Concurrent Ascaris suum and Oesophagostomum dentatum infections in pigs.

The aim of this study was to examine interactions between Ascaris suum and Oesophagostomum dentatum infections in pigs with regard to population dynamics of the worms such as recovery, location and length; and host reactions such as weight gain, pathological changes in the liver and immune response. Seventy-two helminth-na?ve pigs were allocated into four groups. Group A was inoculated twice weekly with 10000 O. dentatum larvae for 8 weeks and subsequently challenge-infected with 1000 A. suum eggs, while Group B was infected with only 1000 A. suum eggs; Group C was inoculated twice weekly with 500 A. suum eggs for 8 weeks and subsequently challenge-infected with 5000 O. dentatum larvae, whereas Group D was given only 5000 O. dentatum larvae. All trickle infections continued until slaughter. Twelve pigs from Group A and B were slaughtered 10 days post challenge infection (p.c.i.) and the remaining 12 pigs from the each of the four groups were slaughtered 28 days p.c.i.. No clinical signs of parasitism were observed. The total worm burdens and the distributions of the challenge infection species were not influenced by previous primary trickle-infections with the heterologous species. Until day 10 p.c.i. the ELISA response between A. suum antigen and sera from the O. dentatum trickle infected pigs (Group A) pigs were significantly higher compared to the uninfected Group B. This was correlated with a significantly higher number of white spots on the liver surface both on Day 10 and 28 p.c.i. in Group A compared to Group B. The mean length of the adult O. dentatum worms was significantly reduced in the A. suum trickle infected group compared to the control group. These results indicate low level of interaction between the two parasite species investigated.     

Evidence of interaction between Ascaris suum and Metastrongylus apri in experimentally infected pigs

A study has been carried out with the aim to determine possible interactions between Ascaris suum and Metastrongylus apri under experimentally infected pigs. Twenty-eight Iberian pigs were allocated into four groups. Group 1 was inoculated with 5000 infective A. suum eggs; group 2 received concurrently 5000 infective A. suum eggs and 5000 infective M. apri larvae; group 3 received 5000 infective M. apri larvae; group 4 served as uninfected controls. In each group, pigs were necropsied on day 7 (n = 4) and day 28 (n = 3) post-infection (p.i.). Pigs with single M. apri infections showed earlier and more severe respiratory symptoms compared to pigs with mixed infection, while no clinical signs were observed in pigs single infected with A. suum. Mean burdens of immature A. suum and immature and adult M. apri were reduced in pigs with concomitant infection both on day 7 and 28 p.i., respectively. In contrast, the number of white spots was significantly increased on day 7 in pigs with mixed infection. In addition, pigs of group 1 showed the highest eosinophil levels in blood compared to pigs in groups 2 (intermediate levels) and 3 (moderate levels). The results suggest an antagonistic interaction between A. suum and M. apri in concomitantly infected pigs.     

Immunization of pigs against Ascaris suum by sequential experimental infections terminated with fenbendazole during larval migration

Three experimental infections of weaning pigs with 2000 embryonated Ascaris suum eggs each, 11 days apart, followed each time by fenbendazole treatment, produced a significant host response when compared with similar infected or uninfected control pigs as assessed by response to a subsequent challenge with 100 embryonated A. suum eggs. The response elicited from pigs treated with fenbendazole on either 2, 3, and 4 days or, 6, 7, and 8 days after each experimental infection was expressed as a reduction in the number of pigs with A. suum, in the number of worms per pig, in the weight of male and female worms, and in the length of male and female worms. No differences in average daily weight gain, feed-conversion efficiency or histology of lungs and liver were noted among the 4 treatment groups.     

Effect of fenbendazole and pyrantel tartrate on the induction of protective immunity in pigs naturally or experimentally infected with Ascaris suum

An experiment was conducted with 96 weanling pigs (avg initial wt 18.5 kg) divided into six treatment with two replicates of eight pigs each. Pigs in Treatments 1, 2 and 3 were penned in outside pens with dirt lots that previously were contaminated with A. suum ova to induce a natural ascaris infection. Pigs in Treatments 4, 5 and 6 were penned in an open-front building with solid concrete floors and were experimentally infected with 2,000 embryonated A. suum. ova on d 1, 15 and 29 of the experiment. Pigs in Treatments 1 and 4 were medicated with fenbendazole (FBZ, 3 mg/[kg BW.d]) for three consecutive days during three consecutive time periods. Pigs in Treatments 2 and 5 were medicated with pyrantel tartrate (PT, 106 mg/kg feed) for 28 d. Pigs in Treatments 3 and 6 served as infected, unmedicated controls. All pigs were challenged with 100 A. suum eggs 7 d after termination of the final FBZ treatment. All pigs were killed 66 d after challenge and worms were recovered. Fenbendazole treatment resulted in greater (P less than .07) average daily gain than PT treatment in pigs penned outside. Among inside pigs, FBZ treatment resulted in better (P less than .02) feed utilization than in controls. The FBZ and PT treatments reduced (P less than .03) the total number of A. suum, the length and weight of female ascarids and the length of male ascarids compared with controls. A natural continual infection with A. suum was less effective than experimental infection in inducing protective immunity in pigs.     

