Which parasite is diagnosed by vaginal washing?

• A. Tritrichomonas species
• B. Anaplasma species
• C. Dictyocaulus species
• D. Dioctophyma species

Answer: (C)

The sample type matters: some parasites dwell in specific body sites, so collecting material from that site increases the chance of detection. Tritrichomonas foetus is a flagellated protozoan that colonizes the bovine reproductive tract, especially the vagina and cervix in females and the prepuce in males. Because it inhabits the reproductive tract, a vaginal washing provides the direct material needed to detect the organism, typically by culture on specialized media or by PCR to confirm its presence.

The other organisms involve different tissues and diagnostic samples. Anaplasma species are intracellular bacteria in red blood cells and are diagnosed from blood smears, serology, or PCR. Dictyocaulus species are lungworms diagnosed from respiratory samples or fecal Baermann findings. Dioctophyma species (the kidney worm) is diagnosed via urine analysis or imaging.