Relationship of the prevalence of swine helminths to management practices and anthelmintic treatment in Danish sow herds

The strong influence of management factors on coccidian infections in smallholder pig farms and the first molecular identification of Cystoisospora suis in Myanmar

A cross-sectional study was conducted to investigate coccidian infection and associated factors in smallholder pigs, and to identify Cystoisospora oocysts by PCR. A total of 500 pig faecal samples from 330 smallholder farms were collected in Nay Pyi Taw, Myanmar. The faecal flotation method was used to identify Eimeria and Cystoisospora species, and oocyst counts per gram (OPG) of faeces were recorded. Oocysts were differentiated after sporulation. Oocyst DNA was subjected to ITS1-targeted Cystoisospora-specific PCR. The overall coccidian oocyst detection rate by microscopic was 89.0% (445/500). Among the studied samples, 74.0% (370/500) and 70.6% (353/500), were found to be positive with Eimeria spp. and Cystoisospora suis oocysts, respectively. The sequences of C. suis detected were 100% identical to those of C. suis reported from Japan, and had 99.5% resemblance to sequences from Australia and China. Weaner pigs showed the significantly highest (p < 0.05) OPG when compared to other age groups. The highest intensity of coccidian infection (p < 0.05) was found in pigs fed local feed, pigs raised on earthen floors and pigs under poor hygienic conditions. Factors such as age, breed, feed type, and housing floors were found to be significantly associated with coccidian infection (p < 0.05). Age, as well as management factors including floor type, feed type, and hygiene practices on the farm, had a strong influence on the occurrence of coccidian infection in pigs. This is the first study in Myanmar on coccidian infection in pigs and molecular detection of C. suis.

First report on reduced efficacy of ivermectin on Oesophagostomum spp. on Swedish pig farms

Anthelmintic efficacy was investigated in nine sow herds that had been identified with high faecal egg counts in a prevalence study. Faecal samples were collected from a total of 104 individual sows, and analysed using a centrifugal flotation McMaster technique. Samples positive for strongyle eggs were cultured to third stage larvae (L3) for genus identification and then further identified to Oesophagostomum species by sequencing. Following the initial sample collection, the sows were treated with either fenbendazole (FBZ, n = 5 farms) or ivermectin (IVM, n = 4 farms) at the recommended dosing and sampled again 14 days post treatment. Faecal Egg Count Reduction (FECR) was used to determine the treatment efficacy. With respect to Ascaris suum, the anthelmintic treatment was successful (FECR >90%) on the five farms where this parasite was detected, regardless of what drug had been used. In contrast, 4/9 farms were positive for Oesophagostomum spp. post treatment, out of which three had a FECR of <90%. These three herds had all been treated with injectable IVM. Out of the six farms where treatment showed good efficacy (FECR 95-100%), five herds had used FBZ and one herd IVM. This study is the first to recognise reduced efficacy to IVM on Oesophagostomum spp. in Swedish pigs. Sequencing of the Oesophagostomum L3 showed that both O. dentatum and O. quadrispinulatum were present on 5/9 farms pre-treatment and on 2/9 farms post-treatment, unrelated to what anthelmintic had been used. Given these findings we could not correlate the reduced efficacy by the species of Oesophagostomum present in the herd. Prolonged usage of only one class of anthelmintic may predispose selection of resistance and has been suspected as a cause of treatment failure of porcine Oesophagostomum spp. in other studies. On all three farms showing reduced efficacy, IVM had been used as the sole anthelmintic drug for several years, and two of the farms also used IVM twice or more per year to control sarcoptic mange. A reduced efficacy to the available anthelmintic drugs used in the control of Oesophagostomum spp., may result in a subsequent surge of the possible negative effects caused by this parasite.

Gastrointestinal parasites in Swedish pigs: Prevalence and associated risk factors for infection in herds where animal welfare standards are improved

