Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. IV. Pathogenicity of porcine rotavirus

Colostrum-deprived piglets inoculated with rotavirus 24 h after birth developed a profuse diarrhoea that spread to non-inoculated, colostrum-deprived litter mates and, occassionally, to colostrum-fed piglets. Case fatality rates in these 3 categories of piglets were 63.2%, 35.7% and 8.3%, respectively. Surviving piglets recovered in 1-2 weeks, but shedded virus via the faeces for up to 3 weeks p.i. The D-xylose test revealed severe malabsorption, with extremely flat absorption curves for up to 3-4 weeks p.i. Malabsorption was more marked in piglets with a long-lasting faecal virus excretion than in piglets where virus disappeared from the faeces within 10 days p.i. Infected piglets (colostrum-fed and colostrum-deprived) had decreased weight gains and were 5 days older at a bodyweight of 25 kg than non-inoculated controls. It is concluded that rotavirus is probably of significance in diarrhoeal syndromes in suckling piglets, alone or in combination with E. coli or other pathogens.     

Intestinal changes associated with rotavirus and enterotoxigenic Escherichia coli infection in calves

Newborn calves inoculated with rotavirus, enterotoxigenic Escherichia coli (ETEC) serotype 020:K' x 106':K99:HNM, either alone or in combination, became depressed, anorectic, diarrhoeic and dehydrated. ETEC did not adhere to the intestine although there was extensive proliferation in the lumen. Only slight mucosal changes were induced by ETEC and the activity of membrane bound lactase remained normal. More severe mucosal damage and a decrease in lactase activity were found in newborn calves inoculated with either rotavirus or rotavirus and ETEC in combination. The most severe clinical illness was found in calves inoculated with both rotavirus and ETEC. Calves inoculated at 1 week of age with either rotavirus or ETEC remained clinically normal. Rotavirus infection produced slight mucosal changes and a reduction of lactase activity. In contrast, colostrum-fed or suckling calves up to 2 weeks old inoculated with both rotavirus and ETEC became clinically affected, showed severe mucosal damage and decreased lactase activity. There was no bacterial adhesion to the intestinal mucosa as observed by immunofluorescent labelling and light microscopy.     

Role of Cryptosporidium parvum as a pathogen in neonatal diarrhoea complex in suckling and dairy calves in France.

This study was carried out to find the importance of Cryptosporidium parvum in diarrhoea of neonatal calves in two types of breeding - suckling and dairy calves - in France. Different agents causing neonatal diarrhoea, E. coli, rotavirus, coronavirus, Salmonella and Cryptosporidium were systematically researched in faeces. 1. Suckling calves: In 40 livestock farms selected for diarrhoea, 311 calves 4 to 10 days old which had diarrhoea for less than 24h or no diarrhoea, were included in the study. A prophylaxis of neonatal diarrhoea had been carried out in 21 of the 40 livestock farms. On D0 (inclusion day), the mean age was 6 days, 82% presented a good initial general condition and 76.2% had a good appetite; 48.6% were diarrhoeic but 91.3% presented no sign of dehydration. Only 6.1% were infected by E. coli K99, 14.3% by rotavirus, 6.8% by coronavirus, 0.3% by Salmonella but 50% excreted C. parvum oocysts. This later percentage increases up to 84% and 86% by D3 and D7, respectively . We note that 16% of the 4-day-old calves on D0 are excreting oocysts and this percentage increases as a function of the age of the calf on D0 to reach 90% to 95% by the age of 8 days. 10 out of 12 dead calves excreted C. parvum oocysts. From D0 to D14 the other pathogen agents show a relative or a decreasing stability. 2. Dairy calves: 382 calves which had diarrhoea for less than 24 h or no diarrhoea, aged 8 to 15 days coming from six industrial livestock farms were included in the study. On D0, 99% of the calves presented a good initial general condition, 99.7% had a good appetite and no calf was dehydrated. At this date (D0), 16.8% of the calves excreted cryptosporidia. This percentage increases up to 23% and 51.8% on D3 and D8, respectively, then decreases to 31.9% on D14. The pressure of the other pathogenicagents remains relatively stable, excepted for rotavirus on D7 (from 9.9% on D0 to 27.2% on D7, then 12.6% on D14) which does not explain the concomitantpeak in diarrhoea because the infection by rotavirus on D7 is more frequent in non-diarrhoeic calves than in diarrhoeic calves. Our results show that Cryptosporidium prevalence is higher in suckling than in dairy calves and C. parvum constitutes actually in both cases the major aetiological agent of neonatal diarrhoea.     

