a retrospective study on poult enteritis syndrome in minnesota

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A Retrospective Study on Poult Enteritis Syndrome in MinnesotaAuthor(s): Naresh Jindal, Devi P. Patnayak, Andre F. Ziegler, Alfonso Lago, and Sagar M. GoyalSource: Avian Diseases, 53(2):268-275. 2009.Published By: American Association of Avian PathologistsDOI: http://dx.doi.org/10.1637/8513-110308-Reg.1URL: http://www.bioone.org/doi/full/10.1637/8513-110308-Reg.1

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A Retrospective Study on Poult Enteritis Syndrome in Minnesota

Naresh Jindal, Devi P. Patnayak, Andre F. Ziegler, Alfonso Lago, and Sagar M. GoyalA

Department of Veterinary Population Medicine, University of Minnesota, College of Veterinary Medicine, 1333 Gortner Avenue,Saint Paul, MN 55108

Received 9 November 2008; Accepted and published ahead of print 6 February 2009

SUMMARY. A retrospective study was conducted to determine the occurrence of poult enteritis syndrome (PES) in Minnesotafrom January 2002 to December 2007. PES is an infectious intestinal disease of young turkeys between 1 day and 7 wk of age andis characterized by diarrhea, depression, and lethargy with pale intestines and/or excessively fluid cecal contents. During the studyperiod, samples from 1736 turkey flocks were submitted to the Minnesota Veterinary Diagnostic Laboratory for diseaseinvestigation. Of these, 151 flocks (8.7%) were PES positive. Cases of PES were seen throughout the year with higher prevalence infall. The PES was statistically associated with age with higher occurrence in poults less than 3 wk of age. Rotavirus, small roundvirus (SRV), Salmonella, nonhemolytic Escherichia coli, Enterococcus, and Eimeria oocysts were detected alone or in differentcombinations. Reovirus and adenovirus were found in one flock each. The most commonly identified pathogens were Salmonella(85 flocks) and rotavirus (73 flocks). Of PES-affected flocks, 39 (25.8%), 66 (43.7%), and 37 (24.5%) had one, two, and three ormore pathogens, respectively. Rotavirus, SRV, and reovirus occurred mostly in poults of less than 6 wk of age while Salmonella, E.coli, and Eimeria were seen in poults of all age groups. Minimum age for rotavirus detection was in 2-day-old poults.Histopathologically, moderate to severe mixed intestinal villus or lamina propria inflammatory infiltrates, necrosis of distal villustips in intestinal specimens, and mild to severe lymphocellular depletion in thymus, bursa, and spleen were seen. Antimicrobialsensitivity patterns of bacterial isolates from PES-affected flocks revealed maximum sensitivity to trimethoprim/sulfamethoxazoleand ceftiofur and a varying degree of resistance to other antimicrobials.

RESUMEN. Estudio retrospectivo del sındrome de la enteritis de los pavipollos en Minnesota.Se condujo un estudio retrospectivo para determinar la presentacion del sındrome de la enteritis en pavipollos (de las siglas en

ingles PES) en Minnesota de Enero de 2002 a Diciembre 2007. El sındrome de la enteritis en pavipollos es una enfermedadintestinal de pavos jovenes que ocurre entre el dıa primero y las siete semanas de edad y es caracterizado por diarrea, depresion yletargia con la presencia de palidez en intestinos y/o excesivo contenido fluido en los ciegos. Durante el periodo de estudio, muestrasde 1736 parvadas de pavos fueron remitidas al Laboratorio de Diagnostico Veterinario de Minnesota para realizar investigacionessobre la enfermedad. Del total de las parvadas, 151 parvadas (8.7%) fueron positivas a la enfermedad. Casos de enteritis enpavipollos se han observado durante todo el ano con alta prevalencia en el otono. Este sındrome estuvo asociado de maneraestadıstica con la edad, con mayor ocurrencia en pavitos menores de tres semanas de edad. Se ha detectado la presencia de rotavirus,virus redondos pequenos, Salmonella, Escherichia coli no hemolıtica, Enterococcus y oocistos de Eimeria por separado o en diferentescombinaciones. Se encontraron reovirus y adenovirus por separado en una parvada cada uno. Los patogenos mas frecuentementeidentificados fueron Salmonella (85 parvadas) y rotavirus (73 parvadas). De las parvadas afectadas, 39 (25.8%), 66 (43.7%) y 37(24.5%) presentaron uno, dos, tres o mas patogenos, respectivamente. La mayorıa de los pavipollos menores de seis semanaspresentaron rotavirus, virus redondos pequenos y reovirus, mientras que Salmonella, E. coli e Eimeria se observaron en pavipollos detodas las edades. La edad mınima de presentacion de rotavirus en pavipollos fue de dos dıas de edad. En el estudio histopatologico,se observo en las muestras intestinales, infiltrado inflamatorio mixto de moderado a severo en las vellosidades intestinales o en lalamina propria y necrosis del extremo distal de las vellosidades y se observo despoblacion de celulas linfocitarias de leve a severa en eltimo, bolsa de Fabricio y bazo. Los patrones de sensibilidad antimicrobiana de los aislamientos bacterianos de las parvadas afectadascon este sındrome revelaron la mayor sensibilidad al trimetoprim-sulfametoxazol y al ceftiofur y un grado variable de resistencia aotros antimicrobianos.

