Reoviruses: Colorado Tick Fever Virus and Other Vector-Borne Reoviruses

Increase in Colorado Tick Fever Virus Disease Cases and Effect of COVID-19 Pandemic on Behaviors and Testing Practices, Montana, 2020

“…Unlike most domestic arthropodborne viruses, CTF virus infection is characterized by a sustained viremic period caused by infection of hematopoietic progenitor cells and delayed antibody response ( 12 ). CTF viral RNA can usually be detected by RT-PCR during the first 2 weeks of illness and for up to 6 weeks after illness onset ( 1 , 7 , 12 ). CTF virus–specific antibodies are undetectable in >50% of patients at 2 weeks after illness onset, but neutralizing antibodies are detectable in >90% of patients by 4 weeks after illness onset ( 1 , 7 , 11 , 16 ).…”

“…CTF viral RNA can usually be detected by RT-PCR during the first 2 weeks of illness and for up to 6 weeks after illness onset ( 1 , 7 , 12 ). CTF virus–specific antibodies are undetectable in >50% of patients at 2 weeks after illness onset, but neutralizing antibodies are detectable in >90% of patients by 4 weeks after illness onset ( 1 , 7 , 11 , 16 ). Therefore, RT-PCR testing is recommended for acute-phase specimens (collected <14 days after symptom onset), and serologic testing (e.g., IFA or PRNT) is recommended for specimens collected > 2 weeks symptom onset ( 11 , 12 , 18 ).…”

“…Colorado tick fever (CTF) virus is a coltivirus in the family Reoviridae ( 1 ). The primary vector for CTF virus is the Rocky Mountain wood tick ( Dermacentor andersoni ), which is found at elevations of 4,000–10,000 feet in the western United States and Canada ( 2 , 3 ).…”