igS AIDS TO BACTERIOLOGY 



Hydrophobia (Rabies). Infection in man and animals 

 takes place as a result of bites from dogs, cats, wolves, 

 jackals, cattle, or other animals. The virus is present in 

 the saliva and in the central nervous system. The 

 incubation period in a dog is from about three to eight 

 weeks, though it may extend to six months. In man the 

 disease usually develops in from eight days to six weeks, 

 up to perhaps two years. In the majority of cases it is 

 in the neighbourhood of ten weeks. 



Negri bodies, varying from small structureless round 

 bodies to larger ones, which may be round or ovoid and 

 show a circle of chromatoid granules round a central 

 granule, are constantly present, and afford a means of 

 diagnosis. The virus is probably ultra-microscopic. 

 The Pasteur method of treatment commences with in- 

 oculation of the spinal cords of rabbits which have been 

 attenuated by suspension in a drying chamber for fourteen 

 days, and then made into an emulsion. Virus of gradu- 

 ally increasing strength is injected until a much more 

 virulent emulsion from a cord that has only been dried 

 for three days is tolerated, which, without previous treat- 

 ment, would be dangerous. Such is the success of these 

 antirabic inoculations, that among the persons treated 

 (over 1,000) at the Pasteur Institute, during 1912, 1913 

 and 1914, no death occurred. The immune serum of a 

 protected animal is said to have a marked curative effect. 



Swine Fever (see also p. 96). Swine fever may be 

 disseminated by the excreta of infected pigs or by contact 

 with infected pigs. Stockman mentions that pigs which 

 to all appearance had recovered from the disease may, 

 in a small proportion of cases, be capable of spreading 

 infection for months. The Departmental Committee on 

 Swine Fever found that rats are not pathological carriers 

 of the disease, nor is the disease propagated by external 

 parasites, and that, while infection may be carried locally 

 by persons, vehicles, or animals in contact with infected 

 pigs, wide dissemination is due to the movement of pigs. 



The Board of Agriculture considers that, if proper 

 precautions are taken, immunity from swine fever can be 

 established by serum treatment. The Committee recom- 

 mended the immunisation of herds by simultaneous 

 administration of serum and virus. They consider the 

 lapse of a short period of time (a fortnight is suggested) 