Concurrent infection with Trichinella spiralis and other helminths in pigs

The aim of this study was to investigate possible influence of different helmintosis in the development of Trichinella spiralis in experimental infected pigs. Forty-two Iberian pigs were allocated to six groups. Three groups were single inoculated with Ascaris suum, Metastrongylus apri or T. spiralis, respectively. Two groups were co-infected with T. spiralis and A. suum or T. spiralis and M. apri, respectively, while the last group included uninfected control pigs. Clinical signs were only observed in pigs with single or concurrent M. apri infections, with more severe respiratory symptoms in pigs with mixed M. apri infection. The number of A. suum and M. apri lung larvae, intestinal larvae of A. suum and adult M. apri were reduced in pigs with mixed Trichinella infections compared to pigs with single infections. In contrast, the number of liver white spots was higher in pigs with mixed infections. While T. spiralis muscular larval burdens were increased in pigs concomitantly infected with M. apri, they were reduced in pigs concomitantly infected with A. suum, compared to pigs receiving single infections with either of these helminths. Pigs with single or mixed A. suum infections showed higher eosinophil levels compared to the remaining groups. IgGt, IgG1, IgG2 and IgM against T. spiralis antigen could not be detected in pigs with single Ascaris or Metastrongylus infections, indicating that no cross-antibodies were produced. IgGt, IgG1 and IgM antibodies were detected earlier and generally at higher levels in mixed T. spiralis infections compared to single T. spiralis infections. The results suggest that T. spiralis had a low synergistic interaction with M. apri in concomitantly infected pigs, and an antagonistic interaction in concurrent infection with A. suum.     

Susceptibility of fourth-stage Ascaris suum larvae to fenbendazole and to host response in the pig

Fenbendazole given at the rate of 2.5 g/kg of feed for 3 days had 100% efficacy against 4th-stage Ascaris suum larvae in 8 pigs. Eight control pigs had a total of 108 A suum. In 6 pigs infected 3 times with 3rd-stage A suum larvae and treated with fenbendazole after the larvae molted to the 4th stage, the challenge exposure-derived population was decreased by 64%. Similar sequential infections in 6 pigs similarly infected, but not treated with fenbendazole, decreased the challenge exposure-derived population by 98%; however, developing and/or adult worms from the vaccinating infections were present.     

Serum levels of gastrin, insulin and glucagon as possible factors of anorexia in pigs infected once with Ascaris suum

In order to determine possible mediators for development of anorexia in pigs infected with Ascaris suum, serum levels of gastrin, insulin and glucagon were measured. After a single high oral dose of 100,000-200,000 embryonated eggs the serum levels of gastrin and insulin in the infected pigs did not significantly differ from those in controls. Serum glucagon levels in the infected groups, however, were lower than those in controls and the difference was more evident 24 days postinoculation and later.     

Effects of multiple dose infections with Ascaris suum on blood gastrointestinal hormone levels in pigs

Ten consecutive daily doses of infective Ascaris suum eggs were administered to pigs in two experiments and the levels of gastrointestinal hormones in their blood were measured. The piglets in each experiment were divided into low-dose (LDI) and high-dose (HDI) infections and control groups. Infected pigs had lower feed consumption, lower weight gains, and lower feed efficiency than control pigs. Serum gastrin levels in infected pigs were significantly lower than the controls from Days 7 to 17 post first inoculation (PFI), and so were their serum glucagon levels from Days 12 to 24 PFI. Serum insulin levels in infected animals were sometimes lower than those in controls. These differences were usually more intense in the LDI pigs than in HDI pigs. The plasma cholecystokinin (CCK) levels in the LDI group were significantly higher than those in controls from Day 10 PFI to the end of the experiment, while the CCK levels in the HDI group did not differ significantly from the controls. Increased plasma CCK levels could be a satiety factor in A. suum infection since the time of occurrence of high levels of CCK matched the period of reduced feed consumption.     

