AFRICAN HORSE-SICKNESS— PESTIS EQUORUM 337 



against it by inoculating healthy cattle with various secre- 

 tions (bile, nasal discharge, tears), blood serum and blood 

 from affected animals. The inoculated animals, however, 

 can spread the disease which has led to considerable losses 

 where the method of vaccination has been practised. In 

 badly infected districts, like South Africa, however, fair 

 results have been obtained: (For details see larger works.) 



AFRICAN HORSE-SICKNESS. PESTIS EQUORUM. 



Definition. — African horse-sickness is an infectious disease 

 of solipeds due to an ultramicroscopic virus. It is charac- 

 terized by extensive edematous swellings under the skin and 

 hemorrhages in the internal organs. 



Occurrence. — The disease is indigenous to South Africa 

 where it occurs epizootically and leads to enormous losses- 

 among horses and mules. It therefore attains economic 

 importance. 



Etiology. — The cause is a filterable virus. The blood of a 

 horse affected with the disease will readily transmit it to 

 susceptible animals no matter what way the inoculation is 

 attempted. The manure is thought not to be infectious. It 

 does not seem possible to infect animals other than horses, 

 asses and mules, although Angora goats have been success- 

 fully inoculated. 



Natural Infection. — The disease appears during the warm, 

 rainy months of January, February, and March. It disap- 

 pears after the first frost. Horses on pasture during these 

 months are most often affected. The night season is more 

 dangerous than the daytime in this regard. Probably the 

 infection is carried by insects (mosquitoes, anopheles, stego- 

 myia). Keeping a fire smudge near horses on pasture at 

 night or protection with mosquito netting is said to prevent 

 the infection. 



Necropsy. — Gelatinous infiltration of the subcutaneous and 

 intramuscular connective' tissue about the eyes and throat is 

 commonly noted. Evidence of gastro-intestinal catarrh or in 

 some cases hemorrhage and ulceration of the intestine is a 

 common finding. The serous membranes show petechise and 



22 



Digitized by Microsoft® 



