Parasitic helminths of the pig: factors influencing transmission and infection levels

The occurrence of parasitic helminth species as well as infection intensiti es are markedly influenced by the type of swine production system used. The present review focusses mainly on the situation in temperate climate regio ns. Generally, over the past decades there has been a decrease in the numbe r of worm species and worm loads in domestic pigs due to a gradual change f ron traditional to modern, intensive production systems. The reasons for so me species being apparently more influenced by management changes than othe rs are differences in the basic biological requirements of the pre-infectiv e developmental stages, together with differences in transmission character istics and immunogenicity of the different worm species. Control methods re levant for the different production systems are discussed. Outdoor rearing and organic pig production may in the future be confronted with serious pro blems because of particularly favourable conditions for helminth transmissi on. In addition, in organic farms preventive usage of anthelmintics is not permitted. (C) 1999 Australian Society for Parasitology Inc. Published by E lsevier Science Ltd. All rights reserved.