Evaluation of a serodiagnostic test using Ascaris suum haemoglobin for the detection of roundworm infections in pig populations

The significant economical consequences of infections with Ascaris suum in pigs are already well documented. However, due to the subclinical nature of the disease and the lack of practical diagnostic means, ascariasis often remains undiagnosed. Here we describe the development and evaluation of a novel indirect ELISA using the purified A. suum haemoglobin (AsHb) molecule as an antigen. Initial validation using sera from 190 pigs experimentally infected twice a week with A. suum and Trichuris suis (25 and 5eggskg(-1)day(-1) respectively) demonstrated that the AsHb ELISA is able to detect long-term exposure to A. suum with a high sensitivity and specificity (99.5% and 100.0% respectively). Furthermore, this serological technique proved to be more sensitive than faecal examination on week 7 and 14 of the experiment (99.5% and 100% compared to 59.5% and 68.4% respectively). Cross-reactivity caused by T. suis infection was shown to be limited after analysing sera from pigs with an experimental T. suis mono-infection. Seroconversion was shown to occur from week 6 onwards in pigs receiving 100 A. suum eggs 5 times a week. Preliminary testing of the ELISA on six randomly selected farms confirmed the results obtained in the artificial infection trials, showing a higher sensitivity of the serologic method compared to faecal examination. Finally, the ELISA was used to investigate Ascaris infection rates on 101 conventional Flemish pig farms. The results showed that on 38.6% of the farms less than 20% of the tested samples were seropositive, while in 19.8% of the farms 80-100% of all pigs were seropositive. The results of this study suggest that the AsHb ELISA could provide pig farmers and veterinarians with an easier and more sensitive way to estimate the overall prevalence of A. suum on their farm.     

Immunohistochemical distribution of antigens in liver of infected and immunized pigs with Ascaris suum

In the present work, we carry out an immunopathological study of the swine ascariosis, under different conditions (control, infection and immunization). Twenty-one Iberian pigs were used and divided in seven groups. Groups 1 and 2 were the uninfected and challenged controls, respectively. Groups 3 and 4 were weakly infected with increasing doses of Ascaris suum eggs and treated with pyrantel (Group 4). Groups 5-7 were immunized with 14, 42 and 97 kDa proteins from the parasite, respectively. Groups 2-7 were challenged with 10,000 infective eggs 7 days before the sacrifice. The focal parasitic granulomata with eosinophils and lymphocytes were the main histopathological lesions in the liver of reinfected pigs, while more marked cellular infiltrate and abundant connective tissue were seen in the livers of immunized animals. There were important deposits of antigens in the livers of immunized and infected pigs. Antigens were mainly located in the connective tissue, with positive staining detection of the somatic larvae antigen, the body wall from the adult worms and the 14-, 42- and 97-kDa proteins. However, cholangiols, biliary ducts and macrophages presented an immunohistochemical positive stain against excretory-secretory and somatic antigens from the larvae and the body fluid antigen from the adult parasite. The detection of A. suum antigens in the liver of infected pigs improves the diagnosis of swine ascariosis. It may be possible to apply these procedures for diagnosis of human ascariosis in liver biopsies since A. suum from swine have been previously used as a substitute for the study of the human parasite Ascaris lumbricoides.     

Influence of an experimental infection of Ascaris suum on performance of pigs

Thirty-two pigs (average 26.6 kg live weight) were individually housed and fed to study the effect of an infection of Ascaris suum (either 0, 600, 6,000 or 60,000 A. suum eggs/pig) on performance of growing-finishing pigs. Increasing the level of A. suum infection produced linear (P less than .07) and quadratic (P less than .09) effects on final weight, weight gain and average daily gain. Feed to gain ratio and number of A. suum worms recovered from the intestines of pigs at slaughter increased linearly (P less than .01) with increasing doses of A. suum eggs. Pigs receiving 60,000 A. suum eggs were 13% less (P less than .01) efficient than the noninfected controls. In each of two trials, eight crossbred barrows (15.7 kg in trial 1 and 16.1 kg body weight in trial 2) were examined for the effects of two levels of A. suum infection (0 and 20,000 eggs/pig) on digestibility coefficients for dry matter, crude protein and gross energy. The infection did not affect (P greater than .05) digestibility coefficients during the first two collection periods (d 6 through 10 and 19 through 23). However, digestion coefficients for dry matter, crude protein and gross energy obtained from the total collection period on d 33 through 37 postinfection were greater (P less than .01) for control pigs than for pigs given 20,000 A. suum eggs each. Also, N retention was greater (P less than .05) for control pigs than for infected pigs.     

