Factors affecting host response:
(1) sudden release of antigenic material
(2) migration of microfilaria through the central nervous system
Risk factors for encephalitis:
(1) high density of microfilaria in the peripheral blood (especially if > 30,000 per mL) when chemotherapy is started
(2) high initial dose of deithylcarbamazine (DEC)
(3) rapid escalation in DEC dose
(4) failure to provide anti-allergic therapy
Reducing the microfilarial load by apheresis prior to starting DEC chemotherapy can significantly reduce neurological complications.
Ivermectin has been associated with a lower risk of neurologic complications, but risks occur with hypermicrofilaremic loads.
