A parasite. Brugia malayi and Brugia timori. They cause filariasis. (But not Dr. Phil-ariasis, an annoyingly grating awfulness).
B. malayi: South and Southeast Asia.
B. timori: eastern Indonesian archipelago.
Lymphangitis or lymphadenitis with fever, headache, backache, and nausea; occasionally epididymitis, or orchitis may be seen. Later they get chronic lymphedema and elephantiasis.
Diethylcarbamazine citrate po 6 mg/kg daily for 2 weeks reduces the number of microfilariae in the peripheral blood. Ivermectin in a single dose of 200 to 400 mg/kg. 6-weeks of doxycycline, either alone or in combination with diethylcarbamazine-albendazole, decreases microfilaremia and reduces adverse reactions to antifilarial treatment in B. malayi (PubMed). Expect relapse.
Get a smear obtained at midnight for diagnosis, for that is when there are the most filaria in the blood, which coincidently is the time the mosquitos are most likely to feed. Evolution is so cool.