Alterations of serum insulin-like growth factor-I (IGF-I) and IGF-binding proteins (IGFBPs) in swine infected with the protozoan parasite Sarcocystis miescheriana.

The effects of a Sarcocystis miescheriana infection on insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBPs) were investigated to determine possible mechanisms of growth retardation in growing pigs. Sixteen pigs averaging 14 kg body weight were divided into 4 groups of 4 pigs each and infected either with 0.5, 1.0, or 3.0 × 10⁶ sporocysts of S. miescheriana. Four pigs were retained as non-infected controls; however, they became serologically positive during the course of the infection. Effects also were investigated in 2 groups of 3 pregnant sows. One group was infected with 0.5 × 10⁶ sporocysts and the other group was retained as uninfected controls. Body weights of infected growing pigs were depressed as compared to controls following the acute phase 15 d after infection (dai). Serum concentrations of IGF-I dropped significantly (p < 0.05) during the acute phase of infection in all infected groups of growing pigs. Conversely, the amounts of unsaturated serum IGFBPs were elevated significantly (p < 0.05) during the acute phase of infection. Specifically, serum concentrations of IGFBP-1, IGFBP-2, and IGFBP-4 were elevated at this time, as determined by ligand blot analysis. There was no association between growth factor alterations and tissue damage as measured by serum creatinine kinase and aspartate aminotransferase levels. The extent of effects in growing pigs was related to the amount of the original parasite inoculum.

During the acute phase of infection 2 of 3 pregnant sows aborted. The third sow went to term, but piglets were stillborn or died within 24 hr. Compared to uninfected controls, serum concentrations of IGF-I in infected pregnant sows were depressed during and after the acute phase of the infection. Levels of unsaturated serum IGFBPs in pregnant sows were not affected.

These data suggest that decreased IGF-I levels and/or elevated levels of specific forms of IGFBPs may be a mechanism by which growth is affected in feeder pigs infected with S. miescheriana.     

Presence of immunoglobulins and antigens in serum, lung and small intestine in Ascaris suum infected and immunised pigs

The immunodetection of local Ascaris suum antigens and local and systemic antibodies were analysed in pigs reinfected with eggs or immunized with the 14, 42 and 97 kilodalton (kDa) fractions from A. suum. Twenty-one Iberian pigs were divided in 7 groups of 3 pigs. Groups 1 and 2 were uninfected and challenge control groups, respectively. Groups 3 and 4 were infected weekly with increasing doses of A. suum eggs and Group 4 was additionally treated with pyrantel pamoate. Groups 5, 6 and 7 were immunised with the 14, 42 or 97 kDa fractions from adult worms, respectively. Groups 2-7 were challenged with 10,000 infective eggs. Animals of Groups 3 and 4 showed a pulmonary granulomatous reaction with moderate number of eosinophils and leukocytes, while Groups 5-7 presented higher number of cells, especially in animals immunized with the 42 kDa fraction. These immunized groups presented abundant deposition of Ascaris body fluid (BF) and body wall (BW) antigens as well as the 14 and 42 kDa fractions in the pulmonary and intestinal tissues, while lower deposition of antigens was observed in animals of Groups 3 and 4. The immunized pigs of Groups 5 and 6 showed the highest systemic IgG titres in serum and these antibodies were negatively correlated with the number of larvae recovered in the lungs, suggesting that the IgG response may have a protective function against the ascariosis. The highest concentrations of IgA-bearing cells were observed in animals of Groups 3 and 4 compared to the immunised pigs (Groups 5-7), suggesting that local IgA production may be involved in the protection against migrating larvae. The main localisations of IgA-bearing cells were the bronchial and peribronchial areas of lungs and the lamina propia of duodenum. Low numbers of local IgG-bearing cells were observed in all animals and no IgM-bearing cells were detected in the local tissues.     