Key words: poult enteritis syndrome, turkey poults, Minnesota

Abbreviations: EPEC 5 enteropathogenic strains of E. coli; MVDL 5 Minnesota Veterinary Diagnostic Laboratory;NCCLS 5 National Committee for Clinical Laboratory Standards; PEC 5 poult enteritis complex; PEMS 5 poult enteritis andmortality syndrome; PES 5 poult enteritis syndrome; RVLVs 5 rotavirus-like-viruses; SRV 5 small round virus

An acute diarrheal disease with high morbidity and mortality inyoung turkeys was recorded in the 1950s in the United States andwas known locally as mud fever (33). Due to clinical similarities withbluecomb disease of chickens, this disease was named the ‘‘bluecombdisease.’’ Later, with the identification of coronavirus from thesecases, the name was changed to ‘‘coronaviral enteritis of turkeys’’(1,30,36). Subsequently, other intestinal diseases such as maldiges-tion syndrome, runting and stunting syndrome of turkeys, poultmalabsorption syndrome, poult enteritis and mortality syndrome(PEMS), spiking mortality of turkeys, and turkey viral enteritis were

described in young turkeys and were included in the poult enteritiscomplex (PEC) (4). PEC is a general term that describes infectiousintestinal diseases of young turkeys and is characterized by enteritis,moderate to marked growth depression, retarded development,increased mortality (as seen in case of PEMS), and impaired feedutilization. A number of viruses (coronavirus, reovirus, astrovirus,small round virus [SRV], rotavirus, and adenovirus), bacteria(Escherichia coli, Salmonella spp., clostridia, Campylobacter, andEnterococcus), and protozoa (coccidia, cryptosporidium) have beenimplicated in PEC (4).

Turkey growers and poultry veterinarians in Minnesota haveobserved a disease syndrome in young turkeys that has been referredto as poult enteritis syndrome (PES). PES is defined as an infectious,ACorresponding author. E-mail: [email protected]

AVIAN DISEASES 53:268–275, 2009

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multifactorial disease of young turkeys usually identified between 1day and 7 wk of age. Clinical signs include diarrhea, depression, andlethargy. Gross lesions associated with PES include pale intestinesand/or ceca with watery contents. Rarely, poults as old as 9 wk ofage are affected. This syndrome is not usually associated with thehigh mortality seen in PEMS that appeared in North Carolinaapproximately 10 yr ago.

The presence of disease agents with enteric syndromes may varydepending on the geographical location and different managementpractices on farms. For example, we have not detected coronavirus inPES-affected cases in Minnesota although this virus was the primaryagent recognized in PEMS in North Carolina (3,11). Thus, data ondisease prevalence may better define the disease epidemiologyleading to the development of meaningful approaches to diseasecontrol. In this retrospective study, we describe the occurrence ofPES and its associated pathogens in Minnesota from January 2002to December 2007.

MATERIALS AND METHODS

Collection of data. Data pertaining to PES in turkey poults werecollected retrospectively from the Minnesota Veterinary DiagnosticLaboratory (MVDL), Saint Paul, Minnesota, from January 2002 toDecember 2007. Laboratory submissions for serology and avianinfluenza testing by PCR were not taken into consideration. Live ordead birds or tissues from 1736 turkey flocks were submitted to theMVDL for disease diagnosis. Gross changes in different organs wererecorded at necropsy followed by collection of tissue specimens fornegative stain transmission electron microscopy and microbiological,histopathological, and other examinations. The data were analyzed withrespect to age group involved, monthly and seasonal occurrence, andagents identified.

