Lyme disease (LD) is the most common tick-borne illness in the United States. It has protean systemic manifestations and is caused by the spirochete Borrelia burgdorferi, but intraocular inflammation is rare. Animal reservoirs include deer, horses, cows, rodents, birds, cats, and dogs. The spirochete is transmitted to humans through the bite of infected ticks, Ixodes scapularis in the northeast, mid-Atlantic, and midwestern United States and Ixodes pacificus in the western United States. Numbers of reported cases of LD have been increasing steadily in the United States, recently peaking at almost 40,000 in 2015. The disease affects men (53%) slightly more often than women and has a bimodal distribution, with peaks in children aged 5–14 years and in adults aged 50–59 years. Whites are affected more commonly than are other races. There is a seasonal variation, with most cases occurring between May and August. Lyme disease may be found worldwide, but outside the United States it is caused by different species of Borrelia, such as B afzelii and B garinii.
Clinical Features
The clinical manifestations of LD are divided into 3 stages; ocular findings vary within each stage.
Stage 1
The most characteristic feature of stage 1, or local disease, is a macular rash known as erythema chronicum migrans at the site of the tick bite; it appears within 2–28 days in ~70% of patients, forming a “bull’s-eye” lesion (Fig 10-6). Constitutional symptoms appear at this stage and include fever, malaise, fatigue, myalgias, and arthralgias.
Stage 2
Stage 2, or disseminated disease, occurs several weeks to 4 months after exposure. Spirochetes spread hematogenously to the skin, CNS, joints, heart, and eyes. A secondary erythema chronicum migrans rash may appear at sites remote from the tick bite. Left untreated, up to 80% of patients with erythema chronicum migrans develop joint manifestations, most commonly monoarthritis or oligoarthritis involving the large joints, typically the knee (Fig 10-7). Joint involvement may be the only clinical manifestation of LD in children, and juvenile idiopathic arthritis must be considered in the differential diagnosis.
Neurologic involvement, which occurs in up to 40% of patients, may include meningitis, encephalitis, painful radiculitis, or unilateral or bilateral Bell palsy. In endemic areas, as many as 25% of new-onset cranial nerve VII palsies may be attributed to B burgdorferi infection.
Stage 3
The most frequent systemic manifestation of stage 3, or persistent disease, which occurs more than 5 months after the initial infection, is episodic arthritis that may become chronic. Chronic arthritis has been associated with HLA-DR4 and -DR2 haplotypes in North America; individuals expressing HLA-DR4 have a poorer response to antibiotics. Acrodermatitis chronica atrophicans, a bluish red lesion on the extremities that may progress to fibrous bands and nodules, can occur in some patients, as may chronic neurologic syndromes such as neuropsychiatric disease, radiculopathy, chronic fatigue, peripheral neuropathy, and memory loss.
Excerpted from BCSC 2020-2021 series: Section 9 - Uveitis and Ocular Inflammation. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.