Serologic test for antibody to Sarcocystis in cattle

Area of Science:

• Veterinary Parasitology
• Immunodiagnostics

Background:

• Sarcocystis is a protozoan parasite affecting livestock.
• Accurate diagnostic methods are crucial for managing Sarcocystis infections in cattle.

Purpose of the Study:

• To develop and evaluate serological tests for detecting antibodies to Sarcocystis in cattle.
• To assess the diagnostic sensitivity and specificity of the indirect hemagglutination (IHA) and agar gel diffusion (AGD) tests.

Main Methods:

• Soluble Sarcocystis antigen was prepared from infected bovine heart muscle.
• Indirect hemagglutination (IHA) and agar gel diffusion (AGD) tests were employed to detect anti-Sarcocystis antibodies in experimentally and naturally infected cattle.
• Human sera positive for Toxoplasma were tested to evaluate cross-reactivity.

Main Results:

• IHA serum titers in experimentally infected cattle rose by 30-45 days post-infection, peaking at 1:39,000 by 90 days.
• Field-collected sera from healthy dairy cows showed IHA titers up to 1:486, suggesting these are non-significant for clinical disease diagnosis.
• Precipitins in the AGD test appeared by 30 days and were pronounced by 65-90 days post-infection.
• No cross-reactivity was observed between Sarcocystis and Toxoplasma antibodies in human sera.

Conclusions:

• The IHA test is a sensitive method for detecting Sarcocystis antibodies in cattle.
• Titers of 1:486 or less in dairy cows likely indicate non-clinical Sarcocystis infections.
• The developed serological tests can aid in the diagnosis and epidemiological studies of Sarcocystis in cattle.