The global pig production has undergone major changes over the past 30 years with larger farms, more intensified production as well as improved hygiene and biosecurity practices. To investigate whether these changes, along with expanded pig welfare, have had an impact on parasite occurrence, a cross-sectional study was conducted in Sweden on farms where the pigs are always loose-housed, floors are solid and bedding material is provided. A total of 1615 faecal samples were collected on 42 conventional indoor farms from a) post-weaning piglets (n = 337); b) growers (n = 345); c) fatteners (n = 308); d) dry sows (n = 277) and e) pre-partum sows (n = 348). Samples were analysed using centrifugal flotation with a saturated glucose-salt solution and a modified McMaster technique, with a lower detection limit of 50 eggs or oocysts per gram. Samples positive for strongyle-type eggs were cultured to third stage larvae for genus identification. Farms also responded to a questionnaire regarding biosecurity, hygienic measures, and other management routines. Risk factors for parasite occurrence were assessed using mixed-effects logistical regression to account for farm-level clustering of samples. Interestingly, the prevalence of Ascaris suum was reduced compared to a similar investigation in the 1980s. In the present study A. suum was detected only in 43 % of the herds, with the highest prevalence in pre-partum sows (37 %) followed by fatteners (25 %). Small sized farms were associated with higher odds of being positive, compared to large sized farms (OR = 159.1, P = 0.010). Oesophagostomum spp. were detected in 64 % of the herds and again mainly in pre-partum sows (63 %). Trichuris suis was detected in 10 % of the herds but only in <1% of the samples. Moreover, Cystoisospora suis and Eimeria spp. were detected on 60 % and 64 % the farms, with the highest prevalence in post-weaning piglets and sows, respectively. Anthelmintic drugs (ivermectin or fenbendazole) were commonly used and administered mainly to pre-partum sows on 93 % of the farms. Toltrazuril against neonatal coccidiosis was administered to piglets on 14 % of the farms. The use of antiparasitic drugs did not significantly affect parasite prevalence. Overall, it appears that the altered farming routines with focus on improved pig welfare have not solely resulted in a higher occurrence of parasites, most likely due to the adequate biosecurity and hygiene practices instituted. Thus, there seems to be no conflict between implementing measures to promote pig welfare and adequately control the more pathogenic and economically important parasites.

Management practices related to the control of gastrointestinal parasites on Swedish pig farms

Background

Internal parasites are common in pigs worldwide and may induce clinical disease or subclinical infections with negative effects such as poor weight gain and reduced welfare, which in turn affect productivity. Effective parasite control to reduce the negative impact of parasitic infections demands a combination of antiparasitic drugs as well as various hygiene and biosecurity practices. The aim of this study was to obtain information on current management practices and parasite control routines used on Swedish pig farms using an online questionnaire.

Results

Antiparasitic drugs were used on 69% of the farms routinely and were mainly administered to sows just prior to farrowing. Less than 5% of the herds conducted faecal analysis for parasites. Batchwise, age segregated rearing was common and overall, it was practiced for piglets, growers, and fatteners on 88, 80 and 75% of the farms, respectively. Large and medium sized farms appeared to apply stricter hygiene and biosecurity measures to the growing pigs compared to small farms. Dry sows were mainly housed in groups on deep litter straw beds and cleaning, as well as disinfection, between each group was less common compared to what was practiced for growing pigs. Outdoor access was rare and only occurred on organic and small farms. Most of the farms, 54, 74 and 82% of small, medium, and large sized herds respectively, reported to have less than 5% white spot lesions, caused by migrating A. suum larvae, registered at slaughter.

Conclusion

Several risk factors for parasite infections, such as bedding material, group housing and solid floors, are mandatory requirements by national law. However, it was evident from this study that although strategic hygiene and biosecurity practices appeared common, they were not practiced in all herds and less so for dry sows. Antiparasitic drugs were used frequently and mainly through routine prophylactic treatments without prior testing for parasites. A holistic approach is necessary when designing efficient parasite control programs, and it is essential that management factors and routine monitoring of parasites are given attention. This to achieve efficient parasite control and reduce the risk of unnecessary use of antiparasitic drugs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-021-00193-3.

Enriched Housing Reduces Disease Susceptibility to Co-Infection with Porcine Reproductive and Respiratory Virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae) in Young Pigs

