MAN'S FIGHT FOR SURVIVAL 615 



the first endemic centers of the broad tapeworm of man in this 

 country was in the region in and about Ely, Minnesota, which is a 

 community with a high percentage of Finns. More recently, the 

 parasite has been found to be spreading to other parts of the country 

 and it is possible that it may prove to be one of the more important 

 parasitic worms with which health authorities have to deal, since 

 both of the intermediate hosts are found in nearly all of our inland 

 waters. 



Another parasite that is perhaps the most universally distributed 

 form in this country is the pork roundworm Trichinella spiralis, 

 an organism so minute that the government does not take the respon- 

 sibility of inspecting for it. Great care should be exercised in pre- 

 paring pork to have it thoroughly cooked. The life history of this 

 worm is described on page 225. 



The presence of the larvae of Trichinella in the blood stream stimu- 

 lates the production of one group of white blood corpuscles, the 

 eosinophils, which is a characteristic symptom of trichinosis, as this 

 parasitic disease is called. At the time of the penetration of the 

 larvae into the muscles, severe muscular pain, especially in the 

 extensors and flexors, is usually experienced, which is followed by a 

 period when the patient becomes emaciated and anemic, and is fre- 

 quently succeeded by a secondary complication in the form of pneu- 

 monia. Death may ensue due to exhaustion or pneumonia. 



On the basis of 1895 autopsies made between 1881 and 1910, 39 

 (2.5 per cent) were infected with Trichinella spiralis. More recently 

 Queen (1931) reported a total of 18.6 per cent in 403 autopsies and Hall 

 (1936), 13.7 per cent. This does not necessarily mean that trichinosis 

 is on the increase in this country but rather that the methods of de- 

 tection have improved, more representative samplings of the popula- 

 tion have been made, and that the examinations are more careful. It 

 appears probable from the above that a much greater proportion of 

 the population harbors this parasite than was previously supposed. 



Parasites Acquired Directly by Man 



There are several rather important parasites of man found in this 

 country that are not carried by an intermediate host, but which reach 

 him directly. The two most important forms are the hookworm 

 (Necator americanus) and the roundworm, Ascaris. Children fre- 

 quently pick up other parasitic worms, but these two are probably 

 the most important from the standpoint of public health. 

 H. w. H. — 40 