Identification of enteric viruses. Intestinal contents from affectedbirds were collected, pooled, and examined for the presence of entericviruses by negative contrast electron microscopy (10).

Isolation of bacteria. Tissue pools (of visceral organs excludingintestines) from affected birds at necropsy were examined for Salmonellaby first enriching the samples in tetrathionate brilliant-green bile-enrichment broth for 24 hr at 37 C followed by subcultivation onbrilliant green agar for 24 hr at 37 C. Salmonella-like colonies wereselected and confirmed by a slide agglutination test using a polyvalentantiserum against Salmonella. For the isolation of E. coli, the tissues wereplated on to MacConkey agar plates followed by incubation at 37 C for

24 hr. Suspect colonies were confirmed using biochemical tests; e.g.,triple sugar iron agar, lysine, citrate, and motility-indole-ornithine. ForEnterococcus isolation, tissue homogenates were plated on sheep bloodagar and Columbia nalidixic acid agar. The plates were incubated at37 C for 24 hr in a 5% CO2 atmosphere. Suspect colonies wereconfirmed using biochemical tests including growth in 6.5% sodiumchloride and bile esculin agar (26).

Antimicrobial drug resistance. Susceptibility testing of Salmonella,E. coli, and Enterococcus isolates was carried out by the sensititre method(Trek Diagnostic System, Cleveland, OH). Briefly, isolated colonies ofbacteria were inoculated in trypticase soy broth followed by 1–2 hrincubation at 37 C. The broth culture was adjusted to 0.5 McFarlandstandard. One hundred microliters of trypticase soy broth culture wasadded to Mueller Hinton broth (11 ml) and processed further forantimicrobial drug resistance. Resistance or susceptibility to antimicro-bials was determined using criteria established by the NationalCommittee for Clinical Laboratory Standards (NCCLS) (26). Thebacterial isolates in intermediate category for an antimicrobial werecounted as resistant to that antimicrobial.

Identification of protozoa. Pooled intestinal contents were examinedfor the presence of protozoa (coccidia) by the fecal flotation technique(40).

Histopathology. Samples of intestine, spleen, bursa, and thymuswere collected in 10% neutral buffered formalin from majority of thecases. Thin sections from paraffin-embedded formalin fixed tissue blockswere cut, stained by standard hematoxylin and eosin stain (19), and thenexamined under a light microscope.

Statistical analysis of data. We evaluated the association betweenrow and column counts by the chi-square test using the FREQprocedure of SAS version 9.1 (SAS Institute, Cary, NC).

RESULTS

Occurrence of disease. During the study period, 151 (8.7%) of1736 flocks received at MVDL were characterized as having PES. In2002, only 2 (0.9%) of 217 flocks were PES positive. In 2007, thisnumber increased to 52 (12%) out of a total 432 flocks (Fig. 1).Rotavirus, Salmonella, nonhemolytic E. coli, and Eimeria oocystswere detected from 2002 onwards, whereas SRV and Enterococcuswere detected only after 2005. Reovirus and adenovirus weredetected only in one flock each in 2003 and 2006, respectively.

PES was recorded throughout the year with higher occurrence inSeptember and October (14%–15%) than in other months (5%–

Fig. 1. Cases of PES reported annually from 2002 to 2007 (percentage of PES flocks calculated by dividing number of PES flocks in a year bytotal flocks in that year).

Poult enteritis syndrome 269

10%) (Fig. 2). During the study period, 6.4%, 8.0%, 13.0%, and8.0% flocks were PES positive during spring, summer, fall, andwinter, respectively (Fig. 3). Statistical analysis of PES versus non-PES flocks revealed significant association of PES with season (P 5

0.004).Detection of different pathogens in PES flocks. A number of

enteric viruses (rotavirus, SRV, reovirus, and adenovirus) weredetected alone or in combination with bacteria (Salmonella,nonhemolytic E. coli, and Enterococcus) or protozoa (Eimeria sp.)in PES flocks. Among the different pathogens detected, theproportion of Salmonella and rotavirus was significantly higher thanthe other pathogens (P # 0.0001).

Rotavirus was the most common virus identified. Of the 73(48%) rotavirus-positive flocks (Table 1), rotavirus alone wasdetected in only 15 flocks (Table 2). In the remaining 58 flocks,other pathogens were also detected with rotavirus and Salmonella (14flocks), rotavirus and Eimeria (10 flocks), and rotavirus and E. coli(seven flocks) being the predominant combinations identified(Table 2). SRV was detected in 26 (17%) flocks (Table 1). SRValone was detected only in one flock, while in the remaining 25flocks other pathogens were also detected. SRV and Salmonella (fiveflocks) and SRV, rotavirus and Salmonella (five flocks) were thepredominant combinations (Table 2).

