Branch retinal vein occlusion in the right eye and retinal hemorrhage in the left in a patient with classical Tsutsugamushi disease

Clinical Characteristics and Evolution of Ocular Manifestations in Scrub Typhus

Scrub typhus, caused by Orientia tsutsugamushi infection, manifests with fever, rash, eschar, pneumonia, hepatosplenomegaly, and lymphadenopathy. We conducted a review of the ocular manifestations post-infection and found a high incidence (67%) during the recovery phase (2-4 weeks), particularly prevalent in the tropical Tsutsugamushi triangle. Despite China, only three cases of optic neuritis had been reported, suggesting its rarity due to early antibiotic administration, we present the first documented case of binocular optic neuroretinitis due to Orientia tsutsugamushi infection in China. Ophthalmologic screenings should be conducted for patients with systemic scrub typhus infection to rule out ocular involvement. Based on previous literature and our case findings, whether scrub typhus affects the anterior or posterior segment of the eye may be determined by different strains of the pathogen, and this in turn influences the visual prognosis. Early initiation of antibiotics effectively eradicated the pathogens. Studies have indicated that delayed immune inflammation, rather than direct infection, may be the underlying pathogenesis of ocular manifestations. Early and comprehensive corticosteroid therapy during secondary ocular inflammation has shown to effectively curb disease progression and preserve visual function.

Usefulness of next-generation sequencing for laboratory diagnosis of rickettsiosis

Rickettsiosis includes a diversity of culture-negative non-specific systemic infections. Laboratory diagnosis of rickettsiosis is often not easy. In this 12-month study, six patients with a variety of rickettsia infections of the spotted fever group, typhus group and scrub typhus were diagnosed directly or indirectly by metagenomic next-generation sequencing (mNGS). The patient with Japanese spotted fever was rapidly made when mNGS analysis of the patient's blood revealed Rickettsia japonica sequences. For the two patients with Rickettsia felis chest infections, the bacterium was detected in the bronchoalveolar lavage of one case and lung biopsy of the other. Both patients had underlying malignancies, carcinoma of the breast and carcinoma of the lung respectively, and were on chemotherapy with immunosuppressive effect. For the remaining three patients who presented over a period of 13 weeks, all had fever, headache and the typical eschar. They also had increased serum transaminases and responded promptly to doxycycline. However, the Weil-Felix test results of all three patients were negative. Since we considered the three cases typical of rickettsiosis, we submitted their serum samples for mNGS analysis. Results showed that Orientia tsutsugamushi sequences were present in the serum of one case. In view of the positive mNGS results, we repeated the Weil-Felix test for the residual sera of all three patients and it revealed that those of the other two cases showed OX-19 titers of 1:640 and 1:160 respectively, inferring that these two patients probably had rickettsiosis of the typhus group. As for the patient positive for O. tsutsugamushi sequences, we also detected IgM for O. tsutsugamushi in the serum, which double confirmed that it was a case of scrub typhus. mNGS is an important molecular tool and can complement serology for laboratory diagnosis of rickettsiosis.

Every lid swelling is not stye: A rare presentation of scrub typhus eschar

A 17-year-old female patient presented to us with complaints of diffuse swelling in her left upper eyelid with preauricular lymphadenopathy for three days. She was diagnosed with a case of hordeolum externum and was treated on the same line. However, during follow-up, she developed a mild- to moderate-grade fever, which did not subside with treatment. On further investigation, her IgM rapid ELISA for Scrub typhus was positive, which was further confirmed by the Weil-Fellix test (OXK=1:360). She was treated with systemic doxycycline. Within a week, her fever returned to normal baseline, with resolution of local eye lid swelling, and her black scab was also gone. We have reported a case of scrub typhus as a rare manifestation with lid swelling and subsequently eschar formation on the upper eye lid. The patient was promptly treated with oral antibiotics without any morbidity.

Case Report: Optic neuritis as the initial presentation of Orientia tsutsugamushi infection detected by metagenomic next-generation sequencing

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi infection, and typically manifested as fever, eschar, lymphadenopathy, rash, and other flu-like signs. Ocular involvement was not uncommon, and mostly occurred at post-fever or recovery stage in scrub typhus cases. We hereby report a case of scrub typhus presenting as unilateral optic neuritis (ON). A 56-year-old man going wild fishing nearly every day complained of a blurred vision and an inferior visual field defect in the right eye two or three days after an insect-bite like shin induration in his left leg. He was diagnosed as ON, and treated with dexamethasone in the local hospital. Unfortunately, his right eye vision progressively deteriorated during steroid therapy. Three days after steroid therapy ceased, he suffered from a high fever and painful subcutaneous masses in the left groin. Peripheral blood test by metagenomic next-generation sequencing (mNGS) was positive for Orientia tsutsugamushi, but negative for other pathogens. The diagnosis was then revised to scrub typhus and ON. His systemic symptoms rapidly disappeared after oral doxycycline and omadacycline therapy. However, his right eye vision continuously deteriorated to hand motion. Further serum tests for aquaporin 4-IgG antibody and myelin oligodendrocyte glycoprotein-IgG antibody were both negative, but for anticardiolipin IgM and beta-2-glycoprotein-I IgM were both positive. The patient's right eye vision gradually improved after doxycycline combined with steroid pulse therapy. Our case indicates that ON in scrub typhus cases may present as a parainfectious inflammation, and that mNGS is a useful and valuable method for early diagnosis of scrub typhus.

