Dr. Murai Éva szerk.: Parasitologia Hungarica 12. (Budapest, 1979)

Localization It is known that in the rat on day six after a primary Nippostrongylus infection the owerwhelming majority of the worm burden is located in the upper half of the small intestine concentrating, as a rule, to an intestinal segment, some 20 cm in length beginning about 10 cm away from the pylorus. According to our own experience, the site location of adult Nippostrongyles in the Mastomys is less characteristic. Although in this host species, too, the bulk of worms (66. 8%) habitâtes the anterior half of the gut, worms are far more evenly disseminated, and a fair number of worms can be detected also in distal segments of the small intestine as early as 6 days after infection (Fig. 1). Table 4 Summary of data available on the course of infection of the rat and Mastomys natalensis with Nippostrongylus brasiliensis Lämmler et al. (1968) Pande et al. (1977) Present observations Mastomys 6-8-week-old Rat 5-week-old Mastomys 6-week-old Rat 6-week- old Mastomys 5-week-old Rat 5-10-week-old Larval dose 220 220 1000 1000 500 500 Prépaient period duration 7 days 6 days 5 days 5 days 6 days 5 days Maximum egg output by day 8 by days 8-10 by day 9 by day 7 by days 7-9 Patent period duration 3 days 7 days 7 days 2 days 9-12 days Rejection of worms by day 10 ? ? by day 9 after day 14 Egg output and worm rejection According to LÄMMLER et al. (1968) in the multimammate rat faecal discharge of Nippostrongylus eggs begins 7 days after larval infection, maximum faecal egg counts being reached on day 8, and by day 10 not only the egg output stops, but usually also the worms will be expelled. It follows that the pattern of egg output seen in Mastomys differs considerably from that found in the rat. The life cycle of Nippostrongylus in the latter host is characterized by a 5-day prépaient period, maximum egg output on days 7-9, and a subsequent gradual decrease of faecal egg counts lasting not infrequently as long as until days 18-20 (KASSAI, 1968). In contrast, the Indian authors (PANDE et al. , 1977) observed in Mastomys a 5-day prépaient period, maximum egg output on days 8-10, and a subsequent slow decrease of EPG (still notable on day 15, the terminal day of observation), i.e. a pattern similar to that found in the rat (Table 4). In the present studies the prépaient period was 1 day longer in the Mastomys than in the rat, i. e. egg discharge began as a rule on day 6. From days 8-9 after infection very few worm eggs were detectable in the faeces. The maximum EPGs recorded in the rat surpassed 7-20 time over those found in Mastomys (Fig. 2). These results indicate that in the multimammate rat the development of sexually mature worms is followed by a relatively low level