Blackleg in cattle: current understanding and future research needs / Carbúnculo sintomático: compreensão atual e futuras necessidades de pesquisa

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.(AU)

O carbúnculo sintomático é uma infecção endógena, aguda, que acomete principalmente bovinos, cujo agente etiológico é a bactéria anaeróbica Clostridium chauvoei. Recentemente, os principais fatores de virulência do C. chauvoei foram descobertos e descritos. Contudo, a patogênese do carbúnculo sintomático em bovinos, especialmente a circulação do patógeno desde o ponto de entrada até os tecidos acometidos ainda não está completamente elucidada. O controle desta enfermidade é baseado em medidas adequadas de manejo e vacinação. Esta revisão reúne as mais recentes descobertas que contribuíram para o entendimento da doença em bovinos, fornece embasamento para medidas preventivas e aponta futuras necessidades de pesquisa.(AU)

Blackleg in cattle: current understanding and future research needs / Carbúnculo sintomático: compreensão atual e futuras necessidades de pesquisa

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.

O carbúnculo sintomático é uma infecção endógena, aguda, que acomete principalmente bovinos, cujo agente etiológico é a bactéria anaeróbica Clostridium chauvoei. Recentemente, os principais fatores de virulência do C. chauvoei foram descobertos e descritos. Contudo, a patogênese do carbúnculo sintomático em bovinos, especialmente a circulação do patógeno desde o ponto de entrada até os tecidos acometidos ainda não está completamente elucidada. O controle desta enfermidade é baseado em medidas adequadas de manejo e vacinação. Esta revisão reúne as mais recentes descobertas que contribuíram para o entendimento da doença em bovinos, fornece embasamento para medidas preventivas e aponta futuras necessidades de pesquisa.

Edema maligno em equino causado por Clostridium chauvoei / Malignant Edema Caused by Clostridium chauvoei in a Horse

Background: Malignant edema occurs when a wound is contaminated by one or a combination of the following bacteria: Clostridium septicum, C. sordellii, C. chauvoei, C. novyi type A, and C. perfringens type A. Although malignant edema has been recognized as a disease of economic importance in domestic ruminants, it has rarely been reported in horses in Brazil. Immunohistochemistry is a method that combines histological, immunological and biochemical techniques which, with the use of specific antibodies, detects the agent in situ. This paper reports a case of malignant edema by Clostridium chauvoei in a horse in Bahia, Brazil. Case: A 4.5-year-old male horse was submitted for necropsy. The clinical history was obtained from the owner. Samples from the abdominal cavity, thoracic cavity, central nervous system and integumentary system were collected. The samples were fixed in 10% formalin, processed routinely for histology, embedded in paraffin, sectioned at five microns, and stained with hematoxylin and eosin. Additionally, histological sections were subjected to immunohistochemistry anti-Clostridium perfringens type A, C. septicum, C. chauvoei, C. novyi type A, and C. sordellii. Positive and negative controls were included. The animal presented difficulty in walking, swelling of the pelvic limbs two days after intramuscular anti-inflammatory treatment, and died seven hours after the onset of clinical signs. Macroscopically, large amounts of hemorrhagic edema and tissue emphysema in the subcutaneous tissue and skeletal muscles were seen. Microscopically, there was moderate bleeding, particularly in subcutaneous areas and between myofiber bundles, with few and discrete degeneration foci. Immunohistochemistry technique was positive for Clostridium chauvoei. Discussion: The diagnosis of malignant edema was confirmed considering clinical and pathological alterations as well as the positive immunohistochemistry result for Clostridium chauvoei. Cases of malignant edema are occasionally observed in horses, and Clostridium perfringens and Clostridium septicum are the major etiological agents involved. Two cases have been reported in Brazil, both caused by Clostridium septicum. As in the present report, the animals developed the disease after administration of intramuscular anti-inflammatory medication. The clinical course of the disease in horses is considered severe, with the first clinical signs occurring between 24 and 48 h post infection. Clinical signs, particularly the marked difficulty in walking, edema, and crepitus of the affected areas, may be considered characteristic. The pathological findings were similar to those described by other authors, which are attributed to toxins produced by the bacteria; however, the lesions described in this study were similar to those reported in less severe infections by Clostridium septicum. Bacterial culture and polymerase chain reaction (PCR) are standards for the identification of Clostridium species; however, immunohistochemistry is considered a very sensitive and specific diagnostic technique. To control the disease, animals may be treated with high doses of penicillin or broad-spectrum antibiotics, which are efficient when used during the early stages of the disease. Prophylactic measures include good hygiene while handling syringes and surgical instruments, as well as annual vaccination of the animals.