Among bacteria, Salmonella was the most prevalent; it was isolatedfrom 85 (56%) PES-affected flocks (Table 1). Salmonella wasdetected alone in 17 flocks while in the remaining 68 flocks, it wasdetected with rotavirus (14 flocks), E. coli (eight flocks), or SRV (fiveflocks). In 41 flocks, Salmonella was detected in differentcombinations involving more than two pathogens (Table 2).Salmonella serovars belonged to B4,5; C; C1; C2; E and G serotypesand included: Agona, Anatum, Brandenburg, Bredeney, Cubana,Hadar, Heidelberg, Infantis, Kentucky, Muenster, Oranienburg,Senftenberg, Typhimurium, Uganda, and Worthington. E. coli andEnterococcus were detected in 54 (36%) and 16 (11%) flocks,respectively (Table 1). Both of these pathogens were detected eitherwith rotavirus, SRV, or Salmonella or from flocks that involved morethan two pathogens (Table 2). In 44 flocks (29%), Eimeria oocystswere also detected (Table 1). Similar to E. coli and Enterococcus,Eimeria oocysts were also observed in flocks that involved more thanone pathogen.

Of PES-affected flocks, 39 (25.8%), 66 (43.7%), and 37 (24.5%)had one, two, and three or more pathogens, respectively. In oneflock, as many as six pathogens (rotavirus, SRV, Salmonella, E. coli,Enterococcus, and Eimeria) were detected (Table 2). In nine flocks(6%), these pathogens were not detected and these flocks werereferred to as flocks with ‘‘enteritis of unknown etiology’’ (Tables 1,2).

Age-wise distribution. There was a statistically significantrelationship between PES and age of birds (P # 0.0001). Of the151 PES flocks, 111 (73.5%), 35 (23.2%), and 5 (3.3%) flocks hadpoults less than 3 wk, 3–6 wk, and 6–9 wk of age, respectively

Fig. 2. Monthly distribution of cases of PES from 2002 to 2007 (percentage of PES flocks calculated by dividing number of PES flocks in amonth by total flocks in that month).

Table 1. Occurrence of various pathogens in PES-affected flocksduring 2002–2007.

Pathogen No. (%) of PES flocksA

Rotavirus 73 (48)Small round virus 26 (17)Reovirus 1 (0.6)Adenovirus 1 (0.6)Salmonella 85 (56)E. coli 54 (36)Enterococcus 16 (11)Eimeria 44 (29)Unknown 9 (6)

ATotal number of PES flocks during the study period was 151.

Fig. 3. Seasonal distribution of cases of PES from 2002 to 2007(percentage of PES flocks calculated by dividing number of PES flocksin a season by total flocks in that season; spring 5 March to May;summer 5 June to August; fall 5 September to November, and winter5 December to February).

270 N. Jindal et al.

(Fig. 4). The latter two categories (3–6 wk and 6–9 wk) werecombined to compare statistically the flocks less than 3 wk and morethan 3 wk of age with PES. PES was significantly more in poults lessthan 3 wk of age as compared to poults more than 3 wk of age (P #

0.001). Of 111 PES flocks with poults less than 3 wk of age, the ageof the poults in 27, 67, and 17 flocks was less than 1 wk, 1–2 wk,and 2–3 wk, respectively.

As far as the distribution of various pathogens in different agegroups among PES flocks is concerned, rotavirus was frequentlyidentified in PES-affected poults up to 6 wk of age (Table 3). Onlyone flock older than 6 wk of age was positive for rotavirus.Occurrence of rotavirus was 48% (53 flocks) and 54% (19 flocks) inpoults less than 3 wk of age and 3–6 wk of age, respectively(Table 3). Of 27 PES flocks with poults less than 1 wk of age,rotaviruses were detected in 18 (67%) flocks. Rotavirus was detected

