Abstract
Cases of human Ascaris infection occur sporadically in areas such as N. America and Western Europe, where this parasite is thought to be non-endemic. Clinical case histories suggest that many of these cases may be cross-infections from pigs. I describe patterns of variation in the ribosomal DNA of Ascaris from 9 such cases. For comparative purposes, I also describe patterns of variation in parasites obtained from pigs and humans from worldwide locations. A Hae III restriction site distinguishes two classes of rDNA repeats; repeats bearing this restriction site were found in > 96 % of parasites from pig populations worldwide and in all 9 worms from humans in N. America. In contrast, repeats bearing this restriction site were detected in < 2 % of parasites from humans in endemic areas. The molecular data clearly incriminate pigs as the source of infection in the N. American cases. I discuss evolutionary and public health implications of incomplete host fidelity in Ascaris.
Original language | English (US) |
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Pages (from-to) | 215-219 |
Number of pages | 5 |
Journal | Parasitology |
Volume | 110 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1995 |
Keywords
- Ascaris
- humans
- pigs
- ribosomal DNA
ASJC Scopus subject areas
- Parasitology
- Animal Science and Zoology
- Infectious Diseases