[Epidemiological study of healthy carriers of Australia antigen. Analysis of contagiousness, and mechanism of spread of the infection (author's transl)]. / Estudio epidemiológico de los portadores sanos de antíaeno Australia. Análisis de su infecto-contagiosidad y mecanismo de aparición de nuevos casos.

Epidemiological studies in healthy carriers of HB Ag show variable results that might depend on the geographical area, ethnic group, and socio-economic level analyzed. For that reason an study was undertaken in the Spanish population with the purpose of analysing contagiousness of healthy carriers and mechanism of spread of the infection. The incidence of HB Ag and HB Ab was determined by radioimmunoassay in 211 relatives of 76 healthy carriers; all members of the family could be studied in 51 cases. The results were compared to those of a sizeable sample of the normal population. The overall incidence of HB Ag (13.1 %), and of HB Ab (18.9 %) in the probands was significantly higher than in the normal population (0.8 %, and 9 %, respectively). The distribution of new cases of HB Ag positivity in the 51 families in which the members could be studied demonstrated a significantly higher frequency in children of a carrier mother (28.9 %) than in those of a carrier father (10.8 %). In conclusion, the contagiousness of healthy carriers for their families can not be disregarded. It is likely that the mechanism of spread of the infection depends on a multifactorial inheritance of the genetic alteration of the selective immunologic response to the HB Ag, compounded by environmental factors.

[Persistent and asymptomatic carriers of Australia antigen. A method for the evaluation of big series (author's transl)]. / Portadores persistentes y asintomáticos de antígeno Australia. Sistemática para la valoración de series amplias.

The existence of an increasing number of apparently healthy carriers of the HBsAg demands a specific assisting attitude which must be highly reliable without increasing health care expenses. With that purpose, 129 asymptomatic carriers without prior history of jaundice and/or alcohol abuse were studied. The following discriminant criteria were used: hepatomegaly, other physical evidence of liver disease, hypertransaminasemia, and sulfobromophthalein retention. The carrier was defined as healthy after two consecutive examinations disclosing no abnormalities at intervals of six months, which occurred in 108 patients (84 %). No patient underwent liver biopsy, but the examination was still normal after two years in all cases. The presence of one or more abnormal findings was an indication for liver biopsy in 21 patients (16 %), and the procedure was accepted by 11 (52 %). The efficiency of the selection method was evaluated according to the histologic findings. The most useful criteria were hypertransaminasemia and sulfobromophthalein retention, in this order.