Bovine Mastitis due to Prototheca zopfi II

Area of Science:

• Veterinary Medicine
• Microbiology
• Dairy Science

Background:

• Protothecosis, an infection caused by the alga Prototheca zopfi, can occur in dairy cattle.
• Cattle herds may be quarantined under programs like the National Brucellosis Eradication Program.
• Diagnosing Prototheca infection involves specific serological and microbiological methods.

Purpose of the Study:

• To report the occurrence and characteristics of protothecosis in a dairy herd.
• To investigate the diagnostic methods for Prototheca infection in cattle.
• To understand the transmission, persistence, and antibody response related to Prototheca zopfi in dairy cows.

Main Methods:

• Milk cultures were used to detect Prototheca zopfi.
• Serum precipitins against Prototheca zopfi antigens were measured.
• Whey antibodies were assessed in infected quarters.
• A naturally infected cow was monitored for 20 months, including during dry periods and parturition.
• An experimental infection was performed on a healthy cow.

Main Results:

• Prototheca zopfi was consistently cultured from milk when serum precipitins were present.
• Whey antibodies were detected in infected mammary quarters.
• Serum antibodies in a naturally infected cow disappeared after lactation but reappeared post-parturition, with algal cells and antibodies in colostrum.
• Prototheca zopfi survived a 13-month dry period without spreading to the calf.
• Experimental infection induced transient serum and whey antibodies.
• No cross-reactions were observed between Prototheca and Brucella abortus antigens.

Conclusions:

• Prototheca zopfi infection in dairy cattle is diagnosable through milk culture and serological tests.
• The alga can persist in infected cows and be transmitted via colostrum.
• The association with Brucella abortus in the studied herd was coincidental, with no antigenic cross-reactivity observed.