Retinochoroiditis secondary to Rickettsia typhi infection: a case report.

BACKGROUND: To report a case of unusual presentation of retinochoroiditis caused by Rickettsia typhi in a patient without prior uveitis. CASE PRESENTATION: In this case, we describe a 24-year-old male soldier with no previous eye disease, who was referred to our ophthalmology department due to bilateral retinochoroiditis and vitritis. The patient initially presented with a paracentral scotoma in his right eye persisting for 7 days and scattered dark spots in his left eye for 2 days in June 2023. Preceding these ocular symptoms, he experienced a two-week episode of fever, headaches, night sweats, and rapid weight loss of 10 kg. A transient rash covered his body briefly. His mother had a history of recurrent eye inflammation. Physical examination revealed bilateral keratic precipitates on the lower corneal periphery, 1 + anterior vitreous cells, small retinal lesions and mild optic discs elevation. Fluorescein angiography indicated mild discs hyperfluorescence, and the clinically visible round punctate lesions on OCT showed inner retinal hyper-reflective lesion with a depth till outer plexiform layer possibly suggestive of a retinitis lesion. Laboratory tests were normal except thrombocytosis, elevated ESR, liver enzymes and ACE levels, with positive Rickettsia typhi serology tests. Rheumatology and infectious disease consultations ruled out autoimmune diseases, confirming Rickettsia typhi infection. Treatment included systemic doxycycline and prednisone, with improvement of visual acuity, ocular symptoms, OCT abnormalities and resolution of inflammation. Prednisone was discontinued, and after two months, additional improvement was seen clinically, with preserved retinal structures on OCT. CONCLUSION: This study explores retinochoroiditis as a rare ocular presentation of Rickettsia typhi, an unusual infection in the Middle East. Previously reported ocular manifestations include conjunctivitis, vitritis, post infectious optic neuropathy and a few cases of uveitis. Ocular symptoms followed systemic illness, highlighting the need for awareness among clinicians. Diagnosis relies on seroconversion, with fluorescein angiography and OCT aiding in assessment. Empiric doxycycline and systemic corticosteroid therapy is recommended. Ocular symptoms resolved in two months. Awareness of these ocular manifestations is essential for timely diagnosis and management. Further research is needed to fully understand this aspect of murine typhus.

Epidemiology of Murine Typhus in Taiwan from 2013 to 2020.

Murine typhus is a flea-borne disease caused by Rickettsia typhi infection. The disease is a notifiable infectious disease in Taiwan. Specimens from suspected cases are required to be sent to the Taiwan Centers for Disease Control and Prevention for laboratory diagnosis. In this study, 204 cases of murine typhus were identified by bacterial isolation, real-time polymerase chain reaction, or indirect immunofluorescence assay between 2013 and 2020. The average incidence rate was 0.11/100,000 person-years (95% CI: 0.08-0.13). Murine typhus occurred throughout the year, but it was most prevalent in summer (May to August). The majority of patients were males (75%), residents of Kaohsiung city (31%), and worked in agriculture, forestry, fishing, and animal husbandry (27%). Fever was the most common symptom, present in 95.6% of patients, followed by headache (41%), myalgia (33%), and liver dysfunction (33%). Only 13% of patients had a rash. Up to 80% of cases were among hospitalized patients, and 43% of patients developed severe manifestations. Serological assays also indicated coinfection events. Seven patients showed a 4-fold increase in antibody titers against Orientia tsutsugamushi (N = 2), Coxiella burnetii (n = 2), and Leptospira (N = 3). In conclusion, murine typhus is an endemic and important zoonotic rickettsial disease in Taiwan that cannot be ignored. Further epidemiological surveillance and clinical characteristics should be continuously investigated to prevent and control murine typhus.

Case Report: Cardiovascular Manifestations due to Flea-Borne Typhus.

Flea-borne typhus is a vector-borne disease caused by Rickettsia typhi that occurs worldwide, except in Antarctica. In the United States, most cases are restricted to California, Hawaii, and Texas. The syndrome is characterized by nonspecific signs and symptoms: fever, headache, rash, arthralgia, cough, hepatosplenomegaly, diarrhea, and abdominal pain. Although flea-borne typhus can cause pulmonary, neurological, and renal complications, the cardiovascular system is rarely affected. We present a case of endocarditis resulting from flea-borne typhus diagnosed by blood microbial cell-free DNA testing that required valve replacement and antibiotic therapy for 6 months. In addition, we review 20 cases of presumed and confirmed cardiovascular manifestations resulting from flea-borne typhus in the literature.

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 Rickettsia typhi Infections, Costa Rica.

