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

Flea-Borne Typhus as a COVID-19 Mimic: A Report of Four Cases

Flea-borne typhus (FBT), due to Rickettsia typhi and R. felis, is an infection causing fever, headache, rash, hepatitis, thrombocytopenia, and diverse organ manifestations. Cough occurs in about 30% of patients with FBT, and chest X-ray abnormalities are seen in 17%. Severe pulmonary manifestations have also been reported in FBT, including adult respiratory distress syndrome and pulmonary embolism. Because of these pulmonary manifestations, FBT can mimic Coronavirus Illness 2019 (COVID-19), a febrile illness with prominent respiratory involvement. Flea-borne typhus and COVID-19 may also have similar laboratory abnormalities, including elevated ferritin, C-reactive protein, and D-dimer. However, elevated transaminase levels, rash, and thrombocytopenia are more common in FBT. Herein, we present four cases of patients with FBT who were initially suspected to have COVID-19. These cases illustrate the problem of availability bias, in which the clinician thinks a particular common condition (COVID-19 in this case) is more prevalent than it actually is.

Surveillance of Flea-Borne Typhus in California, 2011-2019

Flea-borne typhus (FBT), also referred to as murine typhus, is an acute febrile disease in humans caused by the bacteria Rickettsia typhi. Currently, cases of FBT are reported for public health surveillance purposes (i.e., to detect incidence and outbreaks) in a few U.S. states. In California, healthcare providers and testing laboratories are mandated to report to their respective local public health jurisdictions whenever R. typhi or antibodies reactive to R. typhi are detected in a patient, who then report cases to state health department. In this study, we characterize the epidemiology of flea-borne typhus cases in California from 2011 to 2019. A total of 881 cases were reported during this period, with most cases reported among residents of Los Angeles and Orange Counties (97%). Demographics, animal exposures, and clinical courses for case patients were summarized. Additionally, spatiotemporal cluster analyses pointed to five areas in southern California with persistent FBT transmission.

Murine Typhus: A Review of a Reemerging Flea-Borne Rickettsiosis with Potential for Neurologic Manifestations and Sequalae

Murine typhus is an acute febrile illness caused by Rickettsia typhi, an obligately intracellular Gram-negative coccobacillus. Rats (Rattus species) and their fleas (Xenopsylla cheopis) serve as the reservoir and vector of R. typhi, respectively. Humans become infected when R. typhi-infected flea feces are rubbed into flea bite wounds or onto mucous membranes. The disease is endemic throughout much of the world, especially in tropical and subtropical seaboard regions where rats are common. Murine typhus is reemerging as an important cause of febrile illness in Texas and Southern California, where an alternate transmission cycle likely involves opossums (Didelphis virginiana) and cat fleas (Ctenocephalides felis). Although primarily an undifferentiated febrile illness, a range of neurologic manifestations may occur, especially when treatment is delayed. Serology is the mainstay of diagnostic testing, but confirmation usually requires demonstrating seroconversion or a fourfold increase in antibody titer from acute- and convalescent-phase sera (antibodies are seldom detectable in the first week of illness). Thus, early empiric treatment with doxycycline, the drug of choice, is imperative. The purpose of this review is to highlight murine typhus as an important emerging and reemerging infectious disease, review its neurologic manifestations, and discuss areas in need of further study.

Fleaborne Typhus-Associated Deaths - Los Angeles County, California, 2022

Fleaborne typhus (also known as murine typhus), a widely distributed vectorborne zoonosis caused by Rickettsia typhi, is a moderately severe, but infrequently fatal illness; among patients who receive doxycycline, the case-fatality rate is <1%. Fleaborne typhus is a mandated reportable condition in California. Reported fleaborne typhus cases in Los Angeles County have been increasing since 2010, with the highest number (171) reported during 2022. During June-October 2022, Los Angeles County Department of Public Health learned of three fleaborne typhus-associated deaths. This report describes the clinical presentation, illness course, and methods used to diagnose fleaborne typhus in these three cases. Severe fleaborne typhus manifestations among these cases included hemophagocytic lymphohistiocytosis, a rare immune hyperactivation syndrome that can occur in the infection setting; myocarditis; and septic shock with disseminated intravascular coagulation. Increased health care provider and public health awareness of the prevalence and severity of fleaborne typhus and of the importance of early doxycycline therapy is essential for prevention and treatment efforts.

