Roxana Loayza Mafayle, Maria E. Morales-Betoulle, Carla Romero, Caitlin M. Cossaboom, Shannon Whitmer, Carlos E. Alvarez Aguilera, Cinthia Avila Ardaya, Mirian Cruz Zambrana, Andrés Dávalos Anajia, Nelly Mendoza Loayza, Ana-Maria Montaño, Fernando L. Morales Alvis, Jimmy Revollo Guzmán, Sebastián Sasías Martínez, Gricel Alarcón De La Vega, Armando Medina Ramírez, Jhemis T. Molina Gutiérrez, Alex J. Cornejo Pinto, Renata Salas Bacci, Julia Brignone, Jorge Garcia, Arletta Añez, Jairo Mendez-Rico, Kleber Luz, Ariel Segales, Karen M. Torrez Cruz, Adolfo Valdivia-Cayoja, Brian R. Amman, Mary J. Choi, Bobbie-Rae Erickson, Cynthia Goldsmith, James C. Graziano, Allison Joyce, John D. Klena, Austin Leach, Jason H. Malenfant, Stuart T. Nichol, Ketan Patel, Tara Sealy, Trevor Shoemaker, Christina F. Spiropoulou, Alison Todres, Jonathan S. Towner, and Joel M. Montgomery
BACKGROUND: In June 2019, the Bolivian Ministry of Health reported a cluster of cases of hemorrhagic fever that started in the municipality of Caranavi and expanded to La Paz. The cause of these cases was unknown. METHODS: We obtained samples for next-generation sequencing and virus isolation. Human and rodent specimens were tested by means of virus-specific real-time quantitative reverse-transcriptase–polymerase-chain-reaction assays, next-generation sequencing, and virus isolation. RESULTS: Nine cases of hemorrhagic fever were identified; four of the patients with this illness died. The etiologic agent was identified as Mammarenavirus Chapare mammarenavirus, or Chapare virus (CHAPV), which causes Chapare hemorrhagic fever (CHHF). Probable nosocomial transmission among health care workers was identified. Some patients with CHHF had neurologic manifestations, and those who survived had a prolonged recovery period. CHAPV RNA was detected in a variety of human body fluids (including blood; urine; nasopharyngeal, oropharyngeal, and bronchoalveolar-lavage fluid; conjunctiva; and semen) and in specimens obtained from captured small-eared pygmy rice rats (Oligoryzomys microtis). In survivors of CHHF, viral RNA was detected up to 170 days after symptom onset; CHAPV was isolated from a semen sample obtained 86 days after symptom onset. CONCLUSIONS: M. Chapare mammarenavirus was identified as the etiologic agent of CHHF. Both spillover from a zoonotic reservoir and possible person-to-person transmission were identified. This virus was detected in a rodent species, O. microtis. (Funded by the Bolivian Ministry of Health and others.)