Diarrhea associated with enterotoxigenic Bacteroides fragilis in foals

Enterotoxigenic Bacteroides fragilis (ETBF) was isolated from the feces of 10 of 40 Thoroughbred foals with naturally acquired diarrhea. Of the 10 foals positive for ETBF, 6 were less than or equal to 7 days old. Fecal specimens from 4 of the 10 foals also were positive for rotavirus, and one fecal specimen was positive for Salmonella enteritidis. Clinical or hematologic differences were not evident between foals infected with ETBF only and those infected with ETBF and another recognized enteric pathogen. Only 1 of 10 foals infected with ETBF died. Of 25 adult rabbits with ligated ceca, 23 developed mucoid, often hemorrhagic, diarrhea after inoculation of 5 X 10(9) viable ETBF cells into the ileum. Nine of 13 (69%) rabbits inoculated with 1 of 3 isolates of ETBF died, but none of 12 inoculated with 1 of 6 other isolates of ETBF died. Enteric disease did not develop in 15 rabbits inoculated with nonenterotoxigenic B fragilis.     

Epizootiology of bovine rotavirus infection.

Published information on rotaviruses as pathogens, the source of virus infection and the method of transmission of infection under normal conditions are reviewed. The antigenic differences between rotavirus isolates from children, calves, pigs, foals and mice are discussed. Bovine rotaviruses isolated in the USA and the UK were shown to be closely related antigenically and the US vaccine strain protected calves from challenge with the UK rotavirus. Nineteen normally reared calves, with 20 or more ZnSO4 units of serum delta globulin, were susceptible to rotavirus inoculation at two days of age. They developed diarrhoea, showed body weight loss but recovered. Three calves with less than 10 ZnSO4 units of serum delta globulin developed diarrhoea and died. In a serological survey of 654 adult cows and calves from three herds, between 2 per cent and 37 per cent of individuals in a group had low rotavirus antibody titres and were probably susceptible to rotavirus infection. These were found in all age groups of animals studied, whether or not the group had suffered a recent rotavirus epizootic. It was not possible to predict whether an epizootic would develop on the basis of a serological survey.     

Interaction of rotavirus and enterotoxigenic Escherichia coli in conventionally-reared dairy calves

A study was made of the effects of rotavirus and/or enterotoxigenic Escherichia coli (ETEC) on dairy calves born and suckled on the farm and subsequently reared in isolation. Calves were orally inoculated at 6 days old with either rotavirus (5), ETEC (7), rotavirus and ETEC (5) or remained uninoculated controls (4), and their reactions were recorded by clinical, microbiological, and pathological observations. Rotavirus infection consistently produced diarrhoea, while ETEC inoculated alone did not colonise the intestine. In dual infections, both rotavirus and ETEC multiplied, although the severity of diarrhoea was not greater than that caused by rotavirus alone. Some ETEC-inoculated calves developed subsequent naturally-acquired rotavirus infections, but in these no ETEC multiplication occurred. The results suggest that prior or simultaneous rotavirus infection is necessary to enable ETEC colonisation of the intestine in convenstional calves of this age.     

ESCHERICHIA COLI AND ROTAVIRUS INFECTIONS IN FOUR-WEEKOLD GNOTOBIOTIC PIGLETS FED MILK OR DRY FOOD

A haemolytic enteropathogenic E. coli (WG) and pig rotavirus were isolated from a field case of postweaning diarrhoea in pigs. Four-week-old gnotobiotic piglets fed on milk diet were found to be extremely susceptible to infection with WG E. coli . Piglets were less susceptible to the infection immediately after the diet was changed from milk to dry food, and were almost completely resistant 4 days after the change to dry food. There was no difference in the clinical response to infection with WG E. coli when the piglets were fed either a high energy diet or low energy diet. Four-week-old piglets fed milk showed mild symptoms of diarrhoea when inoculated with pig rotavirus. Symptoms were more severe when piglets were inoculated immediately after the change from milk to dry food. Piglets inoculated 4 days after the change of diet showed no symptoms of diarrhoea at all. Under the conditions of these experiments the enteropathogenic E. col produced a more serious disease than did pig rotavirus. Infection of 4-week-old gnotobiotic piglets with both agents given sequentially produced a diarrhoeal disease that was more severe than that produced by each agent separately.     

