Type C waterborne botulism outbreaks in buffaloes (Bubalus bubalis) in the Amazon region

Polioencephalomalacia in Buffaloes in the Amazon Biome

The epidemiological and clinical pathological aspects of polioencephalomalacia (PEM) in five buffaloes in the Amazon biome are described. Epidemiological data were obtained during the clinical visit in which buffalos were submitted to an examination of the nervous system. The diagnosis of PEM was based on epidemiological, clinical-pathological, and histopathological findings, similar to findings in other ruminants. In the clinical examination, all buffaloes had a body score between 2.5 and 3 (scale from 1 to 5), with decreased alertness, postural changes, marked hypermetria when stimulated to move, total or partial blindness demonstrated by colliding with the corral structures, head pressing and circumduction of the hindquarters when supported on the thoracic limbs, opisthotonos, muscle tremors, convulsions, paddling movements, sialorrhea, decrease in palpebral and pupillary reflexes, and eyeball rotation placing the pupillary slit in a vertical position. At necropsy, mild lesions characterized by edema and flattening of the cerebral convolutions were observed. A histopathological examination showed laminar necrosis of the cerebral cortex. The cause of PEM in the studied buffaloes was not established, which indicates the need for further studies to elucidate this disease in the species, particularly in the Amazon region.

Fate of Clostridia and other spore-forming Firmicute bacteria during feedstock anaerobic digestion and aerobic composting

Pathogenic spore-forming Firmicutes are commonly present in animal and human wastes that are used as fertilizers in crop production. Pre-treatments of organic waste prior to land application offer the potential to abate enteric microorganisms, and therefore reduce the risk of contamination of crops or adjacent water resources with pathogens carried in these materials. The inactivation and reduction of gram-positive spore formers such as Clostridium spp., Clostridioides spp. and Bacillus spp. from animal and human waste can be challenging given the recalcitrance of the spores these bacteria produce. Given the significance of these organisms to human and animal health, information concerning spore-forming bacteria inactivation during anaerobic digestion (AD) and aerobic composting (AC) is required as the basis for recommending safe organic waste management practices. In this review, an assessment of the inactivation of spore-forming Firmicutes during AD and AC was conducted to provide guidance for practical management of organic matrices of animal or human origin. Temperature and pH may be the main factors contributing to the inactivation of spore-forming Firmicutes during batch lab-scale AD (log reduction <0.5-5 log). In continuous digesters, wet AD systems do not effectively inactivate spore-forming Firmicutes even under thermopholic conditions (log reduction -1.09 - 0.98), but dry AD systems could be a feasible management practice to inactivate spore-forming Firmicutes from organic materials with high solid content (log reduction 1.77-3.1). In contrast, composting is an effective treatment to abate spore-forming Firmicutes (log reduction 1.7-6.5) when thermophilic conditions last at least six consecutive days. Temperature, moisture content and composting scale are the key operating conditions influencing the inactivation of spore-forming Firmicutes during composting. Where possible, undertaking AD with subsequent composting to ensure the biosafety of digestate before its downstream processing and recycling is recommended to abate recalcitrant bacteria in digestate.

Recombinant vaccine against botulism in buffaloes: Evaluation of the humoral immune response over 12 months

Botulism is a neuroparalytic intoxication, usually fatal, caused by the botulinum toxins (BoNTs). Vaccination is the best-known strategy to prevent this disease in ruminants. Serotypes C and D and their variants CD and DC are the main types responsible for botulism in bovine and buffaloes in Brazil and cattle in Japan and Europe. Brazil has a herd of approximately 1.39 million buffaloes and is the largest producer in the Western world. This study aimed to assess the humoral immune response of buffaloes during the 12-month period after vaccination against BoNT serotypes C and D with a recombinant vaccine in three different concentrations (100, 200, and 400 μg) of non-purified recombinant proteins (Vrec) and also with a bivalent commercial toxoid (Vcom). Vrec400 was the best vaccine among those tested because it induced higher levels of antibodies and maintained higher levels of antibodies for the longest time, while Vrec200 could be considered the most cost-effective vaccine for large-scale production. None of the vaccines were able to promote continuous immunological protection within the timeframe proposed by the current Brazilian vaccination protocol. Further studies should focus on vaccine adjustments to ensure continued humoral protection against botulism.

Humoral Response of Buffaloes to a Recombinant Vaccine against Botulism Serotypes C and D

Botulism is a fatal intoxication caused by botulinum neurotoxins (BoNTs), which are mainly produced by Clostridium botulinum and characterized by flaccid paralysis. The BoNTs C and D are the main serotypes responsible for botulism in animals, including buffaloes. Botulism is one of the leading causes of death in adult ruminants in Brazil due to the high mortality rates, even though botulism in buffaloes is poorly reported and does not reflect the real economic impact of this disease in Brazilian herds. Vaccination is reported as the most important prophylactic measure for botulism control, although there are no specific vaccines commercially available for buffaloes in Brazil. This study aimed to evaluate the humoral immune response of buffalo groups vaccinated with three different concentrations of recombinant proteins (100, 200, and 400 µg) against BoNTs serotypes C and D as well as to compare the groups to each other and with a group vaccinated with a bivalent commercial toxoid. The recombinant vaccine with a concentration of 400 μg of proteins induced the highest titers among the tested vaccines and was proven to be the best choice among the formulations evaluated and should be considered as a potential vaccine against botulism in buffalo.