Iron and transferrin in acute experimental Salmonella cholerae-suis infection in pigs

The effects of experimental Salmonella cholerae-suis inoculation with a virulent and an avirulent strain on serum iron (SI), total iron-binding capacity (TIBC), and transferrin (TF) were evaluated. Inoculation of virulent strain 38 was followed by significant (P less than 0.05) decreases of SI, TIBC, and TF. Exposure to avirulent strain 33 was followed by moderate decreases of SI, TIBC, and TF. When exposure to avirulent strain 33 was followed by challenge exposure with virulent strain 38, the SI, TIBC, and TF values remained at initial values or were higher. Negative correlation was observed between rectal temperature and SI and TIBC values, but was significant (P less than 0.0001) only 7 days after inoculation of the virulent strain 38.     

Presumptive Babesia ovis infection in a spanish ibex (Capra pyrenaica)

On December 29 1995, a 13-year old, male Spanish ibex was easily captured by hand, with depression, weakness and severe tick infestation, mainly in the periocular and auricular regions. Blood and serum samples were collected and haematological analysis and serum iron levels were determined. Red blood cell count, haematocrit, haemoglobin concentration and mean corpuscular haemoglobin concentration (MCHC) were decreased and mean corpuscular volume (MCV) increased (macrocytic-hypochromic anemia). Serum iron and transferrin saturation were decreased and total and unbound iron-binding capacity were increased. Piroplasms were observed within parasitized erythrocytes and presumptively identified as Babesia spp. Ticks were identified exclusively as Ripicephalus bursa. The animal was treated with imidocarb but died after 15 days of capture. Histopathological examination revealed congestion of pulmonary capillaries and spleen, glomerulonephritis, hemoglobinuric nephrosis and generalized hemosiderosis. An indirect fluorescent antibody test was performed using a Babesia ovis isolate of ovine origin as antigen and the animal was positive with a titre of 1:640.     

Mucosal uptake,mucosal transfer and retention of iron in veal calves

A method for studying iron absorption in humans was adapted to veal calves. Three 10-week-old calves with moderate (calves 1 and 2) or severe (calf 3) iron deficiency were given an abomasal injection of⁵⁹Fe and⁵¹Cr and all their faeces were collected over 15 days in order to measure mucosal uptake, mucosal transfer and retention of iron. The mucosal uptake was 62.2, 53.4 and 71.8% in calves 1, 2 and 3, respectively. The iron retention measured 14 days after administration of the test dose was 57.4, 52.3 and 56.4% in calves 1, 2 and 3, respectively. Maximal plasma activity was found in all three calves between 1 1/2 and 2 h after injection of the test dose. The plasma activity decreased rapidly, with a slight increase between the 5th and the 10th hour. After 21 h, less than 0.25% of the injected dose was still present in 1 litre of plasma. Not all the⁵¹Cr was recovered in the faeces. No⁵⁹Fe was found in the urine but some⁵¹Cr could be detected. The results of this study show that the method described is useful for measuring the different steps of iron absorption in iron-deficient veal calves.Abbreviations Hb haemoglobin concentration - MCV mean corpuscular volume - PCV packed cell volume - PI plasma iron - RBC red blood cell count - R iron retention - TIBC total iron-binding capacity - TIBC-SAT saturation of the total iron-binding capacity - U mucosal uptake     

Pathophysiologic correlates of acute porcine pleuropneumonia

OBJECTIVE: To develop and evaluate an in vivo model to study early events in the pathogenesis of acute porcine pleuropneumonia. ANIMALS: Thirty-six 6- to 8-week-old pigs. PROCEDURE: Pigs were inoculated intranasally or endotracheally with Actinobacillus pleuropneumoniae; inoculation routes were compared by evaluation of clinical signs, gross and microscopic lung lesions, hematologic changes, serum zinc, iron, and haptoglobin concentrations, and inflammatory cytokines. RESULTS: The 2 inoculation routes resulted in similar findings, although intranasal inoculation caused unilateral gross lung lesions, whereas endotracheal inoculation caused bilateral gross lesions. Clinical signs of disease were observed < 2 hours after endotracheal inoculation and 6 to 8 hours after intranasal inoculation. Total WBC counts did not differ significantly after inoculation by either inoculation route, although band neutrophils increased significantly. The earliest findings associated with A pleuropneumoniae inoculation, irrespective of route, were decreased serum zinc and iron concentrations. Serum haptoglobin concentrations were significantly increased after inoculation. Inoculation induced rapid influx of macrophages into the lung and local induction of proinflammatory cytokines. Northern blot analysis of total RNA from lung tissue indicated that inoculated pigs had increased concentrations of interleukin (IL)-1beta, IL-1alpha, and IL-8; tumor necrosis factor messenger RNA concentration was not increased. CONCLUSIONS: Endotracheal inoculation with A pleuropneumoniae rapidly and consistently induced diffuse bilateral pneumonia; thus, this method may be useful for the study of acute pathophysiologic changes associated with bacterial pneumonia and may provide an experimental model for testing modalities for prevention and treatment of this and other respiratory tract diseases of pigs.     

