesia.

Methods

Acute and convalescent blood from 975 hospitalized non-dengue patients was tested for Rickettsia IgM and IgG by ELISA. Specimens from cases with seroconversion or increasing IgM and/or IgG titers were tested for Rickettsia IgM and IgG by IFA and Rickettsia genomes using primers for Rickettsia (R.) sp, R. typhi, and Orientia tsutsugamushi. Testing was performed retrospectively on stored specimens; results did not inform patient management.

Results

R. typhi, R. rickettsii, and O. tsutsugamushi IgG antibodies were identified in 269/872 (30.8%), 36/634 (5.7%), and 19/504 (3.8%) of samples, respectively. For the 103/975 (10.6%) non-dengue patients diagnosed with acute rickettsial infection, presenting symptoms included nausea (72%), headache (69%), vomiting (43%), lethargy (33%), anorexia (32%), arthralgia (30%), myalgia (28%), chills (28%), epigastric pain (28%), and rash (17%). No acute rickettsioses cases were suspected during hospitalization. Discharge diagnoses included typhoid fever (44), dengue fever (20), respiratory infections (7), leptospirosis (6), unknown fever (6), sepsis (5), hepatobiliary infections (3), UTI (3), and others (9). Fatalities occurred in 7 (6.8%) patients, mostly with co-morbidities.

Conclusions

Rickettsial infections are consistently misdiagnosed, often as leptospirosis, dengue, or Salmonella typhi infection. Clinicians should include rickettsioses in their differential diagnosis of fever to guide empiric management; laboratories should support evaluation for rickettsial etiologies; and public policy should be implemented to reduce burden of disease.

High Morbidity Due to Murine Typhus Upsurge in Urban Neighborhoods in Central Israel

The incidence of murine typhus in Israel has decreased substantially since 1950 to a low of 0.04/100,000 population in 2010. We present the experience of a single university medical center in central Israel. Hospitalized patients serologically positive for Rickettsia typhi by indirect immunofluorescence antibody assay during 2006-2016 were retrospectively identified. Clinical and laboratory data from patients' charts were used to analyze disease trends and distribution. Seventy-eight patients were studied (mean age: 27.9 years), mostly of Arab ethnicity (68, 87.2%). Seventy-one (91%) patients resided in two large mixed Jewish-Arab cities-Lod and Ramla. The incidence of murine typhus among the Arab population in Lod increased 8.4-fold from 6.4/100,000 in 2006 to a peak of 53.4/100,000 in 2013. The average annual incidence among Arabs in Ramla was 10.1/100,000. Among Jews, incidences were 0.8/100,000 in Lod and 0.4/100,000 in Ramla. The classical triad of fever, headache, and rash was noted in 20.8% patients. Substantial morbidity included prolonged fever before hospitalization and hospital stay (mean of 8.4 and 5.1 days, respectively), and severe complications in six patients, including pneumonitis in three patients, and splenic infarctions, pericardial effusion, and retinitis, each in one. One previously healthy patient died of multiorgan failure. The study describes a high incidence of murine typhus with a recent upsurge in an urban setting in central Israel. High morbidity and a single fatal outcome challenge the concept of murine typhus being a mild disease. The study calls for better rodent control and sanitation measures in the affected neighborhoods.

Case Report: Early Doxycycline Therapy for Potential Rickettsiosis in Critically Ill Patients in Flea-Borne Typhus-Endemic Areas