Murine typhus is a febrile, fleaborne disease caused by infection with Rickettsia typhi bacteria. Cases can range from mild and nonspecific to fatal. We report 2 cases of murine typhus in Costa Rica, confirming the presence and circulation of R. typhi causing severe disease in the country.

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.

Isothermal amplification technology (IAT) for rapid diagnosis of Rickettsioses: scope, overview, existing evidence, and the way forward.

Rickettsioses, a category of zoonosis primarily caused by Rickettsia and Orientia, is a huge cause of public health concern worldwide. Diseases like murine typhus, scrub typhus, Mediterranean spotted fever and rocky mountain spotted fever are major contributors of Rickettsioses globally, with peculiar distributions in south-east Asia, Africa, Arabia and the Americas. With the innovations in molecular diagnostics, Isothermal Amplification Technology is gaining popularity for its fidelity, rapidity and cost-effectiveness. Compared to commercial assays, they are easily adaptable for point-of-care (PoC) settings. Due to nonspecific presentation as an acute undifferentiated febrile illness, diagnosis of Rickettsioses poses a great challenge. Certain isothermal amplification assays have proven to be highly efficient in diagnosing vector borne diseases like dengue, malaria, and chikungunya. The purpose of this review is to provide readers the current advancements, scope, challenges, and future prospects of isothermal amplification technologies in the detection of zoonotic pathogens like Rickettsia and Orientia.

Murine typhus is a common cause of acute febrile illness in Bandung, Indonesia.

Murine typhus (MT), an infection caused by the gram-negative bacteria Rickettsia typhi (R. typhi), is a significant cause of acute febrile illness (AFI) in Southeast Asia but is rarely reported in Indonesia. The current study aimed to describe the clinical characteristics of MT cases in Bandung, West Java. Non-confirmed AFI cases (n = 176) from a prospective cohort study of whom paired serum samples (acute (T1), midterm (T2), or convalescent (T3)) were available were screened using MT serology. IgG against R. typhi was detected in the T2 or T3 samples using an in-house ELISA. Positive IgG samples were further screened for the presence of IgM. If both IgM and IgG were positive, the endpoint titer of T1, T2, or T3 was determined. In cases with a fourfold increase in titer, real-time PCR of T1 samples was performed to detect R. typhi DNA. In total, 71/176 (40.3%) patients tested positive for IgG antibody, and 26 AFI cases were confirmed as MT (23 cases by PCR, 3 cases by fourfold titer increased IgG or IgM titer). The most common clinical symptoms in the confirmed cases were headache (80%), arthralgia (73%), malaise (69%), and myalgia (54%). In these cases, the presumptive clinical diagnoses were typhoid fever (43.2%), dengue (38.5%), and leptospirosis (19.2%). MT was not considered in any of the patients, and no patients received doxycycline. These findings confirmed that MT is an important cause of AFI in Indonesia. MT should be included in the differential diagnosis of AFI, and empirical treatment with doxycycline should be considered.

Detection of Severe Murine Typhus by Nanopore Targeted Sequencing, China.

We report a case of murine typhus in China caused by Rickettsia typhi and diagnosed by nanopore targeted sequencing of a bronchoalveolar lavage fluid sample. This case highlights that nanopore targeted sequencing can effectively detect clinically unexplained infections and be especially useful for detecting infections in patients without typical signs and symptoms.

Serological cross-reactivity between spotted fever and typhus groups of rickettsia infection in Japan.

OBJECTIVES: We examined the frequency of cross-reactions to Rickettsia typhi in patients with Japanese spotted fever (JSF) and evaluated the differences between two rickettsiae using antibody endpoint titers. METHODS: Patients' immunoglobulin (Ig)M and IgG titers against Rickettsia japonica and Rickettsia typhi in two phases were measured using an indirect immunoperoxidase assay at two reference centers for rickettsiosis in Japan. Cross-reaction was defined as a higher titer against R. typhi in convalescent sera than in acute sera among patients fulfilling the criteria for JSF diagnosis. The frequencies of IgM and IgG were also evaluated. RESULTS: Approximately 20% of cases showed positive cross-reactions. A comparison of antibody titers revealed the difficulty in identifying some positive cases. CONCLUSION: Cross-reactions of 20% in serodiagnosis may lead to the misclassification of rickettsial diseases. However, with the exception of some cases, we were able to successfully differentiate JSF from murine typhus using each endpoint titer.

Increased Seroprevalence of Typhus Group Rickettsiosis, Galveston County, Texas, USA.

Whether increases in typhus group rickettsiosis in Galveston County, Texas, USA, are caused by increased recognition or true reemergence is unclear. We conducted a serosurvey that demonstrated Rickettsia typhi antibodies increased from 1.2% in 2013 to 7.8% in 2021 (p<0.001). These findings support pathogen reemergence rather than enhanced recognition alone.