Until today, anti-microbial drugs have been the therapy of choice to combat bacterial diseases. Resistance against antibiotics is of growing concern in man and animals. Stress, caused by demanding environmental conditions, can reduce immune protection in the host, influencing the onset and outcome of infectious diseases. Therefore psychoneuro-immunological intervention may prove to be a successful approach to diminish the impact of diseases and antibiotics use. This study was designed to investigate the effect of social and environmental enrichment on the impact of disease, referred to as “disease susceptibility”, in pigs using a co-infection model of PRRSV and A. pleuropneumoniae. Twenty-eight pigs were raised in four pens under barren conditions and twenty-eight other pigs were raised in four pens under enriched conditions. In the enriched pens a combination of established social and environmental enrichment factors were introduced. Two pens of the barren (BH) and two pens of the enriched housed (EH) pigs were infected with PRRSV followed by A. pleuropneumoniae, the other two pens in each housing treatment served as control groups. We tested if differences in disease susceptibility in terms of pathological and clinical outcome were related to the different housing regimes and if this was reflected in differences in behavioural and immunological states of the animals. Enriched housed pigs showed a faster clearance of viral PRRSV RNA in blood serum (p = 0.014) and histologically 2.8 fold less interstitial pneumonia signs in the lungs (p = 0.014). More barren housed than enriched housed pigs developed lesions in the lungs (OR = 19.2, p = 0.048) and the lesions in the barren housed pigs showed a higher total pathologic tissue damage score (p<0.001) than those in enriched housed pigs. EH pigs showed less stress-related behaviour and differed immunologically and clinically from BH pigs. We conclude that enriched housing management reduces disease susceptibility to co-infection of PRRSV and A. pleuropneumoniae in pigs. Enrichment positively influences behavioural state, immunological response and clinical outcome in pigs.

The influence of endoparasites on selected production parameters in pigs in various housing systems

The aim of the study was to determine the level of lean meat content and daily gains of 400 fatteners infected by endoparasites and kept in two systems (shallow and deep litter). Slaughter evaluation of the pigs was conducted according to the EUROP carcass classification. In order to evaluate the average daily gains (g) during finishing period, body weights were investigated twice: at the beginning and at the end of the finishing period. The housing system affected the presence of Ascaris suum and Oesophagostomum spp. Infestation was found to be higher on shallow than on deep litter, and it significantly affected selected fattening and slaughter parameters of the fatteners. Infected animals were characterized by gains approximately 60 g lower than those of uninfected ones, while meatiness was higher in fatteners which were not infected at the end of the fattening period compared to animals with parasites (55.2% vs. 52.0%).

Identification of factors influencing the occurrence of milk spot livers in slaughtered pigs: A novel approach to understanding Ascaris suum epidemiology in British farmed pigs

Ascariosis is the most important internal parasitism present worldwide in farmed pigs. Milk spots are healing lesions occurring when Ascaris suum larvae migrate through the liver. This study aimed to identify current husbandry practices (e.g. wet/compound feeding, outdoors/indoors production, bedded/slatted floors) that influence the prevalence of milk spots in batches of slaughtered pigs, accounting for geographical locations and seasonality. Farm information was accessed through the British farm quality assurance programmes (QAPs) and information on milk spots was obtained from the pig abattoir based health schemes. Two working datasets were created. The first consisted of 505 farms recruited from the whole of Great Britain (GB). The second combined 338 farms from England and Wales (EW) with housing and feed category-specific information (e.g. for growers and finishers separately), which was not fully available for inclusion in the previous dataset. The variables were studied in multivariable beta-binomial models with the presence of milk spots being the response variable. Solid floor with bedding appeared as a risk factor, OR 1.52 (95% confidence intervals (CI) 1.26-1.85) for the GB sample, and OR 1.47 (CI 1.19-1.81) for the EW subset. Those GB herds that had all the stages of production indoors appeared to be at lower risk of milk spots (OR 0.4, CI 0.32-0.49). Changes were detected within year, with higher risk of milk spots in the second 6 months of the year OR 1.17 (CI 1.02-1.35) in the GB sample and 1.21 (95% CI 1.04-1.41) in EW farms. Overall this study suggests that those husbandry practices facilitating optimal levels of hygiene posed lower risk of milk spots in slaughtered pigs, potentially reflecting lower levels of ascariosis in the later stages of production.

Prevalence of Enteropathogens in Suckling and Weaned Piglets with Diarrhoea in Southern Germany

