Widespread genetic exchange in disease-causing parasites revealed

Mississippi State University biologist Matthew W. Brown is part of an international research team whose latest findings, published this spring in the Proceedings of the National Academy of Sciences, are reshaping scientific understanding of how parasitic organisms evolve and ultimately spread disease.

New insights into parasitic evolution

Focusing on the protistan parasite Leishmania, a genus of trypanosomatids that is spread globally through insect bites, the study provides critical insight for developing more effective interventions and treatments of parasitical infections.

Brown, the Donald L. Hall Professor of Biology in MSU’s Department of Biological Sciences, contributed to the study’s genetic analyses and interpretation of evolutionary patterns.

“Understanding how these parasites exchange genetic material fundamentally changes how we think about their evolution and adaptability,” Brown said. “This work shows these parasitic organisms readily exchange genetic material—it’s actually a dominant force shaping these organisms, with real implications for disease dynamics and control strategies worldwide.”

The study, “Extensive heterozygosity and genetic exchange among natural populations of Leishmania species,” challenges longstanding assumptions that Leishmania populations reproduce primarily through clonal, or asexual, expansion. Instead, researchers found more than 70% of sampled parasite isolates showed evidence of genetic mixing, indicating sexual reproduction and hybridization play a major role in their evolution.

Building on a track record of discovery

This latest publication builds on Brown’s broader body of work exploring how complex organisms evolved from microbial ancestors.

Last fall, Brown was part of a different international team whose groundbreaking discovery was published in Nature, identifying a new organism, Solarion arienae, and establishing a new phylum and previously unrecognized eukaryotic supergroup. That work provided new insight into the earliest stages of complex life on Earth.