Loiasis B74.30

Infectious disease caused by Loa loa (migrating filiaria), filariae with typical subcutaneous swelling as a sign of a hypersensitivity reaction to the filariae migrating in the subcutaneous connective tissue.

Only indigenous to the West and Central African rainforest zone (Benin, Angola, Western Sudan).

Transmission of the approximately 0.2-0.3 cm large L3 larvae through the painful sting of the brake Chrysops demidiata. Chrysops demidiata is dependent on shady, humid biotopes of African rainforests. The larvae transferred during the sting grow into mature adults in 6-12 months (lifetime 15 years in subcutaneous fatty tissue). Microfilariae are cyclically released into the blood by the females, which can then be taken up again by horseflies.

Integument: The metabolic products of the migrating adult worm cause allergic reactions. Usually alternating, reddened, itchy swellings lasting about 3-4 days, depending on the location of the worm (5-7 cm long) in the skin.

Extracutaneous manifestation: Infestation of the conjunctiva of the eye (very painful when filariae are present; pathognomonic).

In rare cases, prolonged infestation with high eosinophilia can lead to chronic inflammatory processes with eosinophilic granulomas, especially on serous skins.

Late complications: endocarditis, renal damage and meningoencephalitis (adult worms can persist in the body for more than 10 years).

Travel history

Detection of microfiliaria in the blood smear (usually possible at the earliest 1-2 years after infection). The blood sample should be taken during the day, preferably at noon. Detection of worms in skin or conjunctiva.

Eosinophilia in the blood

DEC provocation test

Serological antibody detection against filarial raw antigen

IgG4 serum antibodies.

Diethylcarbamazine (e.g. Hetrazan): Start therapy gradually, as severe febrile reactions with danger of shock due to decay of the filariae are possible. Capillary blockage due to microfilariae in the brain, meninges, retina and other areas may occur. Initial dosage: 0.5 mg/kg bw/day (avoidance of serious side effects), then increase to 8-10 mg/kg bw/day (max. 600 mg/day) spread over 3 days (intake after meals) over 3 weeks (total dosage: max. 126 mg/kg bw). As NW it can lead to pruritus, fever, joint pain, dyspnoea, circulatory collapse, etc.

In severe cases reduce combination with betamethasone 3-5 mg/day i.v. 2 days before the 1st DEC-dose and continuously balance.

Alternative: In case of therapy failure Albendazole (400 mg/day for 3 weeks).

Alternative: There are also positive reports of experience with ivermectin (Twum-Danso NA et al. 2003).

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