2020–2021 BCSC Basic and Clinical Science Course™
8 External Disease and Cornea
Chapter 10: Infectious Diseases of the External Eye: Microbial and Parasitic Infections
Microbial and Parasitic Infections of the Cornea and Sclera
Infection with Loa loa (loiasis) and other filarial nematodes can cause conjunctivitis; these infections also have dermatologic manifestations. After the bite of an infected vector, such parasites can burrow subcutaneously to reach the eye area. The microfilarial stage is transmitted from human to human by the bite of an infected female deer fly (genus Chrysops) indigenous to West and Central Africa. A migrating worm moves under the skin at about 1 cm/min but is most conspicuous when it is seen or felt wriggling under the periocular skin or bulbar conjunctiva (Fig 10-24). Extraction of the filarial worm cures the conjunctivitis; antiparasitic treatment for disseminated infestation follows. Diethylcarbamazine is generally given 2 mg/kg 3 times a day for 3 weeks and repeated as necessary. Ivermectin 150 mg/kg may also be effective, but significant adverse effects have been reported in patients with prominent intravascular loiasis. Concurrent administration of corticosteroids and/or antihistamines may be necessary to minimize allergic reactions.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.