In the epidemiological study on hepatitis B antigen (HB Ag) in family, members of 22 HB Ag positive families were examined for HBs Ag and HBs antibody (HBs Ab) during the period from 1970 to 1975. Each case was bled once a year and serum was tested for the presence of HBs Ag by IAHA and HBs Ab by PHA.
In 1975, the positive rates of HBs Ag and HBs Ab in general population of Iriomote were 1.6%(3 of 183) and 35.5%(65. out of 183) respectively. HBs Ag and HBs Ab were detected in 26 (28.6%) and 54 (59.3%) out of 91 cases in 22 HBs Ag positive families.
Eighty nine cases of the 22 families were followed for 2-6 years. In the course of this series, the presence of HBs Ag and HBs Ab and its course were tested in 93 occasions. Antigenemia persisted in 19 cases in which 16 were under 19 years old and HBs Ag disappeared in 5 cases and 3 of them were under 9 years. HBs Ab appeared in 23 cases and 19 cases were remained negative for both HBs Ag and HBs Ab throughout the study.
In 2 families (K and U) in which parents were HBs Ag negative and most of siblings were positive (6/8 in K and 8/10 in U), 2 children (2 years old female and 3 years old male) were shown to become positive for HBs Ag during the period of observation. In contrast, no spread of HBs Ag from healthy carriers in class or school was observed in 2 primary and 2 middle schools in the island.
It was noted that both HBs Ag and HBs Ab negative members of HBs Ag positive family acquired HBs Ag and/or HBs Ab in younger age than in the other general population.
The results obtained suggest that transmissions of HBs Ag tend to occur in younger age in children in carriers in HBs Ag positive family by not only maternal route but also horizontal route among family members. Close contact within family may play an important role in spread of HBs Ag from healthy carriers.

View full abstract

Persistent infection with Mycoplasma (M) in the brains and the respiratory tracts of mice was described. The summarized data are as follows.
1. All the dd mice tested had been supplied in apparently healthy condition from commercial breeders in Tokyo. The, mice collected by this route would usually be contaminated with M sofar.
In total, 126 strains of M. pulmonis and 27 of M. neurolyticum were isolated. M was isolated from 34.3% of the brains, 100% of the nasal washings, 50.7% of the tracheas and 24.6% of the lungs of the 73 mice tested.
2. Intranasal inoculation experiments with M. pulmonis strain m53 were carried out in 80 germ free ICR mice. Apparent infections with clinical signs and gross pulmonary lesions had developed in 3-7 days after inoculation. Sequential titrations of the M in each organ were performed in the period of 3 days to 16 weeks after inoculation. The titers of M in mice tissues reached the maximum in 2-3, week and then decreased and stayed as high as approximately 104-5 CFU per g in all the tissues tested.

View full abstract