Thesis defended at IB also identified six species of myxosporeans that had not yet been described
Doctoral thesis developed by biologist Patrick Mathews Delgado, defended at the Biology Institute (IB) at Unicamp, found for the first time the presence of myxosporidians in ornamental fish from the Amazon Basin. These parasites have great pathogenic potential and can cause serious illnesses in their hosts, some of them fatal. The work also identified six species of myxosporeans that had not yet been described in the literature.
The data generated by the study conducted by Mathews is important because the so-called “ornamental fish industry” generates billions of dollars worldwide and accounts for significant rates of employment and income generation for residents of riverside communities in the Amazon region. Furthermore, almost all production from Colombia, Peru and Brazil is exported to numerous countries. “Our study serves as a warning to public authorities about the risk that myxosporidians can pose to this economic activity. Some species of this group of parasites are capable of decimating fish populations in the natural environment and in cultivation”, warns the biologist.
Another problem, continues the author of the thesis, is that the export of fish infected by parasites could favor the spread of these organisms around the world, which could pose a risk to the environment, notably the fauna of other countries. “Our study focused on ornamental fish. However, myxosporidians can also parasitize fish species of food importance, as well as birds and small vertebrates. I think that the greatest contribution of the work is to draw attention to the problem and the need to develop new research that can support actions to prevent and control the circulation of these parasites”, understands Mathews.
Currently, the researcher reports, more than 2.300 species of myxosporeans are known, the vast majority of which parasitize fish in the natural environment or in fish farms. However, no previous study had found the presence of these organisms in ornamental fish from the Amazon Basin. “To carry out the investigation, we collected fish from rivers in the Brazilian and Peruvian Amazon. We noted the presence of myxosporidians in several specimens, from different species. An important fact is that parasites can lodge in different organs of their hosts. With the pathogenic potential of these organisms, they can cause a series of complications, including inflammation, hemorrhage and even tissue necrosis”, he points out.
According to the biologist, science has a lot to discover about this group of organisms. However, it is already known that they can also infect people and cause negative impacts on human health. “People can be infected by myxosporides when consuming, for example, raw fish. These organisms can be especially harmful to people who have low immunity. In the literature, some studies indicate that these parasites can cause problems for people with the HIV virus. Therefore, the possible pathogenic role of myxosporidians still needs to be elucidated”, says Mathews.
Still regarding the risk of spreading parasites, the researcher understands that Brazil should not only worry about external issues. “We also have to pay attention to the internal sphere. Amazonian ornamental fish are distributed to several states in the country. Therefore, it is necessary to define a strategy to prevent the introduction of these organisms into the environment. This can even occur unintentionally, when the water used in fish farming is released into natural bodies or when a person who is an aquarist gets tired of this activity and decides to discard their fish in a river or lake close to home. A fundamental step to prevent this from happening is to inform people that ornamental fish can be contaminated with these parasites and that they need to be very careful with the destination that will be given to these animals”, he reinforces.
The study, continues Mathews, also concluded that, depending on the species, myxosporidians have different strategies through which they obtain nutrients necessary for their development and that the parasites tend to group together according to infection sites, host affinity and Geographical area. The research has already yielded seven scientific articles, six of which have already been published by important scientific journals and one has been submitted. Part of the study, which was financed by the São Paulo Research Foundation (Fapesp), was developed at Oregon State University, in the United States, where the biologist analyzed the genetic components involved in the pattern of infection caused by myxosporidians.