Endobronchial inoculation of various doses of Haemophilus (Actinobacillus) pleuropneumoniae in pigs

Twelve-week-old specific-pathogen-free pigs were inoculated deep in the bronchi with Haemophilus (Actinobacillus) pleuropneumoniae strain 13261 in doses ranging from 8 x 10(1) to 9 x 10(7) colony-forming units (CFU). Pigs that survived infection were euthanatized and examined 48 hours after inoculation. The relationship between dose and severity of disease was evaluated clinically and the weight of pneumonic lesions was compared. The relationship between infection dose and weight of pneumonic lesions proved to be unimodal and not linear. Inoculation of 10(4) CFU of strain 13261 resulted in severe pneumonic lesions and mortality of 29%. In contrast, death was not observed after inoculation with 10(6) CFU of strain 13261 and pneumonic lesions were less severe (P less than 0.05). An infective dose of 10(3) CFU induced pneumonic lesions that tended (not statistically significant) to be less severe than those induced by a dose of 10(4) CFU. The peak fever response in all infected pigs was observed from 6 to 12 hours after inoculation. Leukocytosis developed within 12 hours after inoculation, because of an increase of neutrophilic granulocytes. Thereafter, WBC count decreased owing to lymphopenia. Serum iron concentration decreased 80% after inoculation, and zinc concentration decreased 54%.     

Haematological, serological and pathological effects in chicks of one or more intravenous injections of Salmonella gallinarum endotoxin

Abnormalities appeared a few hours after groups of 14-day-old chicks (Gallus domesticus) were injected intravenously with 15 mg/kg of endotoxin (LPS) from Salmonella gallinarum. Clinical illness without mortality was accompanied by significant (P less than 0.05) falls in body temperature, bursa weight, the main haematological parameters, serum iron (SI) and transferrin saturation (TS) and a significant increase in unsaturated iron-binding capacity. All responses, apart from bursa weight, SI values and total and differential white-cell counts, returned to normal within 24 to 48 h. LPS given daily for three consecutive days did not cause changes in the main haematological parameters during the 48 h period following the third injection. However body and bursa weight and heterophil counts were significantly depressed, whereas body temperature, SI and TS were affected biphasically, being first depressed and then raised above normal. Chicks injected with LPS daily for six consecutive days showed broadly similar responses but a persistent microcytosis was also present.     

Iron Status and Erythrocyte Volume in Dogs With Congenital Portosystemic Vascular Anomalies

Microcytosis, hypochromasia, and low mean corpuscular hemoglobin are frequent hematologic abnormalities in dogs with portosystemic vascular anomalies (PSVA). The relationship of iron status to these abnormalities is unclear. We evaluated iron status and hematologic and biochemical parameters in dogs with congenital PSVA before (25 dogs) and after (11 dogs) partial ligation of the vascular anomaly. Serum iron concentration and total iron binding capacity were subnormal in 56% and 20% of dogs with PSVA, respectively. Transferrin saturation was normal in 68%, decreased in 20%, and increased in 12% of the dogs. Plasma ferritin concentration was either normal (56%) or high (44%), and was not associated with increases in ceruloplasmin concentration. Hepatic stainable iron was increased in 10 of 16 dogs. Mean corpuscular volume (MCV), mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were decreased in more than 60% of dogs with PSVA. Serum biochemical abnormalities included high bile acid concentration and alanine transaminase (ALT) and alkaline phosphatase (ALP) activities; and low urea, creatinine, cholesterol, and total protein concentrations. Serum iron concentration and clinical status (normal or PSVA) significantly influenced MCV ( P = .003 and P < .001, respectively), whereas age, ceruloplasmin, ferritin, cholesterol, bile acids, and total iron binding capacity did not. Partial ligation of PSVA was associated with resolution of clinical signs and the return to normal of iron status and all clinicopathologic abnormalities, except total fasting bile acid concentrations. These findings indicate that iron status is frequently abnormal in dogs with PSVA and that low serum iron concentration appears to be related to the development of microcytosis. The normalization of iron status and clinicopathologic abnormalities after treatment suggests that they are direct consequences of PSVA.     

