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HK NATIONAL GEOGRAPHIC MAGAZINE 



A WEST INDIAN NEGRO WOMAN WHO IS 

 PROUD OF HER HEALTH CERTIFICATE 



designs, successive scenes illustrating the 

 causes of soil pollution, the process of in- 

 fection, the symptoms of the disease, the 

 methods of treatment, the results of cure, 

 and the need of sanitary precaution. The 

 film is being exhibited to-day under some 

 twenty different flags. 



SUCCESS GREATER THAN WAS ANTICIPATED 



For a long time it was believed that 

 hookworm disease could not be reduced to 

 a stage where it would be harmless, with- 

 out completely successful efforts to pre- 

 vent soil pollution. 



Resurveys of various areas in the South, 

 in Porto Rico, and elsewhere, where com- 

 munity treatments had been administered, 

 showed a gratifying reduction in the per- 



centage of people infected, but not enough 

 to promise- the extirpation of the disease. 



But, on a reexamination of those pre- 

 viously treated, the percentage, based on 

 the number of worms found, was shown 

 to be vastly lower than the percentage of 

 those completely free from the invaders. 



Richmond County, Virginia, where the 

 war on the hookworm as a world-wide 

 fight had its inception, stands out as an 

 example of what may be accomplished 

 and as an evidence that it can be accom- 

 plished with much less difficulty than was 

 formerly supposed. 



When the work began there, about thir- 

 teen years ago, 82 per cent of the people 

 had the disease. A few years later a re- 

 survey showed that this had been reduced 

 to 35 per cent. A more recent resurvey 

 reduced it to 2 per cent, and in 1922 it 

 can be announced that there is not a single 

 person in the entire county in whose body 

 the worms are numerous enough to pro- 

 duce any of the symptoms of the malady. 



THE WAYS OF THE NECATOR 



There are two kinds of hookworms 

 that invade the human body, an Old 

 World species known as Ancylostoma 

 duodenale and the "New World'' form 

 known as Necator amcricanus. The latter 

 was described by Dr. Charles Wardell 

 Stiles in 1902, and it was through his 

 efforts that the South first came to realize 

 the great drawback under which it had 

 to labor as a result of the prevalence of 

 the disease. 



Some years ago specimens of the 

 "American" species were found in Africa, 

 and it is believed that it was imported to 

 America with negroes, in the days of the 

 African slave trade. It is interesting to 

 note that the negro is far less susceptible 

 to the disease than either the white man 

 or the Indian, just as both the malaria 

 and the yellow- fever mosquito show a 

 preference for biting white folks. In 

 British Honduras, in Barbados, and in 

 other communities where large black 

 populations live, the whites and the In- 

 dians are found to be much more sus- 

 ceptible to its attack than the negroes, 

 both in the number of worms found and 

 in the effect on the individual. 



The New World species of hookworm 

 is a small parasitic creature about as 

 thick as an ordinary pin and half as long. 