as early as in 2-day-old poults. SRV was detected in poults up to6 wk of age but only in one flock with poults greater than 6 wk ofage. SRV was detected more in poults less than 3 wk of age (20%)than in poults between 3 and 6 wk of age (9%) (Table 3). Thoughthe rotavirus or SRVs were detected more in poults less than 3 wk ofage than in poults more than 3 wk of age, but there was no statisticaldifference between probability of detection of these two viruses andage of PES-affected poults (Table 3). Reovirus was detected at 1–2 wk of age and adenovirus at 6–7 wk. The probability ofSalmonella isolation was significantly related with the age of birds(P 5 0.0015) (Table 3). Though Salmonella was isolated frompoults of all age groups, isolations were more frequent up to 3 wk ofage. The pattern of E. coli isolation was similar to that of Salmonella.In contrast, Enterococcus was isolated from poults of less than 3 wk ofage. Analysis of data also revealed that isolation of Enterococcus wassignificantly higher in PES-affected poults of less than 3 wk of agethan in poults older than 3 wk of age (Table 3). Detection ofEimeria sp. also had an association with age with higher occurrenceat 3–6 wk (Table 3).

Antimicrobial sensitivity pattern of bacterial isolates fromPES-affected flocks. The maximum sensitivity of Salmonella wasagainst trimethoprim/sulfamethoxazole (98%) followed by ceftiofur(57%) and gentamicin (51%) (Table 4). All Salmonella isolates wereresistant to clindamycin, erythromycin, novobiocin, penicillin,spectinomycin, sulfathiazole, and tylosin. Resistance of Salmonellato amoxycillin, neomycin, oxytetracycline, streptomycin, sulfadi-methoxine, and tetracycline ranged between 51% and 90%.Similarly, E. coli isolates were also sensitive to trimethoprim/sulfamethoxazole (98%) and ceftiofur (55%). Varying degrees ofresistance were noted for the remaining antimicrobials. More than90% of E. coli isolates were resistant to clindamycin, erythromycin,

Table 2. Detection of pathogens alone or in combination: PES-affected flocks during 2002–2007.

PathogenA

No. of cases by year

2002 2003 2004 2005 2006 2007 Total

RV 0 2 3 5 2 3 15Sal. 0 1 1 5 7 3 17Eimeria 0 0 0 1 2 0 3E. coli 0 0 1 0 1 0 2RV + Sal. 0 0 1 2 2 9 14RV + Eimeria 0 0 1 0 6 3 10RV + E. coli 1 0 1 0 3 2 7Eimeria + E. coli 0 0 2 2 3 0 7Sal. + Eimeria 0 0 0 1 2 4 7Sal. + E. coli 0 1 1 0 2 4 8SRV + Sal. 0 0 0 1 3 1 5E. coli + Ent. 0 0 0 0 0 3 3SRV + Eimeria 0 0 0 1 0 1 2RV + SRV + Sal. 0 0 0 0 2 3 5Sal. + E. coli + Ent. 0 0 0 1 0 3 4SRV + Sal. + E. coli 0 0 0 0 1 1 2Sal. + Eimeria + E. coli 0 0 0 0 1 1 2RV+ Sal. + Eimeria 1 0 0 0 0 1 2RV + Eimeria + E. coli 0 0 0 1 1 0 2RV + SRV + Sal. + E. coli 0 0 0 0 2 2 4RV+ Sal. + E. coli + Ent. 0 0 0 0 1 2 3RV + Sal. + Eimeria + E. coli 0 0 0 1 1 1 3OthersB 0 1 0 3 6 5 15Enteritis of unknown etiology 0 3 2 3 1 0 9

ARV 5 rotavirus; Sal. 5 Salmonella; Ent. 5 Enterococcus.BInclude either SRV (1 case), reovirus (1), RV+ SRV (1), Sal. + Ent. (1), RV + Ent. (1), RV+ Sal. + Ent. (1), RV+ Sal. + E. coli (1), RV + E. coli +

Ent. (1), SRV + Sal. + Eimeria (1), RV + SRV + Eimeria (1), SRV + Sal. + E. coli + Ent. (1), Adenovirus + Sal. + Eimeria + E. coli (1), SRV+ Sal. +Eimeria + E. coli (1), RV + SRV+ Sal. + Eimeria + E. coli (1), and RV + SRV+ Sal. + Eimeria + E. coli + Ent. (1).

Fig. 4. Cases of PES in different age groups of turkey poults from2002 to 2007 (percentage of PES flocks calculated by dividing numberof PES flocks in an age group by total flocks in that age group).


novobiocin, oxytetracycline, penicillin, spectinomycin, sulfathiazole,tetracyclines, and tylosin. In contrast, Enterococcus isolates showedsensitivity to amoxycillin (94%), penicillin (75%), and trimetho-prim/sulfamethoxazole (100%). All Enterococcus isolates wereresistant to clindamycin, neomycin, spectinomycin, streptomycin,sulfathiazole, and sulfadimethoxine (Table 4).