Comparison of sensitivity and specificity in three commercial foot-and-mouth disease virus non-structural protein ELISA kits with swine sera in Taiwan

Three commercialized ELISA kits for the detection of antibodies to the non-structural proteins (NSPs) of FMD virus were compared, using sera from uninfected, vaccinated, challenged and naturally infected pigs. The kinetics of the antibody response to NSPs was compared on sequential serum samples in swine from challenge studies and outbreaks. The results showed that ELISA A (UBI) and ELISA B (CEDI) had better sensitivity than that of the 3ABC recombinant protein-based ELISA C (Chekit). The peak for detection of antibodies to NSPs in ELISA C was significantly delayed in sera from natural infection and challenged swine as compared to the ELISA A and B. The sensitivity of the three ELISAs gradually declined during the 6-month post-infection as antibodies to NSP decline. ELISA kits A and B detected NSP antibody in 50% of challenged pigs by the 9-10th-day and 7-8th-day post-challenge, respectively. ELISA B and C had better specificity than ELISA A on sequential serum samples obtained from swine immunized with a type O FMD vaccine commercially available in Taiwan. Antibody to NSPs before vaccination was not detected in swine not exposed to FMD virus, however, antibody to NSPs was found in sera of some pigs after vaccination. All assays had significantly lower specificity when testing sera from repeatedly vaccinated sows and finishers in 1997 that were tested after the 1997 FMD outbreak. However, when testing sera from repeatedly vaccinated sows or finishers in 2003-2004, the specificity for ELISAs A, B and C were significantly better than those in 1997. This effect was less marked for ELISA A. The ELISA B was the best test in terms of the highest sensitivity and specificity and the lowest reactivity with residual NSP in vaccinates.     

Efficacy of an in-feed preparation of ivermectin against endoparasites and scabies mites in swine.

In 2 trials, the efficacy of an in-feed preparation of ivermectin was evaluated in 40 pigs naturally infected with endoparasites and Sarcoptes scabiei var suis. Treated pigs (n = 10 in each trial) were fed a ration containing 2 ppm ivermectin for 7 days, followed by consumption of a nonmedicated ration for the remainder of the trial. Control pigs (n = 10 in each trial) were fed a complete, nonmedicated ration for the duration of the trial. Pigs in trial A were monitored for 14 days after treatment; those in trial B were monitored for 35 days after treatment. In trial A, treatment efficacy of ivermectin was 100% against Ascaris suum, Physocephalus sexalatus, Oesophagostomum dentatum, O brevicaudum, Metastrongylus spp; 99.8% against Ascarops strongylina; 90.9% against Trichuris suis; and 13.1% against Macracanthorhynchus hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were observed between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Oesophagostomum spp. On posttreatment day 14, S scabiei were not found in any scrapings taken from treated pigs, but were found in scrapings from 3 of 10 control pigs. The number of infested pigs in the treatment group was not statistically different from the number of infested pigs in the control group. In trial B, treatment efficacy was 100% for A suum and Metastrongylus spp; 96.9% for Ascarops strongylina; and 76.9% for M hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were evident between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Metastrongylus spp.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative studies of experimental oral inoculation of pigs with Ascaris suum eggs or third stage larvae

This experimental study was designed to compare the acquired resistance in pigs to Ascaris suum eggs following 4-weekly oral immunizations with either 200 A. suum infective eggs or 50 A. suum third stage larvae (L3). The two immunized groups (n = 7) together with an unimmunized control group (n = 7) of pigs were challenged orally with 50 infective A. suum eggs per kilogram bodyweight on day 19 after the last immunization. Seven days post-challenge the group immunized with eggs showed signs of resistance as evidenced by reduced lung larval counts compared with the challenge control group. Such significant resistance was not observed in the L3-immunized group. However, a markedly increased inflammatory liver reaction and white spot formation was demonstrated in the L3-immunized pigs after challenge compared with both control animals and egg-immunized pigs. On the day of challenge only the egg-immunized pigs mounted an anti-Ascaris antibody response both in serum and in lung lavage fluid. Ascaris-antigen induced increased histamine release from peripheral leucocytes following both immunization and challenge could only be demonstrated in the egg-immunized pigs. On day 7 post-challenge local IgA-anti-Ascaris antibodies were further demonstrated in bile of the egg-immunized group and in the small intestine of both immunized groups. In conclusion, oral A. suum egg immunization of pigs induced a significant reduction in lung larval counts upon challenge. In contrast, oral L3 immunization seemed to prime the pigs as observed by the presence of stunted lung larval growth and increased liver reaction post-challenge with A. suum eggs.     

