title: Population dynamics of Ascaris suum in trickle-infected pigs.
abstract: The population dynamics of Ascaris suum was studied by long-term exposure of pigs to infective eggs. The pigs were experimentally inoculated with 25 A. suum eggs/kg/day, and 7, 8, and 8 pigs were necropsied at weeks 4, 8, and 14 postinoculation (PI), respectively. Despite the fact that the pigs were continuously reinfected, dramatic reductions in numbers of liver lesions (white spots) and migrating lung larvae were observed as a function of time. However, even at the end of the study, a few larvae were able to complete migration, but these larvae seemed unable to mature in the small intestine. Thus, the adult worm population seemed to consist of worms from the first part of the exposure period. The noticeable decrease in number of white spots suggests that the level of exposure is not reflected in the number of white spots in the late phase of a continuous infection. The serum levels of A. suum L3-specific IgG1 and IgA were significantly elevated by week 4 PI, after which the antibody levels declined. The population dynamics and parasite regulating mechanisms are discussed for A. suum in pigs as well as for the closely related species A. lumbricoides in humans.
authors: Danish Centre for Experimental Parasitology, Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark. pn@life.ku.dk
authors: Peter
authors: P
authors: Nejsum
authors: Stig M
authors: SM
authors: Thamsborg
authors: Heidi H
authors: HH
authors: Petersen
authors: Helene
authors: H
authors: Kringel
authors: Merete
authors: M
authors: Fredholm
authors: Allan
authors: A
authors: Roepstorff
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D001196:Ascariasis / Q000469:parasitology / Q000662:veterinary*; D017165:Ascaris suum / Q000254:growth & development* / Q000276:immunology; D005243:Feces / Q000469:parasitology; D005260:Female; D006790:Host-Parasite Interactions; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007421:Intestine, Small / Q000469:parasitology; D008099:Liver / Q000473:pathology; D008168:Lung / Q000469:parasitology; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D011157:Population Dynamics; D011897:Random Allocation; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013553:Swine Diseases / Q000469:parasitology*
chemical_list: D000909:Antibodies, Helminth; D007070:Immunoglobulin A; D007074:Immunoglobulin G