Pathology. Thin walled intestines with excessively watery or fluidintestinal contents were the major necropsy findings in all PES-affected flocks. In addition, ceca were distended with loose cecalcontents. Moderate to severe mixed (lymphocytic/plasmacytic/heterophilic) villus inflammatory infiltrates in the lamina propriaor villi of the intestinal specimens were consistently noted. Sectionswith necrosis of distal villus tips with mild lymphocytic/plasmocyticvillar and laminar infiltrates and clubbing of the distal villus tipswere noted in many cases. In most cases, inflammatory infiltrateswere diffusely distributed. Moderate numbers of protozoal (Eimeriasp.) organisms were present within intestinal villus epithelium or inthe intestinal lumen in cases that were positive for coccidiosis.Changes in thymus consisted of mild to severe regional corticallymphocellular cortiomedullary depletion and heterophilic inflam-matory infiltrates surrounding the Hassel corpuscle. Mild tomoderate generalized lymphocellular depletion and multifocal bursalfollicular epithelial cyst changes were the major microscopic changesin bursa. Mild to moderate white pulp and/or red pulplymphocellular depletion was observed in splenic specimens.

DISCUSSION

This study is based on data obtained from MVDL for the past6 yr (2002–2007). During this period, 8.7% turkey flocks werefound to be affected with PES. Since all PES-affected flocks are notbrought to the MVDL for disease investigation, the actual numberof flocks affected with PES is unknown, but may be higher. It shouldbe realized that data in this study are from samples that weresubmitted to the MVDL for disease diagnosis and should not beconstrued as ‘‘active surveillance.’’ An increase in the number of PEScases from 2002 to 2007 could either be due to increased occurrenceof the disease or to increased reporting and laboratory casesubmission. Higher occurrence of PES in fall is not surprising. Forexample, most cases of PEC in the southeastern United States werereported to occur between May and September (4). It could be dueto more conducive environment leading to rapid multiplication ofpathogens detected from PES-affected poults.

Rotavirus and Salmonella were the agents present in the greatestproportion in PES cases. Significantly higher detection of rotavirusand Salmonella from PES cases suggests that the causality pathshould be further explored. Rotaviruses are the major cause ofdiarrhea in human infants and several mammalian species.Rotaviruses have also been detected in many avian species likepheasants, turkeys, ducks, chickens, and wild birds, but their role asa causative agent of diarrhea varies (9,18,23,43,44). In turkeys and

Table 3. Occurrence of pathogens in PES-affected flocks of different age groups during 2002–2007.

Pathogen

No. (%) of PES flocks in different age groupsA

P valueB#3 week 3–6 week 6–9 week

(n 5 111) (n 5 35) (n 5 5)Rotavirus 53 (48) 19 (54) 1 (20) 0.8069Small round virus 22 (20) 3 (9) 1 (20) 0.1584Reovirus 1 (0.09) 0 (0) 0 (0) NDC

Adenovirus 0 (0) 0 (0) 1 (20) NDSalmonella 71 (64) 12 (34) 2 (40) 0.0015E. coli 36 (32) 14 (40) 4 (80) 0.1551Enterococcus 16 (14) 0 (0) 0 (0) 0.0111Eimeria 16 (14) 25 (71) 3 (60) 0.0001Unknown 6 (5) 3 (9) 0 (0) ND

APercentage has been calculated on the basis of total PES flocks in each category.BFor P values, PES flocks in categories 3–6 wk and 6–9 wk were combined and then compared with PES flocks less than 3 wk of age.CP values were not calculated for reovirus, adenovirus and unknown etiology because of the fewer number of flocks in these categories.

Table 4. Antimicrobial resistance pattern of bacteria isolated from PES-affected flocks during 2002–2007.

