Experimental Ascaris suum infection in the pig: worm population kinetics following single inoculations with three doses of infective eggs.
To study population kinetics during primary Ascaris suum infections, 3 groups of 52 pigs each were inoculated with 100, 1000, or 10,000 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.
Roepstorff
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A
Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Frederiksberg, Copenhagen, Denmark. aro@kvl.dk
Eriksen
L
L
Slotved
H C
HC
Nansen
P
P
D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D001196:Ascariasis / Q000662:veterinary*; D017165:Ascaris suum / Q000254:growth & development*; D005260:Female; D007421:Intestine, Small / Q000469:parasitology; D008099:Liver / Q000469:parasitology / Q000473:pathology; D008168:Lung / Q000469:parasitology; D008208:Lymphatic System / Q000469:parasitology / Q000473:pathology; D008297:Male; D010063:Ovum; D010270:Parasite Egg Count; D011157:Population Dynamics; D013552:Swine; D013553:Swine Diseases / Q000469:parasitology*
D000909:Antibodies, Helminth