Analysis of the infection system of human T-cell leukaemia virus type I based on a mathematical epidemic model.

Human T-cell leukaemia virus type I (HTLV-I) is a retrovirus that causes adult T-cell leukaemia (ATL). HTLV-I has existed in Japanese people for thousands of years. In order to prevent an epidemic of HTLV-I, it is important to explain the infection system by a mathematical approach. By considering the main infection routes in Japan, that is: (i) mother-to-child transmission; (ii) male (husband)-to-female (wife) transmission; and (iii) female (wife)-to-male (husband) transmission, a mathematical model for describing the time-dependent change of the infection proportion can be constructed. An upper bound of the present infection rate per year in male-to-female transmission and that in female-to-male transmission is given by the model, and theoretical results related to HTLV-I infection are also deduced from the mathematical model. A simulation study based on the present model demonstrates the theoretical results relating to the HTLV-I infection.

Chromosomal abnormalities in a selected population in Kurume.

Chromosomal aberrations were evaluated between 1974 and 1987 in 1077 individuals, consisting of 1042 pediatric patients and 35 adults who visited Kurume University Medical Center. Chromosomal aberrations were detected in 187 out of the 1042 (18%) children. These 187 children exhibited at least 108 types of symptoms or syndromes which were suggestive of chromosomal aberrations. Chromosomal aberrations were suspected in 757 pediatric patients who presented with 22 types of symptoms or syndromes. Among these 757, a total of 187 patients with chromosomal aberrations were identified, resulting in an overall incidence of 24.7% (187/757). Autosomal aberrations were demonstrated in 150 out of 672 children in whom autosomal aberrations had been suspected, yielding a detection ratio of 22.3% (150/672), whereas sex chromosome aberrations were found in 37 patients out of 85 who were suspected of possible sex chromosome aberrations, with a detection rate of 43.5% (37/85). The detection rate of chromosome aberrations was almost 20 to 30 times higher than that in the random surveys carried out by others in general newborn populations. This high detection rate suggests that a high incidence of chromosomal aberrations may be encountered in medical centers to which patients at risk with respect to chromosomal aberration syndromes are referred by local physicians. Chromosomes were analyzed also in a total of 37 adults, consisting of 26 women and 9 men, who had had abortions. The age at which abortions had occurred ranged from 23 to 39 years in women, and 25 to 35 years in men, respectively. Twelve women and 6 men out of the 35 people exhibited normal karyotypes. The satellite associations of D group and G group chromosomes were observed in 15 out of the 35 people.