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

LOCALIZED MYOSITIS AND TRANSIENT ENCEPHALOPATHY AS PRESENTING SYMPTOMS IN MURINE TYPHUS

Murine typhus in the pediatric population has increased substantially in recent years. The most common clinical presentation of murine typhus includes fever, rash, headaches and myalgias. Murine typhus presenting with predominant myositis and/or encephalopathy is rare. It is important to recognize unusual clinical manifestations of murine typhus in children for early diagnosis and treatment.

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.

Severe murine typhus complicated by multiple organ dysfunctions: A case report

Background

Rickettsioses are infectious diseases which are caused by intracellular bacteria which belong to the family Rickettsiaceae. This zoonosis endemically prefers tropical and subtropical regions of which the Mediterranean is included. Murine typhus is a type of rickettsial disease that commonly presents with undulating fever, headache rash, chills, malaise, and myalgias. It can lead to complications such as multi-organ failure and has a lethality rate of <5% in such cases.

Case Presentation

A 70-year-old male was hospitalized at the Unit of Infectious Diseases, Mother Teresa Hospital, Tirana, Albania in a comatose condition. He had a seven-day history of fever up to 39-40°C, headache, fatigue, anorexia, vomiting, cough, and myalgia. He was a farmer and had contact with animals. Upon admission, he had scleral hemorrhages, hepatosplenomegaly, jaundice, maculopapular rash over the trunk, abdomen, and palms of his hands as well as severe acidosis, depressed bicarbonate levels, alteration in liver, kidney, and pancreas function tests. He was urgently transferred to the Intensive care unit of the Infectious Diseases Department. He was hemodynamically unstable and was put immediately on vasoactive agents and mechanical ventilation. ELISA Rickettsia typhi IgM resulted positive. Supportive treatment along with antibiotics Levofloxacin and Ceftriaxone was initiated. However, the patient died on the 4th day of hospitalization and the 11th of the disease onset.

Conclusion

Murine typhus should be included in the investigation of possible causes when dealing with patients presenting with fever and maculopapular rash complicated by multi-organ failure and coming from a typhus-endemic area, especially in the summer season.

Flea-Borne Typhus Presenting with Acalculous Cholecystitis and Severe Anemia

Background

Flea-borne typhus (FBT), an uncommon illness in the United States, typically presents as a high continuous fever with commonly associated symptoms including headache, myalgias, and rashes on the trunk and extremities. Patients infected with FBT may also present with atypical symptoms. As such, the combination of its relatively low incidence in the United States coupled with its variability in associated symptoms poses a diagnostic challenge for clinicians; early empiric treatment with doxycycline is warranted prior to a definitive diagnosis to reduce the risk of damage to vital organs. Case Report. This case describes a 54-year-old male who presented to an emergency room in Houston, Texas, with one week of constant right upper quadrant abdominal pain and fevers up to 40°C. The patient was initially diagnosed with Grade III severe acute cholangitis after abdominal ultrasound revealed gallbladder sludge and wall thickening without ductal dilatation, but a subsequent endoscopic retrograde cholangiopancreatography was unremarkable. Following intermittent fevers and worsening anemia, the patient was started on oral doxycycline for atypical infection, and an infectious disease workup subsequently returned a positive titer for Rickettsia typhi. He experienced rapid symptomatic and clinical improvement, and the patient was discharged home with a final diagnosis of flea-borne typhus.

Conclusion

Albeit uncommon, the presentation of this patient's symptoms and final diagnosis of flea-borne typhus demonstrates the importance of (1) keeping atypical infections such as FBT in the differential diagnosis and (2) beginning empiric treatment to prevent damage to vital organs if suspicion of FBT is high.

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.

The Microbial Etiology of Community-Acquired Pneumonia in Adults: from Classical Bacteriology to Host Transcriptional Signatures

All modern advances notwithstanding, pneumonia remains a common infection with substantial morbidity and mortality. Understanding of the etiology of pneumonia continues to evolve as new techniques enable identification of already known organisms and as new organisms emerge. We now review the etiology of pneumonia (at present often called "community-acquired pneumonia") beginning with classic bacteriologic techniques, which identified Streptococcus pneumoniae as the overwhelmingly common cause, to more modern bacteriologic studies, which emphasize Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, Enterobacteriaceae, Pseudomonas, and normal respiratory flora. Urine antigen detection is useful in identifying Legionella and pneumococcus. The low yield of bacteria in recent studies is due to the failure to obtain valid sputum samples before antibiotics are administered. The use of high-quality sputum specimens enables identification of recognized ("typical") bacterial pathogens as well as a role for commensal bacteria ("normal respiratory flora"). Nucleic acid amplification technology for viruses has revolutionized diagnosis, showing the importance of viral pneumonia leading to hospitalization with or without coinfecting bacterial organisms. Quantitative PCR study of sputum is in its early stages of application, but regular detection of high counts of bacterial DNA from organisms that are not seen on Gram stain or grown in quantitative culture presents a therapeutic dilemma. This finding may reflect the host microbiome of the respiratory tract, in which case treatment may not need to be given for them. Finally, host transcriptional signatures might enable clinicians to distinguish between viral and bacterial pneumonia, an important practical consideration.