Effects of the antimicrobial growth promoter tylosin on subclinical infection of pigs with Salmonella enterica serotype Typhimurium

OBJECTIVE: To determine whether feeding tylosin, an antimicrobial growth promoter, to pigs was associated with increased risk of infection with and excretion of Salmonella enterica serotype Typhimurium. ANIMALS: 17 healthy pigs. PROCEDURE: A commercial pelleted dry feed was given in 2 feeding trials. In trial A, 11 pigs were given feed with tylosin, 11 pigs were given feed without tylosin, and 11 pigs were given feed with tylosin before and feed without tylosin after inoculation with S Typhimurium. In trial B, 44 pigs were given feed that contained tylosin, and 44 pigs were given feed without tylosin. Three weeks after the start of each trial, pigs were orally inoculated with approximately 5 x 10(6) colony-forming units of S Typhimurium. Feces were examined for S Typhimurium, using semiquantitative microbiologic techniques before and for 5 or 6 weeks after inoculation. Serum antibody titers against S enterica were measured by use of ELISA. RESULTS: None of the pigs developed clinical signs of salmonellosis. However, after inoculation, S Typhimurium was isolated from feces of most pigs, and all but 2 pigs developed serum antibodies against S enterica. Significant differences were not detected between experimental and control groups in either trial. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that tylosin fed as an antimicrobial growth promoter to pigs may not be an important factor in promoting infection with or excretion of S enterica serotype Typhimurium.     

Suppression of resistance to Salmonella typhimurium in young chickens inoculated with Corynebacterium parvum

The effect of Corynebacterium parvum on resistance to Salmonella typhimurium infection was evaluated in young chickens. One-day-old chickens were inoculated subcutaneously (SC) or intraperitoneally (IP) with 1.4 mg killed C. parvum and challenged by IP injection with 5.0 X 10(7) S. typhimurium 4 days later. Spleen and bursa of Fabricius weights were not altered in the C. parvum-inoculated chickens. A transient increase in thymus weight occurred 3 days after inoculation with C. parvum. Phytohemagglutinin-elicited cutaneous hypersensitivity was significantly suppressed in the C. parvum-inoculated chickens. Morbidity due to Salmonella infection increased significantly from 15% and 21% in the control groups to 43% and 46% in the chickens inoculated IP or SC with C. parvum. The results indicated that inoculation of 1-day-old chickens with C. parvum suppressed cell-mediated immune responsiveness and decreased resistance to peritoneal infection with S. typhimurium.     

Diet manipulation as treatment for elevated serum iron parameters in captive raggiana bird of paradise (Paradisaea raggiana)

Elevated serum iron parameters were lowered through dietary manipulation in captive Raggiana bird of paradise (Paradisaea raggiana). Study birds were part of a captive breeding program consisting of two males and one female, captive born, 3.5-9 yr of age. Serum iron, total iron binding capacity (TIBC), percentage saturation, body weight, albumin, aspartate aminotransferase, and hematocrit were monitored at regular intervals for 2.5 yr. Routine diet consisted of a variety of fruits, vegetables, a multivitamin supplement, and a commercial low iron avian pellet, with a dietary iron content of 55 mg/kg (dry matter basis) or 1.12 mg iron/bird/day. Dietary treatment involved removal of the commercial avian pellet for 30 days at 6-to 12-mo intervals, resulting in an iron content of 42 mg/kg (dry matter basis) or 0.64 mg iron/bird/day. Average serum iron and TIBC were decreased by 75% (TIBC) to 80% (serum iron) ofpretreatment values after one 30-day treatment. Average iron saturation levels were lowered by 10% of pretreatment values after one 30-day treatment. Average hematocrit, albumin, aspartate aminotransferase, and body weight remained unchanged. No adverse effects were noted through the 2.5-yr evaluation period, and breeding behavior was undisturbed. Periodic removal of low iron commercial pellets in the diet of captive bird of paradise is a safe and effective method for lowering serum iron values without need for handling. Periodic application of this technique may be useful as a preventive tool to maintain appropriate serum iron values in avian species susceptible to iron storage disease.     