Murine Typhus in Latin America: Perspectives of a Once Recognized but Now Neglected Vector-Borne Disease

Murine typhus is an undifferentiated febrile illness. Historically recognized throughout Latin America, it has been seldom reported in recent decades. When clinicians and researchers are attuned, endemic foci have reemerged. The demonstrable seroprevalence in areas devoid of reported cases indicates murine typhus is an underappreciated infectious disease in Latin America.

Murine typhus complicated by sHLH mimicking adult-onset Still's disease

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.

Murine Typhus Presenting as Septic Acute Cholangitis in a Young Woman From South Texas

Murine (endemic) typhus is a zoonotic disease spread by fleas carrying Rickettsia typhi bacteria. Typically, murine typhus presents with mild and nonspecific flu-like symptoms. However, it can manifest with severe systemic complications potentially leading to delayed treatment or unnecessary interventions.

We present the case of a young woman from South Texas who presented to the emergency department after 10 days of fever, myalgia, headache, nausea, and right-sided abdominal pain. She was found to be febrile, severely hypotensive, suffering from acute liver injury with a predominantly cholestatic pattern, acute kidney injury, severe thrombocytopenia, and hyponatremia. She was initially managed with broad-spectrum antibiotics for undifferentiated septic shock, and doxycycline was added due to suspicion of a Rickettsial infection. Although radiographic findings showed some evidence of biliary involvement, they were not typical for common biliary diseases. However, due to her severe clinical presentation and findings suggesting possible acute cholangitis, she underwent an endoscopic ultrasound with endoscopic retrograde cholangiopancreatography, which revealed no evidence of acute obstructive biliary disease. Without strong evidence to explain her presentation, an extensive chronic liver disease workup was done, which was negative. The patient ultimately clinically improved with antibiotics alone.

This case demonstrates an atypical presentation of murine typhus, presenting with septic shock and masquerading as acute cholangitis. With the rising incidence of murine typhus in endemic areas of the United States, this case reinforces the importance of being cognizant of the typical and atypical presentations of murine typhus, which may allow for early appropriate treatment and potentially avoid unnecessary interventions. Additionally, in this study, we conducted a literature review of murine typhus cases associated with acute biliary dysfunction.

Patient characteristics, treatment patterns, and outcomes of Rickettsial diseases among a commercially insured population in the United States, 2005-2017

Rickettsial diseases (RDs) are transmitted to humans by ectoparasites, including ticks and fleas. Symptoms range from mild febrile illness, to severe disease or death. Doxycycline is the treatment of choice for patients of all ages; early treatment based on clinical diagnosis is critical to prevent severe outcomes. We conducted a descriptive analysis using insurance claims data captured by IBM MarketScan^® research databases to describe demographics, treatment patterns, and outcomes of patients diagnosed with RDs in the United States during 2005–2017. Overall, 14,830 patients had a RD diagnosis during 2005–2017; 7,517 (50.7%) spotted fever rickettsiosis (SFR), 4,571 ( 30.8%) ehrlichiosis, 1,362 (9.2%) typhus group rickettsiosis (TGR), and 1,193 (8.0%) other rickettsial diseases. Among all patients diagnosed, 53.1% received doxycycline. Prescription rates varied by diagnosis and age; 24.1% of TGR and 61.1% of SFR patients received doxycycline; 23.9% of persons < 8 years received doxycycline, compared with 47.7% for 8–17 years, and 55.4% for ≥ 18 years. RDs are frequently diagnosed in the outpatient population; however, providers prescribed the recommended treatment to about half of patients. Continued education of treatment recommendations is critical to prevent severe outcomes.

