Previous literature demonstrated six reports of tick adherence to the conjunctiva. Four of the six reports were secondary to Amblyomma americanum, one was secondary to Otobius megninii, and the last was of unknown species. The species unique to each report occurred in areas where the ticks are commonly found; for example, the four reports of A. americanum occurred in Arkansas, Texas, and Alabama. Our patient was camping in the Adirondacks, a portion of the Northeastern United States where the I. scapularis is more prevalent. Despite the limited number of reported cases, there appears to be no predilection for gender, age, or ocular location of tick attachment. In any case of suspected tick penetration to the ocular surface, immediate ophthalmologic consultation and prompt removal via the method mentioned above is recommended in order to minimize the localized inflammatory reaction and potential for infection transmission. Additionally, attention should be paid to the IDSA guidelines on when to initiate prophylaxis for any tick-borne diseases endemic to the region where the patient was affected.
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Eastern equine encephalitis (EEE) is an arboviral infection transmitted by mosquitos that is rarely symptomatic in humans, unless there is central nervous system involvement progressing to coma and death. The life elastase of EEE virus in North America involves enzootic transmission among songbirds and mosquitos, followed by transmission to horses and man (dead-end hosts). The incubation period in humans typically ranges from 4 to 10 days. The virus multiplies in the blood, then it passes to the nasal mucosa and to the brain.
Most patients have abrupt onset of high fever, chills, nausea, myalgias, and intense headache with neck stiffness. Encephalitis ensues in 1–2 days, results in altered mental status and possibly impaired vision, and progresses to coma and/or death. Feemster and Haymaker (1958) included impaired vision as a possible sequel to eastern equine encephalitis. In another form of arboviral infection that may result in encephalitis, Rift Valley fever, ocular manifestations are well-described. The Zika virus has been recently shown to cause pathological changes in the retina and the optic nerve in the majority of affected infants. However, no published ophthalmological observations in patients with EEE have been documented. We describe the first report of ophthalmic histopathological findings in a human case of EEE, which parallel the changes in the brain.
We are unaware of any published ophthalmological observations in EEE patients, although Feemster and Haymaker included impaired vision as a possible sequel to EEE. One review stated that horses affected with EEE often have visual problems resulting in partial blindness. In the guinea pig, the EEE virus was shown to produce an insignificant, non-specific reaction in the posterior chamber, with a few occasional leukocytes in the vitreous and retina, and rare necrotic ganglion cells. There was complete absence of overt necrosis or a focal reaction similar to that found in the brain. By contrast, in Rift Valley fever, another form of arboviral infection that may result in encephalitis, ocular manifestations are well-described in patients including exudative lesions of the macula and paramacular region that are frequently associated with hemorrhage, edema, and less often with vasculitis, retinitis, and vascular occlusion. A related arbovirus of recent importance, the Zika virus, has been associated with an epidemic of microcephaly in the western world. The ophthalmologic findings present in 85% of infants examined were focal pigmentary clumping, well circumscribed chorioretinal atrophy surrounded by hyperpigmentation, optic nerve hypoplasia and severe disc cupping, and possibly bilateral iris colobomas and lens subluxation.