A change in the timing of the Bacillus Calmette-Guérin vaccination in 2013 was associated with an increase in the incidence rate of infants with latent tuberculosis infection

BACKGROUND

A change in the timing of the Bacillus Calmette-Guérin (BCG) vaccination among infants in Japan appears to be associated with an increase in the incidence rate of latent tuberculosis infection (LTBI).

METHODS

Data on both active and latent tuberculosis (TB) infections from 2007 to 2019, which were reported by the Japan Anti-Tuberculosis Association, were statistically analyzed by comparing TB incidence rates in 2007-2012 and 2013-2019.

RESULTS

Although the incidence rate for active TB disease did not statistically increase nor decrease in the infant age group for either sex (and in fact decreased for some of the other age groups), the incidence rates of LTBI for both sexes were increased in the infant age group, while the incidence rates decreased in the other age groups. Between 2007 and 2012, the incidence rate of LTBI in females was statistically greater than those of males in the 1-4-year-old age group. From 2013 to 2019, the incidence rates of females were greater than those of males in both the infant and 1-4-year-old age groups, suggesting a growing preponderance of infections among female children in the youngest age groups.

CONCLUSION

It may be that the change of BCG vaccination timing in Japan which took place in 2013 affected the infant incidence rate of LTBI, with a more prominent effect on females than males. In order to control TB infection, the ramifications of a change in vaccination timing therefore need careful exploration, as one such change appears associated with increased numbers of infants with LTBI, with disproportionate effects on females.

Sex- and age-related differences in morbidity rates of 2009 pandemic influenza A H1N1 virus of swine origin in Japan

BACKGROUND

The objective of the present study was to determine whether the morbidity rates of the 2009 pandemic influenza A H1N1 virus (pdmH1N1) varied by age and/or sex.

METHODS AND FINDINGS

Retrospective analysis of 2,024,367 cases of pdmH1N1 was performed using the national surveillance data from influenza sentinel points in Japan. The male-to-female morbidity ratios (M/F ratios) in nineteen age groups were estimated as the primary outcome. The M/F ratios for pdmH1N1 influenza were: >1 in age groups <20 years and ≥80 years (p<0.001); <1 in age groups 20-79 years (p<0.001). This data suggests that males <20 years of age may be more likely to suffer from pdmH1N1 influenza than females in the same age categories. When the infection pattern for pdmH1N1 was compared with that of seasonal influenza outbreaks between 2000 and 2008, the M/F ratio for pdmH1N1 influenza was higher in ages 3-29 years and lower in ages 40-79 years. Because the present study was based on the national surveillance, it was impossible to estimate the morbidity rate for the Japanese population. It is also likely that the data did not capture asymptomatic or mild infections.

CONCLUSIONS

Although exposure to the pdmH1N1 virus is assumed to be similar in both boys and girls, M/F ratios were >1 in those younger than 20 years. The subsequent reversal of the M/F ratio in the adult generation could be due to several possibilities, including: greater immunity among adult males, more asymptomatic infections among males, less reporting of illness by males, or differences in exposure to the virus and probability of visiting a clinic. These results suggest that the infection and virulence patterns of pdmH1N1 are more complex than previously considered.

Age and gender specific prevalence of HTLV-1

BACKGROUND

The seroprevalence of Human T-cell Leukemia Virus Type 1 (HTLV-1) is female predominant despite the higher incidence of Adult T-cell Leukemia (ATL) in males. If the mother-to-child transmission of HTLV-1 is more common for male infants than in female infants, longer exposure to the virus for males may explain the paradoxically higher incidence of ATL.

OBJECTIVES

To test the hypothesis that the seroprevalence of HTLV-1 is male predominant during adolescence.

STUDY DESIGN

The presence of HTLV-1 antibody in 272,043 blood samples donated to a regional blood bank in an HTLV-1 high-endemic region was assessed.

RESULTS

The entire population of female donors had a significantly higher seroprevalence compared to males (2.05% and 1.80%, respectively, p<0.0001). However, compared with male donors, the carrier rate for female donors was lower for the youngest subgroup (16-19 years, p=0.0011); was similar for the next two age subgroups (20-29 years and 30-39 years); and was significantly higher for the last two age subgroups (40-49 years and over 50-64 years, both p<0.0001). In general, older age subgroups led to higher seroprevalence in both genders.

CONCLUSIONS

HTLV-1 infection is more common for males until after age 20, when male to female sexual transmission becomes likely. This suggests that mother-to-child transmission is more common for males.

[A questionnaire survey on daily medical care problems at special schools for severely neurologically impaired students in southern Fukuoka prefecture]

With increasing numbers of children having severe motor and intellectual disabilities, there is growing demand for daily medical care such as tube feeding and sputum suctioning in special schools. We devised a questionnaire survey for special school teachers investigating the need for daily medical care in four schools in southern Fukuoka prefecture. One-hundred fifty-two out of 633 (24%) students needed medical care; specifically, 38 of 152 (25%) needed tube feeding and 41 of 152 (27%) required sputum suctioning. Such patients lived in their houses, hospitals or medical centers for the severely disabled. Mothers whose children commuted from home had to go to school themselves to provide medical care for their children, such as sputum suctioning. School teachers were worried about their students' feeding difficulties and respiratory disorders. More support for teachers to care for students is needed and provision of medical care under supervision of school nurses and doctors should be promoted.

Population dynamics of HTLV-I infection: a discrete-time mathematical epidemic model approach

Human T-cell Leukaemia Virus Type I (HTLV-I) is a retrovirus that causes Adult T-cell Leukaemia (ATL). The transmission routes of HTLV-I are (i) from infected mothers to their newborn babies, (ii) from infected males (husbands) to females (their wives) by long-term sexual intercourse, and (iii) from infected females (wives) to males (their husbands). Eshima et al. (2001) analysed a continuous-time HTLV-I model with no age structure in the population. In this paper, we consider the population dynamics of HTLV-I infection in a discrete-time mathematical model incorporating an age structure. The necessary and sufficient condition for the extinction of HTLV-I is derived from the mathematical model. A simulation of the HTLV-I infection based on the model demonstrates a rapid reduction of the HTLV-I infection proportion in Japan.

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.