Infectious Disease Compendium

Loa loa

Microbiology

Nematode round worm.

Epidemiologic Risks

Spread by biting flies in West and Central Africa from deerfly bite. In endemic area 40% have had an eye worm.

Especially common around rubber plantations. I did not know male contraception was produced in plantations.

Severity of disease likely has a genetic component and, like noses, runs in families (PubMed).

Syndromes

Subcutaneous filariasis: swellings, especially around joints, with marked eosinophilia as it wanders about the body. It can cause focal infections (meningitis) and can be seen migrating across the conjunctiva where it causes little damage. Ick.

It can survive up to 15 years with inflammation known as Calabar swellings.

Diagnose by finding microfilariae in the blood, in the eye, and in skin swellings. Check the blood around noon for best results. There is also serology.

Treatment

Diethylcarbamazine 8–10 mg/kg/day po divided tid for 21 days. Patients with high worm loads (≥8,000 microfilariae per mL) can get a fatal encephalopathy with treatment and need apheresis. Want the load to 2500 microfilariae per mL before starting therapy.

Notes

They are in the peripheral blood during the day and got to the lungs at night. It is interesting that they have evolved to be in the blood at the time humans are mostly likely to get bit by the vector, a feature of many worms and parasites.

Last update: 05/05/18