520 The Philippine Journal of Science ms 



type of rinderpest. This suggests one of the possible causes 

 for mild rinderpest frequently encountered in the field. 



6. It was observed that the large leech held the virus alive 

 considerably longer than small leeches. 



7. It was noted that when leeches had been out of water for 

 any length of time they disgorged the blood. Carabaos coming 

 from wallows have frequently been observed to be covered with 

 leeches. Carabaos are in the habit of eating grass around the 

 edges of wallows, and there is a possibility of leeches getting out 

 of the water and disgorging blood on the grass. If this were 

 eaten by a susceptible animal within twenty-four hours, there 

 would be a possibility of the animal contracting rinderpest, if 

 the leech previously had fed, within the limits of time the virus 

 is known to remain alive in the ingested blood, on an animal sick 

 with rinderpest. 



8. It has been observed that the virus will continue alive much 

 longer in a leech if it be allowed to feed on an animal during the 

 early stages of the disease. The immune bodies formed in the 

 blood serum may have considerable effect on the virus in the 

 later stages of the disease. Since the temperature of an animal 

 suffering from rinderpest is usually highest during the first three 

 or four days after the initial rise, it is possible that animals would 

 seek cool places and water holes during the early stages of the 

 disease rather than during the later period. This condition 

 would give the leech ample opportunity to feed upon animals in 

 the early stage of the disease. 



9. Experiments 10, 12, 14, and 27 show that the water in which 

 leeches have been kept is not infective to a susceptible animal, 

 provided the leeches have not been injured in any way that would 

 cause them to disgorge the blood which they contained. 



10. The results of experiments 25, 28, 29, and 30 show that 

 leeches cannot transmit the disease to a susceptible animal by 

 feeding on it, after they have fed upon an animal suffering from 

 rinderpest. 



11. The results from experiments 31, 32, 33, and 34 indicate 

 that the trypanosome of surra does not remain alive for any 

 length of time in the ingested blood of a leech, and that a leech 

 cannot transmit the disease by biting. 



12. From the results obtained in the foregoing experiments, it 

 appears that a leech may be responsible for the appearance of 

 recognizable rinderpest forty days after imbibing virulent blood. 

 Of this period, the leech could hold the blood twenty-five days, 

 and to this may be added an incubation period of ten days, which 

 was observed in one of the preceding experiments. 



