Bilateral optic disc edema with subconjunctival hemorrhage: Attributed to scrub typhus?

A 15-year-old female patient presented with complaints of headache, blurring of vision, and redness of both eyes for 15 days and fever for 20 days. Her best-corrected visual acuity (BCVA) was 20/40 in both eyes. Anterior segment examination was normal except for subconjunctival haemorrhage in both eyes. Examination of the posterior segment showed disc oedema in both eyes. Her blood investigations revealed platelet count to be 1.5 lakhs per cubic mm, and leucocyte count to be10,700 per cubic mm. CSF culture showed seven cells per microlitre,76% lymphocytes and CSF samples negative for gram stain, acid-fast bacilli, and culture. Further investigation for IgM titre for scrub typhus was positive. She was treated with oral doxycycline. On follow up after three weeks, both the subconjunctival haemorrhage and bilateral disc oedema resolved with BCVA of 20/20 in both eyes. She was kept on follow up and has not presented with any fresh complaints until six months after the initial presentation." Copyright:

Introduction

Scrub typhus is a rickettsial disease caused by Orientia tsutsugamushi and transmitted to humans via the bite of mites. They are prevalent in rural areas of Southeast Asia, China, Japan, and India.[1] Neurologic manifestations are quite common in these groups though less in comparison to Rocky Mountain spotted fever.[2] Ocular involvement, although common, may be asymptomatic too. It can present as subtle anterior segment involvement to severe retinochoroidal involvement. These groups have an excellent response to treatment. Hence, every patient with systemic symptoms such as fever and vomiting with blurred vision should comprehensively be evaluated and treated. Our case has isolated bilateral optic disc edema without retinochoroiditis. Few such types of cases have been reported.

Case Report

A 15-year-old female patient from Eastern India presented to us with complaints of headache, blurring of vision, and redness of eye for 15 days. She gave a history of fever 20 days before the presentation to us. The fever was associated with puffiness of eyes, redness, and vomiting for which she treated with amoxicillin-clavulanic acid combination for 7 days before the patient presented to us. All these symptoms had marginally improved when the patient presented to us. Her best-corrected visual acuity (BCVA) was 20/40 with normal intraocular pressures in both eyes. Anterior segment examination was normal except for subconjunctival hemorrhage in both eyes [Figure 1]. Examination of the posterior segment showed disc edema in both eyes [Figure 2a and b]. Optical coherence tomography macula was normal in both eyes. Routine blood investigations revealed platelet count to be 1.5 lakhs per cubic mm (1.5–4) and hemoglobin to be 11.2 g/dl (11–16). Total leukocyte count was 10700 per cubic mm (4000–11,000). Red blood cell count was 4.52 lakhs/cumm (3.9–5.6), packed cell volume was 30% (36–44), mean corpuscular volume was 66.4 fl (82–98), mean corpuscular hemoglobin was 23.7 pg (27–32), and mean corpuscular hemoglobin concentration was 35.7% (32–36). Cerebrospinal fluid (CSF) opening pressure was 15 cmH2O (normal range 6–25 cmH2O), CSF culture showed seven cells per microliter (up to 5 cells) and 76% lymphocytes (up to 80%), and CSF samples were negative for Gram stain, acid–fast bacilli, and culture. Tests for malaria, leptospirosis, dengue, and typhoid were all negative. All other routine investigations were normal. Computed tomography (CT) and magnetic resonance imaging (MRI) scans, including MR venography, showed no abnormality causing papilledema. She further investigated, and immunoglobulin M (IgM) titer for scrub typhus, which tested by enzyme-linked immunosorbent assay method, was positive (1.2 optical density). IgG titer was not significant. She had a visual field scan from the previous hospital, which showed normal reliable fields. As the patient was improving, brain scans were normal, and visual acuity was good, visual field not repeated immediately. All routine blood tests for common causes of fever were negative. Normal CT and MRI scan brain report ruled out any intracranial pathology causing bilateral disc edema. In the presence of positive IgM titer for scrub typhus along with supportive evidence of subconjunctival hemorrhage, the diagnosis of scrub typhus was made. Absence of lymphadenopathy ruled out the rarer disease of cat-scratch disease in India. The patient was treated with oral doxycycline tablets (100 mg twice daily) which is the treatment of choice for scrub typhus for 10 days along with paracetamol (625 mg twice daily) for 5 days. On follow-up after 3 weeks, the subconjunctival hemorrhage had resolved, and anterior segment showed no other abnormality. The patient had BCVA of 20/20 in both eyes. Fundus examination revealed resolved disc edema in both eyes [Figure 3a and b]. The patient was kept on follow-up and has not presented with any fresh complaints until 6 months after the initial presentation.

