Liver involvement in murine typhus

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.

Survey of rodent-borne pathogens in Singapore reveals the circulation of Leptospira spp., Seoul hantavirus, and Rickettsia typhi

Rodents living alongside humans increases the probability of encounter and also the transmission of rodent-borne diseases. Singapore’s cosmopolitan urban landscape provides a perfect setting to study the prevalence of four rodent-borne pathogens: Seoul hantavirus (SEOV), Leptospira species, Rickettsia typhi and Yersinia pestis, and identify the potential risk factors which may influence rodent density and transmission of rodent-borne diseases. A total of 1143 rodents were trapped from 10 unique landscape structures throughout Singapore. Real-time quantitative Polymerase Chain Reactions were used to detect pathogenic and intermediate Leptospira spp. and Yersinia pestis, whereas the seroprevalence of SEOV and R. typhi were analysed by Enzyme-Linked Immunosorbent Assay and Immunofluorescence Assay respectively. Multivariable logistic regression analysis was used to evaluate the association between prevalence of infection in rodent reservoirs and risk factors. Most of the rodents were caught in public residential developments (62.2%). Among the tested rodents, 42.4% were infected with Leptospira spp., while 35.5% and 32.2% were seropositive for SEOV and R. typhi respectively, whereas Yersinia pestis was not detected. Furthermore, risk factors including habitat, species, gender, and weight of rodents, influenced prevalence of infection to a varying extent. This study highlights the presence of Leptospira spp., SEOV and R. typhi in Singapore’s rodent population, suggesting the need for effective rodent management and sanitation strategies to prevent further circulation and transmission to humans.

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.

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.

Severe Murine Typhus Presenting with Acalculous Cholecystitis: A Case Report and Literature Review

A 54-year-old otherwise healthy male, who was being evaluated for prolonged fever, developed clinical and ultrasonographic signs compatible with acute acalculous cholecystitis. Diagnosis of murine typhus was confirmed by serology and the patient was treated with doxycycline. He improved rapidly and all clinical and laboratory abnormalities returned to normal. The present case dictates that knowledge of the local epidemiology and keeping a high index of clinical suspicion can help recognize uncommon manifestations of murine typhus, in order to treat appropriately and avoid unnecessary investigations and interventions.

Dot-ELISA Rapid Test Using Recombinant 56-kDa Protein Antigens for Serodiagnosis of Scrub Typhus

We developed a rapid dot-enzyme-linked immunosorbent assay (dot-ELISA) using the combination of recombinant 56-kDa protein antigens that exhibited broad reactivity with serum antibodies against the four most prevalent strains (Karp, Kato, Gilliam, and TA763) of Orientia tsutsugamushi. The assay is rapid (30 minutes), and can be done at room temperature, and results can be read by the naked eye. Only a simple shaker is required to wash the membrane. Sera from 338 patients suspected of being ill with scrub typhus from rural hospitals around Thailand were tested using this dot-ELISA. Seventy-five (22.2%) patients were found to be positive. The sensitivity and specificity of dot-ELISA were determined using the indirect immunofluorescent assay (IFA) test as the gold standard, with the cutoff titer of immunoglobulin peroxidase conjugate M (IgM)/G (IgG) greater than 1:400/1:400. The dot-ELISA had a sensitivity of 98.5%, a specificity of 96.3%, a positive predictive value of 86.7%, and a negative predictive value of 99.6% for the acute-phase specimens. The results indicate that dot-ELISA rapid test using recombinant 56-kDa protein antigen was comparable with the IFA test and may be very useful for the diagnosis of scrub typhus in rural hospitals, where IFA is not available.

Clinical and Epidemiological Characteristics of Scrub Typhus and Murine Typhus among Hospitalized Patients with Acute Undifferentiated Fever in Northern Vietnam

A descriptive study on rickettsiosis was conducted at the largest referral hospital in Hanoi, Vietnam, to identify epidemiological and clinical characteristics of specific rickettsiosis. Between March 2001 and February 2003, we enrolled 579 patients with acute undifferentiated fever (AUF), excluding patients with malaria, dengue fever, and typhoid fever, and serologically tested for Orientia tsutsugamushi and Rickettsia typhi. Of the patients, 237 (40.9%) and 193 (33.3%) had scrub and murine typhus, respectively, and 149 (25.7%) had neither of them (non-scrub and murine typhus [non-ST/MT]). The proportion of murine typhus was highest among patients living in Hanoi whereas that of scrub typhus was highest in national or regional border areas. The presence of an eschar, dyspnea, hypotension, and lymphadenopathy was significantly associated with a diagnosis of scrub typhus (OR = 46.56, 10.90, 9.01, and 7.92, respectively). Patients with murine typhus were less likely to have these findings but more likely to have myalgia, rash, and relative bradycardia (OR = 1.60, 1.56, and 1.45, respectively). Scrub typhus and murine typhus were shown to be common causes of AUF in northern Vietnam although the occurrence of spotted fever group rickettsiae was not determined. Clinical and epidemiological information may help local clinicians make clinical diagnosis of specific rickettsioses in a resource-limited setting.

