Investigation of bacterial agents (Mycobacterium spp. and Francisella spp.) Causing granulomatous diseases in commercial freshwater and marine fish farms in southeastern Brazil

• Grant number: 18/13393-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2019
• End date: October 31, 2021
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Alessandra Figueiredo de Castro Nassar
• Grantee: Luara Lucena Cassiano
• Host Institution: Instituto Biológico (IB). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

It is estimated that Brazil should record a growth of 104% in fishing and aquaculture production in 2025. The increase in Brazilian production will be the highest recorded in the region, followed by Mexico (54.2%) and Argentina (53.9%) over the next decade. Globally, production is expected to grow to 195.9 million tons by 2025. Studies indicate that this commodity is one of the highest risk associated with its consumption considering the diversity of related pathogens (bacteria, viruses, parasites, chemicals and toxins), many of these zoonoses. In aquaculture, bacteria have caused large losses in production by killing infected animals. The main agents of emerging diseases are: Mycobacterium marinum, M. fortuitum and M. chelonae, called mycobacterioses or fish tuberculosis, wild or captive. The severity of infection varies from chronic, without major tissue changes in which few fish die to severe and acute infections with high mortality. Francisella spp. It is also an emerging bacterial pathogen that causes acute and / or chronic disease in fish, cultivated and wild, with hot and cold weather, and is associated with massive mortalities in commercial crops. The objective of this work is to develop histological techniques for the identification of granulomas, immunohistochemistry, in situ hybridization, negative staining, immunoblotting and immunoadhesion with colloidal gold, microbiological culture, PCR and molecular typing to identify the agents in tissue samples from commercial fish farms. Thus, to know the extent of the presence of the disease in Brazilian Aquaculture and its distribution and, thus, to establish methods for the diagnosis of these diseases. (AU)