Flea-borne typhus (FBT), although usually perceived as a self-resolving febrile illness, actually encompasses a wide spectrum of disease severity, including fulminant sepsis with multi-organ failure. In endemic Texas and California, the incidence of FBT has more than doubled over the last decade. Clinicians remain unfamiliar with severe septic presentations of FBT when considering the etiologies of acute undifferentiated febrile syndromes. The diagnostic challenges of FBT include the nonspecific and variable nature of both history and physical examination and the lack of diagnostic testing that can provide clinically relevant information early in the course of infection. These barriers perpetuate misdiagnoses in critically ill patients and lead to delay in initiating appropriate antibiotics, which may contribute to preventable morbidity and mortality. This case series describes the clinical and diagnostic trajectories of three patients who developed FBT-associated multi-organ dysfunction. These patients achieved resolution of infection after receiving doxycycline in the context of a high clinical suspicion. Patients residing in FBT-endemic areas presenting with a febrile illness of unknown etiology with a suggestive constellation of hyponatremia, elevated transaminase levels, and thrombocytopenia should be suspected of having FBT. Clinicians should proceed to serologic testing with early doxycycline therapy for potential rickettsiosis. Familiarizing clinicians with the presentation of rickettsiosis-associated septic syndromes and its early and appropriate antibiotic treatment can provide lifesaving care and reduce health-care costs through prevention of the morbidity associated with FBT.

Clinicoepidemiologic characteristics of scrub typhus and murine typhus: A multi-center study in southern Taiwan

BACKGROUND

This study aimed to offer key features to differentiate scrub typhus (ST) and murine typhus (MT) at the early stage of the diseases and provide clinicoepidemiologic characteristics of ST and MT in southern Taiwan, a region where both diseases are endemic. Comparison of doxycycline treatment efficacy between the two diseases by matching disease severity and delayed treatment had never been investigated.

METHODS

We reviewed the medical records of cases of ST and MT in four hospitals in southern Taiwan. Propensity-score matching was used to analyze the defervescence curves between patients with doxycycline-treated ST and MT by log-rank test.

RESULTS

Between 2004 and 2016, 265 ST and 63 MT cases were diagnosed. The number of cases of ST was significantly related to temperature (Rs = 0.77) and rainfall (Rs = 0.63). Island area exposure, arthropod bite, eschar, and lymphadenopathy were only recorded in ST patients. Multivariate analysis revealed that mountainous area exposure (odds ratio [OR], 11.0; 95% confidence interval [CI], 4.4-27.2) was an independent predictor for ST, while contact with rats (OR, 8.4; 95% CI, 3.3-21.3) was that for MT. After propensity-score matching, there was no difference in defervescence curves between these two rickettsioses treated with doxycycline (p = 0.24).

CONCLUSION

In the present study, island area exposure, arthropod bite, eschar, and lymphadenopathy were unique manifestations of ST. Mountainous area exposure is a predictive factor for ST, while contact with rats predicted MT. There was no difference in defervescence time between these two rickettsioses after doxycycline treatment.

Murine Typhus Mimicking Kawasaki Disease in a Preadolescent Girl

We report the case of an 11-year-old preadolescent girl presenting with prolonged fever, lymphadenitis, nonpurulent conjunctivitis, a generalized maculopapular rash, erythematous lips and edema of hands/feet. Although major diagnostic criteria for Kawasaki disease were met, local epidemiologic data suggested a possible vector-borne etiology. Treatment with doxycycline was initiated, and defervescence occurred. Laboratory investigation confirmed the diagnosis of Rickettsia typhi infection.

Case Report: Fulminant Murine Typhus Presenting with Status Epilepticus and Multi-Organ Failure: an Autopsy Case and a Review of the Neurologic Presentations of Murine Typhus

Murine typhus (MT) is an important cause of febrile illness in endemic areas, and there is an epidemiologic resurgence of this infection currently transpiring in Texas and California. Fatal cases and severe neurological complications are rare. A fatal case of MT in a middle-aged man is reported with a course culminating in multi-organ failure and refractory status epilepticus. An autopsy revealed hemorrhagic pneumonia, acute tubular necrosis, and ischemic necrosis in the liver, adrenals, and brain. We have also reviewed the neurologic complications of MT.

