Collective outbreaks of bovine actinobacillosis

Infection Due to Actinobacillus lignieresii in Cattle with Brain and Ocular Involvement: Histological and Microbiological Features

The actinobacillosis is rare and to date the biological profile of the agent is not yet fully understood. The knowledge about the possible hosts of the pathogen is incomplete and is generally only associated with granulomatous lesions in cattle and sheep. The primary organs involved are the mouth, tongue and pharynx. Human infection is extremely rare. Actinobacillus lignieresii is the causative agent of a rare bovine granulomatous disease known as "wooden tongue". In this research, we describe a case of cerebral and ocular metastatic diffusion of granuloma due to infection with Actinobacillus lignieresii in cattle, probably resulting from primary oral localization. Diagnosis was made using histopathological assay which made it possible to highlight the typical lesion of actinobacillosis, and bacteriological assay that allowed to isolate the pathogen.

Natural lymphatic ("atypical") actinobacillosis in cattle caused by Actinobacillus lignieresii

Bovine actinobacillosis is typically characterized by pyogranulomatous glossitis (wooden tongue). The involvement of other tissues, generally the skin or lymph nodes, has been regarded as atypical or cutaneous. We describe herein 2 outbreaks of actinobacillosis affecting primarily the lymph nodes of the head and neck. The disease affected 40 of 540 lactating cows in a dairy herd, and 5 of 335 two-y-old steers in a beef herd. Multiple or single, occasionally ulcerated nodules were observed in the region of the mandible, neck, and shoulder, including the parotid, submandibular, retropharyngeal, and prescapular lymph nodes. The histologic lesions were multifocal pyogranulomatous lymphadenitis, dermatitis, and cellulitis with Splendore-Hoeppli material. One steer had an exophytic pyogranuloma in the gingiva and another died because of ruminal tympany secondary to oropharyngeal and esophageal obstruction by a pyogranulomatous mass. Actinobacillus lignieresii was isolated from the lesions and identified by amplification, sequencing, and analysis of the 16S ribosomal (r)DNA gene. Seven of 8 cows recovered after treatment with sodium iodide. Lymphatic actinobacillosis is a frequent disease in Uruguay, southern Brazil, and Argentina. Morbidity is 1-50%; mortality is <1%. A. lignieresii apparently penetrates the intact oral and pharyngeal mucosa, infecting primarily the regional lymph nodes. Later, lesions may extend to the subcutaneous tissue and the skin, causing ulceration. Affected cattle with draining pyogranulomas contaminate the environment, favoring disease transmission, and should be treated with sodium iodide or antibiotics and isolated from the herd in order to control the disease.

The occurrence of lesions in the tongue of adult cattle and their implications for the development of actinobacillosis

The occurrence of lesions on the tongue and the concurrence of actinobacillosis was investigated in samples consisting of totally 2,423 corpora and 947 apices linguarum of adult cattle. The investigation was made as an extended recording in connection with routine meat inspection. The diagnosis actinobacillosis is an assessment made on the gross pathological findings confirmed by consistent results of randomised samplings for histopathological and microbiological examination. The sampling was found to be representative of the mean of the phenomena investigated, and the samples were submitted to statistical analysis. Actinobacillosis was found in 2% of the lesions of the corpus as well as the apex, and the frequency on all tongues was 0.7%. These results are compared to previous findings. The importance of initial lesions for the development of actinobacilosis, and some factors predisposing for lesion infliction are discussed on the basis of the present results and literature sources. It is concluded, that there is a connection between primary lesions and actinobacillosis.