Effects of different iron contents in the milk replacer on the development of iron deficiency anaemia in veal calves.

The effect of different iron concentrations in the milk replacer on the development of iron deficiency anaemia during a fattening period of 28 weeks was studied in three groups of 14 calves. The iron contents in the milk replacer differed during the first seven weeks: 60, 100 and 150 mg Fe/kg in groups A, B and C, respectively. In all three groups blood haemoglobin, mean corpuscular volume, plasma iron concentration and saturation decreased during the fattening period, whereas the total iron-binding capacity increased. At week 7, liver iron concentrations were high with a large individual variation [A: 201 (61-706), B: 99 (47-129), C: 296 (77-1572) micrograms/g dry matter]. During the fattening period, liver iron concentrations decreased, with the lowest values at week 25 [A: 54 (34-82), B: 55 (44-83), C: 57 (42-79) micrograms/g dry matter]. Muscle iron concentrations decreased between week 7 and 19. Except plasma iron and saturation in group C, no differences in haematological and tissue iron variables were found throughout the fattening period in spite of different iron contents in the milk replacer during the first seven weeks.     

Experimental fecal transmission of human cryptosporidia to pigs, and attempted treatment with an ornithine decarboxylase inhibitor

Fecal material collected from an immunologically deficient man with persistent cryptosporidia infection was stored in potassium dichromate for two weeks and then fed (inoculated) to newborn pigs. The six inoculated newborn pigs shed the organism in their feces starting four to five days afer inoculation and continuing for as long as 22 days after inoculation. Pigs which were killed and necropsied while shedding had cryptosporidia infection of ileum, cecum, and colon. Infected pigs had atrophied ileal villi and flattened irregular cecal and colonic epithelium. Uninoculated littermate controls remained free to the infection and had histologically normal intestinal tracts at necropsy. Treatment of three of the six inoculated pigs with the ornithine decarboxylase inhibitor, DL-alpha-difluoromethylornithine, orally for ten days had no apparent effect on the infection.     

Effects of intranasal inoculation of porcine reproductive and respiratory syndrome virus, Bordetella bronchiseptica, or a combination of both organisms in pigs

OBJECTIVE: To examine effects of co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and Bordetella bronchiseptica in pigs. ANIMALS: Forty 3-week-old pigs. Procedure-30 pigs (10 pigs/group) were inoculated with PRRSV, B bronchiseptica, or both. Ten noninoculated pigs were control animals. RESULTS: Clinical signs, febrile response, and decreased weight gain were most severe in the group inoculated with both organisms. The PRRSV was isolated from all pigs in both groups inoculated with virus. All pigs in both groups that received PRRSV had gross and microscopic lesions consistent with interstitial pneumonia. Bordetella bronchiseptica was cultured from all pigs in both groups inoculated with that bacterium. Colonization of anatomic sites by B bronchiseptica was comparable between both groups. Pigs in the group that received only B bronchiseptica lacked gross or microscopic lung lesions, and B bronchiseptica was not isolated from lung tissue. In the group inoculated with B bronchiseptica and PRRSV, 3 of 5 pigs 10 days after inoculation and 5 of 5 pigs 21 days after inoculation had gross and microscopic lesions consistent with bacterial bronchopneumonia, and B bronchiseptica was isolated from the lungs of 7 of those 10 pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Clinical disease was exacerbated in co-infected pigs, including an increased febrile response, decreased weight gain, and B bronchiseptica-induced pneumonia. Bordetella bronchiseptica and PRRSV may circulate in a herd and cause subclinical infections. Therefore, co-infection with these organisms may cause clinical respiratory tract disease and leave pigs more susceptible to subsequent infection with opportunistic bacteria.     

The fibronectin binding protein ShdA is not a prerequisite for long term faecal shedding of Salmonella typhimurium in pigs

Porcine carcasses contaminated with Salmonella typhimurium pose significant public health problems. Prolonged faecal shedding of Salmonella in pigs contributes to the contamination level of carcasses. Although the mechanism of prolonged faecal shedding is not yet clarified, the CS54 Island, and more specifically the shdA gene encoding a fibronectin binding autotransporter protein, was identified as an important locus for intestinal colonization and persistence of Salmonella typhimurium in mice. The aim of this study was to assess the contribution of ShdA in faecal shedding of Salmonella typhimurium in pigs. Pigs were orally inoculated with a Salmonella typhimurium wild type field strain or its isogenic shdA mutant strain. For the first few days after inoculation, the shdA mutant strain was excreted more, the diarrhoea was more pronounced and higher numbers of internal organs were infected. No effect on long-term shedding was found. In a porcine ileal loop model, the wild type strain and shdA mutant strain did not show any differences in the induction of neutrophil influx into the intestinal wall and lumen. In conclusion, we have shown that a Salmonella typhimurium deletion mutant in shdA is more virulent during the first days after inoculation and is not significantly impaired in persistence or prolonged shedding in pigs.     

