VACCINATION 



1493 



VACCINATION. 



Vaccination from arm to arm is very dangerous- in the tropics, as syphilis, 

 yaws, relapsing fever, sleeping sickness, etc., may be inoculated. It should 

 therefore only be performed when calf-lymph is not available, and only by 

 means of children under eight years of age who are found to be healthy. 

 These vaccinifers can be sent to suitable districts if necessary; and if the 

 amount of lymph required is considerable, two or three drops of glycerine may 

 be placed on the vesicles, which are then punctured in several places, and the 

 mixture used for immediate vaccination. With regard to the systematic work, 

 lanolated seed-lymph can be obtained from many institutes at present; for 

 example, from the Lister Institute in London. 



Preparation of Lymph, — The vaccine institute requires an inoculating-room, 

 a preparation-room for the lymph, an office, a store-room, a good stable for 

 the calves — all of which should be rendered flyproof , and should have cement 

 floors and be as cool as possible, and have a good supply of water. The special 

 apparatus required are means for sterilization, Dornig's hand roller machine 

 for trituration, and Entrican's machine, fitted with a small Geryk pump, for 

 filling the tubes, as well as the ordinary glass and other materials of a laboratory. 



The lymph should be obtained as lanolated seed-lymph from a reliable 

 institute, and should be inoculated into fair-skinned heifers, not into black- 

 skinned heifers, which should be specially fed during and after inoculation. 



When tubes of calf-lymph cannot be obtained, monkeys may be directly 

 inoculated from cases of variola, and the calves may then be subinoculated 

 from the monkeys, and if calves cannot be obtained rabbits may be used. 



All animals should be carefully isolated and watched for a week before being 

 used for inoculation. During this period the temperature should be taken 

 and a tuberculin test applied . 



When lymph first arrives in a tropical countr^T- from the temperate zone it 

 requires to be acclimatized — that is to say, its virulence should be increased 

 by passing it through about three calves before use, otherwise failures may 

 occur. 



The calves are vaccinated on the shaved abdomen, which has been washed 

 with soap and sterile water, by linear incisions, about i inch apart, into which 

 the lymph is gently and immediately rubbed, and a sterile cloth tied over 

 the vaccinated area. No straw should be given for bedding, but a wooden 

 grating should be used, and the calf's head should be secured by two tie-ropev«« 

 to prevent it kicking the inoculated area. 



The lymph may be collected after 96 to 120 hours by first washing the area 

 with soap and water, then with sterile water and a sterile gauze mop, and then 

 removing the contents of the liver vesicles by means of a Volkmann's spoon. 



The lymph is now weighed and mixed with an equal weight of sterile 

 distilled water or glycerine, and after being worked into a paste is triturated 

 until it is in an extremely fine condition, and if urgently required is treated 

 with a stream of chloroform vapour for fifteen to thirty minutes, after which 

 sterile air is bubbled through until no chloroform remains, and another part 

 of sterile water and 2 parts of sterile glycerine, or 3 to 5 parts of anhydrous 

 lanoline are added . The lymph is now filtered through a special fine sieve info 

 test-tubes till nearly filled, and stored in cold climates for four to five weeks 

 at a temperature of 15° to 20° C, v^^hen the number of micro-organisms is 

 found to have decreased considerably. The chloroform method of purifying 

 the lymph is to be preferred in the tropics, as it is much quicker. The tech- 

 nique is found in any modern work on the preparation of lymph. 



A bacteriological examination is always necessary, especially to discover 

 whether tetanus bacilli are present, and if these are found the lymph must 

 be rejected. The lymph must be stored at temperatures at 5° to 10° C; if 

 this precaution is not used the lymph becomes inert very quickly in tropical 

 countries. 



The capillary tubes are filled in a vacuum in the Entrican filling-machine, 

 and should be tested for vaccine activity before being issued. 



