Loa loa - Clinical Manifestation, Complications, Prognosis

Clinical Manifestation of Loa loa

In most cases, Loa loa infection (loiasis) is asymptomatic and one-third of patients are amicrofilaremic.

In symptomatic cases, which appear months to more than a decade after infection, clinical manifestations include skin and ocular lesions. Dying adult worms cal also causes chronic abscesses resulting in the formation of granulomatous reactions and fibrosis.

The parasites may also reside in the testes, kidneys, heart, penis, nipples, bridge of the nose, etc.

Skin lesions

Skin lesions due to Loa loa infection include fugitive swelling or Calabar swelling.

Calabar swelling

• Calabar swelling is the transient migratory swelling of the localised sub-cutaneous host tissue

• caused due to migration of adult worms

• itching and localized pain for several hours is followed by the onset of swelling

• swelling measures 3 to 10 cm in diameter, non-erythematous and lats for a few days to weeks

• mostly affected areas include knee joints or wrist joints

• the parasites are not present in the swellings but rather below the surface of the skin

• associated with pruritus (itching) and urticaria (skin eruptions)

• in chronic cases, cyst-like enlargements of the connective tissue around the sheaths of muscle tendons can take place

Ocular lesions

Ocular lesions caused by Loa loa infection can be clinically classified into three types:

1. Conjunctival granuloma

2. Oedema of the eyelid

3. Proptosis

Conjunctival granuloma

• conjunctival granuloma due to Loa loa infection is caused by the migration of adult worms in the subconjunctival tissue

• may present as single or multiple small nodules measuring about 2mm in diameter

• found in deeper layers of the conjunctiva and close to the scleral tissue

• painless but may be itchy

Oedema of the eyelid

• oedema of the eyelid is a painless condition

• accompanied by itching

• no other clinical syndromes have been noted

Proptosis

• proptosis is known as ‘bug-eye’ or ‘bulge-eye’

• caused by oedema of the orbital cellular tissue

• rapidly onset

• painless condition

• associated with itching

Complications of Loa loa

The complication of Loa loa includes retinopathy, arthritis, endomyocardial fibrosis, fugitive swellings, retinopathy, and neuropathy.

A severe and often fatal complication of Loa loa infection is meningoencephalopathy. This condition can occur spontaneously or after treatment with diethylcarbamazine (DEC) in patients with high levels of microfilariae.

Prognosis of Loa loa

The prognosis of Loa loa infection is good if treated early.