Antimicrobials

% Isolates resistant to antimicrobials

Salmonella E. coli Enterococcus

Amoxycillin 61 64 6Ceftiofur 43 45 88Clindamycin 100 98 100Erythromycin 100 96 69Gentamycin 49 53 94Neomycin 51 70 100Novobiocin 100 98 86Oxytetracycline 73 93 93Penicillin 100 98 25Spectinomycin 100 96 100Streptomycin 90 86 100Sulfadimethoxine 88 86 100Sulfathiazole 100 100 100Tetracycline 72 91 94Trimethoprim/sulfamethoxazole 2 2 0Tylosin 100 100 60


pheasants, rotavirus has been reported as a cause of diarrhea(18,22,37). Rotavirus has also been associated with PEC (4) andrunting and stunting syndrome in broiler chickens (28). Analysis of10-yr data (1993–2003) of poult enteritis in California turkeysrevealed that rotavirus-like viruses (RVLVs; all viruses that haverotavirus-like appearance on electron microscopy) were identified in46% of enteric virus positive poult enteritis cases (48). In the presentstudy, rotavirus was detected in poults less than 6 wk of age. Theseresults are similar to those of Reynolds et al. (35) who monitoredfour turkey flocks for the presence of enteric viruses from placementuntil 7 wk of age. During the first 4 wk of life, astrovirus was themost frequently detected virus followed by RVLVs and rotavirus. Inone flock, rotavirus and astrovirus were detected in samples collectedat 3 days of age. Theil and Saif (46) detected rotavirus in commercialturkeys between the ages of 3 and 35 days. Woolcock andShivaprasad (48) also detected a majority of RVLVs by 36 days ofage. In a longitudinal survey of enteric viruses in eight commercialturkey operations, rotavirus was the only virus detected prior toplacement (31). In the present study, the minimum age at whichrotavirus was detected was in 2-day-old poults. Further, rotaviruseswere detected in 18 flocks that had poults up to 1 wk of age.Detection of rotavirus at such an early age may indicate either fecalcontamination of hatching eggs and/or vertical transmission ofrotaviruses (31,35). However, further studies are needed to confirmor refute these observations and their relevance to Minnesota PEScases.

SRVs were detected in young poults either alone or incombination with other pathogens. Enterovirus, astrovirus, entero-virus-like particles, and picornavirus have all been referred to asSRVs and their sizes vary from 15 to 30 nm. Though SRVs havedistinct morphologies visible by electron microscopy (5), thecharacteristic physical properties may become less prominent dueto the emergence of new subgroups and strains within these viruses(17). Due to this, there are chances of misidentification ormisclassification of a virus on electron microscopy (47). Thus, it isoften difficult to determine if SRVs detected on electron microscopyare actually enterovirus or astrovirus or other SRVs. We can onlyconfirm the viral genus by using other methods including molecularmethods. The chance of these SRVs being astroviruses is greaterbecause we have detected astroviruses from intestinal contents ofsome of the PES-affected flocks (unpublished data) by RT-PCRwhile these same samples were negative when examined by electronmicroscopy. Astroviruses have also been detected from turkey poultssuffering from enteritis (12,25,34). Enterovirus-like viral particleswere identified for the first time in the feces of poults with diarrheain the United Kingdom (24). Subsequently, the detection ofenterovirus in the feces of young turkeys has been reported bydifferent workers (35,37,38).

Viruses other than rotavirus and SRV associated with PEC areturkey coronavirus (11,16,45), reovirus (15,41), and adenovirus(39,42). Adenovirus in the present study was detected only from oneflock. This finding is in agreement with that of Woolcock andShivaprasad (48) who also reported low positivity of adenovirus inpoult enteritis cases by electron microscopy. Reovirus was alsodetected only from one flock. No coronavirus was detected in thepresent study indicating that either it is not associated with PES ortheir concentration was too low to be detected by electronmicroscopy.

Amongst bacteria, Salmonella and E. coli are important pathogensassociated with PEC (4,7,29). Salmonella was isolated from PES-affected poults of all age groups (with more probability of occurrencein younger birds). E. coli was isolated from poults of all age groups

but Enterococcus was more prevalent in poults less than 3 wk of age.The role of these bacteria as primary pathogen or as co-pathogen/swith enteric viruses cannot be determined. Perhaps these bacteriaprolong the illness after the birds are infected with enteric viruses orthey may increase the severity of enteric disease in concert withenteric viruses. Salmonella serovars isolated in the present study arereferred to as paratyphoid salmonellae. These serovars can causedisease in young turkeys under stressful conditions and generallycolonize the intestinal tract. Salmonella and enteric virusesparticularly the rotavirus (if transmitted vertically) can occupy aniche in the intestines of day-old poults and may lead to PES at avery young age.

