Acute sensorineural hearing loss and severe otalgia due to scrub typhus
© Kang et al; licensee BioMed Central Ltd. 2009
Received: 20 May 2009
Accepted: 22 October 2009
Published: 22 October 2009
Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi.
We encountered a patient with sensorineural hearing loss complicating scrub typhus, and three patients with scrub typhus who complained of otalgia, which was sudden onset, severe, paroxysmal, intermittent yet persistent pain lasting for several seconds, appeared within 1 week after the onset of fever and rash. The acute sensorineural hearing loss and otalgia were resolved after antibiotic administration.
When patients in endemic areas present with fever and rash and have sensorineural hearing loss or otalgia without otoscopic abnormalities, clinicians should suspect scrub typhus and consider empirical antibiotic therapy.
Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi, an obligate intracellular bacterium; it is transmitted via the bites of Leptotrombidium chigger mites . O. tsutsugamushi spreads throughout the body via the blood and lymphatic vessels, so that patients infected with this microorganism manifest a variety of clinical symptoms and signs such as myalgia and diffuse lymphadenopathy . Complications include pneumonia, myocarditis, meningitis, hepatitis, acute renal failure and hearing loss [3–5]. A sensory neural type of hearing loss has been reported in patients infected with Rickettsia rickettsii (R. rickettsii), R. typhi or R. coronii [6–8]. Hearing loss described in scrub typhus infected patients is rare in Korea. However, in a recent Sri Lanka study, hearing loss appeared in 19% of patients with scrub typhus, and can affect up to one third of the patients [3, 4]. However, the performance of audiometry studies in these patients is not common.
We report four confirmed cases of scrub typhus with otological complaints. One patient presented with sensory-neural hearing loss and other three patients presented with severe otalgia.
Clinical and serologic findings in four patients with scrub typhus and otologic problems
Serum antibody titer
Days from symptom onset to otologic problems
Pure tone audiometry
Patients 2-4 presented with unilateral otalgia associated with fever and rash. On presentation, generalized rash with eschars were observed, and a history of working in fields in recent past was obtained. Patient 2 & 3 presented with otalgia without any hearing loss. Otalgia was paroxysmal, intermittent and severe which was followed by persistent pain for several hours. Patient 4 had history of wearing hearing aids for two months before presenting to the hostpital with pain in the ear, and had no vertigo or tinnitus on admission. The otolaryngologic examination of patient 1, 2 & 3 was normal. Pure tone audiometery was normal in patient 2 and it could not be done in patient 3 & 4. All patients received antibiotic therapy under a clinical diagnosis of scrub typhus, and the otalgia was resolved within 1 week. A four-fold or greater increase in antibody titer against O. tsutsugamushi was observed in indirect fluorescence antibody assays in the convalescent stage compared to that in the acute stage.
The 56-kDa type-specific antigen is a major outer membrane protein located on the surface of Orientia species that may be involved in penetration into host cells . This 56-kDa antigen is an immunodominant antigen that induces strong humoral immunity. It also contains both group-specific and type-specific epitopes, which are useful for the diagnosis of scrub typhus . Nested PCR was performed with blood buffy coat or eschars and IFA was conducted with serum by the method described previously . Primers 34 (5-TCA AGC TTA TTG CTA GTG CAA TGT CTGC-3) and 55 (5-AGG GAT CCC TGC TGC TGT GCT TGC TGCG-3) were used in the first PCR. Nested PCR primers 10 (5-GAT CAA GCT TCC TCA GCC TAC TAT AAT GCC-3) and 11 (5-CTA GGG ATC CCG ACA GAT GCA CTA TTA GGC-3) were used in the second PCR amplification of the resulting 483 bp fragment (Figure 1). The DNA sequences of amplicons were compared with the nucleotide sequences of O. tsutsuganushi registered in GenBank.
Our patients presented with scrub typhus and associated sensory neural hearing loss and severe otalgia. A sensory neural type of hearing loss has been reported in patients infected with Rickettsia rickettsii (R. rickettsii), R. typhi or R. coronii [6–8]. Although the mechanism of hearing loss in scrub typhus has not yet been elucidated, at least two mechanisms have been proposed. In the first, the rickettsiae directly invade the central nervous system and induce vasculitis in the acute stage, and this damages the cochlear division of the eighth cranial nerve [6, 11, 12]. In the second, vasculitis is produced in the vasa vasorum of the cochlear nerve by a secondary immune mechanism. In our first patient, acute hearing loss was so severe that she could not hear the sounds on television; this was suggestive of bilateral sensorineural hearing loss. Pure tone audiometry performed after administration of rifampin revealed that her hearing had only improved in the right ear. Rifampin was administered based on a randomized trial by Watt et al reporting superior clinical results for treating scrub typhus patients with rifampin compared to doxycycline . In this patient, hearing loss was of the sensory neural type, as it is in other rickettsial disease. Premarantna et al have reported that deafness and tinnitus appear on the second week after the onset of scrub typhus . Similarly, in our patient sensorineural hearing loss appeared 10 days after the onset of scrub typhus. However, otalgia in three patients appeared within the first week. Thus, hearing loss and tinnitus tend to appear on the second week after the onset of scrub typhus, whereas otalgia appears in the first week. This may indicate that the mechanism of hearing loss and tinnitus may differ from that of otalgia. Further studies are needed to determine whether hearing loss, and otalgia are caused by direct damage to the sensory nerves or by a secondary immune mechanism. Although the definite pathology of sensorineural hearing loss is not known, such complications seem to respond to effective antibiotic treatment, early diagnosis of these complications and prompt institution of antirickettsial therapy are crucial for achieving good clinical outcomes.
When patients in endemic areas present with fever and rash and have sensorineural hearing loss or severe otalgia without otoscopic abnormalities, clinicians should suspect scrub typhus and consider empirical antibiotic therapy.
Written informed consent was obtained from the patient or their relative for publication of this study. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) through the Research Center for Resistant Cells (R13-2003-009).
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