379
"cash". This system of cash payment for calves has now been adopted and so far as one can gather will do away with the ever-recurring difficulties of the past, namely, the apparent scarcity of calves for inoculation. The animals are bought outright from the owner, an average sum of $25 being paid for each calf. They are inoculated, the vaccine collected, and the animals are re-sold after their recovery for an average of $10 each. It is estimated that about $120 clear profit is to be made out of each calf if purchased and re-sold according to the present method.
Issues of Vaccine during 1905.
Vaccine paid for,
The Victoria Gaol....
The Tung Wal Hospital,
The Civil Hospital,
The Alice Hospital,
The New Territory,
The Public Vaccinators,
The Sanitary Board,
Total,.....
.4,393
.1,075
950
550
424
100
90
56
.7.638
As is well known, the lymph, as obtained from the calf, contains numerous extraneous micro-organisms. As the latter are capable of occasioning untoward symptoms in the individual vaccinated, and at the same time vitiating an otherwise completely successful vaccination, many methods have been advocated, and even adopted, by different manufac- turers, in order to supply the general public with a reliable and germ-free vaccine virus. The method which has been most widely adopted, is the intimate mixture of glycerine with the freshly drawn lymph and pulp. This process has obtained general acceptance, and glycerinated calf lymph is known to give good and more or less uniform results. It would appear, however, that the use of glycerine as a germicide in the production of pure calf lymph, has several disadvantages, especially in tropical countries. This may be summarised as follows:-
(1.) Considerable care has to be taken in order to keep up the efficiency of the vaccine. As is well known the specific action of the virus of the vaccine. is weakened by the use of glycerine. Further, in tropical countries, this action of the glycerine would appear to be exerted more strongly. As has already been noted in my previous Reports, glycerinated vaccine lymph as prepared in Hongkong, only retains its virulence for a month or six weeks. (2.) Vaccine lymph which has been glycerinated cannot be used for the general purposes of human vaccination until it has been kept in reserve for at least a mouth or six weeks. It has been estimated that this period or even longer must elapse before the majority of the extraneous micro-organisms has been destroyed.
(3.) The use of glycerine as a purifier of the vaccine virus is applicable only to organisms of a non-sporing nature. Resisting spore-bearing germs would not appear to be materially restrained in the multiplication in glycerinated lymph, and might become a fruitful source of danger to those vaccinated. Tetanus, and other diseases, have been known to occur after vaccination, the causal agent having been simultaneously introduced subcutaneously with the vaccine lymph.
These, and indeed other objections are applicable to the general employment of glyceri- nated calf lymph. In the tropics, such disadvantages become even more real. Vaccine is often requisitioned for urgently. It will not keep during the hot weather. If mixed with glycerine it has to mature for at least six weeks. Glycerinated calf lymph-so far as past experience in Hougkong teaches us does not guarantee a constant and reliable source of protection. It would appear to be of great importance to have at our disposal a rapid method of obtaining a gerin free lymph.
Up to the present time, many methods of preparing vaccine lymph have been advocated. The majority have as their object the manufacture of a good strain of vaccine in the shortest time possible.