Strange new bacteria found in Amazon sand flies. Could it spread to humans?

There is currently no evidence in Brazil that this new species of bacteria can cause disease. However, since species of the genus Bartonella are responsible for several diseases in other countries, further studies are needed.

The research was conducted by Marcos Rogério André in partnership with Eunice Aparecida Bianchi Galati. Both researchers are affiliated with Brazilian institutions: the Faculty of Agricultural and Veterinary Sciences of São Paulo State University (FCAV-UNESP) in Jaboticabal campus and the School of Public Health of the University of São Paulo (FSP-USP). The study was supported by FAPESP through two projects (22/08543-2 and 22/16085-4).

It was published in the scientific journal Acta Tropica and included the participation of researchers Paulo Vitor Cadina Arantes, Israel de Souza Pinto, Daniel Antônio Braga Lee, Anna Cláudia Baumel Mongruel, and Rosângela Zacarias Machado.

What is the disease?

Bartonellosis is a term that refers to a group of diseases caused by bacteria of the genus Bartonella. These bacteria are transmitted by various vectors. In addition to sand flies, they can be transmitted by fleas and lice.

Symptoms usually include infections that take a long time to clear up in both humans and animals. These bacteria can remain in the body for a long time without being detected and end up harming patients with preexisting immune problems.

“Bartonellosis is a neglected disease. The disease best known to health professionals is cat scratch disease, caused by Bartonella henselae. It’s important to understand the real prevalence of these diseases, especially in isolated regions with low human development indices, where populations don’t have easy access to health services,” explains André.

The objective of the study was to investigate the presence of Bartonella spp. DNA in 297 specimens of female sand flies (Diptera: Psychodidae) collected in the Amazon National Park in the state of Pará. “This park has caves and receives many visitors, so it’s important to study it,” says the researcher.

The phlebotomine sand flies were collected between February 2022 and February 2023. Every month, the researchers collected samples along two trails near the banks of the Uruá and Tracoá rivers, which are located within the conservation unit.

“The discovery of Bartonella species in phlebotomine sand flies here in Brazil may indicate that B. bacilliformis and B. ancashensis, which cause Carrión’s disease or Peruvian wart, can adapt to non-Andean species and be transmitted in areas outside the Andes. This isn’t too much of an extrapolation, as two species that have been identified as vectors of B. bacilliformis, Pintomyia robusta and Pintomyia maranonensis in Peru, are very similar to species found in Brazil, namely Pintomyia serrana and Pintomyia nevesi,” explains Galati.

In recent years, the group has been studying the diversity of bacteria found in this genus and the diseases they cause in both humans and animals. According to the scientists, the sequences found in the Amazon differ from those found in Peru; however, the results corroborate data collected in a previous study.

According to André, this second article by the research group confirms evidence found in previous studies, such as the discovery of new species of Bartonella in Acre, another Brazilian state in the Amazon region. Therefore, they decided to expand the investigation and analyze samples from Pará and other locations.

“We’re detecting a strain here in Brazil that’s never been described and is very similar to two species of the Bartonella genus that cause disease in Andean countries. Despite this similarity, we don’t yet have information on whether it can cause disease with distinct symptoms. That’s why we need to study them further,” the professor points out.

To continue mapping the insects and the bacteria with which they may be infected, the researchers are collecting samples in various biomes.

“The next steps are to continue investigations involving more populations of phlebotomine sand flies and other diptera from different biomes in search of these strains, as well as to look for other strains,” says Galati.

According to the researcher, the next step would be to investigate what animals these insects feed on to find “reservoirs.”

“I have a project funded by FAPESP in which I was able to store many specimens of phlebotomine sand flies from the Atlantic Forest of São Paulo, and the idea is to explore this material in partnership with Professor André,” reveals Galati.

Although the results are preliminary, the project has helped the researchers uncover the possibility of finding disease agents that had not yet been detected.

According to André, since this is a new finding, it would be beneficial for doctors and researchers to collaborate on investigating this group of bacteria in individuals with fever of unknown origin.

“Could people with fever who are often sent home and who have repeated episodes of fever be infected with this pathogen? Could patients with Leishmania also be co-infected with this new species of Bartonella?” asks the professor.