Investigation of Neospora caninum, Hammondia sp., and Toxoplasma gondii in tissues from slaughtered beef cattle in Bahia, Brazil.

Neospora caninum, Hammondia sp., and Toxoplasma gondii are parasites with morphological and genetic similarities. N.

Loss of infectivity of Neospora caninum oocysts maintained for a prolonged time.

The purpose of this study was to investigate whether sporulated Neospora caninum oocysts, which had been stored for 46 mo in a 2% sulfuric acid solution at 4 degrees C, remain morphologically viable and infective to gerbils (Meriones unguiculatus). Six gerbils were orally inoculated with doses of 400 or 1,200 oocysts. Two mo after inoculation, the animals did not show any clinical signs, had no histological lesions, and were seronegative for N.