IMMUNIZ..A.TION BY INJECTIONS OF AN TITOXIN.—By the injection of small doses of antitoxin it has been found possible to induce an artificial immunity which holds good for a period of at least four weeks, as a rule. Epidemics of diphtheria in children's hospitals or asylums have been repeatedly checked by protective injections of antitoxin in all the children exposed.
The value of immunizing injections in hospitals upon 254 children of ages vary ing from 2 months to 14 years observed, these observations covering a period of twenty-one months. The strength of serums varied from 100 to 3000 units, and the dose from 1 to 10 cubic centi metres. In the beginning, when the in jections were made only upon patients in beds near to those which had been occupied by the diphtheritic patients, 4 cases of infection occurred. When, how ever, the injections were made upon all the patients of the ward, and, later, upon all patients subsequently admitted, the disease did not reappear, except in 3 cases thirty to forty days after injec tion, twice in children readmitted to tho hospital, and once with a child that had been discharged well and returned at the end of a month with an attack of the disease. TWO children admitted, but not injected on account of the grav ity of their condition (pleurisy, articular rheumatism), contracted diphtheria and 1 of them died. On account of the 3 cases of infection developing one month after prophylactic injection, the injec tions were repeated monthly upon chil dren who remained for any length of time in the hospital. After this plan was adopted no new case of diphtheria developed in the ward. Another series of immunizing injections was made in the measles ward upon 99 children. Of this number there were 21 eases that died, all of them under 1 year of age; but in no case was there diphtheria or croup.
In the Children's Hospital of Boston, of 1SOS patients immunized at least once every twenty-eight days, the amount ot serum varying from 150 to 500 units, 7 had diphtheria, 3 from insufficient dos ing, 2 ivithin twenty-four hours of the injection, and 2 in whom the time of infection came twenty-three and twenty two days, respectively, after giving an amount which had previously been ef fective when given every three weeks. Of 829 who were not given antitoxin, or in whom. more than twenty-eight
days elapsed after the injections, 9 had diphtheria, besides 3 immunized adults. Immunity in any given case, of no matter bow thorough exposure to diph theria, may be conferred for at least ten days by the injection of a small dose (100 to 250 units) of serum, provided it is given twenty-four hours previous to actual infection. A larger dose (250 units for a child of two, up to 500 units for one of eight or over) will confer safety for three weeks under similar conditions. Morrill (Boston Med. and Surg. Jour., Mar. 3, '98).
Prophylactic use of antitoxin will fur nish an effective means of lessening the number of cases. In over a thousand cases immunized only six contracted the disease, which was in every instance mild in form. It is better to use 300 units in children and 500 units in adults to im munize against the disease. J. S. Bill ings (N. Y. Med. Jour., Feb. 17, 1900). As diphtheria antitoxin is practically harmless, all exposed persons should re ceive an immunizing dose in proportion to age. Two hundred and fifty units should be given to children under two years and 500 to all others. The inAll munity will last for at least three weeks, provided a reliable antitoxin is used. _All exposed persons should be removed from infected surroundings. either by thoroutzh disinfection of their own quarters or by removal to other plaees. this be impo.sible, the im mrmizing doses should be repeated every third week. II. D. Jiiinp (Phila. 1\led. Jour., Jan. 11, 1902).
In the article on the "Use of Anti toxin" by I3iggs and Guerard previously quoted, a summary of thirty-five reports covering 17,516 injections of antitoxin for the purpose of immunization is given. Following these injections, 131 cases of diphtheria developed, 109 mild cases and 1 fatal case within thirty days of the date of injection; 20 mild cases and 1 fatal after thirty days. The writers state that "the duration of immunity after injec tion has not been definitely determined and undoubtedly varies. Some hold the opinion that it lasts only one or two weeks, others that it extends over thirty days or more. Four weeks may probably be considered as the average duration." The results certainly justify the further trial of this method of protection.