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.

Socio-ecological determinants of rickettsial seroprevalence in a rural community of Yucatán, Mexico

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 (X² [n = 175, df = 4, (p < 0.001)] = 180.26), level of education, (X² [n = 180, df = 4, (p < 0.001)] = 44.0), and by tick species found in residential area, (X² [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.

Zoonotic Disease Testing Practices in Pediatric Patients with Meningitis and Encephalitis in a Subtropical Region

Emerging vector-borne and zoonotic pathogens can cause neuroinvasive disease in children; utilization of appropriate diagnostic testing can be low, hindering diagnosis and clinical management of these cases. We must understand factors that influence healthcare providers’ decisions to order diagnostic testing. We reviewed medical charts for pediatric meningitis and encephalitis patients (90 days–18 years) between 2010 and 2017 and analyzed variables associated with testing for known neuroinvasive zoonotic pathogens in the southern United States: West Nile virus (WNV), Bartonella spp., and Rickettsia spp. Among 620 cases of meningitis and encephalitis, ~1/3 (n = 209, 34%) were tested for WNV. Fewer cases were tested for Bartonella (n = 77, 12%) and Rickettsia (n = 47, 8%). Among those tested, 14 (7%) WNV, 7 (9%) Bartonella, and 6 (13%) Rickettsia cases were identified. Factors predicting testing were similar between all agents: clinical presentation of encephalitis, focal neurologic symptoms, new onset seizure, and decreased Glasgow Coma Scale on admission. Cases with a history of arthropod contact were more likely to be tested; however, we did not see an increase in testing during the summer season, when vector exposure typically increases. While our test utilization was higher than that reported in other studies, improvement is needed to identify zoonotic causes of neuroinvasive diseases.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

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.

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.

Leptospirosis and Rickettsial Diseases Sero-Conversion Surveillance Among U.S. Military Personnel in Honduras

INTRODUCTION

Leptospirosis and rickettsial diseases are global zoonotic diseases. In severe infection cases, mortality can range from 10% to 30%. Currently most epidemiological data available are based on outbreak investigations and hospital-based studies from endemic countries. The U.S. soldiers at military bases in these countries are highly vulnerable due to the fact that most of them are immunologically naïve to these pathogens. No risk assessment of leptospirosis and rickettsial diseases among U.S. military personnel in Honduras is currently available. This study was aimed at determining the prevalence of leptospirosis and rickettsial diseases in U.S. military personnel deployed to Honduras using serological assays.

MATERIALS AND METHODS

A cohort of pre- and post-deployment sera from the most recent 1,000 military personnel stationed in Honduras for at least 6 months between 2000 and 2016 was identified for this study. Serum specimens from these eligible subjects were retrieved. All post-deployment serum specimens were screened at a dilution of 1:100 for the presence of IgG antibodies to Leptospira and Rickettsia pathogens. The pre-deployment sera from those individuals with post-deployment IgG antibodies above cutoff (i.e., seropositive) were tested to determine seroconversion. Seroconversion was defined as conversion of an optical density value from below the cutoff (i.e., negative) in a pre-deployed specimen to above the cutoff (i.e., positive) in a post-deployed specimen at a titer of 100.

RESULTS

The seropositive post-deployment specimens for antibodies against Leptospira (causing leptospirosis), Rickettsia typhi (causing murine typhus [MT]), spotted fever group rickettsioses (SFGR, causing SFG Rickettsia), Orientia tsutsugamushi (causing scrub typhus [ST]), and Coxiella burnetii (causing Q fever [QF]) were 11.6%, 11.3%, 6%, 5.6%, and 8.0%, respectively. The seroconverted rate in those assigned to Honduras from 2000 to 2016 was 7.3%, 1.9%, 3.9%, 4.3%, and 2.7% for leptospirosis, MT, SFGR, ST, and QF, respectively. Among the seroconverted specimens, 27 showed seroconversion of at least two antibodies. These seroconverted individuals accounted for 8.8% (3 out of 34) of the personnel who looked for medical attention during their deployment.

CONCLUSIONS

Our results suggest a leptospirosis seroconversion rate of 7.3%, which is higher than the 0.9% and 3.9% seroconversion in Korea and Japan, respectively. The higher rate of seroconversion indicates potential risk of Leptospira exposure. Additional testing of water samples in the pools and pits around the training sites to locate the infected areas is important to eliminate or reduce future exposure to Leptospira during trainings. The rates of seroconversion for ST, MT, spotted fever Rickettsia, and QF were 4.3%, 1.9%, 3.9%, and 2.7%, respectively, indicating the potential exposure to a variety of rickettsial-related pathogens. Testing of vectors for rickettsial pathogens in the areas could inform effective vector control countermeasures to prevent exposure. Proper precaution and protective measures are needed to better protect military personnel deployed to Honduras.

