A major outbreak of hantavirus pulmonary syndrome caused by person-to-person transmission of Andes virus in Epuyén, Southwestern Argentina

ALONSO DANIEL; IGLESIAS AYELÉN; COELHO ROCIO; PERIOLO NATALIA,; BELLOMO CARLA; MARTINEZ VALERIA

Leuven,

Congreso; 11TH INTERNATIONAL CONFERENCE ON HANTAVIRUSES; 2019

Context: In 1995, 3 clustered cases of hantavirus pulmonary syndrome in the Andean region of Patagonia led to the characterization of Andes virus (ANDV) in Argentina, since then around 1200 cases have been reported in the country. Hantaviruses are enveloped single-stranded RNA viruses with tripartite negativesense genomes: S (small, 1.8-2.1kb), M (medium, 3.6-3.8kb), L (large, 6.5-6.7kb). They are maintained in nature by small mammals and humans usually become infected through inhalation of aerosolized excretaproduced by infected rodents. Among all hantaviruses known worldwide, ANDV is unique due to its ability to be transmitted from person-to-person.Objectives: The aim of this study was to analyze and compare complete viral genome sequences from a cluster of 3 cases reported in 2014 and suspected of person-to-person transmission from El Bolsón,Rio Negro.Methods: Two patients living in the same house began symptoms with a difference of 15-days from each other (P1, P2), and a third case (P3) who only performed medical assistance to one of those patients duringtheir prodromal phase. Not related cases were also included in the analysis. Next-generation sequencing techniques were used. RNA sequencing libraries were prepared and viral enrichment was performed by specific probes designed for ANDV. FASTQ files were analysed by in house pipelines for viral genomes. Nucleotide sequence analysis was performed with Mega 6 and BioEdit v7.0.5.3.Results: Viral genetic analysis showed that P1 presented 100% nucleotide identity in the complete S and M segments with P2 and P3, but 2 nucleotide changes were detected in the L segment (99.96% of nucleotide identity in the L segment, from which 84% could be sequenced). However, P2 and P3 showed100% nucleotide identity in the complete S, M and L segments.Conclusions: We could confirm person-to-person transmission among P2 and P3 (100% nucleotide identity). To accurately define if P2 was infected by co-exposure or by person-to-person transmission more complete genomes of ANDV are needed to accurately establish the nucleotide variation rate in person to person transmission chains and also within the natural rodent reservoir population. These will help to differentiate between rodent exposure and person-to-person transmission mechanism.