THE BRAZILIAN EXPERIENCE IN PREVENTION OF TUBERCULOSIS WITH A CONCURRENT METHOD OF BCG VACCINATION

摘要

The BCG-Moreau Strain, which has been experimentally studied and used in the vaccination against tuberculosis in Brazil for 30 years, is tolerated so well by human beings that it can be given orally in repeated high doses to individuals in any allergic condition, inclusive of tuberculosis, without any inconvenience and without the glandular enlargements produced by administration of the other BCG strains by mouth.When the BCG-Moreau vaccine is prepared from 10-day cultures and its vitality is properly preserved, a single dose of 100 mg to newborn infants and 200 mg to other individuals with negative tuberculin tests confers cutaneous tuberculin allergy in more than 97% of the cases; so, the oral dose is equivalent to the parenteral methods of BCG vaccination as to the postvaccinal allergization.The protection so conferred against active tuberculosis reduces mortality and morbidity from tuberculosis to levels six and eight times lower.The fortnightly or monthly repetition of such doses until reaching a total of 600 mg (newborns) or 1200 mg (other individuals), i.e., the concurrent BCG vaccination, does not produce lymphadenitis, and generally makes the post vaccinal tuberculin allergy disappear; but the specific protection conferred by the single dose against the forms of the virulent tuberculosis is brought to a maximum by it.The inhibitory effects of the concurrent BCG vaccination can be also observed in patients who continue to be exposed to contagion; these present very low morbidity and mortality from tuberculosis also.The newborn infants who received concurrent BCG vaccination, even those who live with tubercubous people, have presented low morbidity and mortality from tuberculosis since 11 years of age when they were vaccinated; they have not received any additional dose of vaccine.In the individuals vaccinated with concurrent BCG, virulent super-infections frequently cause exacerbation of the tuberculin allergy, but rarely provoke roentgenographic pulmonary signs coinciding with hyperergy, and exceptionally determine progredient tuberculosis on guinea pigs inoculated with gastric contents.Few deaths of children vaccinated with concurrent BCG have been observed; all of them occurred in very infective places ("favelas").When presenting positive tuberculin tests, children, adolescents and adults tolerate, without any inconvenience, repeated BCG-Moreau doses of 200 to 400 mg, at weekly, fortnightly or monthly intervals, even a total of several 10 gm doses of the vaccinegerm; these vaccinations determine a variable frequency of deallergization coinciding with a manifest increase in the specific resistance against tuberculosis.Children who contracted primary infections of tuberculosis tolerate oral BCG-Moreau vaccination perfectly, even if high doses are repeated; the vaccine gives them variable deallergization, and their specific resistance against the disease is always increased; it is no matter whether they are treated with antibiotics or not. The same facts are being observed regarding the tuberculous reinfection of adults.These data indicate that the original idea of prevention "e sensu strictiori" by the BCG has yielded ground to the concept of true immunization with live bacilli. In the course of this immunization there is both exaltation of the specific resistance (which can reach complete immunity) and attenuation, sometimes extinction, of the allergy which is created at first.