Rotavirus replication in colostrum-fed and colostrum-deprived pigs

A porcine rotavirus isolate was titrated in neonatal colostrum-fed and colostrum-deprived pigs. The stock rotavirus suspension had a titer of 10(-6.5)/ml and was in its fifteenth cell culture passage in MA-104 cells. Fourteen colostrum-fed pigs were orally inoculated with dilutions of the stock virus suspension ranging from undiluted to 10(-5). These pigs did not develop notable clinical signs during the 7-day experimental trial and no pathologic changes were found in intestine, liver, lung, kidney, spleen, or brain. However, rotavirus was detected in feces of the colostrum-fed pigs, using virus isolation and electron microscopic techniques. Rotavirus was also isolated from lung, brain, or spleen of 4 of 12 of these pigs. Sixteen colostrum-deprived pigs were orally inoculated with dilutions of the stock virus suspension ranging from 10(-1) to 10(-8). Diarrhea developed in 10 of 12 pigs that were given up to the 10(-6) dilution. Seven of these 12 pigs died because of the severity of diarrhea. Pigs that died of rotavirus-induced diarrhea had severe villus loss in the jejunum and ileum. Villi of the small intestine of colostrum-deprived pigs that survived the severe diarrhea were within normal limits at the end of the 7-day trial. The colostrum-deprived pigs that were inoculated with a dilution less than 10(-6) and survived past 96 hours underwent seroconversion. Rotavirus was detected by virus isolation and electron microscopy in the feces of all colostrum-deprived pigs that survived beyond 18.5 hours after inoculation. Virus was isolated from lungs, brain, or spleen of 12 of 16 colostrum-deprived pigs.     

Rotavirus infection in foals

Fecal samples from 86 foals with diarrhea were examined by electron microscopy during a 2.5 year period. Of these, 26 (30%) were positive for rotavirus. All of the cases were found in epizootic areas. The disease was produced in an experimental foal by inoculation via stomach tube of a bacteria-free fecal filtrate containing rotavirus. Examination of postmortem tissues from the duodenum and jejunum of 2 naturally infected foals and an experimentally infected foal revealed replicating virus in the intestinal epithelial cells. A limited survey of complement-fixing antibody to rotavirus in horses from Kentucky, Virginia, and France indicated that all horses had antibody to the virus. The sole exception was 1 foal from which blood samples were collected prior to suckling. These results were presumptive evidence that rotavirus is a major cause of diarrhea in foals, and the presence of antibody in horses from diverse areas is evidence for the ubiquitousness of this infection.     

Prevalence of gastric lesions in foals without signs of gastric disease: an endoscopic survey

Gastroendoscopic examinations were conducted on 75 Thoroughbred foals aged two to 85 days on seven breeding farms in England and Ireland. The foals showed no signs of gastric disease. There was no significant difference between lesion prevalence in foals in England (16 of 28 foals; 57 per cent) or Ireland (22 of 47 foals; 47 per cent). Neither was there any sex predilection (18 of 36 males; 20 of 39 females). Lesions were most prevalent in foals under 10 days old (8 of 9) and least prevalent in foals older than 70 days (3 of 10). Lesions occurred most frequently in the squamous mucosa immediately adjacent to the margo plicatus along the greater curvature (34 foals), whereas lesions in the squamous fundus, the glandular fundus, and the lesser curvature were observed in 11, six and three foals, respectively. Lesions were not observed in the squamous mucosa surrounding the cardia. Gastric lesions were more prevalent in foals with a previous disorder than in those without (68 vs 43 per cent) and particularly with a history of recent or concurrent diarrhoea (9 of 14).     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. III. Rotavirus infection

The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.     

Effects of oral supplementation of probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium on diarrhoea events of foals in their first weeks of life

Foal first diarrhoea is one of the most prominent problems in the early life of horses. Probiotics might have the potency to prevent or at least diminish neonatal diarrhoea. We hypothesised that the treatment of foals with probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium starting early after birth and then daily over 2 weeks would prevent or mitigate foal heat diarrhoea. The influence of this probiotic treatment on diarrhoea incidence and growth and health performance of young foals was investigated. Thirty‐four foals were randomly allocated to two groups. From day 1 to 14 of life, the foals received either placebo (PG, n = 16) or the probiotic treatment (TG, n = 18). Clinical examination was performed, and the faeces consistency score (FCS, 1–5; with diarrhoea defined by ≤3) was recorded once per day in weeks 1 and 2 and once weekly in weeks 3–8 of life (WL). The body height was measured at birth and after two and eight WL. Diarrhoea occurred in the 1st WL in 19% and 61% of PG and TG foals respectively. In the 1st WL, diarrhoea lasted 0.3 ± 0.8 and 1.6 ± 1.4 days in PG and TG foals respectively. In the 2nd WL, diarrhoea occurred in 94% and 84% of PG and TG foals, respectively, and lasted for 3.0 ± 1.5 and 3.7 ± 1.6 days respectively. At least two periods of diarrhoea developed in 33% and 65% of PG and TG foals respectively. The TG foals grew slightly slower than the PG foals. The results indicated that the probiotic treatment of neonatal foals as performed in this study was not suitable to reduce diarrhoea within the first two WL, because contrary to the hypothesis, the TG foals suffered more frequently and for longer periods from diarrhoea than the PG foals.     

