SUBCONJUNCTIVAL LOIASIS : A CASE REPORT

Loiasis is a strictly African filariasis, especially equatorial and western, limited to the great forests, it occurs from Guinea in the North to Uganda in the East. Due to the development of population movements, it can be recorded anywhere in the world. Its vector is a horsefly, the chryspos or “red fly”. The Loa Loa is a specifically human parasite. Adults are round, whitish worms, 2 to 7 cm long, living in the subcutaneous tissue and whose longevity can exceed 15 years.

The clinical picture of loiasis is polymorphous, the adult worm can pass under the skin creating a palpable, mobile cord. It can also pass under the eyelid conjunctiva like the case of our patient. Exceptional cases of passage of adult filaria into the anterior chamber of the eye have been described. Loiasis can also be responsible for allergic reactions. It can gradually become complicated by immunological reactions associated with hypereosinophilia, affecting the cardiac, renal and cerebral endothelia.

A 40-year-old soldier, who returned to Morocco a month ago after an eighteen-month stay in the Democratic Republic of Congo, consulted the emergency room for a sensation of a mobile foreign body in the right eye, accompanied by irritation and tearing.

The clinical examination revealed the presence of a mobile worm under the lower bulbar conjunctiva of the right eye associated with conjunctival hyperemia without alteration of visual acuity, thus suggesting the diagnosis of filariasis. On the blood count, there was hypereosinophilia at 0.526 G/L. On a blood sample taken at noon, direct microscopic examination of a thick drop and after leucoconcentration was negative. The parasitological examination identified the worm, after its extraction with forceps, as a Loa Loa type macrofilariae 5 cm long

The diagnosis of Loiasis was retained given the notion of staying in an area of ​​high filarial endemicity and the identification of the adult worm under the conjunctiva.

Treatment with diethyl-carbamazine  was started at a dose of 10 mg on the first day, gradually doubled to reach after one week the daily dose of 500 mg, divided into two doses per day. This dose was maintained for 21 days. In order to prevent the occurrence of incidents of filarial lysis, corticosteroid therapy was combined. The evolution was quickly favorable.

The direct arguments for certainty are the detection of microfilaria in the blood or adult filaria in the skin or under the conjunctiva. Direct examination may be negative, especially in patients living in an endemic area. In this case, other techniques such as serology and Polymerase Chain Reaction (PCR) can be performed.

Curative treatment for loiasis is dangerous and sometimes fatal. It must be driven with caution; it is based on two microfilaricidal drugs: diethyl-carbamazine, prescribed in very gradually increasing doses accompanied by antihistamines or corticosteroids, and ivermectin used as a single annual course.