Faecal samples from suckling (n=205) and weaned piglets (n=82) with diarrhoea from 24 farms in Southern Germany were examined for shedding of important metazoic parasitic, viral and bacterial pathogens using culture, microscopic and electronmicroscopic methods. Escherichia coli isolates were tested further for the enterotoxin genes est‐Ia and elt‐I by colony blot hybridization. Isospora suis was diagnosed in 26.9 % and Cryptosporidium parvum in 1.4 % of the piglets investigated. The proportion of coronavirus‐positive animals was 13.4 % and 4 % were positive for rotavirus. It was found that 17.6 % of the animals were infected with enterotoxigenic E. coli (ETEC; 10.1 % ETEC‐ST‐Ia and 8.6 % ETEC‐LT‐I, respectively). The occurrence of the pathogens was significantly associated with the age of the animals examined (P < 0.001). Isospora suis was predominantly isolated from suckling piglets (in the second and third week of life), while in weaned piglets (fourth week of life) rotavirus and ETEC were most prevalent. On 22 of the 24 piglet production farms examined at least one of the investigated pathogens was detected. Coronavirus was diagnosed in 66.7 %, I. suis in 62.5 %, rotavirus in 20.8 % and C. parvum in 8.3 % of the farms. These results underline the fact that despite the hygienic, technical and immune preventive efforts during the last years, enteropathogens are still common in German piglet production units.

Empirical and theoretical evidence for herd size as a risk factor for swine diseases

Herd size is frequently studied as a risk factor for swine diseases, yet the biological rationale for a reported association with herd size (whether positive or negative) is rarely adequately discussed in published epidemiological studies. Biologically plausible reasons for a positive association between herd size and disease include a greater risk of introduction of pathogens from outside the herd, greater risk of transmission of pathogens within and among herds when the herd is large, and effects of management and environmental factors that are related to herd size. However, compared with owners of small herds, owners of large herds might more frequently adopt management and housing practices that mitigate this theoretically increased risk. We used studies of pleuritis, pneumonia and pseudorabies to describe the epidemiological issues involved in evaluations of the relationship between management factors, herd size and disease. In future studies, we recommend that (i) herd size be measured in a way that best characterizes the true population at risk; (ii) studies that evaluate management-related risk factors should account for herd size wherever possible; (iii) population-based studies of the interrelationships among management factors and between management factors, herd size, herd density and pig density be done; (iv) likely biological reasons for any herd-size effect be postulated; and (v) the distribution of herd sizes in the source population and the study sample be described.

Excretion in feces and mucosal persistence of Salmonellaser. Typhimurium in pigs subclinically infected with Oesophagostomum spp

OBJECTIVE

To determine interactions between Oesophagostomum spp and Salmonella ser. Typhimurium in pigs.

ANIMALS

30 healthy 5- to 6-week-old pigs.

PROCEDURE

Pigs were allotted to 3 groups (n = 10 pigs/group) and treated as follows: group A was given Oesophagostomum dentatum and O quadrispinulatum; group B was given O dentatum, O quadrispinulatum, and S Typhimurium; and group C was given S Typhimurium only. Pigs in groups A and B were trickle infected with Oesophagostomum spp 3 times weekly throughout the study. After 19 days, groups B and C were inoculated once with S Typhimurium. One pig from each group was euthanatized on the day of Salmonella exposure and 2 and 4 days after Salmonella exposure. The remaining pigs were euthanatized on days 16 and 17 after Salmonella exposure.

RESULTS

Pigs with dual infections of nematodes and bacteria (group B) excreted significantly higher amounts of S Typhimurium in feces, compared with nematode-free pigs (group C). In addition, group-B pigs excreted S Typhimurium on more days than pigs in group C. Salmonella Typhimurium was detected in the cecum and colon in the majority of pigs in group B, whereas S Typhimurium was only detected in the colon in pigs in group C. Immunohistochemical examination detected S Typhimurium in 7 of 9 pigs in group B but only 2 of 9 pigs in group C.

CONCLUSIONS AND CLINICAL RELEVANCE

Interactions between intestinal nematodes and bacteria may play an important role in the dynamics of S Typhimurium infections.

Prevalence of enteropathogens in suckling and weaned piglets with diarrhoea in southern Germany

Faecal samples from suckling (n = 205) and weaned piglets (n = 82) with diarrhoea from 24 farms in Southern Germany were examined for shedding of important metazoic parasitic, viral and bacterial pathogens using culture, microscopic and electronmicroscopic methods. Escherichia coli isolates were tested further for the enterotoxin genes est-Ia and elt-I by colony blot hybridization. Isospora suis was diagnosed in 26.9% and Cryptosporidium parvum in 1.4% of the piglets investigated. The proportion of coronavirus-positive animals was 13.4% and 4% were positive for rotavirus. It was found that 17.6% of the animals were infected with enterotoxigenic E. coli (ETEC; 10.1% ETEC-ST-Ia and 8.6% ETEC-LT-I, respectively). The occurrence of the pathogens was significantly associated with the age of the animals examined (P < 0.001). Isospora suis was predominantly isolated from suckling piglets (in the second and third week of life), while in weaned piglets (fourth week of life) rotavirus and ETEC were most prevalent. On 22 of the 24 piglet production farms examined at least one of the investigated pathogens was detected. Coronavirus was diagnosed in 66.7%, I. suis in 62.5%, rotavirus in 20.8% and C. parvum in 8.3% of the farms. These results underline the fact that despite the hygienic, technical and immune preventive efforts during the last years, enteropathogens are still common in German piglet production units.