Scrub typhus hepatitis confirmed by immunohistochemical staining

Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi (O. tsutsugamushi). We report herein the case of a woman who presented with fever and elevated serum levels of liver enzymes and who was definitively diagnosed with scrub typhus by histopathological examination of liver biopsy specimens, serological tests and nested polymerase chain reaction. Immunohistochemical staining using a monoclonal anti-O. tsutsugamushi antibody showed focally scattered positive immunoreactions in the cytoplasm of some hepatocytes. This case suggests that scrub typhus hepatitis causes mild focal inflammation due to direct liver damage without causing piecemeal necrosis or interface hepatitis. Thus, scrub typhus hepatitis differs from acute viral hepatitis secondary to liver damage due to host immune responses, which causes severe lobular disarray with diffuse hepatocytic degeneration, necrosis and apoptosis as well as findings indicative of hepatic cholestasis, such as hepatic bile plugs or brown pigmentation of hepatocytes.

Murine typhus in southern Taiwan during 1992-2009

Clinical information regarding murine typhus in Taiwan is limited. In this study, 81 cases of serologically documented murine typhus during 1992-2009 at four referral hospitals in southern Taiwan were analyzed. There was a significant correlation between average environmental temperature and case numbers of murine typhus (r = 0.747, P = 0.005). Acute hepatitis was found in 67% of cases, and hyperbilirubinemia (serum total bilirubin ≥ 23.9 μmol/L) was found in 38%. The intervals between the initiation of appropriate therapy to defervescence were longer in patients with hyperbilirubinemia than those without hyperbilirubinemia (6.1 versus 4.1 days; P = 0.015). Nine (11.1%) showed development of severe illnesses such as acute respiratory distress syndrome (2 patients), aseptic meningitis (3), and acute renal failure (4). Only one died of acute respiratory distress syndrome. Cases of murine typhus were often found during the summer and had acute febrile hepatitis. Those patients with hyperbilirubinemia tended to have a delayed recovery even with appropriate therapy.

New insight into immunity and immunopathology of Rickettsial diseases

Human rickettsial diseases comprise a variety of clinical entities caused by microorganisms belonging to the genera Rickettsia, Orientia, Ehrlichia, and Anaplasma. These microorganisms are characterized by a strictly intracellular location which has, for long, impaired their detailed study. In this paper, the critical steps taken by these microorganisms to play their pathogenic roles are discussed in detail on the basis of recent advances in our understanding of molecular Rickettsia-host interactions, preferential target cells, virulence mechanisms, three-dimensional structures of bacteria effector proteins, upstream signalling pathways and signal transduction systems, and modulation of gene expression. The roles of innate and adaptive immune responses are discussed, and potential new targets for therapies to block host-pathogen interactions and pathogen virulence mechanisms are considered.

Host, pathogen and treatment-related prognostic factors in rickettsioses

Diseases caused by rickettsiae, which are vector-borne bacteria, vary widely from mild and self-limiting, to severe and life-threatening. Factors influencing this diversity of outcome are related to the host, to the infectious agent and to the treatment used to treat the infection. A literature search was conducted on PubMed using the phrases "factors-related severity, outcome, host, pathogen, Rickettsia conorii, R. rickettsii, R. africae, R. felis, R. prowazekii, R. typhi, genomics". Among host factors, old age and the male gender have been associated with poor outcome in rickettsioses. Co-morbidities, ethnical factors and the genetic background of the host also seem to influence the outcome of rickettsial diseases. Moreover, although the degree of the host response is beneficial, it could also partly explain the severity observed in some patients. Among pathogen-related factors, traditional concepts of factors of virulence had been challenged and genomic reductive evolution with loss of regulatory genes is the main hypothesis to explain virulence observed in some species, such as Rickettsia prowazekii, the agent of epidemic typhus. R. prowazekii is the more pathogenic rickettsiae and harbours the smaller genome size (1.1 Mb) compared to less or non-virulent species, and is not intracellularly motile, a factor considered as a virulence factor for other intracellular bacteria. The antibiotic regimen used to treat rickettsioses also has an influence on prognosis. Usual concepts of severity and virulence in rickettsioses are challenging and are frequently paradoxical. In this mini-review, we will describe factors currently thought to influence the outcome of the main rickettsioses responsible for illness in humans.

