The risk of development of HTLV-I-associated myelopathy/tropical spastic paraparesis among persons infected with HTLV-I.
Using data obtained in national surveys of human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) conducted in Japan in 1987 and 1988, we estimated the yearly and lifetime risk that HAM/TSP will develop in an HTLV-I-infected person. "Definite" HAM/TSP was defined as slowly progressive myelopathy with antibodies to HTLV-I in both serum and cerebrospinal fluid. Estimates of HTLV-I infection rates in eight endemic prefectures, by age group and sex, were obtained from serologic studies of blood donors; population figures, by age group, sex, and prefecture, were obtained from the census. Of 589 definite cases of HAM/TSP reported nationally, 397 occurred in residents of the eight endemic prefectures; of these, 170 reported onset of illness during the years 1982-1988 (average incidence, 24.3 cases/year). Using the estimated HTLV-I infection rates and the 1985 census figures, we estimated the number of HTLV-I-infected persons in the eight prefectures in 1985 at 794,800. We therefore estimated the incidence of HAM/TSP among HTLV-I-infected persons at 3.1 x 10(-5) cases/year; assuming a lifetime of 75 years, the lifetime incidence is approximately one quarter of 1%. This estimate is important in counseling persons such as blood donors found to be infected with HTLV-I.
Kaplan
J E
JE
Division of Viral and Rickettsial Diseases, Centers for Disease Control, U.S. Department of Health and Human Services, Atlanta, Georgia 30333.
Osame
M
M
Kubota
H
H
Igata
A
A
Nishitani
H
H
Maeda
Y
Y
Khabbaz
R F
RF
Janssen
R S
RS
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D015528:HIV Seroprevalence; D015490:HTLV-I Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015493:Paraparesis, Tropical Spastic / Q000150:complications / Q000453:epidemiology*; D012307:Risk Factors