Acute Febrile Illness and Complications Due to Murine Typhus, Texas, USA1,2

Murine typhus occurs relatively commonly in southern Texas, as well as in California. We reviewed records of 90 adults and children in whom murine typhus was diagnosed during a 3-year period in 2 hospitals in southern Texas, USA. Most patients lacked notable comorbidities; all were immunocompetent. Initial signs and symptoms included fever (99%), malaise (82%), headache (77%), fatigue (70%), myalgias (68%), and rash (39%). Complications, often severe, in 28% of patients included bronchiolitis, pneumonia, meningitis, septic shock, cholecystitis, pancreatitis, myositis, and rhabdomyolysis; the last 3 are previously unreported in murine typhus. Low serum albumin and elevated procalcitonin, consistent with bacterial sepsis, were observed in >70% of cases. Rash was more common in children; thrombocytopenia, hyponatremia, elevated hepatic transaminases, and complications were more frequent in adults. Murine typhus should be considered as a diagnostic possibility in cases of acute febrile illness in southern and even in more northern US states.

Analysis of Health-Care Charges in Murine Typhus: Need for Improved Clinical Recognition and Diagnostics for Acute Disease

Murine typhus, caused by Rickettsia typhi, is an undifferentiated febrile illness with no available rapid and sensitive diagnostic assay for use during early disease. We aimed to compare the health-care charges in those diagnosed with murine typhus to those with influenza, a febrile illness with an available rapid diagnostic test. A comparison of health-care-associated charges at the University of Texas Medical Branch at Galveston demonstrated a median of $817 for influenza versus $16,760 for murine typhus (P < 0.0001). Median laboratory ($184 versus $3,254 [P < 0.0001]) and imaging charges ($0 versus $514 [P < 0.0001]) were also higher in those with murine typhus. Those receiving at least one imaging study during their illness were greater in the murine typhus group (91.3% versus 20.3%) (P < 0.0001). The median time needed to establish a confirmed or presumptive diagnosis was 2 days for influenza compared with 9 days for murine typhus (P < 0.0001). The median number of health-care encounters was greater for those with murine typhus (2 versus 1) (P < 0.0001). Eleven patients (15.9%) with influenza were hospitalized as a result of their illness compared with 16 (69.6%) with murine typhus (P < 0.0001). The estimated mortality based on disease severity at presentation by Acute Physiology and Chronic Health Evaluation II scoring was similar in the two groups-both had a median 4% mortality risk (P = 0.0893). These results highlight the need for improved clinical recognition and diagnostics for acute rickettsioses such as murine typhus.

A Severe Case of Murine Typhus Presenting With Anemia and Severe Thrombocytopenia

We discuss a child with severe thrombocytopenia and mild anemia admitted to the Hematology service who quickly deteriorated to a life-threatening state. However, once rickettsial disease was considered in the differential diagnosis and empiric doxycycline begun, she quickly and fully recovered. A diagnostic panel, including Rickettsia typhi serology, confirmed the diagnosis of murine typhus but this occurred weeks after she had recovered. Given the potential severity of rickettsial diseases and the ease of modern travel across geographic borders, hematology-oncology providers everywhere must consider rickettsial diseases in their differential diagnosis of critically ill children and begin empiric therapy with doxycycline promptly.

Potential exposure of humans to Rickettsia felis in Greece

Rickettsia felis is a flea-transmitted pathogen however, in Greece, much work has been done on another flea-borne pathogen, R. typhi; human cases have been described and high-risk areas have been characterized. Nevertheless, little is known about human infections caused by R. felis in the country since human cases are not routinely tested for antibodies against this pathogen. During the past seven years, we have set up a protocol at the National Reference Centre in order to improve the testing of tick-borne diseases in Greece. Based on this protocol, R. conorii, R. typhi R. slovaca, R. felis, and R. mongolotimonae have been added into the routine analysis; during these last years, eight (8) cases of potential exposure to R. felis were identified by serology. On an environmental investigation carried out at the residences of the patients, the pathogen was detected in C. felis only. The demonstration of R. felis potential presence highlights the need for better testing and surveillance of the pathogen.

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985-2015

AbstractFlea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi. Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985-2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36-84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0-5 days). The median time from symptom onset to death was 14 days (range, 1-34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology.

