19 After a single dose of IVM (150 µg/kg), Loa microfilaremia decreases by 70–80% within the first 3 days.20–22The densities then plateau or decrease more slowly, and remain at very low values up to
1 year after treatment.23 Whether this is due to a partial macrofilaricidal Ku-0059436 ic50 or to an embryostatic effect (preventing the release of developed mf from the uteri of the adult female worms) is not known. Monthly treatment with IVM has a cumulative effect, leading after six doses to extremely low microfilarial densities, which remain so for at least several months.24 Besides its effects on the parasite, IVM also has a beneficial effect on the clinical manifestations of loiasis, and seems to prevent the reappearance of Calabar swellings for several months.25 Lastly, it should be reminded that as L loa does not harbor Wolbachia endosymbionts,26 antibiotics (doxycyclin) are useless in the treatment of loiasis. This being said, the treatment strategy depends firstly on the risk of adverse events, which is related to the
patient’s Loa microfilarial density. The latter must mandatorily be quantified before any therapy decision by examining a Giemsa-stained thick blood smear (50 µL) prepared between 10:00 am and 4:00 pm, ie, when Loa microfilaremia in the peripheral blood is the highest. In countries located outside the loiasis distribution area, this assessment and the resulting treatment Protein Tyrosine Kinase inhibitor should be conducted in specialized units or by specialized physicians. DEC and IVM can induce potentially fatal encephalopathies in persons harboring >30,000–50,000 mf/mL of blood.27,28 Functional impairment without alteration of consciousness but requiring assistance for several days can occur after DEC in individuals with >2000 mf/mL,29 and after IVM in patients with densities exceeding 8000 mf/mL.28 Use of ALB in loiasis patients is usually very safe. Given the risk of serious adverse events after DEC or IVM treatment, one can propose the following strategy: 1 If the patient’s microfilarial
density is below 2000 mf/mL, DEC—the only proven macrofilaricidal drug—can be administered straightaway. The first course should last 3–4 weeks and start with low doses (3 or 6 mg/d if mf are present in the blood, or 50 mg/d if the patient is amicrofilaremic) Miconazole divided into two or three doses. The dose is doubled every day until 400 mg/d (or 8–10 mg/kg/d) still divided in two to three doses. Treatment should be started in hospital and oral antihistamines or corticosteroids may be useful in the first days to reduce the severity of side effects (pruritus, angioedema, arthralgias, headache, fever, etc.) which occur in 50% of the cases. As stated above, several courses of DEC may be needed. If the patient is refractory to DEC, a course of ALB (200 mg twice a day for 21 d) can be useful.16 In conclusion, definitive cure of Loa infection can sometimes be difficult and this is all the more true because DEC is not widely available.