Environmental contamination and transmission of Ascaris suum in Danish organic pig farms

Abstract

BackgroundAlthough Ascaris suum is the most common pig nematode, the on-farm transmission dynamics are not well described.MethodsWe performed a 1-year field study on five organic pig farms, mapping egg contamination levels in pens and pasture soil as well as faecal egg counts in starter pigs, finisher pigs, dry and lactating sows. The uppermost bedding material was sampled from three pen areas (resting, intermediate and latrine) of shallow and deep litter pens.ResultsAscaris suum was found on all farms. Averaged across farm and season, the prevalence of A. suum was 48, 64, 28 and 15 % in starters, finishers, dry and lactating sows, respectively. For starters and finishers, the prevalence varied with season increasing towards the end of the year when 83–96 % of finishing pigs from each farm had fresh liver white spots. Farrowing pastures were contaminated with a mean of 78–171 larvated eggs/kg dry soil depending on farm, while pastures for starter pigs contained 290–5397 larvated eggs/kg dry soil. The concentration of eggs in soil was highest in the autumn. Indoors, all pen areas were contaminated with A. suum eggs at comparable levels for shallow and deep litter. Overall there were 106, 445 and 1331 eggs/g dry straw in the resting, intermediate and latrine areas, respectively. However, more eggs were undergoing development in resting areas (44 %) compared to intermediate (33 %) and latrine areas (13 %). Irrespective of area, more eggs were undergoing development in the autumn, but overall there were very few fully developed (i.e., infective) eggs in the bedding material. Laboratory embryonation of eggs from the bedding material nevertheless revealed that an overall mean of 79 % of the eggs were viable.ConclusionThe organic pigs of all ages were continuously exposed to A. suum, but mainly younger animals were infected. Deep litter appeared to be a less important source of A. suum eggs than previously believed compared to shallow litter. Long-term pasture rotation to eliminate pasture contamination was not possible, and control programs should therefore include thorough cleaning indoors and composting/long-term storage of bedding material and manure to inactivate eggs and reduce transmission to pigs.

Effect of endoparasites occurrence in sows from intensive production system

“…In addition, the lack of an effective control system would require more information on the epidemiological pattern, the availability of the new anthelmintics and the better education of the producers (TAMBOURA et al, 2006). Comparatively, Katakam et al (2016) found the occurrence of A. suum was 15% for lactating sows, a lower value than that obtained by Nissen et al (2011) with growing pigs (39.6% for A. suum). It is possible that the greater A. suum prevalence observed compared the results of other surveys can be explained by the fact that the sows are housed in pens with entirely concrete floors, and thus they were in direct contact with faeces.…”

Changes in the viability of the eggs of Ascaris suum under the influence of flavourings and source materials approved for use in and on foods

“…Therefore pigs in such farms are more heavily affected by A. suum infestation. "Organic" farms decrease the level of environmental contamination with A. suum eggs by regular mechanical cleaning of the pigs' living area from feces with further compulsory composting (Katakam et al, 2016). in their experiments studied the relationship between viability of A. suum eggs in deep litter and the litter's humidity and temperature.…”

“…First of all, these factors include parasitic diseases, such as ascariasis, trichocephalosis, oesophagostomiasis, strongyloidiasis, echinococcosis, cysticercosis, sarcoptosis, balantidiasis and others. The most widespread disease of pigs globally is ascariasis (De Velásquez et al, 2004;Feshenko, 2008;Evstafieva, 2010;Katakam et al, 2016). It causes great damage to swine-rearing.…”

Vaccination against parasites – status quo and the way forward

“…In contrast to these the nodule worm Oesophagostomum induces only a weak reaction of the host’s immune system [1], making the latter unsuitable for immunological intervention. With regard to the economic importance, porcine nematodes, especially Strongyloides , Trichuris and the nodule worms, have decreased in prevalence sind the advent of broad-spectrum anthelminthics and modern management, although A. suum prevalences can still be considerable, especially in traditional management systems or on organic farms [16, 29–31]. …”