250 Arthropod Transmission of Disease 
laeious. In Spartanburg County attacks by Simulium seems to be 
confined to the immediate vicinity of the breeding-places. Our 
records and observations, exceedingly few in number, refer almost 
exclusively to such locations. Statements regarding such attacks, 
secured with much care and discrimination from a large number of 
persons, including many pellagrins, indicate conclusively that these 
insects are seldom a pest of man in this county. A certain number 
of the persons questioned were familiar with the gnats in other 
localities, but the majority were seemingly ignorant of the existence 
of such flies with biting habits. This is especially striking, in view 
of the fact that the average distance of streams from the homes of 
the pellagra cases studied was about 200 yards, many being at a 
distance of less than 100 yards, and that 78 per cent of these streams 
were found to be infested by larval Simulium. Such ignorance in a 
large number of persons cannot be overlooked and indicates strongly 
that our belief in the negligible character of local attacks by Simulium 
is well founded.” 
‘‘In localities infested by ‘sand-flies,’ mosquitoes, etc., these 
pests are always well known and the ignorance described above is 
very significant.” 
‘‘Such positive reports as we received nearly always referred to 
bites received in the open, along streams, etc., and observations made 
of their attack were of those on field laborers in similar situations. 
Males engaged in agricultural pursuits are almost exempt from 
pellagra in Spartanburg County. During the season of 1913, in 
some two or three instances, observations were made of the biting 
of Simulium and some additional and entirely creditable reports 
were received. These observations and reports were under condi¬ 
tions identical with those referred to in the reports of 1912 and con¬ 
firm the conclusions based on the observations of that year. I 
would repeat with emphasis that it is inconceivable that a fly of the 
appearance and habits of the prevalent species of Simulium could be 
present in such a region, especially about the haunts of man and 
attack him with sufficient frequency and regularity to satisfactorily 
account for so active and prevalent a disease as pellagra without 
being a well-known and recognized pest.” 
‘‘In connection with the conditions in the Piedmont region of 
South Carolina, it may be well to cite the results of a study of those 
in the arid region of western Texas.” 
