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Diarrheal Diseases

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Diarrheal diseases

Disease and agent Groups affected Diagnostic features and methods

Enteric colibacillosis

Escherichia coli

Neonates one day old to pigs up to 2-4 weeks postweaning.  Watery diarrhea, possibly vomiting. Minimal lesions; jejunum and ileum may have mild villous atrophy. Many Gram-negative rods on mucosa. Culture uniform population of E. coli from small intestine. Identify enterotoxigenic E. coli enterotoxins(s) and/or pili, usually by PCR. E. coli may also cause fibrinous polyserositis.

Rotaviral enteritis

(Rotavirus, usually group A) 

Usually 1-6 week old piglets. Also common about one week after weaning. Diarrhea, occasional vomiting. Usually nonfatal. Variable enteritis with moderate villous atrophy. Identify rotavirus in feces of early cases by EM or ELISA or in small intestinal epithelium by FAT or IHC.

Transmissible gastroenteritis (TGE)

Coronavirus

All age groups susceptible if previously unexposed. Most severe in piglets <4 weeks old. Acute form: vomiting and very high mortality in piglets <3 weeks old. Bright yellow feces often seen in older piglets. Marked diarrhea in feeder age pigs. Acutely infected sows may vomit, are depressed and refuse to nurse piglets.
Endemic form: similar signs but much less severe and with reduced mortality. FAT or IHC on intestine of acutely affected pigs or PCR on feces from acutely affected pigs.
Clostridium difficile-associated enterotoxemia Piglets 2-10 days of age with diarrhea, variable morbidity and low mortality Mesocolonic edema and colon filled with creamy diarrhea. Microscopically, there is multifocal suppurative and erosive colitis. The presence of C. difficile enterotoxin is confirmed by ELISA test on fresh feces.
Clostridium perfringens type A-associated enterotoxemia Piglets 2-10 days of age with diarrhea, variable morbidity and low mortality Minimal gross lesions, similar to colibacillosis. Microscopically there is mild multifocal suppurative enteritis with large Gram-positive rods. Isolation and genotyping of an enterotoxigenic (beta 2 toxin) C. perfringens type A is warranted.

Salmonellosis

Usually Salmonella serotypes Choleraesuis, Typhimurium, or Heidelberg

Other salmonellae are commonly isolated but primary role in disease is often unclear.

More common in weaned and growing pigs. All ages susceptible if previously unexposed. Intestinal form: Necrotizing enteritis of large and small intestine. Enlarged mesenteric lymph nodes. Congested lungs. Chronic cases may have rectal strictures or “button ulcers” in large intestine.
Septicemic form: Red/purple skin lesions on ears, tail, snout, feet, abdomen. Congested lungs, splenomegaly and hepatomegaly. Perhaps gray foci in liver.
Diagnosis: Severe septicemia or necrotizing enterocolitis. Culture Salmonella from lymph nodes, liver, lungs, spleen, kidneys, perhaps brain if CNS signs.
Histology: Paratyphoid nodules in liver.

Swine dysentery

Brachyspira hyodysenteriae

Previously Serpulina or Treponema

From 3 weeks to adults if previously unexposed. Mucohemorrhagic diarrhea (fresh mucus and fresh blood) is very suggestive. Mucohemorrhagic to fibrinonecrotic typhlitis and colitis but no lesions in small intestine.
Histology: Lesions largely restricted to mucosa with organisms in epithelium and crypts. Culture B. hyodysenteriae from mucosa or feces.
Note: Brachyspira pilosicoli is a sporadic cause of colitis.

Proliferative enteritis

Lawsonia intracellularis

Weaned pigs and all older swine. Signs: Subclinical disease with weight loss most consistent sign. Clinically affected have either an acute form with hemorrhagic diarrhea or chronic form with diarrhea and wasting.
Lesions: Thickening of mucosa of jejunum and/or ileum and/or colon. Curved bacilli in affected enterocytes. PCR (feces) and IHC (lesions) confirm organism and disease.

Whipworm infection

Trichuris suis

Feeder/finishers and mature swine Mucoid or mucohemorrhagic diarrhea with loss of condition is suggestive. Inflammatory nodules, often with protruding parasites, in mucosa of large intestine. Signs similar to those of swine dysentery and they can occur together. No eggs apparent until 8 weeks post-infection. Early cases diagnosed by histopathology or mucosal scrapings.

 

Diarrheal diseases at various ages

Infection with and/or agent Unweaned
piglets
Nursery pigs Grow/finish pigs Adults
Enterotoxigenic E. coli ++++ +++ + (early grower)  
Rotaviral infection ++++ +++ + (early grower)  
Transmissible gastroenteritis virus (TGE) ++++ +++ +++ +++
Clostridium difficile ++++      
Clostridium perfringens Type A ++++      
Clostridium perfringens Type C ++++ + (rare)    

Coccidiosis

Isospora suis

++++ ++ +  
Salmonellosis + ++ ++++ +

Swine dysentery

Brachyspira hyodysenteriae

+ ++ ++++ ++

Proliferative enteropathies

Lawsonia intracellularis

  ++ ++++ ++
Porcine epidemic diarrhea virus (exotic) +++ +++ ++++ ++++

Whipworm infection

Trichuris suis

  ++ ++++ +++

Key:

Clear cells indicate groups that seldom, if ever, are infected; 1+, 2+, and 3+ indicate increasing frequencies of infection, with 4+ indicating the age groups that most often are infected.

 

CNS-central nervous system
ELISA enzyme-linked immunosorbent assay
EM-electron microscopy
FAT-fluorescent antibody
IHC-immunohistochemistry
PCR-polymerase chain reaction 
 


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