Liver Failure, Renal Failure, and a Rash: An Unusually Severe Case of Multi-Organ Failure Due to Murine Typhus

Murine typhus is a vector-borne disease transmitted to humans via fleas and typically causes an infection hallmarked by nonspecific, mild symptoms of fever, rash, and headache. More severe diseases, while rare, can occur. We present a complicated case of murine typhus resulting in liver and renal failure. Our patient was a healthy 64-year-old Hispanic gentleman who presented to his local emergency department (ED) in Southwest Texas for fevers, chills, and myalgia progressing to dyspnea, fatigue, and jaundice. He was transferred to a Central Texas transplant hospital given concern for impending liver failure as well as acute kidney injury later requiring hemodialysis. Broad-spectrum antibiotics were narrowed to empiric doxycycline with eventual improvement in his lab values and symptoms. The return of Rickettsia typhi antibody lab values later revealed murine typhus to be the cause of his disease.

Murine Typhus Infection in Pregnancy: Case Series and Literature Review

Murine typhus is a flea-borne disease of worldwide distribution with a recent reemergence in the United States of America. There are limited data about the presentation, treatment, and outcomes in the pregnant population. We report on two cases of murine typhus during pregnancy and review the literature to compile previously reported cases. A comprehensive search was performed via the PubMed database for published articles between 1990 and 2020. Seven articles met the criteria of symptomatic pregnant murine typhus infection. A total of 37 patients were identified. Patients frequently presented with a prolonged duration of fevers prior to presentation, headache, and elevated hepatic transaminases. The diagnosis was predominantly based on serology. Treatment varied. Overall, the pregnancy outcome was favorable. Murine typhus can mimic other pregnancy-related pathologies. More exclusive and large-scale studies are needed to learn more of murine typhus during pregnancy.

Manifestations and Management of Flea-Borne Rickettsioses

Murine typhus and flea-borne spotted fever are undifferentiated febrile illnesses caused by Rickettsia typhi and Rickettsia felis, 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 (Xenopsylla cheopis) are the vector. In the United States, a cycle of transmission involving opossums and cat fleas (Ctenocephalides felis) are the presumed reservoir and vector, respectively. The incidence and distribution of murine typhus appear to be increasing in endemic areas of the US. Rickettsia felis 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.

Murine typhus mistaken for COVID-19 in a young man

Fever is a widely recognised presenting symptom of COVID-19. Consequently, other febrile illnesses may be difficult to distinguish from COVID-19-leading to delays in diagnosis and treatment. One such illness is murine typhus, a fleaborne illness with worldwide distribution caused by Rickettsia typhi It often presents with fever, headache and myalgia, all of which have been commonly reported with COVID-19. Although the disease is usually mild with a good prognosis, there have been reports of severe illness and death. I present a case of murine typhus in a young male who had 2 weeks of headaches and daily fevers during the COVID-19 pandemic. He was ultimately tested for murine typhus when his occupation as a dog trainer was queried, and he experienced resolution of symptoms after treatment with doxycycline. During this pandemic, clinicians must be vigilant of other febrile illnesses whose symptoms overlap with COVID-19.

