818 Trichina Disease. 



trichinae bore through the sarcok^nuna of the striated muscle and 

 localize in immediate contact with the plasma. They grow here in 

 about 3 weeks to a length of 0.7 to 1.0 mm., curve up usually in the 

 form of a sickle and eventually assume a spirally t\nsted shape. After 

 the immigration of the young trichinae degeneration of the muscle 

 plasma sets in, the fibers of the interfascicular connective tissue be- 

 come hj'pertrophied until finally, through the perforated and thickened 

 sarcolemma and perhaps through connective tissue cells that have wan- 

 dered through these inlets (about 2 months after migration), a long 

 lemon-shaped capsule is produced with a diameter of 0.08 to 0.05 mm. 

 In this capsule there is generally only one, more rarely there are 2 to 

 4 and occasionally 7 trichinae. 



In the capsule and the granular mass situated therein lime salts 

 are deposited about 1 to 114 years after migration. Notwithstanding, 

 it is possible for trichinae to remain alive for a long time (in swine 

 over 11 years, in man over 30 years) and to be capable of producing 

 infection. On the contrary non-encapsuled trichinae are incapable of 

 causing infection, because they die in the stomach. 



Natural Infection. S^^ine infect themselves by eating the 

 flesh of trichinous pigs, from the excrement of trichinous swine 

 and the ofTal, further by eating rats and mice, and also, ac- 

 cording to Hojdjerg, by taking np the dejecta of rats and mice. 

 The last mentioned mode of infection is, however, denied by 

 Strose. With regard to rats Lenckart has proved that they 

 are very susceptible to trichinosis and in fact are very frequent- 

 ly trichinous. Thus Heller found muscle trichinae in 8.3%, 

 Groker in 5%, Frank in 6.9%, Fessler in 50% and Billings of 

 Boston in 100 7o of rats examined. It has further been noticed 

 that most trichinous rats are found in the neighborhood of 

 knackers' yards, slaughter houses and shambles, where they can 

 easily be infected by the offal of dead and slaughtered swine. 

 Johne proved the very frequent occurrence of trichinae in rats 

 in the zoological gardens in Dresden. In any case the spread 

 of trichinae results among rats through eating and devouring 

 rat flesh. 



According to Hoyberg rats and mice are rarely caught by swine under the pres- 

 ent conditions of breeding, and in consequence infection does not often arise in 

 this way. Infection happens much more frequently by the eating of food soiled by 

 the excrement of rats and mice. Hoyberg found in his experiments that after the 

 taking up of muscle trichinae, the feces of rats contain embryo-bearing trichinae for 

 10 days, and the embryos preserve their vitality for four weeks in a sufficiently damp 

 medium. After entrance into the stomach many embryos are killed by the destruc- 

 tive action of the hydrochloric acid; but many escape destruction, the more so as 

 they are protected in a manner by the bodies of the females, which they inhabit. 



Klihn asserts, on the contrary, that the pig is an able rat catcher, and this 

 opinion is supported by Strose, who did not succeed in finding trichinae in the excre- 

 ment of artificially infected rats, or in transmitting trichinosis to rats by feeding 

 them with pregnant trichinae, as well as with the intestines of freshly infected rats. 

 For this reason Strose agrees with earlier observers who consider that the excrement 

 of animals containing sexually mature trichinae is of no importance in the spread of 

 trichinosis, but that, for the transmission of the disease from animal to animal, 

 only muscle trichinae in an advanced stage of growth are effective. Nor could Strose 

 confirm the results of Staubli, according to which rats are not of actual importance 

 as intermediaries for successive generations of trichinae, because they usually Buccumb 

 to intense intestinal trichinosis. 



