Parasitology


Research Article

Experimental Ascaris suum infection in the pig: worm population kinetics following single inoculations with three doses of infective eggs


A. ROEPSTORFF a1 , L. ERIKSEN a2 , H.-C. SLOTVED a1 a2 and P. NANSEN a1
a1 Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Bülowsvej 13, DK-1870 Frederiksberg C, Copenhagen, Denmark
a2 Department of Clinical Studies (Internal Medicine), Royal Veterinary and Agricultural University, Bülowsvej 13, DK-1870 Frederiksberg C, Copenhagen, Denmark

Abstract

To study population kinetics during primary Ascaris suum infections, 3 groups of 52 pigs each were inoculated with 100, 1000, or 10000 infective eggs. In all groups, the majority of larvae was found in the liver on day 3 post inoculation (p.i.) and in the lungs on day 7 p.i. Liver white spots, caused by migrating larvae, were most numerous at day 7 p.i., whereafter they gradually healed, and only low numbers of granulation-tissue type white spots and lymphonodular white spots persisted at days 21–56 p.i. Independent of dose level, 47–58% of the inoculated eggs were recovered as larvae in the small intestine on day 10 p.i., but most larvae were eliminated at days 17–21 p.i. This elimination started earlier and removed a higher percentage of the worms with increasing inoculation dose, resulting in small strongly aggregated worm populations by day 28 p.i. (k of the negative binomial distribution was low: 0·2–0·4) without significant differences between groups. Thus, overdispersion, which is a characteristic of both porcine and human ascarosis, is found here under experimental conditions where aggregation factors like host behaviour, transmission rate, host status etc have been partly or totally controlled.

(Received February 25 1997)
(Revised April 19 1997)
(Accepted April 19 1997)

Key Words: pigs; Ascaris suum; dose rate; migration; overdistribution; white spots.

Correspondence:

Corresponding author: Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Bülowsvej 13, DK-1870 Frederiksberg C, Copenhagen, Denmark. Tel: +45 35282775. Fax: +45 35282774. E-mail: aro@kvl.dk



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