Blackleg in cattle: current understanding and future research needs

Abstract

Blackleg is an endogenous acute infection that principally affects cattle, whose etiologic agent is the anaerobic bacterium Clostridium chauvoei. In recent years, the major virulence factors of C. chauvoei have been discovered and described. However, the pathogenesis of blackleg in cattle, and in particular, the movement of the pathogen from the point of entry to the affected tissues is not yet fully elucidated. Disease control is based on appropriate management and vaccination. This review summarizes the latest research findings that contribute toward the understanding of the disease in cattle, provide a foundation to preventive strategies, and identify future research needs.

Blackleg in inadequately immunized calves and their recovery following antibiotic therapy

“…The diagnosis of blackleg was based on the clinical, epidemiological, and anatomopathological findings. Those were similar to characteristic results reported elsewhere for the disease [3,5,6]. The diagnosis was further confirmed by PCR analysis of skeletal muscle The space between the fibers is somewhat expanded by a faint pink material, which is edema rich in fibrin (asterisk) with some erythrocytes.…”

“…Blackleg is caused by histotoxins of Clostridium chauvoei, an anaerobic spore-forming bacterium. It is primarily a disease of cattle with characteristic lesions of hemorrhagic and emphysematous necrotic myositis and myocarditis [1][2][3][4][5]. Vaccination against blackleg is recommended for 3-6-month-old calves, followed by a booster dose within 30 days, and annual revaccination until cattle reach three years of age [6].…”

“…Vaccination against blackleg is recommended for 3-6-month-old calves, followed by a booster dose within 30 days, and annual revaccination until cattle reach three years of age [6]. However, in large herds held in extensive areas, farming can be a demanding operation in which booster doses may be neglected, increasing the risks of blackleg to occur [5,7].…”

Vaccine Production to Protect Animals Against Pathogenic Clostridia

“…C. chauvoei pathogenesis relies on the release of potent toxins that cause endogenous myonecrosis and edemic lesions, giving to the affected muscles the characteristic dark color from where blackleg takes its name [192,194]. The disease progresses rapidly, causing the death of the animal within 48 h of clinical manifestation [192,195]. On the other hand, C. chauvoei is not considered zoonotic, and only two fatal human cases have been reported [194].…”

“…Because blackleg advances rapidly, antibiotics are not generally used to treat the disease and vaccination is the principal prophylactic measure. Vaccination has been a common practice since 1930, especially in the bovine sector [195]. Nevertheless, although vaccination claims to be 100% effective against blackleg, the scientific evidence showing its efficacy in protecting cattle against C. chauvoei challenges is scant [200].…”