A systematic review of the untreated mortality of murine typhus

Murine typhus is an acute febrile, flea-borne disease caused by the bacteria Rickettsia typhi. The disease occurs worldwide but is likely underrecognized due to its non-specific symptoms, causing significant morbidity. A systematic review found disease complications in one-fourth of all patients and a long fever duration in those untreated. Although mortality in treated cases is estimated to be very low, some case series have shown a notably higher mortality in untreated patients. This study aimed to describe the outcomes and estimate the mortality of untreated murine typhus through a comprehensive systematic literature review. We systematically searched the literature for articles describing untreated murine typhus patients, excluding cases with no laboratory assay confirmed diagnosis, those who received efficacious treatment, had incomplete information on primary outcome and articles describing less than 10 patients and performed a narrative synthesis of the study findings. The study protocol followed the PRISMA guidelines and was part of a more extensive protocol registered at PROSPERO (CRD42018101991). Twelve studies including a total of 239 untreated patients matched the eligibility criteria. Only a single study reported one death in 28 patients, giving a patient series mortality of 3.6% and an overall mortality of 0.4% in 239 untreated patients. Complications were reported in 10 of the 12 studies and included involvement of the central nervous system, kidney and lung, with a hospitalisation rate of 70% and ICU admission rate of 27% in one study. The mean duration of fever in untreated patients was 15 days in two and 12.7 days in one study. Although the untreated mortality in this study was low, the sample size was small. Murine typhus caused significant morbidity when untreated, leading to high hospitalisation rates and highlighting the importance of early diagnosis and treatment of this neglected disease to reduce disease burden and health-care related costs.

Murine typhus is an acute febrile, flea-borne bacterial disease that has been reported worldwide and continues to cause significant morbidity when untreated. The often self-limiting, non-specific clinical symptoms of the disease resemble that of common viral illnesses, suggesting that the disease is underdiagnosed. While the mortality in treated cases is estimated to be very low, disease complications in one-fourth of all patients and a prolonged duration of fever in untreated cases have been reported. We systematically searched the literature to identify articles describing laboratory diagnostically confirmed clinical cases of untreated murine typhus and summarized disease outcomes, including mortality, of patients in eligible studies. Of the 12 studies containing 239 untreated patients that matched the eligibility criteria, only one study reported a single death amongst 28 untreated patients, resulting in a patient series fatality rate of 3.6% and an overall untreated fatality rate of 0.4%. Disease complications were mentioned in 10 of 12 studies and the mean duration of fever in untreated cases was 15 days in two studies and 12.7 days in one study, demonstrating the significant morbidity caused by untreated murine typhus and highlighting the importance of early diagnosis and treatment of this neglected disease.

History, Rats, Fleas, and Opossums: The Ascendency of Flea-Borne Typhus in the United States, 1910-1944

Flea-borne typhus, due to Rickettsia typhi and Rickettsia felis, is an infection causing fever, headache, rash, hepatitis, thrombocytopenia, and diverse organ manifestations. Although most cases are self-limited, 26%-28% have complications and up to one-third require intensive care. Flea-borne typhus was recognized as an illness similar to epidemic typhus, but having a milder course, in the Southeastern United States and TX from 1913 into the 1920s. Kenneth Maxcy of the US Public Health Service (USPHS) first described the illness in detail and proposed a rodent reservoir and an arthropod vector. Other investigators of the USPHS (Eugene Dyer, Adolph Rumreich, Lucius Badger, Elmer Ceder, William Workman, and George Brigham) determined that the brown and black rats were reservoirs and various species of fleas, especially the Oriental rat flea, were the vectors. The disease was recognized as a health concern in the Southern United States in the 1920s and an increasing number of cases were observed in the 1930s and 1940s, with about 42,000 cases reported between 1931-1946. Attempts to control the disease in the 1930s by fumigation and rat proofing and extermination were unsuccessful. The dramatic increase in the number of cases from 1930 through 1944 was due to: the diversification of Southern agriculture away from cotton; the displacement of the smaller black rat by the larger brown rat in many areas; poor housing conditions during the Great Depression and World War II; and shortages of effective rodenticides and insecticides during World War II.

Trends in clinical diagnoses of typhus group rickettsioses among a large U.S. insurance claims database