In the present study, E. coli isolates were of nonhemolytic typeand were isolated along with other pathogen(s). E. coli is anopportunistic pathogen and has the ability to cause disease understress conditions. Enteroinvasive strains and enteropathogenic strainsof E. coli (EPEC) have been reported to play a significant role inPEMS (3). Guy et al. (13) reported that inoculation of turkey poultswith EPEC failed to produce any effect on the birds. However, birdscoinfected with turkey coronavirus and EPEC demonstrateddiarrhea, stunting, mortality, lymphoid organ atrophy, and markedcolonization of EPEC. This finding supports the results of thepresent study that E. coli was isolated along with other pathogensfrom PES-affected flocks (52 of 54 flocks). Species of the genusEnterococcus comprise a large proportion of the autochthonousmicroflora associated with gastrointestinal tracts of animals and arefrequently responsible for significant morbidity in predisposedhumans (8). We do not know at present the significance ofEnterococcus in PES cases. Similar to E. coli, Enterococcus was alsoisolated along with other pathogens from PES cases.

Most of the bacterial isolates from PES flocks were sensitive totrimethoprim/sulfamethoxazole and ceftiofur. These results aresimilar to those of Pedersen et al. (32) who reported that Salmonellaserovars from Danish turkeys were sensitive to colistin, ceftiofur, andamoxycillin with clavulanic acid. Olah et al. (27) reported varyingdegree of resistance to tetracycline, sulfamethoxazole, gentamicin,and streptomycin in Salmonella isolated from turkeys in Midwestregion of the United States. Our results are also similar to those ofMalik et al. (20) who reported that isolates of Salmonella and E. colifrom chickens in Minnesota were maximally sensitive to trimeth-oprim/sulfamethoxazole. Hayes et al. (14) reported that Enterococcussp. isolated from turkey meat in the United States were resistant totetracyclines and erythromycin. In the present study, Enterococcusisolates were resistant to tetracyclines, streptomycin, clindamycin,neomycin, sulfathiazole, and sulfadimethoxine.

Most cases of coccidiosis occurred in PES-affected poults greaterthan 3 wk of age. The life cycle of Eimeria, the causative agent ofcoccidiosis, is typically completed within 4–6 days (21). However,occurrence of disease in a flock also depends upon parasitic load inthe farm, presence or absence of coccidiosis in previous flocks,cleanliness at farm, disposal of Eimeria-contaminated litter from aprevious flock, rodent activity, environmental conditions, etc.Presence of these factors on a farm or vaccination against coccidiosismay lead to identification of Eimeria sp. in younger poults.

Nine flocks in the present study were categorized as flocks withenteritis of unknown etiology. In these flocks, enteric pathogensidentified in other PES-affected flocks could not be detected. Thismay be due to the presence of a low quantity of enteric viruses in theintestinal contents that could not be detected by electronmicroscopy. Another factor could possibly be the noninfectiousetiology; the managemental or nutritional factors might have led toenteritis in poults.


Statistical relationship between PES and age of birds suggests thatyoung poults are more susceptible to PES and that the syndromewould affect the growth potential of affected birds. Experimentalinoculation of 14-day-old turkey poults with intestinal contents(positive for rotavirus, astrovirus, and Salmonella) from PES-affectedbirds resulted in significantly lower body weights than controls.Overall growth depression due to PES treatment was 31.8% (N.Jindal, unpubl. data). Considering such a growth depression and itsoccurrence, it would appear that PES causes considerable economiclosses for turkey producers. In the present study, 24.5% PES-affectedflocks had three or more pathogens. Surprisingly, one of the flockhad six pathogens. In such situations, increasingly additive adverseeffects (particularly on growth) can be expected. Though we do notknow at present up to which age the PES-affected birds will harborthese pathogens, future studies will shed light on the pathogenesis ofPES and the ill effects produced at a later stage. Pathological changesin gastrointestinal tract, similar to those observed in the presentstudy, have earlier been reported in poults affected with rotavirus(49), stunting syndrome (2), and spiking mortality syndrome (6).The depletion of lymphocytes in lymphoid organs observed in thepresent study has the support of Teixeira et al. (45) who alsoobserved depletion of lymphoid organs in turkey poults affected withPEC. Such a depletion may predispose the affected birds tosecondary infections and may further deteriorate poult health byhampering vaccinal immunity. In conclusion, this retrospectivestudy reveals the occurrence of PES in Minnesota turkeys less than6 wk of age. Rotavirus, SRV, Salmonella, E. coli, Enterococcus, andEimeria were the primary pathogens associated with this syndrome.

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ACKNOWLEDGMENT

This work was supported in part by a grant from the RapidAgricultural Response Fund, University of Minnesota.


a retrospective study on poult enteritis syndrome in minnesota

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