TRICHOTRACHELID^: 135 



There is no proof that any disease is caused by the 

 trichocephali. Persons harbouring the parasites may be 

 in perfect health. Cerebral symptoms are said to have 

 been caused by the worms when present in large numbers, 

 but such manifestations are exceptional, even if they ever 

 cause them. They have been suggested as a cause of 

 appendicitis, and the worms may be found in the 

 appendix, but appendicitis is more common in countries 

 where the trichocephali are rarely found than in the 

 Tropics where they are commonly found. There does 

 not seem to be anything in support of this hypothesis. 

 The actual injury done to the intestinal wall is inap- 

 preciable, and no ecchymoses are formed found the point 

 of fixation. 



Treatment. Thymol, or the mixture of eucalyptus oil, 

 chloroform and castor-oil given for ankylostomes and 

 other worms (p. 153), frequently causes the expulsion of 

 trichocephali. 



Etiology. The eggs are passed in the faeces. They are 

 very resistant and may retain their vitality for years. 

 The embryo develops in the shell more rapidly in warm 

 weather. By the time development is complete the 

 faeces will have been completely destroyed and the eggs 

 scattered widely. The eggs are not destroyed by passage 

 through the intestines of larvae of Muscidae, by ordinary 

 air-drying, nor during the decomposition of faeces. 



Prophylaxis would be difficult by any of the ordinary 

 methods of dealing with excreta, particularly if they are 

 required for use as manure after more or less decomposi- 

 tion. Thorough cooking of green vegetables or ground 

 crops would destroy the eggs, whether they contained 

 embryos or not. The contamination with earth of any 

 food or of utensils used in preparing or serving food 

 should also be prevented. Trichocephalus eggs are not 

 proof of direct sewage contamination, as they may be 

 derived from faeces that have been completely destroyed, 

 and may be blown about with dust into water supplies. 