Typhus group rickettsioses (TGRs) are vector-borne diseases that include murine typhus (Rickettsia typhi) and epidemic typhus (R. prowazekii). Twentieth-century public health interventions led to dramatic decreases in incidence; little is known about the contemporary TGR prevalence because neither disease is nationally notifiable. We summarized administrative claims data in a commercially insured population to examine trends in TGR medical encounters. We analysed data from 2003 to 2016 IBM® MarketScan® Commercial Databases to identify persons with inpatient or outpatient visits with an International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification TGR-specific code. We summarized epidemiologic characteristics associated with incident diagnosis. We identified 1,799 patients diagnosed with a TGR. Patients resided in 46 states, and most were female (n = 1,019/1,799; 56.6%); the median age was 42 years (range: 0-64 years). Epidemic typhus (n = 931/1,799; 51.8%) was the most common TGRs, followed by murine typhus (n = 722/1,799; 40.1%). The majority of TGR patients were diagnosed in an outpatient setting (n = 1,725/1,799; 95.9%); among hospitalized patients, the majority received a murine typhus diagnosis (n = 67/74; 90.5%). TGRs are rarely diagnosed diseases. More patients were diagnosed with epidemic than murine typhus, even though R. prowazekii transmission requires body louse or flying squirrel exposure. Patients from all geographic regions were diagnosed with murine and epidemic typhus, despite historically recognized ranges for these diseases. The epidemiologic misalignment of insurance claims data versus historic TGRs data highlights the challenges of finding appropriate alternative data sources to serve as a proxy when national surveillance data do not exist.

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.

The Rickettsioses: A Practical Update

Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness throughout the world. Rickettsioses present as an acute undifferentiated febrile illness and are often accompanied by headache, myalgias, and malaise. Cutaneous manifestations include rash and eschar, which both occur at varying incidence depending on the infecting species. Serology is the mainstay of diagnosis, and the indirect immunofluorescence assay is the test of choice. Reactive antibodies are seldom present during early illness, so testing should be performed on both acute-phase and convalescent-phase sera. Doxycycline is the treatment of choice.

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.

Molecular Survey of Rickettsia spp., Anaplasma spp., Ehrlichia spp., Bartonella spp., and Borrelia spp. in Fleas and Lice in Ethiopia

Bacterial arthropod-borne pathogens can often cause fever in Africa, but rural laboratories in these settings are usually too basic to provide a precise picture of their epidemiological impact. Our aim was to determine the prevalence of bacterial pathogens in fleas and lice in a rural area of southeast Ethiopia. Between July and November 2013, we extracted DNA from 91 fleas (Ctenocephalides felis [n = 50; 54.9%], Pulex irritans [n = 37; 40.1%], and C. canis [n = 4; 4.4%] and 30 lice (Pediculus humanus capitis [n = 16; 53.3%] and Pediculus humanus humanus [n = 14; 46.7%]), using two quantitative PCR (qPCR) analyses to look for bacteria from the genera: Anaplasma, Bartonella, Borrelia, Coxiella, Ehrlichia, Francisella, and Rickettsia. Of the 91 fleas analyzed, pathogens were present in 79 (86.8%), including Rickettsia felis (n = 41; 45%), Anaplasma platys (n = 40; 44.0%), Rickettsia monacensis (n = 2; 2.2%), Ehrlichia muris-like agent (n = 1; 1.1%), and Bartonella clarridgeiae (n = 1; 1.1%). P. irritans was the flea species most frequently infected with A. platys (67.7%), followed by C. felis (30.7%) (p < 0.001). Of the 30 lice identified, pathogens were present in 7 (23.3%): Bartonella quintana (n = 4; 16.7%), E. muris (n = 2, 6.7%), and Borrelia recurrentis (n = 1, 3.3%). Thus, in this rural area of Africa, fleas and lice can transmit parasitic pathogens to humans, causing febrile symptoms.

Emergence of murine typhus in La Réunion, France, 2012-2017

OBJECTIVE

Murine typhus (MT) is an acute zoonosis caused by Rickettsia typhi, a flea-borne rickettsiosis. The first autochthonous case was reported in 2012. Once autochthonous transmission of Rickettsia typhi was proven, we performed a prospective study to describe and raise awareness of this often-misdiagnosed disease among physicians.

PATIENTS AND METHODS

We performed a prospective observational study of MT cases in La Réunion from 2012 to 2017. MT cases were defined as clinically compatible illnesses with a specific positive serology and/or PCR.

