138 TROPICAL MEDICINE AND HYGIENE 



continue during the whole of this period. These sym- 

 ptoms may be general abdominal pain or tenderness 

 associated with pyrexia and may at this stage be mistaken 

 for enteric fever or for peritonitis. 



The invasion of the muscles is usually associated with 

 muscular tenderness, rendering movements acutely pain- 

 ful, and if the muscles of respiration, mastication, or 

 deglutition are invaded there may be serious difficulty in 

 respiration or in taking food. 



There is frequently diarrhoea, and fugitive cedematous 

 swellings, particularly under the eyes, may be present. 

 Blood examination will show marked eosinophilia. The 

 larvae are not found in the peripheral blood. 



The larvae when they reach the voluntary muscles 

 become quiescent and encysted and then cause no further 

 trouble. They increase in size up to o'8 to i mm. in 

 about three weeks and may remain alive for years, but 

 undergo no further development. The cysts are formed 

 at the expense of the muscle-fibre and connective tissue, 

 and adipose tissue collects at the poles. The cyst wall 

 ultimately calcifies in many cases. The cysts are just 

 visible with the naked eye. 



Prognosis is usually good, but fatal peritonitis may 

 occur in a very large infection. 



Treatment. This must be purely symptomatic. The 

 adult worms are too deeply embedded in the tissues for 

 intestinal anthelmintics to be of any value. 



Etiology. The animals that serve as definitive hosts 

 may also serve as intermediate hosts. The sexual stage is 

 passed in or near the intestine, whilst the development of 

 the larvae takes place in the voluntary muscles of the same 

 animals. Any susceptible animals, such as man, the rat, 

 pig, &c., may be infected by eating the uncooked flesh of 

 the same species, or of infected animals of other species. 

 Man is probably always infected from the flesh of pigs 

 by eating pork, or as the embryos may be encysted in the 

 intestinal walls of the pig by eating the skin of sausages if 

 these are the intestine of that animal. The pig is usually 