Experimental Infection with Mycobacterium Avium,Serotype 2, in Pigs: 4. Contact Infection from Orally Inoculated Pigs*

In 3 experiments, 13 pigs were inoculated orally with 0.5 mg Mycobacterium avium daily for 5 days (1 mg = 32–68×10⁶ viable units). Five to 8 days after inoculation, 16 non-inoculated pigs were added to the inoculated pigs.Cultures from faeces showed excretion of M. avium from all the inoculated pigs for some time within the period 16 to 65 days after the last inoculation; the greatest numbers of organisms (62000 per 100 g faeces) were found at about the middle of the excretion period (Table 2). Two of the contact pigs were found to excrete M. avium in small numbers, 1 at 15, the other at 37 and 44 days after contact.All the inoculated pigs and 13 of the contact pigs showed positive intradermal tuberculin reactions. Post-mortem examination showed tuberculous lesions in all the inoculated pigs (Table 3). M. avium was transmitted to 15 of 16 pigs by contact. Five of these pigs showed gross lesions, 10 of them microscopic lesions only; in 9 of them the infection was proved by culture.     

Development and application of an enzyme-linked immunosorbent assay to detect antibodies against prevalent Salmonella serovars in swine in southern Brazil.

The implementation of Salmonella control programs in the pork production chain demands rapid and cost-effective methods to assess the prevalence of infection in pig herds. The objective of the present study was to develop an in-house enzyme-linked immunosorbent assay (ELISA) based on S. Typhimurium lipopolysaccharides (LPS) to measure the prevalence of infection caused by Salmonella in swine herds. Coating antigen was produced by phenol extraction of S. Typhimurium culture. After standardization of ELISA test conditions, the assay was validated by testing serum samples on different animal categories: pigs orally inoculated with S. Typhimurium and sentinel animals in contact with them, naturally infected animals, colostrum-deprived piglets, and bacterin-immunized pigs. Seroconversion was observed in inoculated pigs (7 days postinfection [DPI]) and in the sentinels (21 DPI). Nonspecific reactions were not detected in the sera of colostrum-deprived animals. Serum samples from animals immunized with Salmonella Agona, Salmonella Derby, Salmonella Panama, and Salmonella Bredeney bacterins showed marked cross-reaction with the LPS from the serovar Typhimurium. Moreover, positive results obtained with the in-house ELISA were associated with Salmonella isolation in 75 infected pig herds. Comparisons with 2 commercial kits showed a linear correlation coefficient of 0.847 between the in-house ELISA and kit A and 0.922 with kit B but a low agreement in the qualitative results. In conclusion, the newly developed in-house ELISA based on S. Typhimurium LPS can be a useful tool to determine the intensity of Salmonella sp. infection in swine herds.     

Retention of selenium in tissues of calves, lambs, and pigs after parenteral injection of a selenium-vitamin E preparation.

Four each healthy weaned calves, lambs, and pigs raised in Indiana without selenium supplementation were killed, and their tissues were fluorometrically analyzed to establish base line selenium concentrations. The following mean selenium content (in ppm, wet weight) was found in calves, lambs, and pigs, respectively: liver, 0.12, 0.16, and 0.19; renal cortex, 0.63, 0.89, and 0.70; muscle, 0.05, 0.05, and 0.06. Eight each additional healthy weaned calves, lambs, and pigs were injected with a commercial selenium-vitamin E preparation at dose levels of 0.0825, 0.055, or 0.06 mg of Se (as selenite) per kilogram of body weight, respectively. Selenium content of tissues was measured in animals killed at 1, 7, 14, and 23 days after injection. In calves, concentrations in liver and kidney rapidly increased to moderate values and then slowly decreased, with mean concentrations after 23 days still somewhat greater than base line values. Concentrations for injection site tissue also rapidly increased to moderate values, but had decreased to base line values by 23 days after injection. In lambs, selenium content of liver was moderately increased after injection, but had decreased to base line values after 14 days; kidney and injection site did not have increased selenium content after injection. In pigs, liver and kidney had moderate initial increases in concentration of selenium, but these were at base line values after 14 days, and increase did not occur at injection sites.     

