Diagnostic and Phylogenetic Insights into a Human Rabies Virus Isolate from Romania

Area of Science:

• * Virology
• * Epidemiology
• * Public Health

Background:

• * Rabies is a fatal zoonotic disease with sporadic human cases in Europe despite control programs.
• * A fatal autochthonous human rabies case occurred in Romania in 2025 after a dog bite, with no post-exposure prophylaxis administered.
• * This highlights the continued risk of rabies transmission in the region.

Purpose of the Study:

• * To perform the first molecular characterization of a human rabies virus (RABV) strain from Romania.
• * To analyze the genetic relationship between the human RABV strain and contemporary animal-derived RABV strains in northern Romania.
• * To assess the origin and transmission dynamics of the human rabies case.

Main Methods:

• * Rabies virus infection confirmed using fluorescent antibody testing and RT-PCR on patient samples (CSF, saliva, skin, brain).
• * Whole-genome sequencing of the human RABV isolate and 22 animal-derived RABV strains from northern Romania (2025).
• * Phylogenetic analysis to determine genetic relationships and geographic clustering.

Main Results:

• * All recent Romanian RABV sequences, including the human isolate, clustered within the North-East European (NEE) phylogenetic group.
• * Sequences segregated into two distinct clusters: a north-western cluster (related to Slovakia/Poland) and a larger north-eastern cluster.
• * The human RABV strain belonged to the north-eastern cluster, showing high genetic similarity to local animal strains, indicating local transmission.

Conclusions:

• * The human rabies case in Romania resulted from local transmission of RABV from an animal source.
• * Phylogenetic analysis of viral genomes is crucial for understanding rabies transmission patterns.
• * Integrating human viral genomic data into national surveillance frameworks is essential for effective rabies control.