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 Outbreak Presenting as Multisystem Inflammatory Syndrome in Children During SARS-CoV-2 Pandemic

Multisystem inflammatory syndrome in children is a severe illness associated with the SARS-CoV-2 pandemic that possesses features overlapping with other pediatric diseases causing systemic inflammation. Significant diagnostic and treatment uncertainty remain, and clinicians should maintain a broad differential when evaluating patients for multisystem inflammatory syndrome in children, as antibiotic-susceptible infections such as murine typhus may present similarly.

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.

Hyponatremia in Infectious Diseases-A Literature Review

Hyponatremia is one of the most common water-electrolyte imbalances in the human organism. A serum sodium concentration threshold of less than 135 mmol/L is diagnostic for hyponatremia. The disorder is usually secondary to various diseases, including infections. Our review aims to summarize the diagnostic value and impact of hyponatremia on the prognosis, length of the hospitalization, and mortality among patients with active infection. The scientific literature regarding hyponatremia was reviewed using PubMed, ClinicalKey, and Web of Science databases. Studies published between 2011 and 2020 were screened and eligible studies were selected according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and specific inclusion criteria. The most common infections that were associated with hyponatremia were viral and bacterial infections, including COVID-19 (coronavirus disease 2019). The etiology varied according to the infection site, setting and patient cohort it concerned. In several studies, hyponatremia was associated with prolonged hospitalization, worse outcomes, and higher mortality rates. Hyponatremia can also play a diagnostic role in differentiating pathogens that cause a certain infection type, as it was observed in community-acquired pneumonia. Although many mechanisms leading to hyponatremia have already been described, it is impossible with any certainty to ascribe the etiology of hyponatremia to any of them.

Assessing human exposure to spotted fever and typhus group rickettsiae in Ontario, Canada (2013-2018): a retrospective, cross-sectional study

BACKGROUND

Assessing the burden of rickettsial infections in Ontario, Canada, is challenging since rickettsial infections are not reportable to public health. In the absence of reportable disease data, we assessed the burden of rickettsial infections by examining patient serological data and clinical information.

METHODS

Our retrospective, cross-sectional study included patients who had Rickettsia serological testing ordered by their physician, in Ontario, from 2013 to 2018. We tested sera from 2755 non-travel patients for antibodies against spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) using an indirect immunofluorescence assay (IFA) (positive IgG titers ≥1:64). We classified cases using a sensitive surveillance case definition: confirmed (4-fold increase in IgG titers between acute and convalescent sera with clinical evidence of infection), possible (single positive sera with clinical evidence) and previous rickettsial infection (single positive sera without clinical evidence). We classified cases seropositive for both SFGR and TGR as unspecified Rickettsia infections (URIs).

RESULTS

Less than 5% of all patients had paired acute and convalescent sera tested, and of these, we found a single, laboratory-confirmed SFGR case, with a 4-fold increase in IgG titers and evidence of fever, maculopapular rash and headache. There were 45 possible (19 SFGR, 7 TGR, 19 URI) and 580 previous rickettsial infection (183 SFGR, 89 TGR, 308 URI) cases. The rate of positive tests for SFGR, TGR and URI combined (all case classifications) were 4.4 per 100,000 population. For confirmed and possible cases, the most common signs and symptoms were fever, headache, gastrointestinal complaints and maculopapular rash. The odds of having seropositive patients increased annually by 30% (odds ratio = 1.3, 95% confidence interval: 1.23-1.39).

CONCLUSIONS

The rates of rickettsial infections in Ontario are difficult to determine. Based on confirmed and possible cases, rates are low, but inclusion of previous rickettsial infection cases would indicate higher rates. We highlight the need for education regarding the importance of testing acute and convalescent sera and consistent completion of the laboratory requisition in confirming rickettsial disease. We suggest further research in Ontario to investigate rickettsial agents in potential vectors and clinical studies employing PCR testing of clinical samples.

An Unusual Case of Campylobacter jejuni Gastroenteritis Presenting with Acute Reversible Encephalopathy in an Immunocompetent Host

Campylobacter jejuni gastroenteritis is the most frequent organism associated with acute infectious diarrhea worldwide. The clinical presentation involves fever, diarrhea, rigors, and myalgias. Other extraintestinal symptoms that have been described involve delirium and other neurological complications, and the most well-known is Guillain-Barré, where there is cross-reactivity between the gastrointestinal tract and the brain. Despite previously described multiple neurological complications, there is a lack of clinical data on the association of Campylobacter-related gastroenteritis with acute encephalopathy in immunocompetent patients. The type of population, immunocompetent stage, and unfamiliarity with the clinical presentation makes this a challenging diagnosis for clinicians. We report a case of Campylobacter gastroenteritis associated with acute encephalopathy in an immunocompetent patient.

