Biology Reference
In-Depth Information
thousands of eggs per day. As a consequence, even the survival of
a couple of worms will lead to an uncontrolled egg output, providing
a highly contaminated environment. Moreover, the aim should be to
develop a one-shot or two-shot vaccine and the price of vaccination will
need to be comparable to the price of standard anthelmintic treatment in
order to be profitable for the farmer. All of this, in combination with the
“traditional” difficulties associated with vaccine development like
producing a recombinant protein with equal effectiveness as its native
counterpart, contributes to the fact that today only a few research groups
are focusing on the development of new vaccines against this parasite and
that the chances that a vaccine against Ascaris will be available soon is
quite limited.
Impact of Management Practices
A routine application of anthelmintic drug seems to appeal to pig
farmers for reasons of convenience. 62 However, merely resorting to
anthelmintic treatment could result in little or no improvement due to
continuous reinfection. The use of anthelmintics therefore needs to be
complemented by higher quality farm hygiene and more effective farm
management practices in order to reduce the roundworm infection
pressure on the farm.
There are numerous aspects of farmmanagement that can have a major
impact on the epidemiology of A. suum . Undoubtedly, the type of
production system that is in use will be a key factor regarding the infec-
tion intensity on a farm. 62 For obvious reasons, there is a higher diversity
of parasite species and higher infection intensity on traditional farms and
where pigs have access to outdoor facilities when compared to intensive
indoor systems. 2,65
In intensive indoor systems, the presence of a breeding stock on
afarmseemstobeassociatedwithalowerchanceof A. suum being
present on the farm. More often than not, farmers are unaware of the
parasite status of the pigs that are bought from external producers.
Therefore, importing pigs from piglet producers evidently increases the
risk of introducing new infections into the herd. Farmers with fattening
herds are advised to buy piglets from larger piglet producers with good
management and hygiene 3 and that were preferably treated prior to
delivery. Whether weaners need to be treated at the beginning of
fattening or not is open for discussion. However, if their worm-free
status cannot be warranted, incoming pigs should be treated upon
arrival, thereby reducing the risk of introducing the infection into their
herd. Once A. suum is present on the farm, it is easily dispersed over the
whole farm through moving animals and dirty materials and boots.
Even flies have been shown to carry A. suum eggs. 81
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