Rotavirus as a cause of diarrhea in pigs.

A rotavirus (reovirus-like agent) was associated with diarrheal diseases occurring in 1- to 4-week-old suckling pigs in 8 herds and in weaned pigs in 2 herds. Transmissible gastroenteritis virus was also detected in 2 of these herds, as was enteropathogenic Escherichia coli in 5 herds. Morbidity was generally greater than 80% in pigs of the affected age group within these herds, and mortality from diarrhea ranged from 7 to 20%. The disease due to rotavirus in suckling pigs appeared similar to the syndrome commonly referred to as milk scours, white scours, or 3-week scours. Diarrhea and villous atrophy, resembling that seen in transmissible gastroenteritis, occurred in naturally infected pigs and in gnotobiotic pigs experimentally infected with rotavirus. Diagnosis was accomplished by immune electron microscopy of intestinal contents and by immunofluorescent staining of enterocytes. A massive infection of enterocytes with rotavirus was demonstrated by immunofluorescence, which helps explain the pathogenesis of this disease. The apparent rarity of clinical rotaviral infections in suckling pigs greater than 7 days old is probably due to the acquisition of passive immunity from immune sows.     

Rotaviral diarrhoea and its treatment in a foal

A severely dehydrated foal with a history of acute diarrhoea was presented to Massey University for treatment. Rotavirus was demonstrated in the faeces by electron microscopy. The failure to detect other pathogens suggested that rotavirus was the primary aetiological agent. Successful treatment of this case is described and the principles of treatment for diarrhoea, particularly fluid therapy, are reviewed. Antibodies to rotavirus were detected in the sera of nine mares and their foals on the stud that referred the case, indicating that rotaviral infection was probably endemic.     

Rotaviral diarrhoea and its treatment in a foal

A severely dehydrated foal with a history of acute diarrhoea was presented to Massey University for treatment. Rotavirus was demonstrated in the faeces by electron microscopy. The failure to detect other pathogens suggested that rotavirus was the primary aetiological agent. Successful treatment of this case is described and the principles of treatment for diarrhoea, particularly fluid therapy, are reviewed. Antibodies to rotavirus were detected in the sera of nine mares and their foals on the stud that referred the case, indicating that rotaviral infection was probably endemic.     

Effects of repeated Strongylus vulgaris inoculations and concurrent ivermectin treatments on mesenteric arterial lesions in pony foals

Eight of 10 pony foals reared under helminth-free conditions were inoculated PO with 50 Strongylus vulgaris infective larvae/week for 4 weeks, at which time 1 foal died of acute verminous arteritis. Inoculation of 7 remaining foals continued at 2-week intervals for 20 weeks. Of the 7 foals, 3 were treated with ivermectin (0.2 mg/kg of body weight) in an oral paste formulation at experiment weeks 8, 16, 24; 4 foals were not treated. Two foals were not inoculated or treated and served as controls. After the first ivermectin treatment, ivermectin-treated foals had fewer days (12 +/- 2.9) with rectal temperatures greater than 38.6 C than did nontreated foals (23.3 +/- 3.8). Mean baseline rectal temperatures were 38 +/- 0.2 C. Adverse clinical reactions to ivermectin treatment were not observed in foals. Foals were euthanatized and necropsied 3 weeks after the last ivermectin treatment (week 24). Ivermectin was effective in reducing S vulgaris arterial larval and intestinal adult parasite numbers by 100% in 3 treated foals. Strongylus vulgaris arterial larvae and/or adults were recovered from all 4 nontreated inoculated foals. One nontreated inoculated foal lacked arterial larvae or active arterial lesions, indicating that protective resistance had developed in this individual. Marked gross and histopathologic lesions typical of chronic S vulgaris infection were observed in the 3 nontreated inoculated foals with arterial larvae. Repeated killing of intra-arterial S vulgaris fourth-stage larvae in ivermectin-treated foals did not exacerbate lesions associated with verminous arteritis or induce unique lesions associated with repeated destruction of arterial larvae.(ABSTRACT TRUNCATED AT 250 WORDS)     

The prevalence of enteric pathogens in diarrhoeic thoroughbred foals in Britain and Ireland.