Figure 1

Subconjunctival hemorrhage in temporal conjunctiva near limbus in both eyes

Figure 2

(a) Blurring of optic disc margins with tortuosity of vessels suggestive of optic disc edema in the right eye. (b) Blurring of optic disc margins with tortuosity of vessels suggestive of optic disc edema in the left eye

Figure 3

(a) Disappearance of the blurred margin of the optic disc with a decrease in tortuosity of vessels suggestive of resolved optic disc edema in the right eye. (b) Disappearance of the blurred margin of the optic disc with a decrease in tortuosity of vessels suggestive of resolved optic disc edema in the left eye

Discussion

Rickettsiae are a group of obligate intracellular Gram-negative bacteria transmitted to humans via bites of fleas, lice, ticks, and mites. They are categorized into the spotted fever group, typhus group, and scrub typhus group.[1] The conditions of general toxemia and vasculitis give rise to ocular changes. Though several systemic manifestations of rickettsial diseases have reported from India, types of reports of ocular manifestations have been relatively rare.[3] Cases of rickettsial retinitis have been reported from India, and epidemic typhus and tick typhus are thought to be common causes as compared to scrub typhus.[4]

Various anterior segment manifestations of rickettsial infections include petechial hemorrhages, subconjunctival hemorrhages, keratitis, and nongranulomatous anterior uveitis.[56]

The features of retinitochoroiditis are common in rickettsial infections. It can vary from vitritis with or without whitish infiltrates, serous retinal detachment, vascular sheathing, and hemorrhages. The basic pathogenesis involves microvascular leakage, ischemic changes, and immune response to the systemic infection. A study by Balasundaram et al. has reported multifocal retinitis with macular edema in 12 patients with Rickettsia conorii infection.[7] Similar findings have been reported by Khairallah et al. in their prospective study of 30 patients suffering from R. conorii infection.[8] Neuro-ophthalmic manifestations have been reported in very few cases in the Indian subcontinent.[9] Ours is a unique case of isolated disc edema with no other associated retinal findings.

Optic disc edema, neuroretinitis, optic neuropathy, and cranial nerve palsies have also been reported in scrub typhus infections. The tropism of rickettsial organisms for optic disc vasculature causes an immune mediated reaction of the organism towards the optic nerve, resulting in these neuroophthalmic features.[10] This may also lead to vision loss too.[11]

This disease, when diagnosed early, is treatable with oral doxycycline, azithromycin, and chloramphenicol. Rifampin can also be considered as a second line of treatment after ruling out tuberculosis. Untreated disease may be life-threatening.[12] Diagnosis of scrub typhus, in the absence of the pathognomic eschar rests on other clinical features and serologic testing, which may facilitate early diagnosis and correct treatment. This has been aptly proved in our case.

Conclusion

Test for scrub typhus should be done when the fever does not subside with routine antibiotics, especially in an endemic area. Subconjunctival hemorrhage and isolated bilateral optic disc edema with or without retinochoroiditis in the presence of fever can lead to a diagnosis of scrub typhus. Although few ocular findings are self-limiting in scrub typhus, a high index of suspicion and early treatment helps prevent life and vision-threatening complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understand that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.