Sequence analysis of coltivirus genomes has shown that segment 6 of viral protein 6 (VP6) of CTFV is homologous to segment 7 (VP7) of EYAV (Figure 3).
Antigenic variation between CTFV strains is low, especially between strains from humans (21).
The genome of CTFV contains 29,174 nucleotides, and that of EYAV contains 29,210 nucleotides (18).
The antigenic and genetic relationships between CTFV and EYAV are further corroborated by their identical morphologic features, as analyzed by electron microscopy (8).
Infection of humans with CTFV is characterized by abrupt onset of fever, chills, headache, retroorbital pain, photophobia, myalgia, abdominal pain, and generalized malaise.
The incidence of complications in different reports of infection with CTFV has been reported as [less than or equal to] 7% (23-26).
CTFV infections have been confused with other tickbome diseases such as Rocky Mountain spotted fever (a rickettsial disease), tularemia, relapsing fever, and Lyme disease.
CTFV can be isolated from blood because it is present in circulating erythrocytes for as long as 4 months (28), and it infects the hematopoietic progenitor cells and remains sheltered in erythrocytes after maturation.
An ELISA based on recombinant VP7 and a Western blot based on synthetic VP12 showed good sensitivity in detecting antibodies to CTFV (29,30).