Clinical and laboratory characteristics, epidemiology, and outcomes of murine typhus: A systematic review

Murine or endemic typhus, a febrile disease caused by Rickettsia typhi, is often misdiagnosed due to its non-specific presentation. We sought to evaluate all available evidence in the literature regarding the clinical and laboratory manifestations, epidemiological characteristics, and outcomes of murine typhus. Pubmed was searched for all articles providing available data. In an effort to incorporate contemporary data, only studies from 1980 were included. Thirty-three case series including 2074 patients were included in final analysis. Available evidence suggests that the classic triad of fever, headache and rash is encountered in only one-third of patients. Other frequent symptoms were chills, malaise, myalgia, and anorexia. A tetrad of reported laboratory abnormalities consisting of elevated liver enzymes, lactate dehydrogenase, erythrocyte sedimentation rate and hypoalbuminemia was detected. Complications were observed in one-fourth of patients, reported mortality was extremely low, but untreated patients had notably longer duration of fever. Among epidemiological characteristics, a seasonal distribution with most cases reported during warmer months, was the most prominent finding. Murine typhus in children exhibits several different characteristics, with abdominal pain, diarrhea, and sore throat reported more commonly, higher frequency of anemia, lower frequency of hypoalbuminemia, hematuria and proteinuria and a much lower rate of complications. This systematic review of published evidence provides a thorough description of the clinical and laboratory features of murine typhus and highlights important differences in children.

CD4+ T Cells Are as Protective as CD8+ T Cells against Rickettsia typhi Infection by Activating Macrophage Bactericidal Activity

Rickettsia typhi is an intracellular bacterium that causes endemic typhus, a febrile disease that can be fatal due to complications including pneumonia, hepatitis and meningoencephalitis, the latter being a regular outcome in T and B cell-deficient C57BL/6 RAG1^-/- mice upon Rickettsia typhi infection. Here, we show that CD4⁺ T_H1 cells that are generated in C57BL/6 mice upon R. typhi infection are as protective as cytotoxic CD8⁺ T cells. CD4⁺- as well as CD8⁺-deficient C57BL/6 survived the infection without showing symptoms of disease at any point in time. Moreover, adoptively transferred CD8⁺ and CD4⁺ immune T cells entered the CNS of C57BL/6 RAG1^-/- mice with advanced infection and both eradicated the bacteria. However, immune CD4⁺ T cells protected only approximately 60% of the animals from death. They induced the expression of iNOS in infiltrating macrophages as well as in resident microglia in the CNS which can contribute to bacterial killing but also accelerate pathology. In vitro immune CD4⁺ T cells inhibited bacterial growth in infected macrophages which was in part mediated by the release of IFNγ. Collectively, our data demonstrate that CD4⁺ T cells are as protective as CD8⁺ T cells against R. typhi, provided that CD4⁺ T_H1 effector cells are present in time to support bactericidal activity of phagocytes via the release of IFNγ and other factors. With regard to vaccination against TG Rickettsiae, our findings suggest that the induction of CD4⁺ T_H1 effector cells is sufficient for protection.

Endemic typhus caused by Rickettsia typhi usually is a relatively mild disease. However, CNS inflammation and neurological symptoms are complications that can occur in severe cases. This outcome of disease is regularly observed in T and B cell-deficient C57BL/6 RAG1^-/- mice upon infection with R. typhi. We show here that CD4⁺ T cells are as protective as cytotoxic CD8⁺ T cells against R. typhi as long as they are present in time. This is evidenced by the fact that neither CD8⁺ nor CD4⁺ T cell-deficient C57BL/6 mice develop disease which is also true for R. typhi-infected C57BL/6 RAG1^-/- mice that receive immune CD8⁺ or CD4⁺ at an early point in time. Moreover, adoptive transfer of immune CD4⁺ T cells still protects approximately 60% of C57BL/6 RAG1^-/- mice when applied later in advanced infection when the bacteria start to rise. Although CD8⁺ T cells are faster and more efficient in bacterial elimination, R. typhi is not detectable in CD4⁺ T cell recipients anymore. We further show that immune CD4⁺ T cells activate bactericidal functions of microglia and macrophages in the CNS in vivo and inhibit bacterial growth in infected macrophages in vitro which is in part mediated by the release of IFNγ. Collectively, we demonstrate for the first time that CD4⁺ T cells alone are sufficient to protect against R. typhi infection. With regard to vaccination our findings suggest that the induction of R. typhi-specific CD4⁺ T_H1 effector T cells may be as effective as the much more difficult targeting of cytotoxic CD8⁺ T cells.

