At a Glance
- Researchers discovered DNA from Bartonella bacteria in 12.6% of non-engorged female sand flies collected in Brazil’s Amazon National Park, marking the first time this has been observed in seven of these fly species.
- The newly found bacterial genotypes are genetically similar to Bartonella bacilliformis and Bartonella ancashensis, which are known to cause the human illness Carrión’s disease in the Andes.
- This finding suggests that relatives of disease-causing bacteria could be adapting to new sand fly species and environments outside of their traditionally known regions, posing a potential new health risk.
- Although there is currently no evidence that this newly detected bacterial strain can cause disease in Brazil, its presence in blood-sucking insects warrants further investigation into public health implications.
- Future research will focus on expanding the search to other Brazilian biomes, identifying animal reservoirs, and investigating potential co-infections in humans with unexplained fevers or leishmaniasis.
Researchers have discovered DNA from a novel type of Bartonella bacteria in sand flies within Brazil’s Amazon National Park, raising questions about potential new disease risks in the region. The study, published in the journal Acta Tropica, found that 12.6% of the tested female sand flies carried the bacteria. Bartonella is a genus of bacteria responsible for a group of infectious diseases known as bartonellosis, which are often transmitted by blood-sucking insects like fleas, lice, and sand flies. While many Bartonella infections are known, such as cat scratch disease, this specific discovery in the Amazon is new to science.
The significance of the finding lies in the new bacteria’s genetic similarity to two other species, B. bacilliformis and B. ancashensis. These related bacteria are known to cause Carrión’s disease, a serious illness found in the Andean regions of South America that presents as Oroya fever or Peruvian warts. Because sand flies also transmit Carrión’s disease, scientists are concerned that this newly detected Amazonian strain could potentially adapt and spread outside its currently known boundaries. “The discovery…may indicate that B. bacilliformis and B. ancashensis…can adapt to non-Andean species and be transmitted in areas outside the Andes,” explained researcher Eunice Aparecida Bianchi Galati in a São Paulo Research Foundation (FAPESP, Portuguese: Fundação de Amparo à Pesquisa do Estado de São Paulo) press release.
The scientific team, led by researchers from São Paulo State University and the University of São Paulo, collected 297 female sand flies from the national park in Pará state between 2022 and 2023. By using molecular techniques like quantitative real-time PCR, they analyzed the insects for bacterial DNA. The investigation specifically targeted non-engorged flies—those that had not recently fed—to ensure that the detected DNA represented an active infection within the insect rather than lingering in a recent blood meal. The DNA sequences found in the flies were closely related to those of the Andean pathogens, confirming the existence of a new and distinct bacterial lineage.
While there is currently no evidence that this new Bartonella strain causes disease in humans, the researchers emphasize the need for further study. Bartonellosis is often a neglected disease that can cause persistent infections, particularly in individuals with weakened immune systems. The next steps for the research team include collecting more samples from different Brazilian biomes, identifying the animals these sand flies feed on to locate potential “reservoirs” of the bacteria, and encouraging doctors to consider bartonellosis when diagnosing patients with fevers of unknown origin.
References
- Arantes, P. V. C., Pinto, I. D. S., Lee, D. A. B., Mongruel, A. C. B., Galati, E. A. B., Machado, R. Z., & André, M. R. (2025). Molecular evidence of Bartonella spp. in sand flies (Diptera: Psychodidae) from the Brazilian Amazon. Acta Tropica, 267, 107682. https://doi.org/10.1016/j.actatropica.2025.107682
- FAPESP. (2025, August 27). Bacterium discovered in the Amazon is closely related to Andean species that causes human bartonellosis. Phys.Org; FAPESP. https://phys.org/news/2025-08-bacterium-amazon-andean-species-human.html
