The distribution and persistence of hookworm larvae in the tissues of mice in relation to species and to routes of inoculation.

Numerous confirmations of Looss' (1896) demonstration of skin penetration by hookworm larvae have established the general view that infections are almost exclusively acquired in this manner. On the other hand, it is now well known that after oral inoculation Ancylostoma caninum readily develops in dogs and cats and that development is direct, without migration through the lungs (Foster and Cross, 1934). It has been shown also that after inoculations into mice and other common laboratory hosts, the larvae of Ancylostoma caninum, A. duodenale and N. americanus enter the tissues and undergo development, or not, in much the same manner whether given orally or percutaneously. In a recent study of the identifying features of the infective larvae and more advanced stages of several species of nematodes in the tissues of mice, Nichols (1956a, b) found that for A. caninum and N. americanus the location and character of the larvae were generally similar whether inoculations were given by mouth or by skin. No attempt was made, however, to compare the modes of inoculation in this regard or to describe in detail the distribution and persistence of the larvae. The present investigation was undertaken to examine more closely the migratory behavior and longevity of the larvae of A. caninum, A. duodenale and N. americanus in relation to different methods of inoculation in the mouse.