Comparative evaluation of two Rickettsia typhi-specific quantitative real-time PCRs for research and diagnostic purposes

Rickettsioses are caused by intracellular bacteria of the family of Rickettsiaceae. Rickettsia (R.) typhi is the causative agent of endemic typhus. The disease occurs worldwide and is one of the most prevalent rickettsioses. Rickettsial diseases, however, are generally underdiagnosed which is mainly due to the lack of sensitive and specific methods. In addition, methods for quantitative detection of the bacteria for research purposes are rare. We established two qPCRs for the detection of R. typhi by amplification of the outer membrane protein B (ompB) and parvulin-type PPIase (prsA) genes. Both qPCRs are specific and exclusively recognize R. typhi but no other rickettsiae including the closest relative, R. prowazekii. The prsA-based qPCR revealed to be much more sensitive than the amplification of ompB and provided highly reproducible results in the detection of R. typhi in organs of infected mice. Furthermore, as a nested PCR the prsA qPCR was applicable for the detection of R. typhi in human blood samples. Collectively, the prsA-based qPCR represents a reliable method for the quantitative detection of R. typhi for research purposes and is a promising candidate for differential diagnosis.

Severe murine typhus with pulmonary system involvement

We encountered a case of severe murine typhus complicated by acute respiratory distress syndrome. To determine worldwide prevalence of such cases, we reviewed the literature and found that respiratory symptoms occur in ≈30% of murine typhus patients. In disease-endemic areas, murine typhus should be considered for patients with respiratory symptoms and fever.

Murine typhus, Reunion, France, 2011-2013

Murine typhus case was initially identified in Reunion, France, in 2012 in a tourist. Our investigation confirmed 8 autochthonous cases that occurred during January 2011–January 2013 in Reunion. Murine typhus should be considered in local patients and in travelers returning from Reunion who have fevers of unknown origin.

An Unusual Cutaneous Manifestation in a Patient with Murine Typhus

Murine typhus is a flea-borne febrile illness caused by Rickettsia typhi. Although often accompanied by rash, an inoculation lesion has not been observed as it is with many tick- and mite-transmitted rickettsioses. We describe a patient with murine typhus and an unusual cutaneous manifestation at the site of rickettsial inoculation.

Rickettsioses in Europe

Bacteria of the genera Rickettsia and Orientia (family rickettsiaceae, order rickettsiales) cause rickettsioses worldwide, and are transmitted by lice, fleas, ticks and mites. In Europe, only Rickettsia spp. cause rickettsioses. With improvement of hygiene, the risk of louse-borne rickettsiosis (epidemic typhus) is low in Europe. Nevertheless, recrudescent form of Rickettsia prowazekii infection persists. There could be an epidemic typhus outbreak if a body lice epidemic occurs under unfavorable sanitary conditions. In Europe, endemic typhus or Rickettsia typhi infection, transmitted by rats and fleas, causes febrile illness. At the beginning of this century, flea-borne spotted fever cases caused by Rickettsia felis were diagnosed. Flea-borne rickettsiosis should be suspected after flea bites if fever, with or without rash, is developed. Tick-borne rickettsioses are the main source of rickettsia infections in Europe. Apart from Rickettsia conorii, the Mediterranean Spotted Fever (MSF) agent, other Rickettsia spp. cause MSF-like: Rickettsia helvetica, Rickettsia monacensis, Rickettsia massiliae or Rickettsia aeschlimannii. In the 1990s, two 'new' rickettsioses were diagnosed: Lymphangitis Associated Rickettsiosis (LAR) caused by Rickettsia sibirica mongolitimonae, and Tick-Borne Lymphadenopathy/Dermacentor-Borne-Necrosis-Erythema-Lymphadenopathy/Scalp Eschar Neck Lymphadenopathy (TIBOLA/DEBONEL/SENLAT), caused by Rickettsia slovaca, Candidatus Rickettsia rioja and Rickettsia raoultii. Lastly, European reports about mite-borne rickettsiosis are scarce.

