Subconjuctival Loa loa with Calabar swelling

Abstract

Loa loa is unique among the human filariae in that adult worms are occasionally visible during subconjunctival migration. A 29-yr-old African female student, living in Korea for the past 5 yr without ever visiting her home country, presented with acute eyelid swelling and a sensation of motion on the left eyeball. Her symptoms started one day earlier and became worse over time. Examination revealed a threadlike worm beneath the left upper bulbar conjunctiva with mild eyelid swelling as well as painless swelling of the right forearm. Upon exposure to slit-lamp illumination, a sudden movement of the worm toward the fornix was noted. After surgical extraction, parasitologic analysis confirmed the worm to be a female adult Loa loa with the vulva at the extreme anterior end. On blood smear, the microfilariae had characteristic features of Loa loa, including sheath and body nuclei up to the tip of the tail. The patient also showed eosinophilia (37%) measuring 4,100/microL. She took ivermectin (200 microg/kg) as a single dose and suffered from a mild fever and chills for one day. This patient, to the best of our knowledge, is the first case of subconjunctival loiasis with Calabar swelling in Korea.

Fig. 1

(A) Female adult Loa loa isolated from the patient's conjunctiva. The threadlike semitransparent worm measured 580 mm long and 0.72 mm in diameter after extraction. (B) Opening of vulva (arrow) located 3 mm distance from the anterior end of the body. Bar=0.5 mm.

Fig. 2

Microfilariae of Loa loa on the patient's peripheral blood smear after the Knott's concentration method. The microfilariae were sheathed and measured an average 261.1 µm in length. The nuclei were seen up to the tip of the tail (arrow). Giemsa stain, ×400.