WHIPWORM 277 



testine occupy the thicker posterior part of the body. The fe- 

 male whipworms, which are always far more numerous than the 

 males, are about two inches long, while the males are a Uttle 

 smaller. 



The human whipworm is found in almost every part of the 

 world, but is especially prevalent in warm countries; it para- 

 sitizes both man and monkeys. It usually makes its home in 

 the coecum but occasionally establishes itself in the appendix 

 or large intestine. It is usually said to transfix the wall of the 

 coecum "with its threadlike anterior portion, but there is some evi- 

 dence to show that it merely buries its long head and " neck " 

 between the folds of the intestinal wall. 



Usually the only evidence of the presence of whipworms is 

 the appearance of the characteristic dark-colored, barrel-shaped 

 eggs (Fig. HOB) in the faeces. These eggs, like those of Ascaris, 

 develop in water or moist soil. The embryo-containing eggs are 

 very resistant to adverse conditions and may live for years 

 without losing their vitality. Infection, as far as known, occurs 

 as in the case of Ascaris. The worms may attain maturity 

 and produce eggs in less than a month after the eggs have been 

 swallowed. Although the whipworm feeds on blood to some 

 extent, and undoubtedly produces toxins, as evidenced by the 

 increase in eosinophiles (see p. 203) in the blood which nearly 

 always occurs in case of whipworm infection and by the occa- 

 sional mental disturbances and other nervous symptoms, this 

 worm usually produces very slight, in fact often unnoticeable, 

 effects. It is, however, thought by some workers to be one of 

 the intestinal parasites most frequently involved in causing 

 appendicitis. It is very difficult to dislodge the whipworm by 

 the usual methods used for expelling intestinal parasites, prob- 

 ably due to its very firm attachment by the long slender " neck." 

 Oil of chenopodium administered as for hookworm (see p. 264) 

 is probably the most effective remedy. 



Pinworm. — One of the most frequent and widely distributed 

 intestinal parasites of man is the pinworm, Oxyuris vermicularis 

 (Figs. 106 and 111). This parasite occurs almost universally in 

 children at one time or another in temperate as well as tropical 

 countries; it inhabits the lower part of the small intestine and 

 the coecum. 



The adult females (Fig. Ill 9 ) are whitish worms about two- 