Epidemiological, clinical and laboratory features of murine typhus in central Tunisia

OBJECTIVE

Murine typhus is an endemic zoonosis. It is difficult to diagnose because of its non-specific clinical manifestations. Our objective was to describe the epidemiological, clinical, laboratory, and treatment features of murine typhus.

METHODS

We conducted a retrospective study of 73 adult patients hospitalized for murine typhus from 2006 to 2011. The diagnosis was confirmed by a single titer of IgM≥128 or by seroconversion to typhus group antigen identified by indirect fluorescent assay.

RESULTS

The mean age of patients was 33.1 years (range, 13-68 years). Thirty-eight patients (52%) lived in rural or suburban areas; neither fleabites nor exposure to rats were reported. The most common clinical symptoms were: fever, headache, and myalgia. A maculopapular and non-confluent rash was observed in 47 patients (64.4%). No inoculation eschar was observed in any patient. Eight patients presented with interstitial pneumonia and two with lymphocytic meningitis. The diagnosis was confirmed by indirect fluorescence assay in every case. A single titer of IgM ≥ 128 was found in 62 (84.9%) cases. The other 11 cases were diagnosed by seroconversion. All patients were given antibiotics. Tetracyclines were prescribed in 57 cases (78%). The two patients presenting with meningitis were treated with fluoroquinolone. The outcome was favorable for all patients and no relapse was observed.

CONCLUSION

The features of murine typhus are non-specific. The definitive diagnosis is based on serologic testing by indirect fluorescent assay. Cyclins were the most prescribed antibiotics.

Murine typhus in elderly patients: a prospective study of 49 patients

BACKGROUND

The characteristics of Rickettsia typhi infection in elderly patients have not been extensively described in the literature.

METHODS

We conducted a prospective study on murine typhus in patients > 65 years old in two endemic areas of Greece.

RESULTS

Forty-nine elderly patients were analyzed, including 30 (61.2%) males. The clinical triad of fever (100% of patients), headache (83.7%), and rash (73.5%), occurred in 63% of patients, whereas malaise (85.7%), anorexia (65.3%), and myalgia (59.2%) were also common. Frequent laboratory findings were transaminasemia (89.8%), lactate dehydrogenase elevation (65.3%), hematuria (55.1%), thrombocytopenia (53.1%), anemia (51%), leucopenia (40.8%), and mild hyponatremia (23.5%). Complications developed in 16 patients (32.7%); no deaths were recorded.

CONCLUSIONS

The main clinical and laboratory characteristics of murine typhus are similar in elderly and younger adults. However, elderly patients have a more severe clinical picture, evidenced by a higher complication rate and longer duration of fever, even with appropriate treatment. To our knowledge, this is the first study to focus on murine typhus in a geriatric population.

[Macrophage activation syndrome: rare complication of murine typhus]

INTRODUCTION

Typhi is one of the rickettsial species endemic in the Mediterranean countries and is associated with the zoonotic infection of murine typhus, which may have a complicated course especially in adult patients. The association with macrophage activation syndrome (MAS) has rarely been reported in the medical literature.

CASE REPORT

We describe a case of murine typhus in a diabetic woman complicated with MAS, who was effectively treated with cyclin and parenteral immunoglobulin.

CONCLUSION

The murine typhus can be exceptionally complicated with SAM. This infection should be suspected in front of the discovery of SAM.