Post-fever retinitis - Newer concepts

Post-fever retinitis (PFR) is an infectious or para-infectious uveitic entity caused by bacterial or viral agents and seen mainly in tropical countries. Systemic symptoms such as joint pain, skin rash are common during the febrile stage. On the basis of only clinical presentation, it is difficult to pin-point the exact etiology for PFR. Serological investigations, polymerase chain reaction, and knowledge of concurrent epidemics in the community may help to identify the etiological organism. Bacterial causes of PFR such as rickettsia and typhoid are treated with systemic antibiotics, with or without systemic steroid therapy, whereas PFR of viral causes such as chikungunya, dengue, West Nile virus, and Zika virus have no specific treatment and are managed with steroids. Nevertheless, many authors have advocated mere observation and the uveitis resolved with its natural course of the disease. In this article, we have discussed the clinical features, pathogenesis, investigations, and management of PFR.

Pulmonary Artery Thrombosis Associated with Scrub Typhus

Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi, and the clinical course varies from mild and self-limiting to fatal. We describe a rare case of a pulmonary artery thrombosis associated with scrub typhus. Vasculitis via endothelial dysfunction caused by scrub typhus could be considered as the main mechanism.

Clinical manifestations of scrub typhus

The mite-borne rickettsial zoonosis scrub typhus is widely prevalent in parts of Southeast and Far East Asia, and northern Australia. The disease is an acute febrile illness, associated with rash and often an eschar, which responds dramatically to treatment with antibiotics. In some cases it results in a serious illness leading to multiple organ involvement and death. The disease manifestations are thought to result from a systemic vasculitis, caused by both direct effects of the organisms as well as an exaggerated immune response, although little is understood about its pathogenesis. A wide spectrum of clinical manifestations, affecting nearly every organ system, have been described with scrub typhus. Some of these manifestations are serious and life threatening. In this systematic review, we summarise the typical and atypical manifestations of scrub typhus reported in the literature. Awareness of these unusual manifestations will hopefully guide clinicians towards diagnosing the condition early, and initiating early appropriate antibiotics and other supportive measures.

Scrub typhus: pathophysiology, clinical manifestations and prognosis

Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi (O. tsutsugamushi). The disease has significant prevalence in eastern and Southeast Asia. Usually presenting as an acute febrile illness, the diagnosis is often missed because of similarities with other tropical febrile infections. Many unusual manifestations are present, and these are described in this review, together with an outline of current knowledge of pathophysiology. Awareness of these unusual clinical manifestations will help the clinician to arrive at an early diagnosis, resulting in early administration of appropriate antibiotics. Prognostic indicators for severe disease have not yet been clearly established.

Novel infectious agents causing uveitis

In any patient with uveitis, an infectious cause should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinician should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally. This review recapitulates the systemic and ocular manifestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, Dengue fever, and Chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help establish an early clinical diagnosis, which allows prompt, appropriate management.

Emergent infectious uveitis

Infectious causes should always be considered in all patients with uveitis and it should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinicians should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally, though it is not possible always. This review recapitulates the systemic and ocular mainfestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, dengue fever, and chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help in establishing an early clinical diagnosis, which allows prompt, appropriate management.

Scrub typhus serologic testing with the indirect immunofluorescence method as a diagnostic gold standard: a lack of consensus leads to a lot of confusion

A review was performed to determine the evidence base for scrub typhus indirect immunofluorescence assay (IFA) methodologies and the criteria for positive results. This review included a total of 109 publications, which comprised 123 eligible studies for analysis (14 publications included 2 substudies). There was considerable underreporting of the IFA methodology and seropositivity criteria used, with most studies using a defined cutoff titer rather than an increase in the titer in paired samples. The choice of positivity cutoff titer varied by country and purpose of the IFA test. This variation limits the comparability of seroprevalence rates between studies and, more seriously, raises questions about the appropriateness of the cutoffs for positive IFA results chosen for diagnosis of acute scrub typhus infection. We suggest that the diagnosis of scrub typhus using IFA should be based on a > or =4-fold increase in the titer in paired serum samples and should only be based on a single sample titer when there is an adequate local evidence base.

The eye in systemic infection

Bacterial, fungal, viral, and parasitic pathogens all cause systemic infection and can spread to the eye. Dissemination of pathogens via the bloodstream can lead to direct involvement of the eye. Visual loss is common in bacterial or fungal endophthalmitis, and toxoplasmosis is a major cause of ocular morbidity and poor vision after congenital or acquired infection. Some infections cause intraocular damage by indirect mechanisms (eg, HIV-mediated immunosuppression), leading to opportunistic infections such as cytomegalovirus infection, periocular nerve involvement due to leprosy, and hypersensitivity reactions in tuberculosis. Eye symptoms might indicate the outcome of an underlying infection, such as development of retinal ischaemia in severe malaria, which is associated with a poor prognosis. Successful outcome for patients with ocular infection depends on close collaboration between clinicians identifying and treating underlying disease, specialist ophthalmic review, and ophthalmic interventional skills (when needed).