Post-Graduate Students' Activities

Kai Tiaki : the journal of the nurses of New Zealand, Volume XXII, Issue 1, 1 January 1929, Page 21

Post-Graduate Students' Activities

VACCINATION— The Preparation of Vaccine Lymph

The life of a student taking the PostGraduate Course for nurses, is not an idle or an uninteresting one. The methods of education used by the instructors are varied ; the eye assists the ear, and making use of this fact, we were taken to observe a demonstration of the method of collecting vaccine lymph for use in vaccination against that terrible disease — variola or smallpox. One knows that the lymph is procured from calves, and has a vague idea how it is likely to be done, but the actual seeing of the whole process goes far to impress on one's mind the manner in which this very necessary public health measure is carried out, and also demonstrates the fact that the procedure is not as simple as one might imagine. A short description may interest you. How New Zealand Procures her Supply of Lymph for Inoculation against Smallpox. It is interesting and instructive to know exactly how New Zealand is being protected against possible epidemics of smallpox. The method used in the early days, that of inoculating one child from another, is not now practised to any extent, but a regular supply of vaccine-lymph is always on hand, prepared under good

conditions by expert bacteriologists, and the whole of New Zealand and Samoa are supplied with whatever their requirements may be. Ships' officers can also, on application, procure a supply of lymph, and on no account is the stock allowed to become depleted ; so that we can rest safely in the knowledge that we are armed against any possible outbreak of smallpox. The procedure in connection with the upkeep of this supply is extremely interesting. In the vicinity of the Wellington Hospital is a department specially constructed for the purpose of c; rrying out this important work. It has a living room for the calves, from which the lymph is to be procured; operating room with all necessary equipment for carrying out the work with aseptic precautions, and a small laboratory or workroom in which to treat the raw virus which is obtained. The calves are brought by contract from a farmer in the Hutt Valley, this locality being free from bovine tuberculosis. They are healthy animals, from six to seven months' old, and their living room is kept scrupulously clean, and is heated by electric radiators. This is necessary because a large area of the abdomen and under surface ot the thighs of each calf is 'shaved to ensure a wide clean area for introducing the lymph with which the calf is inoculated.

The calf is strapped on the operating table, and does not seem at all alarmed, no doubt it had found by experience that the shaving was a painless process, and that a warm clean bed and good food would be forthcoming after the performance 1 was over. The shaved area is scrubbed with sterile water and soap. rinsed with plain sterile water, and precautions taken to have everything aseptic as for an operation. No anti-septics are used, as they would destroy the virus. The whole area is dried and then scraped with a blunt scalpel, and the lymph rubbed into the scratches. In no case is the skin scratched deeply enough to draw blood.

The operation finished, the calf is taken back to the living room and kept clean and warm for four or five days, when it is again put on the table, and the pustules scraped to obtain the lymph.

The scrapings contain epithelial cells and the raw virus. From one calf 49 grams of scraping or raw virus were taken, and mixed with 50 per cent, glycerine and water. The glycerine kills all non-filterable viruses. The chief danger of contamination is from the minute filterable viruses, i.e., encephalitis lethargica, acute poliomyelitis, etc.

The mixture is put three or four times through a mixer, which converts it into emulsion. This emulsion is put in jars and kept in cool storage for three or four months, when it is tested for gas or spore forming groups of bacilli. If found to be free from any contamination, the

lymph is tilled into glass capillary tubes by means of an ingenious vacuum machine. The tubes are closed by flaming, and are again put in cool storage till required, and the lymph is quite effective for two years or longer. Before the lymph is considered safe for issue, the precaution is taken of killing each calf from which it has been procured, and a thorough post-mortem examination is made to see that there is no disease present. In order to keep the lymph effective and not too far removed from the human species, from every twentieth calf a child is inoculated, from the child a rabbit is inoculated, and from the rabbit back to the calf again. A complete record of each batch of vaccine lymph is kept by the Department which produces it.

All issues are dated from the time and place of procuring the calf, the record of inoculation, the record of the post-mor-tem examinations and the record of bacteriological examinations and dates of issue, and destination thereof. In fact, all particulars are taken and kept, so that, if necessary, any information required can be readily obtained.

The lymph for vaccination is used at strength of I—31 — 3 for inoculation of a calf and I—lo1 — 10 for a human being.

And so New Zealand is systematically supplied with lymph which is available whenever called for. and is supplied free of cost to medical practitioners on application to the Department.

MM.