Interactions between dietary fibre, endo-parasites and Lawsonia intracellularis bacteria in grower-finisher pigs

Samples of faeces and feed were collected from grower and finisher pigs kept on 25 commercial breeder-finisher units in the West-Midlands region of England. Faecal samples were examined for parasite eggs (Ascaris suis, Trichuris suum and strongylid species) using faecal flotation; and for Lawsonia intracellularis bacteria using the polymerase chain reaction. Feed samples were subjected to proximate analysis for energy, protein and fibre content and enzymic colorimetry for levels of non-starch polysaccharides (NSPs). Characteristics relating to housing, feeding and dung disposal systems and husbandry practices were recorded for each farm and assessed for their association with the presence of parasites and L. intracellularis at the herd level. Ascaris eggs were identified in 8% of herds, Trichuris eggs in 20% of herds and in strongylid eggs (Oesophogostomum and/or Hyostrongylus) in 44% of herds. Lawsonia intracellularis was detected in 15% of herds investigated. Herds positive for Trichuris and Ascaris had significantly lower levels of digestible energy and higher levels of neutral detergent fibre, total and insoluble NSPs in their diets than negative herds (p < 0.05). Housing weaners on slatted floors was associated with a significant decreased risk of parasite infection in grower-finishers (odds ratio = 0.09, p = 0.04) compared to housing on solid floors. The use of grower diets high in NSPs was associated with an increased risk of Trichuris infection (odds ratio = 27.6, p = 0.007). There was also an association at the herd level between infection with L. intracellularis and the presence of Trichuris eggs (odds ratio = 17.43, p = 0.069). It is concluded that control of dietary fibre intake (NSPs in particular) for growers and environmental hygiene (dung removal) for weaners appear to be the most important factors controlling parasite infection in grower-finisher pigs in the UK at present. The current move towards more straw based systems is thus likely to exacerbate the influence of these factors and is likely to result in increased parasite infection in grower-finisher pigs in the UK.

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

The occurrence of parasitic helminth species as well as infection intensities are markedly influenced by the type of swine production system used. The present review focusses mainly on the situation in temperate climate regions. Generally, over the past decades there has been a decrease in the number of worm species and worm loads in domestic pigs due to a gradual change from traditional to modern, intensive production systems. The reasons for some species being apparently more influenced by management changes than others are differences in the basic biological requirements of the pre-infective developmental stages, together with differences in transmission characteristics and immunogenicity of the different worm species. Control methods relevant for the different production systems are discussed. Outdoor rearing and organic pig production may in the future be confronted with serious problems because of particularly favourable conditions for helminth transmission. In addition, in organic farms preventive usage of anthelmintics is not permitted.

Intestinal parasites in swine in the Nordic countries: prevalence and geographical distribution

In Denmark (DK), Finland (FIN), Iceland (I), Norway (N), and Sweden (S), 516 swine herds were randomly selected in 1986-1988. Individual faecal analyses (mean: 27.9 per herd) from eight age categories of swine showed that Ascaris suum, Oesophagostomum spp., Isospora suis, and Eimeria spp. were common, while Trichuris suis and Strongyloides ransomi-like eggs occurred sporadically. Large fatteners and gilts were most frequently infected with A. suum with maximum prevalences of 25-35% in DK, N and S, 13% in I and 5% in FIN. With the exception of the remarkably low A. suum prevalence rates in FIN, no clear national differences were observed. Oesophagostomum spp. were most prevalent in adult pigs in the southern regions (21-43% in DK and southern S), less common in the northern regions (4-17% adult pigs infected), and not recorded in I. I. suis was common in piglets in DK, I, and S (20-32%), while < 1% and 5% were infected in N and FIN, respectively. Eimeria spp. had the highest prevalences in adult pigs (max. 9%) without clear geographical differences. I. suis and Eimeria spp. were recorded for the first time in I, and I. suis for the first time in N.

