NO. I0 COCKROACHES—ROTH AND WILLIS 103 
Gongylonema pulchrum Molin, 1857 
Common name.—Gullet worm. 
Synonymy.—Gongylonema scutatum (Miiller, 1869) Railliet, 1892 
(Baylis et al., 1926; Lucker, 1932; Alicata, 1937; Brumpt, 1949). 
Gongylonema hominis Stiles, 1921 (Faust, 1939; Chandler, 1949). 
The taxonomic status of the Gongylonema species obtained from vari- 
ous definitive hosts is uncertain because authors disagree as to the 
characters used for species determination (Faust, 1939). 
Disease.—Parasite of esophagus and mouth cavity of vertebrate 
hosts including man. 
Experimental intermediate hosts—Blattella germanica, U.S.A. 
(Ransom and Hall, 1915, 1916, 1917; Stiles and Baker, 1927; 
Schwartz and Lucker, 1931; Lucker, 1932; Alicata, 1934a, 1935). 
Europe (Baylis et al., 1925, 1926, 1926a; Sambon, 1926). 
Parcoblatta sp. (Alicata, 1934, 1935). 
Attempts to infect Blatta orientalis were negative (Sambon, 1926; 
Baylis et al., 1925). 
Development in intermediate host—Eggs eaten by B. germanica 
hatched within 24 hours and the larvae developed to the infective third 
stage in about 32 days. The third-stage larvae encysted in the muscles 
of the cockroach (Alicata, 1935). The infective larvae of the Gon- 
gylonema of ruminants can emerge spontaneously from the cockroach 
if the insect is killed and placed in water. The larvae are capable of 
living for 4 to 11 days in water and are a possible source of infection 
for the definitive host. If an infected cockroach drowns in shallow 
water, the worms will be liberated as the insect begins to decompose. 
Although the worms sink to the bottom, in shallow water they may be 
ingested by humans or other animals while drinking. (Baylis et al., 
1926a. ) 
Natural and experimental definitive hosts—White rat, rabbit, rats, 
Swine, sheep, goat, ox, camel, fallow deer, buffalo, zebu, chevrotain, 
guinea pig, wild boar, horse, donkey, macaque, Ateles sp., Pithecus 
entellus, man; some human records in Ward (1916), Stiles (Anony- 
mous, 1921), Sambon (1925), and Chandler (1949). Records of the 
occurrence of this parasite in man are reviewed by Waite and Gorrie 
(1935) and Johnston (1936). 
Development in definitive host-——Cockroaches containing infective 
larvae are eaten by the primary host. In the guinea pig, the third-stage 
larvae penetrate the tissue at the junction of the stomach and esopha- 
gus; the larvae usually enter the esophageal wall where they migrate 
under the linings of the esophagus and the oral cavity. (Alicata, 
1935.) 
