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Volume 32, Number 5—May 2026
Letter
Evidence of Rat Hepatitis E Virus Circulation through Wastewater Surveillance, Central Argentina
Suggested citation for this article
To the Editor: A recently published dispatch about rat hepatitis E virus (rHEV) detected high levels of rHEV in wastewater samples from Argentina (67.7%) (1). The study authors claimed their findings supported further investigation of the virus in animal reservoirs and humans, with a focus on hepatitis cases of unknown etiology.
rHEV is genetically distinct from conventional human-infecting hepatitis E virus (HEV; Paslahepevirus balayani) and is not detected by the PCRs that detect HEV RNA. A recent study in Spain detected an rHEV frequency of 1.4% among patients with hepatitis of unknown etiology (2). The rHEV spillover mechanism to humans is unclear.
We analyzed rHEV in wastewater samples from Toulouse, France, where HEV is endemic (HEV IgG seroprevalence 47.8%) (3). We collected 49 wastewater samples weekly during 2025 and tested the samples for rHEV by using a previously published protocol (4). However, we could not sequence the genomes because of low viral concentration. During 2023–2025, we tested 484 immunocompetent patients with a positive HEV IgM result by using Liaison (Diasorin, https://us.diasorin.com), to detect HEV IgM in patients with rHEV infection (5), and 578 immunocompromised patients living in the same area. We collected the samples at infection onset when the liver enzymes were elevated and RealStar HEV PCR Kit (Altona Diagnostics, https://altona-diagnostics.com) results were negative. None of the samples were positive for rHEV RNA.
The high detection rate of rHEV in wastewater reflecting high circulation in urban rodents contrasts with the rarity of human cases. This contrast could be linked to low exposure of humans to contaminated sources, low human infection capability of rHEV, or cross protection because of immunity conferred by HEV in Toulouse, where the seroprevalence is higher than in Spain, where rHEV human cases are more frequent (2). Future studies to evaluate rHEV-specific serologic response could be useful.
, Clément Castille, Nicolas Marter, Jean Luc Guerin, Sébastien Lhomme, and Jacques Izopet
References
- Filoni B, Lucero ME, Di Cola G, Fantilli A, Roccia A, Sicilia P, et al. Evidence of rat hepatitis E virus circulation through wastewater surveillance, central Argentina. Emerg Infect Dis. 2026;32:133–6. DOIPubMedGoogle Scholar
- Caballero-Gómez J, Casares-Jiménez M, Gallo-Marín M, Pereira-Pardo S, Beato-Benítez A, Poyato A, et al.; GEHEP-014 Study Group. Rat hepatitis E virus as an aetiological agent of acute hepatitis of unknown origin. J Hepatol. 2025;83:662–9. DOIPubMedGoogle Scholar
- Dimeglio C, El Rakaawi M, Boineau J, De Smet C, Abravanel F, Lhomme S, et al. Increase in HEV IgG seroprevalence during the past years in southern France. J Med Virol. 2025;97:
e70483 . DOIPubMedGoogle Scholar - Parraud D, Lhomme S, Péron JM, Da Silva I, Tavitian S, Kamar N, et al. Rat hepatitis E virus: presence in humans in south-western France? Front Med (Lausanne). 2021;8:
726363 . DOIPubMedGoogle Scholar - Fourgeaud J, Veyrenche N, Laloum I, Jais J-P, Roger C, Rabant M, et al. Occult rat hepatitis E virus infection as a cause of cirrhosis and posttransplant recurrence: insights into the role of metagenomics. Am J Transplant. 2026;S1600-6135(26):00007-9.
Suggested citation for this article: Abravanel F, Castille C, Marter N, Guerin JL, Lhomme S, Izopet J. Evidence of rat hepatitis E virus circulation through wastewater surveillance, central Argentina. Emerg Infect Dis. 2026 May [date cited]. https://doi.org/10.3201/eid3205.260304
Original Publication Date: April 27, 2026
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Table of Contents – Volume 32, Number 5—May 2026
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Please use the form below to submit correspondence to the authors or contact them at the following address:
Florence Abravanel, CHU Toulouse Purpan, 330 Avenue de Grande Bretagne, 31059 Toulouse CEDEX 9, France
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