Abstract
Suppression of egg production is the main parasitological manifestation of naturally acquired resistance to Schistosoma bovis in Sudanese cattle. In preliminary investigations on the mechanisms involved, 700-4,000 "suppressed" adult worms were surgically transplanted from six "resistant" donor cattle with very low fecal egg counts (0-8 eggs/g, epg) into six normal recipients. After transplantation, large numbers of eggs were excreted in the feces of the recipient cattle, beginning at between 5 and 16 days after operation, and reaching counts of 55-405 epg at between 6 and 20 days post transplantation. In the cattle with the highest egg counts, egg counts soon fell sharply from peak levels, whereas in cattle with lower peak counts, more steady counts were maintained. All the recipients were perfused at days 46-56, when between 0.1% and 78.5% of the transplanted worms were recovered. In the second experiment, 1,000-ml quantities of pooled sera from "resistant" donors were injected intraperitoneally into each of four normal recipient calves, while another four were injected with pooled sera from uninfected cattle. All the calves were challenged percutaneously the next day with 7,500 cercariae each, and the course of infection was followed by parasitological and clinical measurements until perfusion 18 weeks later. The results showed that the "immune" sera had a negligible effect on the numbers of worms which developed, and had no significant effect on the fecal egg counts or clinical parameters studied. There was, however, some evidence from the tissue egg counts of a reduction in the fecundity of the worms in calves injected with "immune" sera.(ABSTRACT TRUNCATED AT 250 WORDS)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: The American journal of tropical medicine and hygiene
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.