158 ROUNDWORMS— THE NEMATHELMINTHES 



from the body along with the feces and the main method of diagnosis 

 for ascaris infection consists of an examination of the feces for the eggs. 

 If a person has the worms, even a small sample of the excrement from 

 his body will show many of these eggs. This examination is somewhat 

 simplified if the fecal material is stirred up in some saturated salt water 

 and allowed to stand a short time. The eggs will then float to the top, 

 where they can be removed easily for microscopic examination, and the 

 remainder of the material will settle to the bottom. 



Ascaris infections are quite common in our southeastern states, espe- 

 cially in mountainous regions where a lack of sanitation allows these eggs 

 which pass from the body to be spread where others may get them. 

 There is no intermediate host and infection comes with ingestion of the 

 eggs. Such an event might seem extremely unlikely, but examinations 

 of school children in certain rural areas of Tennessee by the State Board 

 of Health revealed up to 80 per cent infection. One explanation for 

 this lies in the longevity and great resistance of the eggs. One worker 

 found the eggs capable of causing infection after four years storage in 

 an icebox, and others have been kept in 5 per cent formalin for a time 

 without being destroyed. It is, therefore, a fairly simple matter for the 

 eggs to be spread around where they may get on the hands of children, 

 and also adults, and eventually into the mouth. When swallowed they 

 reach the intestine where the embryos hatch out as tiny larval forms. 

 A newly hatched ascaris larva is apparently not adapted for life in 

 the strong digestive fluids of the small intestine and so for the first ten 

 days of its life it lives in other parts of the body. First, it bores through 

 the intestine and gets in the blood stream which carries it all over the 

 body and it finally ends up in the lungs. There, it bores through the 

 lung tissue into one of the many little air sacs found in the lungs. This 

 breaking through the tissue causes a little bleeding and a blood clot is 

 formed around the little larva. The presence of this foreign material in 

 the lungs causes a person to cough and the blood clot containing the larva 

 is coughed up. If the person coughs hard enough he may get it all the 

 way up into the mouth where it may be spit out. On the other hand, a 

 polite little "hack" is likely to bring it up only to the throat where it is 

 immediately swallowed back down into the stomach and intestine and 

 rapidly grows to its adult size and begins the vital process of reproduc- 

 tion. 



If a person has ingested a large number of eggs and there is extensive 

 injury to the lung tissue, a type of pneumonia may result which may be 

 quite serious in nature. The adults living in the intestine do not seem 

 to do the body great harm, but there will frequently be anemia and nerv- 

 ous disorders due to the absorption of their poisonous waste products. 