Helminth surveillance as a prerequisite for anthelmintic treatment in intensive sow herds

Helminth prevalences in pigs in intensive production systems are often very low due to housing and management factors, and the present study was carried out to examine whether routine anthelmintic treatment in such herds can be replaced by coprological surveillance of the helminth status combined with anthelmintic treatment when necessary. After an initial examination, 25 out of 28 large herds of Danish sows (> or = 50 sows, production of fatteners) were found to have such light helminth infections that routine deworming could be replaced experimentally by coprological examination every 6 months of 10 weaners (10-12 weeks old), 10 fatteners (5-6 months old), 10 dry sows and 10 lactating sows. This coprological surveillance continued in 21 herds of the selected 25 herds for a 3-year period, while it was stopped immediately in one herd due to increasing Ascaris suum prevalences, and ceased after one year in three herds due to other reasons. A. suum was found in all but one of the 25 herds. The most heavily infected age group was the sows, in which the A. suum prevalence was consistently low in approximately half of the herds, while it increased slowly or rapidly in the other half. When this happened, treatment of the breeding stock was recommended which resulted in low prevalences for varying periods of time. Few farmers neglected the recommendations for some time or for all 3 years, which resulted in consistently high prevalences in the sows (e.g. 40-60%). The fatteners were in general more lightly infected with A. suum than the sows, and in approximately 3/4 of the herds the prevalence remained at a low level, while it fluctuated in the remaining herds. No weaners were ever found to excrete eggs, most likely due to unfavourable conditions for egg development in the farrowing pens. Throughout the study Oesophagostomum sp. eggs were found sporadically in the sows of two herds, and in a third herd, Oesophagostomum sp. was introduced after 2 years, probably due to close contact with a neighbour herd. Oesophagostomum sp. was not found in the remaining herds. Eggs of Trichuris sp. were found sporadically. In conclusion, it is recommended that veterinarian advisers evaluate the production systems before suggesting an anthelmintic routine. If helminth infections may be controlled by intensive management and housing alone, coprological surveillance combined with anthelmintic treatment when necessary may replace routine use of anthelmintics. If the surveillance reveals that the infection levels continue to be low unnecessary medication is avoided, and if the infection levels increase, the coprological data obtained can be used to optimize the anthelmintic strategy.

Epidemiology and control of helminth infections in pigs under intensive and non-intensive production systems

Swine production systems are characterised by a high diversity with regard to management type and the level of intensity of management. The number of helminth species and their infection levels are strongly influenced by the different systems. The present paper focuses on the situation in northern Europe, with examples from Denmark, and describes a decrease in both the number of helminth species and in their infection levels as a result of a shift from non-intensive to highly intensive production systems. Differences in the basic biological requirements of the pre-infective larvae, and in the transmission characteristics and immunogenicity of the various helminth species, explain why some species are more vulnerable to manage mental changes than others. Finally, control measures for the different production systems are discussed. Even though it is well documented that proper hygiene and management may prevent transmission of helminths, use of anthelmintics is still the single most important action taken by pig farmers to control worm infections. It is emphasised that anthelmintics should not be used uncritically, but should be integrated with management practices and the production system to achieve optimum effect and to avoid development of anthelmintic resistance.

Transmission of intestinal helminths in Danish sow herds

Faecal samples from sows and their litters, all untreated with anthelmintics, were examined in eight sow herds, ranging from very intensive to very traditional management. Four helminth genera were recorded, namely Oesophagostomum sp., Ascaris suum, Trichuris suis and Strongyloides ransomi. The herds with the most intensive management were only infected with A. suum, while the more traditionally managed herds were infected with three or four species. In one herd, the sows showed a small relative increase in the excretion of Oesophagostomum eggs during lactation, but in general there was no consistently observable peri-parturient increase in faecal egg output. Furthermore, faecal examination of 5-12-week-old pigs indicated that sow-to-piglet transmission was important in the traditionally managed herds, while it was negligible in the intensive herds. A seasonal variation in the excretion of Oesophagostomum sp. and A. suum eggs was observed in the youngest pigs in the traditional herds, with the highest faecal egg counts occurring in the summer and autumn. However, this pattern became indistinct during the fattening period and did not exist in the sows, except for A. suum infections in the heavily infected traditional herds. The helminths egg excretion in the intensive herds did not show any seasonal variation.