Microfilaria bolivarensis: a new species of filaria from man in Venezuela.

An unsheathed microfilaria, unlike any other already described from man, was found in thick blood smears and Knott samples taken from Amerinds living along the upper Caura River in Bolivar State, Venezuela. The mirofilaria, which measures 256 x 7-8 micrometers in thick blood smears and 300 x 8 micrometers in Knott samples, is easily differentiated morphologically from Mansonella ozzardi with which it often occurs concomitantly. It is readily differentiated, on morphological criteria, from all other species of filariae which infect man, as well. The parasite has been named Microfilaria bolivarensis after the geographical locality in which it was discovered.