Effect of dietary iron content on hematologic and other measures of iron adequacy in dogs

Eighteen 9- to 10-week old Beagles were fed casein-based diets (4,710 kcal of metabolizable energy/kg of body weight) containing either 12, 80, or 160 mg of iron/kg of diet. Growth and feed consumption were monitored throughout the 47-day study. Hematocrit (Hct), hemoglobin (Hb) concentration, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), RBC numbers, erythrocyte protoporphyrin (EP) concentration, serum iron concentration, serum total iron-binding capacity (TIBC), and serum ferritin concentration were determined weekly. Growth rate and feed efficiency were not significantly influenced by dietary iron content. At 14 days, Hb concentration, Hct, MCV, MCH, RBC numbers, and serum iron concentration were significantly (P less than 0.05) lower in dogs fed the 12 mg/kg diet, and remained significantly low for the remainder of the study. Erythrocyte protoporphyrin concentration increased significantly (P less than 0.05) by 14 days in dogs fed the basal diet, and remained significantly high relative to that in dogs of the other dietary groups for the remainder of the study. Serum ferritin concentration decreased in dogs of the group fed the basal diet, with a significant (P less than 0.05) difference beyond day 42. Differences in Hct, MCH, MCV, or hemoglobin, serum iron, serum ferritin, or EP concentration were not found between groups fed 80 and 160 mg of iron/kg of diet. Liver nonheme iron content was significantly (P less than 0.05) affected by dietary iron content.     

Evaluation of transmission of swine influenza type A subtype H1N2 virus in seropositive pigs

OBJECTIVE: To examine clinical signs, virus infection and shedding, and transmission of swine influenza virus (SIV) subtype H1N2 among seropositive pigs. ANIMALS: Eighteen 3-week-old pigs with maternal antibodies against SIV subtypes H1N1, H3N2, and H1N2. PROCEDURE: Ten pigs (principal) were inoculated intranasally with subtype H1N2 and 2 groups of contact pigs (n = 4) each were mixed with principal pigs on day 7 (group 1) or 28 (group 2). Two principal pigs each were necropsied on days 4, 14, 21, 28, and 42 days after inoculation. Four pigs in each contact group were necropsied 35 and 14 days after contact. Virus excretion was evaluated after inoculation or contact. Lung lesions and the presence of SIV in various tissues were examined. RESULTS: Mild coughing and increased rectal temperature were observed in principal pigs but not in contact pigs. Nasal virus shedding was detected in all principal pigs from day 2 for 3 to 5 days, in group 1 pigs from day 2 for 4 to 9 days after contact, and in group 2 pigs from day 4 for 2 to 6 days after contact. Trachea, lung, and lymph node specimens from infected pigs contained virus. Antibody titers against all 3 subtypes in all pigs gradually decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Protection from viral infection and shedding was not observed in pigs with maternal antibodies, but clinical disease did not develop. Vaccination programs and good management practices should be considered for control of SIV subtype H1N2 infection on swine farms.     

Bacterial colonization and morphology of the intestine in porcine Escherichia coli enterotoxemia (edema disease)

Twenty-one pigs were divided into three groups. Pigs in one group were inoculated with the intestinal contents which included bacteria from a pig with edema disease. Pigs in another group were inoculated with a culture of Escherichia coli serogroup O 139:K12(B):H1 isolated from the aforementioned contents, and pigs in a third group served as uninoculated controls. The infection was similar following both inocula. Enterotoxemia developed in 11 of the 14 pigs allowed to survive for more than two days. The onset varied from two to seven days after inoculation. There were maximal viable counts of E. coli in the intestine from the second day post-inoculation and thereafter. In frozen and paraffin sections, as well as by scanning electron microscopy, the organisms were seen on the surface of the small intestinal epithelium where they formed either isolated colonies or continuous layers. They colonized the lower small intestine more intensely than the upper section. The intestinal epithelium and the villi of infected pigs were indistinguishable morphologically from the tissues of three uninoculated control pigs. The diarrhea which was observed in controls and inoculated pigs before inoculation and the villus atrophy in controls and inoculated pigs indicated a preexisting infection with at least one other agent.