RESULTS

Sixty-one confirmed cases were collected. The main clinical features were prolonged fever (90%), asthenia (87%), and headaches (79%). The main biological abnormalities were elevated liver enzymes (84%) and thrombopenia (75%). Renal function was normal in 90% of cases; it was an important feature because leptospirosis is a frequent cause of acute renal failure. A seasonal factor was observed with 79% of cases reported in the warm season and most of them in the west and south of the island (i.e., the dry areas).

CONCLUSION

MT is an emerging disease in La Réunion, and local conditions could lead to an endemic situation. Cases of acute undifferentiated fever with headaches should guide to the diagnosis of MT especially in the warm season and dry areas. Leptospirosis is an alternative diagnosis, which differs from MT by its epidemiological characteristics and by the associated frequent renal dysfunction.

Emerging and re-emerging rickettsial infections

Rickettsial organisms are a diverse group of obligate intracellular bacteria; all species known to cause human disease are dependent on an arthropod vector and many are considered zoonotic diseases. Typical vectors of rickettsia are fleas, ticks, mites or lice. Humans become infected either when bitten or upon contact of broken skin or mucous membranes by infected secretions from an arthropod vector. The emergence and re-emergence of rickettsial diseases is a serious public health concern in the United States and abroad. Herein, the clinical and pathologic features of rickettsial diseases are described in tandem with the current scientific underpinnings. The histopathology of emerging and re-emerging rickettsiosis with species-specific discussion relating to vector issues and control are explored. Concepts of endemicity are addressed in the context of climate change and its impact on vector and sylvatic reservoirs, underscoring the need for clinical vigilance and broad consideration for encounters with these potentially life threating human pathogens.

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.

Rickettsial Infections among Cats and Cat Fleas in Riverside County, California

Presently, few studies have investigated the role of domestic cats (Felis catus) in the recrudescence of flea-borne rickettsioses in California and the southern United States. In this study, we aimed to investigate the presence of Rickettsia typhi or Rickettisa felis in domestic cats (F. catus) and the fleas (primarily Ctenocephalides felis, the cat flea) associated with these cats in Riverside County, California. Thirty cats and 64 pools of fleas collected from these cats were investigated for rickettsial infections. Three cats and 17 flea pools (from 10 cats) tested positive for rickettsial infections. polymerase chain reaction and DNA sequencing indicated that one of the cats was positive for R. felis infections, whereas two were positive for Candidatus Rickettsia senegalensis infection. In addition, 12 of the flea pools were positive for R. felis, whereas five were positive for Ca. R. senegalensis. By contrast, no cats or their associated fleas tested positive for R. typhi. Finally, eight sera from these cats contained spotted fever group Rickettsia (SFGR) antibodies. The detection of R. felis and SFGR antibodies and the lack of R. typhi and TGR antibodies support R. felis as the main rickettsial species infecting cat fleas. The detection of Ca. R. senegalensis in both fleas and cats also provides additional evidence that cats and their associated fleas are infected with other R. felis-like organisms highlighting the potential risk for human infections with R. felis or R. felis-like organisms.

Orbital Inflammatory Syndrome Secondary to Flea Bite

A 34-year-old previously healthy Hispanic male presented to the emergency room complaining of progressive left upper eyelid swelling and pain for more than 2 weeks. He was previously diagnosed and treated for a "pink eye" but failed to improve. He reported a previous "bug bite" around the left lateral canthus a few weeks prior to admission. Computer tomography orbit with contrast showed left exophthalmos, an enhancing left lacrimal gland and orbital inflammatory signs suggestive of possible intraorbital abscess. Intravenous antibiotics did not improve his symptoms. Surgical debridement showed no abscess but inflamed soft tissues and lacrimal gland. Intravenous steroids failed to improve his symptoms. On postoperative day 3, the patient reported that an insect had "jumped" out from his left orbit. Identification of the specimen proved to be a mature flea. Biopsy of the lacrimal gland showed degranulation of eosinophils and foreign body material consistent with probable insect leg parts.

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.