苏云金芽胞杆菌伴胞晶体蛋白对猪体内蛔虫的作用及其血液生理生化指标的分析

感染性猪蛔虫卵以每头份3000个卵的量感染断奶仔猪，于第3天开始肌肉注射不同剂量苏云金芽胞杆菌晶体蛋白（insecticidal crystal proteins，ICPs），每天1次，连续4d。同时测定猪血液生理生化指标，饲喂2个月后收集猪粪便计算虫卵数。结果显示，感染猪出现咳嗽、发热等临床症状，GOT、GPT、ALP、LDH等指标明显升高，经ICPs治疗后又恢复正常。粪便检查，ICPs高剂量组（16．08mg）的EPG（每克粪便虫卵数）为0，而ICPs低剂量组（9．45mg）的EPG为394，未经ICPs作用对照组EPG为2113，差异极显著（P〈0．01），证明ICPs对猪体内猪蛔虫具有较好的杀灭作用。     

Effect of giving enrofloxacin in the diet to pigs experimentally infected with Actinobacillus pleuropneumoniae

Three groups of 16 pigs were exposed individually when four weeks old to intranasal infection with 10(8.9) viable Actinobacillus pleuropneumoniae (serovar 3, strain 2/(10P2); a fourth group was kept in isolation from the others as uninfected controls. Seven days later the 62 surviving animals were killed and necropsied. The organism had caused typical, mainly subacute disease in 12 of the 16 unmedicated animals but in only two of the 16 which had had continuous access to a diet containing 150ppm of enrofloxacin from four hours before exposure to infection, and in six of the 16 given 32 ppm enrofloxacin. However, only 150 ppm enrofloxacin produced marked control of the infection in terms of reduced average severity of thoracic lesions and much reduced prevalence of the organism in the lung at necropsy, and the mean weight gain (1.55 kg) and feed conversion efficiency (2.08) of this infected group over seven days were similar to those of the unmedicated, uninfected controls (1.67 kg and 2.25). The infected but untreated group on average produced detectable antibody seven days after infection whereas in the infected and medicated groups a specific response against serovar 3 was absent.     

Development and validation of an enzyme-linked immunosorbent assay for the diagnosis of porcine proliferative enteropathy.

The objective of this study was to develop an indirect enzyme-linked immunosorbent assay (ELISA) using a sonicated pure culture of Lawsonia intracellularis as the antigen (So-ELISA). A total of 332 serum samples, consisting of 232 experimentally infected animals and 100 animals naturally infected with L. intracellularis, were used to assess the diagnostic sensitivity. Three hundred and fifty-five sera from uninfected animals were used to determine the diagnostic specificity. The receiver operating characteristic and mean +3 standard deviation of optical density (OD) values from uninfected animals were used for selecting cut-off points. The diagnostic accuracy of So-ELISA was considered to be high as the area under the curve index was 0.991 with 0.0029 standard error. The optimal cut-off for So-ELISA was set at 0.45 OD with 89.8% sensitivity and 99.4% specificity based on a combination of good sensitivity and high specificity. No cross-reactivity was found in sera from pigs exposed to Brachyspira pilosicoli, B. hyodysenteriae, Campylobacter mucosalis, C. jejuni, or C. coli. Inter- and intracoefficient of variation of all control sera tested with So-ELISA was less than 10%. The observed agreements between So-ELISA and the immunoperoxidase monolayer assay tested with experimental challenge animals and field samples were 95.08% with 0.88 kappa and 90.65% with 0.74 kappa value, respectively. So-ELISA was able to detect the seroconversion of infected animals at 2 to 4 weeks after exposure to L. intracellularis. Based on the validation results, So-ELISA could be used as an alternative serology for proliferative enteropathy diagnosis.     

Establishment of Ascaris suum in the pig: development of immunity following a single primary infection

Development of immunity after a single primary infection of Ascaris suum in pigs was investigated with regard to the worm population dynamics of a superimposed A. suum infection, host immune response and gross liver pathological changes. Group A was given a primary infection of 60,000 infective A. suum eggs and group B was left uninfected. Four weeks later both groups A and B were inoculated with 1,000 A. suum eggs, and subgroups were slaughtered 7, 14 and 21 days post challenge infection (p.c.i.). An uninfected control group C was slaughtered on day 21 p.c.i. The challenge worm recovery in group A was reduced compared to group B by 12%, 50% and 75% on day 7, 14 and 21 days p.c.i., respectively. In both groups was the expulsion of worms initiated between day 14 and 21 p.c.i. However, in group A the worms were recovered more posteriorly in the small intestine and 21 days p.c.i. the mean worm length was significantly shorter than in group B (p = 0.01). The results above were associated with significantly higher (p < 0.05) antibody response and higher eosinophil counts in group A compared to group B. The present results suggest that the larval growth and survival of a challenge infection are decreased, probably due to higher antibody and eosinophil attack during the migratory phase.