110 The Philippine Journal of Science 1917 



Experiments with monkeys have shown that infection can be 

 effected by injection of the virus into the brain tissue, into the 

 subdural space, intravenously, intraperitoneally, and subcutan- 

 eously, by rubbing the virus on the uninjured or scarified mucous 

 membrane of the nose, or by feeding massive doses through a 

 stomach tube. However, the natural mode of infection seems 

 to be through the mucous membrane of the nose and throat. 



No other disease presents a more widely varying epidemiology 

 than poliomyelitis. From year to year the disease has shown 

 a marked increase in prevalence and extended over greater ter- 

 ritory throughout the world. The most extensive outbreaks 

 have occurred in regions with marked seasonal variations, as 

 the northern United States and Europe. This increase in prev- 

 alence and distribution of the disease is more pronounced in 

 the United States, statistics for the period 1905-1909 showing 

 that of 8,054 cases the United States contributed 5,514. The 

 Public Health Reports for November 10, 1916, listed 49 states 

 reporting poliomyelitis. The maximum of sporadic and epidemic 

 cases occur during the warm, dry months (from May to Novem- 

 ber in the northern hemisphere). Where the seasonal change 

 is a matter of rainfall, the disease prevails during the dry 

 season. The recent epidemic in New York reached its crisis 

 on August 12, 1916. These facts point to insect transmission 

 rather than to contact infections, such as characterize measles, 

 diphtheria, whooping cough, scarlet fever, etc, (Frost). A pe- 

 culiar feature of the outbreak of sporadic cases and epidemics is 

 the frequent lack of apparent connection with previously existing 

 foci, a phenomenon explained probably by the undoubted nu- 

 merous unrecognized cases and "healthy carriers." The inci- 

 dence as compared with other epidemic diseases of children is 

 small, the case rates per 1,000 of population for 27 states during 

 1915 varying from 0.001 to 0.116, Epidemics in a community 

 seem to be self -limiting, lasting a few months and then gradually 

 disappearing until at least two years have elapsed. The inci- 

 dence is noticeably higher in small towns and rural communities 

 than in our large cities. The contagiousness of the disease is 

 not great, as indicated by the low incidence in schools and the 

 occurrence of usually but 1 case in a family. Lavinder reported 

 that out of 7,000 cases in New York 6,748 families were involved, 

 those in which 1 case occurred being 97 per cent of the total. 

 Children under 5 years of age furnish from 50 to 90 per cent 

 of the cases, but as the epidemic advances, the incidence for 

 the higher age groups advances. Cases in adults are rare. 



