ruiber st^pnf 



*— Tmst tube 



- Rubber band 



v_y 



Kig. 201. 

 N-I-H swab (National Institute of Health) for the detection of Ente- 

 robius infections. 



T.Mii.K 11. — IiifiiUiicc of Jiiitcrbiiis vcrmiculan.'i 

 By use of various kinds of swabs and scrapers 



Date 



published Country 



Population 

 group Race 



Age 



No. 

 e,\am. 



No. 

 posi- 

 tive 



posi- 

 tive 



Fig. 202. 

 Egg of Enterohiiis vermirularis. 



EPIDEMIOLOGY 



Critical investigations, based on examination of perianal 

 scrapings, have been made in European countries, in the United 

 States, including Puerto Rico, in Canada, and in the Philippines. 

 The results of these investigations are summarized in table 11. 

 These results show that examinations of 22,376 persons revealed 

 pinworm infections in 9,703 persons, or 43 percent. 



Additional studies, differing in method or scope and not 

 shown in table 11, include .stool examination of 495 children of 

 preschool age in Brazil (Moniz de Aragao, 193S) ; E. venni- 

 ctdaris was found in 49 percent, an extremely high figure con- 

 sidering the method of diagnosis. In Spain, Darriba and de 

 Cardenas (1935), from examination of feces, anal scrapings, 

 finger nails and nasal mucus, found 11 of 46 children, or 34 

 percent, infected with pinworms; in Greece, Pandazis (1937) 

 reported pinworms in 28 percent of infants and 6 percent of 

 adults, apparently from fecal examination supplemented by 

 finger nail examination. 



FACTORS INFLUENCING PREVALENCE 



R.\cE. As noted previously, the Negro race has shown a 

 lower incidence than the white race. Although Sawitz, D'An- 

 toni, Rhude and Lob concluded from a small group of boys of 

 the same ages in institutions of similar environments that the 

 incidence was almost identical in the two races, the eonsideralily 

 lower incidence found in Negroes than in white persons in the 

 general population of Washington, D. C, is contrary to what 

 would be expected if environmental conditions are the deter- 

 mining factor. The significance of the racial factor deserves 

 further study; that many persons classed as Negroes in the 

 United States are mulattoes should be kept in mind, in this 

 connection. Of Interest are racial differences in the relative 

 frequency of pinworms in 2,317 appendices removed surgically; 

 the incidence was 2.88 percent for the white population, 10.04 

 percent for Indians of the United States, and 23.91 percent 

 for Eskimos and Aleutians. 



Age appears significant only to the extent that in the general 



By use of NIH swab — Nouinstitutionalized persons 



Summary 



1937-41 U.S.A. and WN 

 Philippines 



All MF 5,682 1,903 33 1 to 4 



'Mixed group of white, mulatto and Negro persons. 



population the incidence is highest in children of school age, 

 next highest in those of preschool age, and lowest in adults 

 (Cram and Reardon, 1939; Chanco and Soriano, 1939). There 

 is evidence that the school is the determining factor in these 

 differences; the incidence in children of so-called "preschool" 

 age who attended nursery schools has been found as high as 

 that in older children (Table 12). 



Sex. The incidence in males has usually been found slightly 

 higher and in an Alabama institution was much higher, but in 

 the Philippines was slightly lower, than in females. Consider- 

 ing both sex and age, Sawitz et al found the peak of infection 

 at 9 years; after that there was a drop in incidence in females, 

 probably correlated with stricter sanitary habits, whereas in 

 males the incidence remained relatively constant up to 15 years 

 of age. 



The factor of crowding is important in the spread of pin- 

 worms. The familial nature of the infection has been empha- 



323 