Rickettsia typhi infection in a clinically-ill dog from Houston, Texas.

In 2020, Rickettsia typhi was diagnosed in a dog from Houston, Texas, USA based upon R. typhi IFA seroreactivity in both acute and convalescent sera, and PCR with DNA sequencing of 4 different gene regions, all of which were 100% identical to R. typhi. The dog was clinically ill with intermittent fever, lethargy, inappetence, and lymphadenopathy. Clinicopathological abnormalities included a mild nonregenerative anemia, neutrophilia, lymphopenia, thrombocytopenia, hypoalbuminemia, and elevated ALP. The dog rapidly recovered with doxycycline administration.

72-year-old man • fever • new-onset urinary frequency • altered mental state • Dx?

► Fever ► New-onset urinary frequency ► Altered mental state.

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

BACKGROUND: There are few studies about the presence of murine typhus in Greece. Our objective was to conduct a large scale retrospective investigation to determine the clinical and epidemiological features of patients diagnosed with murine typhus in Greece. METHODOLOGY/PRINCIPAL FINDINGS: From 2012 to 2019 serum samples from hospitalized patients and outpatients throughout Greece suspected for murine typhus infection were tested by immunofluorescence assay for Rickettsia typhi. Immunofluorescence positive samples obtained since 2016 were also tested by qPCR targeting R. typhi. Clinical and epidemiological data were retrospectively collected for the patients with confirmed murine typhus. Overall, we tested 5,365 different patients and, in total, 174 patients from all geographic regions of Greece were diagnosed with murine typhus. The most frequently reported sign or symptom was fever (89%), followed by headache (84%) and rash (81%). The classical triad of fever, headache, and rash was present in 72% of patients during their illness. Severe infections with complications including acute renal failure or septic shock were not recorded. The majority of cases (81%) occurred during May-October and peaked in June and September. Most of patients (81%) infected in Athens, recalled that their only activity the last weeks before symptoms onset was swimming on the beach and 59% of them also reported an insect bite while sunbathing. CONCLUSIONS/SIGNIFICANCE: Our results may reflect the reemergence of murine typhus in Greece and we highlight the importance of awareness of this difficult-to-recognize undifferentiated febrile illness.

Seroprevalence of scrub typhus, murine typhus and spotted fever groups in North Korean refugees.

OBJECTIVES: The aim of this study was to investigate the seroprevalence of antibodies against scrub typhus, murine typhus and spotted fever groups among North Korean refugees within 1 year of their arrival in South Korea. METHODS: We recruited North Korean refugees who had settled in South Korea after a short stay in a third country and did not have any health problems. The antibody titer was measured using a commercial indirect fluorescence assay immunoglobulin G antibody kit. RESULTS: The seroprevalence of antibodies against scrub typhus, murine typhus, and spotted fever groups among the 99 participants was 22.2%, 17.2%, and 10.1%, respectively, with 8.1% of participants testing positive for both spotted fever and murine typhus. CONCLUSIONS: Refugees may be exposed to rickettsial infections in North Korea and their journey from North Korea. This study is the first to report the seroprevalence of antibodies against the 3 common rickettsial diseases among North Korean refugees. The findings suggest that rickettsial infections should be added to the list of differential diagnoses for North Koreans with fever after entering South Korea.

Murine Typhus in 5 Children Hospitalized for Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is an emerging disease described in children in association with infection or epidemiological link to severe acute respiratory syndrome coronavirus 2. Signs and symptoms include fever, rash, and cardiac dysfunction; US Centers for Disease Control and Prevention have put forth broad criteria for diagnosis. The illness is serious and can progress rapidly to heart failure and death. However, findings in MIS-C are nonspecific, and there is significant overlap with other systemic illnesses, including Kawasaki disease and several viral and bacterial infections. We present 5 children admitted to a teaching hospital within an 11-day period in May 2020 for MIS-C evaluation who were later diagnosed with murine typhus. Typhus is a rickettsial infection that presents with fever and rash, and, although usually self-limited, responds well to treatment with doxycycline to shorten the course of illness. Clinical and laboratory characteristics of these children are presented to illustrate similarities to MIS-C, which can also be shared with viral, bacterial, or other regional endemic infections, as well as noninfectious inflammatory diseases. This case series serves to remind pediatric hospitalists to be vigilant to avoid premature closure on MIS-C for children admitted with fever and systemic inflammation. Maintaining a wide differential diagnosis in approaching such patients is of utmost importance as community exposure to severe acute respiratory syndrome coronavirus 2 is likely and evidence of past infection becomes commonplace.

Murine Typhus in Canary Islands, Spain, 1999-2015.

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