PREVENTION 267 



school children from sewered houses and from houses with privies. 

 The statistics compiled from the data obtained showed that the 

 children from sewered houses possessed fewer parasites and aver- 

 aged a higher grade in school than those from houses with privies, 

 even though the difference was undoubtedly reduced by the fact 

 that sewered homes suffered from proximity to the privies of 

 unsewered homes and from consequent infection by flies and other 

 agents of transmission. 



The most important and effective preventive measure against 

 hookworm and other intestinal nematodes which can be inaugu- 

 rated is the enforcement of the building of privies or latrines 

 of some sort, if it be only a ditch which is occasionally covered 

 with earth or disinfected, for the use of laborers on plantations 

 and estates, and the placing of a penalty or fine for unnecessary 

 pollution of the ground or water where there is any danger of 

 spreading hookworm infection, especially along roads or on plan- 

 tations. Naturally such practices as the use of night-soil (human 

 faeces) for manure, which is extensively practiced in China, should 

 be stringently forbidden, unless the material can be disinfected 

 by chemical treatment, as suggested by Leiper. The fseces of all 

 infected persons, as well as those of any suspected persons, should 

 be carefully disinfected. The use of common salt as a disinfect- 

 ant against hookworm has been found efficacious, but it must be 

 used in rather large quantities. NicoU, in Australia, in experi- 

 ments recently conducted with hookworms, obtained rather un- 

 satisfactory results with salt treatment of infected fseces, unless 

 the salt was used in very large quantities and was very thoroughly 

 mixed with the infective material. The spraying of the earth 

 walls and floors of mines with a strong salt solution or other 

 disinfectant, and a similar treatment of factories, yards, etc., 

 which are known to be infected, is a preventive measure which 

 is said to bring good results, but in the light of Nicoll's experi- 

 ments this should be reinvestigated. Wearing of boots or shoes 

 by mine workers, agricultural laborers and all who work with 

 brick, pottery, earth roofing, etc., is recommended as a protective 

 measure by the boards of health in some countries. This cer- 

 tainly is a good recommendation when it can be followed, but it 

 should be remembered that many who need protection the most 

 are unable to invest in such luxuries as shoes, and that at best 

 little advance towards the final eradication of the disease is 