A survey of 77 normal and 326 diarrhoeic foals in Britain and Ireland from 1987 to 1989 revealed a significantly higher prevalence of Group A rotaviruses and Aeromonas hydrophila in diarrhoeic foals. The prevalence of cryptosporidia, potentially pathogenic Escherichia coli, Yersinia enterocolitica and Clostridium perfringens was similar in normal or diarrhoeic foals. Rotaviruses had a similar prevalence in all age groups of scouring foals up to three months of age, with an overall prevalence of 37 per cent among diarrhoeic foals. The number of cases of diarrhoea varied considerably from year to year, but in all three years of the survey rotavirus was a significant pathogen. A comparison of diagnostic tests for rotavirus in the faeces showed electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) to have similar sensitivity. The Rotazyme ELISA test kit was found to have the same sensitivity as a combination of EM and PAGE. A. hydrophila had an overall prevalence of 9 per cent among diarrhoeic foals, although its prevalence was higher in some age groups. A. hydrophila has not been established previously as a significant enteric pathogen in foals. Other putative pathogens found at very low prevalence were coronavirus, the putative picobirnavirus, Campylobacter spp. and Salmonella spp. No evidence was found of synergistic effects between rotavirus, cryptosporidia and potentially pathogenic E. coli. Neither coccidia nor non-Group A rotaviruses were found in any of the samples examined.     

Homotypic and heterotypic serum and milk antibody to rotavirus in normal, infected and vaccinated horses.

The homotypic and heterotypic antibody response to rotavirus was determined in three pony mares and their foals. The normal concentrations of anti-rotavirus antibodies in mares' milk and mares' and foals' serum over the first 10 weeks post-partum were measured using IgA, IgG and rotavirus serotype-specific enzyme linked immunosorbent assays. Experimental infection of the foals with serotype 3 equine rotavirus produced a rapid, serotype-specific response which peaked 10 days after infection and a slower heterotypic response which peaked 32 days later. In contrast, vaccination of the mares with an inactivated, adjuvanted serotype 6 bovine rotavirus produced a heterotypic response similar to that of the homotypic response in both serum and milk, although the predominant response in serum was IgG, while in milk it was IgA. These results suggest that non serotype-restricted passive protection of foals against rotavirus may be achieved by parenteral vaccination of mares.     

Electron microscopic detection rate of enteral viruses in diarrhea of dogs, cats, calves, swine and foals in the year 1988--electron microscopic study results

During 1988 fecal and gut samples of 641 dogs, 198 cats, 576 calves, 108 piglets and 64 foals with diarrhoea were investigated for virus infections by electron microscopy. In samples of dogs and cats parvovirus was detected at a proportion of 21.9% and 16.7%, respectively; rotavirus alone or together with coronavirus was found only in 0.3-1.5% of the specimens. In samples of calves rotavirus, as well as coronavirus dominated with a detection rate amounting to 17.4% and 26.6% respectively (including 4.5% of mixed infections); parvovirus was present in a ratio of 0.5%. Specimens of piglets mainly contained coronavirus (25.0%), and in lower percentages rotavirus (2.8%), rota- and coronaviruses (0.9%) and parvovirus (0.9%). In feces of foals rotavirus was detected in 6.3% and particles resembling picornavirus in 4.7% of cases. Not identifiable virus particles resembling corona-or picornaviruses were rarely found (between 0.6-2.5) also in specimens of the other animal species.     

Haemorrhagic necrotising enteritis in foals associated with Clostridium perfringens

Two foals aged 35 and 48 h from 2 Thoroughbred studs died several hours after developing clinical signs of depression, severe haemorrhagic diarrhoea and dehydration. Both foals had an acute haemorrhagic enteritis extending from the anterior jejunum to the terminal ileum which was characterised histologically by villus necrosis. Necrotic villi were surrounded by large numbers of rod-shaped Gram positive bacteria. Clostridium perfringens was recovered from the intestines of both foals and the isolates were considered to be C. perfringens type C. Other cases of diarrhoea were also observed in foals of the same age on these 2 studs, but the aetiology of these was not determined.