The distribution of larval Aspiculuris tetraptera Schulz during a primary infection in Mus musculus, Rattus norvegicus and Apodemus sylvaticus

The larvae of Aspiculuris tetraptera were found in the mid-colon of mice within hours of infection. When the colon was divided into 10 equal sections the larvae were mainly found in sections 5, 6 and 7 during the first 6 days of the infection. The worms entered the crypts of Lieberkühn in this region on day 1 and remained there until day 4 or 5. After this time they left the crypts and returned to the lumen of the colon. On day 7 the worms emigrated anteriorly and thereafter were recovered only from the proximal region of the colon (sections 1–4), although in heavier infections a few larvae remained in the mid-colon.The initial establishment site was the same in both Rattus norvegicus and in Apodemus sylvaticus, but an infection with A. tetraptera in the abnormal hosts, R. norvegicus and A. sylvaticus, was characterized by less than 7% of the inoculum becoming established, a slower rate of growth and a wider distribution centering around the preferred site. The small number of established larvae was lost from the rat before day 12 and from A. sylvaticus before day 8, whereas larvae persisted in laboratory mice for a longer period.