Epidemiology of acute q Fever, scrub typhus, and murine typhus, and identification of their clinical characteristics compared to patients with acute febrile illness in southern taiwan

BACKGROUND/PURPOSE

In Taiwan, acute Q fever, scrub typhus, and murine typhus (QSM diseases) are the most common rickettsioses, but their epidemiology and clinical characteristics have not been clarified. Diagnosis of these three diseases based on clinical manifestations is difficult, and most of their reported characteristics are identified by describing the predominant manifestations, without being compared with other diseases.

METHODS

Serological tests for QSM diseases were examined simultaneously in patients suspected of the three diseases, regardless of which one was suspected. Clinical manifestations were recorded retrospectively from their charts. The characteristics of QSM diseases were identified by comparison with patients who had non-QSM diseases.

RESULTS

From April 2004 to April 2007, a total of 226 cases of suspected QSM diseases were included. One hundred (44.2%) cases were serologically confirmed as QSM diseases (68 acute Q fever, 23 scrub typhus, and 9 murine typhus), and 126 (55.8%) cases were non-QSM diseases. Only 33 cases (33.0%) of QSM diseases were initially suspected at the time of hospital visit, whereas 54 cases (42.9%) of non-QSM diseases were incorrectly suspected as QSM diseases. Cases of Q fever and scrub typhus were distributed over plain and mountain areas, respectively. By multivariate analysis, relative bradycardia (OR [95% CI], 2.885 [1.3-6.4]; p = 0.009), radiographic hepatomegaly (OR [95% CI], 4.454 [1.6-12.3]; p = 0.004), and elevated serum aminotransferases (OR [95% CI], 5.218 [1.2-23.1]; p = 0.029) were independent characteristics for QSM diseases, and leukocytosis (OR [95% CI], 0.167 [0.052-0.534]; p = 0.003) was negative for the diagnosis of QSM diseases.

CONCLUSION

In southern Taiwan, acute Q fever is the most common rickettsiosis. QSM diseases should be suspected in febrile patients who present with relative bradycardia, hepatomegaly, and elevated serum aminotransferases, but without leukocytosis.

Epidemiological study of rickettsial infections in patients with hypertransaminemia in Madrid (Spain)

A retrospective analysis was performed to detect anti-rickettsial antibodies in the serum of patients with hypertransaminemia of unknown etiology, and in that of healthy members of the general population of Madrid (Spain). Among 143 patients 16 (11.2%) were positive for anti-R. conorii IgG antibodies and 7% for R. typhi. PCR analysis was performed in patients with IgM antibodies. Among 143 healthy subjects from the general population, seven (4.9%) were positive for anti-R. conorii IgG antibodies, and 2.8% for R. typhi. These results show that anti-rickettsial antibodies are more commonly detected in patients with hypertransaminemia than in healthy people.

Nitric oxide-mediated inhibition of the ability of Rickettsia prowazekii to infect mouse fibroblasts and mouse macrophagelike cells

The role of the nitric oxide synthase (NOS) pathway in inhibiting the ability of Rickettsia prowazekii to initially infect (invade) mouse cytokine-treated, fibroblastic L929 cells and macrophagelike RAW264.7 cells and the ability of nitric oxide (NO) to damage isolated rickettsiae were investigated. Substantial amounts of nitrite (a degradation product of NO) were produced and the initial rickettsial infection was suppressed in cultures of L929 cells treated with crude lymphokine preparations (LK) or with gamma interferon (IFN-gamma) plus tumor necrosis factor alpha (TNF-alpha) but not in L929 cell cultures treated with IFN-gamma alone or TNF-alpha alone. The NOS inhibitors N(G)-methyl-L-arginine and aminoguanidine both inhibited nitrite production and prevented the suppression of the initial rickettsial infection. Antibody-mediated neutralization of the IFN-gamma in the LK also inhibited both nitrite production and suppression of the initial rickettsial infection. Cultures of RAW264.7 cells treated with IFN-gamma plus lipopolysaccharide exhibited suppression of the initial rickettsial infection, and the suppression was relieved by aminoguanidine. Addition of oxyhemoglobin (a scavenger of extracellular NO) during the rickettsial infection alleviated the suppression of the initial rickettsial infection observed in appropriately treated L929 cells and RAW264.7 cells. In addition, the oxyhemoglobin restored the rickettsia-mediated, rapid killing of the treated RAW264.7 cells. Incubation of isolated rickettsiae with NO inhibited their ability to infect L929 and IFN-gamma-treated RAW264.7 cells and to rapidly kill IFN-gamma-treated RAW264.7 cells. In contrast, incubation of L929 cells with a solution that contained NO and/or degradation products of NO did not affect their ability to be infected by rickettsiae. The data are consistent with the hypothesis that NO released from appropriately stimulated potential host cells kills extracellular rickettsiae and thus prevents the rickettsiae from infecting the cells.