84 



WILLETS. 



too moist. The same results are secured with the rhabditiform embryo 

 of the parasite. On the other hand, the filariform embrj'o will live for 

 a considerable time in water. Now the lowlands of the haciendas are 

 flooded nearly every year. Sometimes they are flooded three or four times 

 in one year and they remain so for three or four days at a time. It is 

 possible that during the floods many of the eggs and embryos are killed, 

 and that many others are washed away. If this were true it would 

 tend to lessen the percentage of persons infected, and the severity of the 

 infections with this parasite. It is also probable that the heavy rains 

 themselves tend to clean the infested soil yearly. These suggestions are 

 offered only as possibilities, not facts. In my opinion, not less than 95 

 per cent of the hookworm infections seen were distinctly mild in degree. 

 If this is correct, it seems necessary to believe that some factor or factors 

 are at work to cleanse the infested soil from time to time. 



SEX. 



The infections with Hymenolepis and Strongyloides are too few to 

 admit of comparison. Males were found to harbor the hookworm and 

 Tcenia more frequently than females, whereas more females than males 

 were infected with Ascaris, Trichuris and Oxyuris, as shown in Table YI. 



Table VI. — Sex distribution of infections. 



Sex. 



Num 



. 



Infected. 



Ascaris. 



Hookworm. 



Trichuris. 



exam- 

 ined. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



1 

 Per 

 cent. 



Males — 



2,290 

 1,988 



1,999 

 1,657 



87.29 

 83.35 



1,349 

 1,304 



58. 91 

 65.59 



1, 432 



894 



62.53 

 44.97 



179 

 163 



7.82 

 8.20 



Females 





Sex. 



Oxyuris. 



Tirnia. 



Hymenolepis. 



Strongy- 

 loides. 



Total infections. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 

 cent. 



Num- 

 ber. 



Per 



cent. 



Males ._- 



23 

 41 



1.00 



35 



1. 53 



3 



2 



0.13 

 0.10 



3 

 1 



0- 13 



3,024 



132-0,'S 



Females 





2.06 





24 



1.2 



1 



C 



.05 



2, 



429 





122. 18 



It will be noted that in the total infections present there were 132.05 

 per 100 males as against 122.18 per 100 females. 



AGE. 



The distribution of the parasites according to age is given in Tables 

 VII, VIII, and IX. Ascaris was found to be more frequent in children 

 than in adults, the highest percentage of infection (85.19) being in 

 girls between 3 and 4 years old. Commencing with the group 7 to 9 



