Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)
stage larvae of Tricho strongylidae can definitely he differentiated from each other,and from those of Ancylostoma , Stron- gyloides and free living nematode spp. Characteristics for species identification are: full length of larva (including sheath of second moulting), shape and size of oesophagus, numher of intestinal cells, shape of hind end in proper third stage larva, shape and length of larval sheath at hind end. The slender larvae, isolated in our cases, measured 700 /t in length; the filariform oesophagus was less than l/3 of full larval length; the numher of intestinal cells, with the shape of an elongate triangle, was 16; the hind end of the proper 'larva was bifid; the undulating hind end of the sheath was tapering and 30 long. On the basis of these features ( Fig. 3, 4 and 5) our cases were diagnosed as Trichostrongylus colub- riformis infection.Other two Trichostrongylus spp.were excluded by egg size ( T.vitrinus ), and by larvae having a plain, not bifid hind end ( T. axei ) . T. colubriformis larvae can be distinguished from other Trichostrongylidae ( Ostertagia , Cooperia , Haemonchus ) by detailed morphological analysis (HOLLÓ, 1969). Such details, however, will not be presented here, as the latter genera are not of practical importance in human medicine. Characterization of Ancylostoma and Strongyloides larvae is more justified though, the former infection can readily be diagnosed by egg structure (as mentioned previously). Ancylostoma duodenale : The third stage larva is about 600 p. long; the oesophagus is divided into two different regions: the anterior part is narrow growing gradually broader while the posterior part is bulblike; the oesophagus is less than 1/3 of full larval length; the intestinal cells can barely be seen if at all; the hind end of the larval sheath becomes filiform and measures about 100 jt^ ( Pig. 6 and 7).