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.

Climate factors driven typhus group rickettsiosis incidence dynamics in Xishuangbanna Dai autonomous prefecture of Yunnan province in China, 2005-2017

BACKGROUND

Typhus group rickettsiosis (TGR), which is a neglected vector-borne infectious disease, including epidemic typhus and endemic typhus. We explored the lag effects and nonlinear association between meteorological factors and TGR incidence in Xishuangbanna Dai autonomous prefecture from 2005 to 2017, China.

METHODS

A Poisson regression with a distributed lag nonlinear model (DLNM) was utilized to analyze TGR cases data and the contemporaneous meteorological data.

RESULTS

A J-shaped nonlinear association between weekly mean temperature and TGR incidence was found. The cumulative exposure to weekly mean temperature indicated that the RR increased with the increment of temperature. Taking the median value as the reference, lower temperatures could decrease the risk of TGR incidence, while higher temperatures could increase the risk of TGR incidence and last for 21 weeks. We also found a reversed U-shaped nonlinear association between weekly mean precipitation and TGR incidence. Precipitation between 5 mm and 13 mm could increase the risk of TGR incidence. Taking the median value as the reference, no precipitation and lower precipitation could decrease the risk of TGR incidence, while higher precipitation could increase the risk of TGR incidence and last for 18 weeks.

CONCLUSIONS

The prevention and control measures of TGR should be implemented according to climatic conditions by the local government and health departments in order to improve the efficiency.

Rickettsia typhi central nervous system infection

A 39 year-old male was residing along the south coast of Texas, the USA, presented with fever, myalgias, headaches, and weight loss for ten days. Symptoms and manifestations progressed to include nuchal rigidity, photophobia, hyponatremia, thrombocytopenia, and transaminitis despite the intravenous administration of ceftriaxone and azithromycin. A lumbar puncture performed in the Emergency Department yielded pleocytosis and glucose cerebrospinal fluid/serum ratio of 0.35, suggestive of meningoencephalitis. Conglomerate data raised the suspicion of meningitis secondary to a zoonotic acquired infection, which was later confirmed to be Rickettsia typhi. Doxycycline is the drug of choice for the suspected Rickettsia disease. After doxycycline administration, the patient improved and was discharged home asymptomatic.

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.

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.

Murine typhus in Mexico City: report of an imported case

Murine typhus is endemic in several countries. We herein report an imported case of murine typhus caused by Rickettsia typhi in Mexico City. This is the first report of a case after almost 20 years since the last report. The species was confirmed by DNA sequencing and phylogenetic reconstruction.

Diagnosis of Murine Typhus by Serology in Peninsular Malaysia: A Case Report Where Rickettsial Illnesses, Leptospirosis and Dengue Co-Circulate

Murine typhus is a rarely diagnosed cause of acute febrile illness in Malaysia, and its true disease burden is unknown. We report a case of an acute murine typhus infection in a patient living in a small city in Peninsular Malaysia, presenting with fever, rash, and headache. Unresponsive to the initial empirical treatment for leptospirosis, he showed a rapid response to doxycycline when murine typhus was diagnosed later. This case highlights the importance of considering murine typhus as a diagnostic in cases of acute febrile illness in urban and sub-urban areas, such as that of in Peninsular Malaysia.

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.

Murine Typhus with Marked Thrombocytopenia in a Child in Northern Greece and Literature Review

We report a case of murine typhus in a 4-year-old boy living in northern Greece. Although the illness started with mild symptoms, a maculopapular rash appeared by the end of the first week of illness followed by marked thrombocytopenia. The detection of IgM antibodies against Rickettsia typhi in the patient's blood and a positive polymerase chain reaction result combined with sequencing confirmed the diagnosis of infection by Rickettsia typhi. Clinicians in northern Greece should be aware of the disease, even in cases presenting with no specific initial symptoms.

Suspected and Confirmed Vector-Borne Rickettsioses of North America Associated with Human Diseases

The identification of pathogenic rickettsial agents has expanded over the last two decades. In North America, the majority of human cases are caused by tick-borne rickettsioses but rickettsiae transmitted by lice, fleas, mites and other arthropods are also responsible for clinical disease. Symptoms are generally nonspecific or mimic other infectious diseases; therefore, diagnosis and treatment may be delayed. While infection with most rickettsioses is relatively mild, delayed diagnosis and treatment may lead to increased morbidity and mortality. This review will discuss the ecology, epidemiology and public health importance of suspected and confirmed vector-transmitted Rickettsia species of North America associated with human diseases.