Studies upon the plague situation in North China / by Wu Lien-teh [and others].

Date:
[1929?]
Catalogue details

Licence: In copyright

Credit: Studies upon the plague situation in North China / by Wu Lien-teh [and others]. Source: Wellcome Collection.

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    corresponding to the bottle). The smears are inspected and whenever there is the slightest suspicion of impurity, the bottle in question is discarded. NB. It might seem superfluous to examine each bottle. However, *ong experience has convinced us that this extra trouble is worth while and better than risking a whole lot of vaccine. g. Collection of vaccine. The contents of the individual bottles are then poured into the large flask (ii), the empty bottles being carefully deposited in a large tin bucket (where they are afterwards boiled). The funnel is replaced by a sterile cotton plug and the contents of the flask are well mixed. For this purpose some glass beads have been inserted before sterilisation. h. Inactivation of vaccine. The flask is heated in a large water-both for 1-2 hours at a temperature of 60-G2°C, its contents being stirred every few minutes. i. Standardisation of vaccine. For this we use a simple method recommended by the Japanese (28). Two dry centrifuge tubes are carefullv weighed, then filled with a known quantity of the vaccine and centrifugated, in the electrical cen¬ trifuge for quarter of an hour at a speed of 1,500 revolutions per minute. The supernatant liquid is then decanted, the last traces of moisture being removed with filter-paper strips. By weighing the tubes again the bacterial contents per c.c. can be calculated, the average value of the two determinations being taken. j. Testing the concentrated vaccine. Together with the samples for standardisa¬ tion a sterile one is taken for cultural and experimental tests. We inoculate agar slants and stabs as well as bouillon tubes and inject two guinea-pigs (sub¬ cutaneously and intraperitoneally) with }-z c.c. each k. Dilution of vaccine. If the cultures are found satisfactory the vaccine (which has been kept in the meantime in a dark cool store room) is diluted with carbolised physiological salt solution so as to contain 6 milligram of killed bacteria per c.c. ], Filling and final testing. With the aid of the syphon apparatus the diluted vaccine is distributed among the small bottles. After proper corking the neck portion is dipped into melted paraffine. Cultures as above are made from the last bottle for final testing. m. Issuing the vaccine. The diluted vaccine (which is kept cool and dark) is only labelled and issued after all cultures have been found perfectly sterile, and the test animals have remained healthy for at least 10 days. Dosage is 1 c.c. for the first and 2 c.c. for the second injection with an interval of 8 days. n. Precautions taken. So long as the plague bacilli are not killed by heating, all our work is performed in a special room devoted entirely to the purpose. No bystanders are allowed and all workers wear anti-plague custume with rubber gloves and masks. The dangers of preparation of anti-plague vaccine should not be underrated as shown by at least two instances of laboratory in¬ fection during such work (1). And, though the above procedure might appear simple, there are many pitfalls as well as dangers for the inexperienced.