Swine Dysentery | Iowa State University (2023)

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Swine Dysentery and Spirochaetal Colitis

(Brachyspira [previously Serpulina and Treponema] hyodysenteriae and Brachyspira pilosicoli)


Swine dysentery (SD) is a severe, infectious disease characterized by mucohemorrhagic diarrhea and marked inflammation limited to the large intestine (cecum and/or colon). Spirochaetal colitis (SC) causes milder colitis in young -pigs.


Swine dysentery (SD) occurs only in swine although the etiologic agent infects and persists in rodents. All ages of swine may have SD although it seldom is apparent in piglets less than three weeks old. The disease occurs more frequently during the growing/finishing periods. Swine dysentery occurs worldwide in the major swine-raising countries and can cause very significant economic losses on affected herds. In the United States, SD now occurs only occasionally because of successful eradication and/or effective manure removal techniques. Outbreaks occur throughout the year, more often in late summer and early fall. With the increased interest in niche pork production (e.g. organic, antibiotic free) in the US, there has been an increase in incidence of SD in these systems.

Spirochaetal colitis associated with Brachyspira pilosicoli also has worldwide distribution, causing a milder, non-hemorrhagic colitis.

Historical information

Swine dysentery was first reported in 1921. Subsequently it was reported from many swine-raising countries throughout the world. The etiology remained unknown until 1971. Much of the extensive research on the disease was reported during the 1970s and 1980s. Spirochaetal colitis associated with Brachyspira pilosicoli was described subsequent to SD.

Prior to the discovery of organic arsenicals as an effective treatment and preventative, SD caused disastrous losses among swine herds. Improved methods of control have markedly reduced losses in the US, although SD is still an important disease in some parts of the world. Methods of elimination of SD from swine herds have been well described and the establishment of a national eradication program has been considered, but lack of a sensitive monitoring test remains a problem.


Brachyspira (previously, Serpulina or Treponema) hyodysenteriae, a spirochete, is the etiologic agent. It has axial filaments, is Gram-negative, anaerobic and the most pathogenic strains are strongly beta-hemolytic. There are a few avirulent or weakly beta-hemolytic Brachyspira strains that are predominantly nonpathogenic. Other organisms in the large intestine, especially anaerobes, may facilitate colonization and lesion formation. Brachyspira hyodysenteriae has the ability to survive under a wide range of environmental conditions but is susceptible to heat, ultraviolet (UV) light, and desiccation, as well as soaps and disinfectants. Other spirochetes, especially B. innocens and B. pilosicoli are found in the large intestine of many swine and are easily mistaken for B. hyodysenteriae.

While considering a diagnosis of swine dysentery, one should be aware of recent work in describing a nonfatal, non-bloody, diarrheal disease in swine caused by Brachyspira (Serpulina) pilosicoli. This agent appears to be common in swine populations and is an occasional cause of catarrhal colitis in young growing swine. Virtually all statements related to B. hyodysenteriae are also true for B. pilosicoli with the exception that disease caused by the latter is much milder.


Transmission of B. hyodysenteriae is by ingestion of infectious feces. It can persist in lagoon water for at least two months, moist feces for two months, and soil for 18 days. Mice have been reported to shed B. hyodysenteriae for 180 days and dogs for 13 days. The organism can be transmitted by birds, flies, and fomites. Carrier swine can transmit the agent for at least 90 days. Clinically normal, purchased carriers, including breeding stock, often are the source of initial exposure. Carrier sows often transmit to their piglets. Infected mice on premises may also be a source of infection.


Brachyspira hyodysenteriae is ingested with clinical signs developing 5-21 days later; incubation period is dependent upon dose but the infective dose is quite small. The organism reaches the large intestine where it colonizes, proliferates, penetrates the mucus layer and becomes closely associated with epithelial cells. Invasion may not be essential for lesion production. The exact mechanism of tissue destruction is not known but lipopolysaccharide in the organism probably is involved. Also, B. hyodysenteriae producestwo known toxins and a hemolysin that may play roles. In typical lesions the organisms can be seen within epithelial cells and occasionally in the lamina propria. Lack of lesions at other sites suggests the entire pathogenesis is associated with the cecal and colonic lesions. B. pilosicoli appears to exert pathogenic effect by attachment to enterocytes and microerosion of epithelium.

Systemic effects presumably are the result of fluid and electrolyte imbalance caused by colitis. Fluid imbalance is the result of failure of the colon to absorb fluid, much of it from endogenous secretions, and explains the progressive dehydration and deaths that occur. Peracute deaths occasionally occur, perhaps caused by the toxins.

Clinical signs

Diarrhea, usually with gray to yellow, mucoid feces often is the first sign noticed. With SD, diarrhea continues and quickly becomes mucohemorrhagic, with excess mucus and fresh blood apparent. In a small percent of the pigs, diarrhea may be preceded by tail twitching or a humped, gaunt appearance. Fresh, red blood in mucus-containing feces often is profuse and the perineal area may become blood stained. Signs that follow prolonged diarrhea are those associated with dehydration. These include sunken eyes, marked weakness, hollow flanks and weight loss. In advanced cases, appetite is erratic but the animals continue to drink. Advanced cases remain unthrifty, even with treatment. Occasionally, sudden death is observed. In untreated herds morbidity is high and mortality can approach 50%.

Spirochaetal colitis is generally seen as a mild persistent diarrhea with mucus. Affected pigs may be less thrifty but effects on growth performance may not be overtly obvious.


Lesions are limited to large intestine, except for dehydration and the nonspecific reddening of the gastric mucosa. The mesentery and serosa are edematous and the serosa is rather opaque. Any or all parts of the large intestine (cecum, spiral colon, rectum) may be affected. It is heavy, thick walled, congested and edematous. The mucosa is thrown into folds and is covered, diffusely or in patches, with a layer of fibrin, necrotic debris and mucus. There often are flecks of blood in the mucus or on uncovered mucosa. The colon contains fibrinonecrotic debris and excessive mucus, often mixed with blood.

In acute cases the mucosa of the affected large intestine is reddened, edematous and swollen. There may be only small amounts of fibrin but excessive mucus. Blood usually can be seen in the feces. Pigs that die suddenly may be in surprisingly thrifty condition although lesions in the large intestine are extensive.

Microscopically, there is moderate nonsuppurative colitis and typhlitis, mucosal metaplasia, edema, and superficial epithelial necrosis. Spiral-shaped organisms can be demonstrated within crypts, enterocytes, and debris by silver stain.

Lesions of spirochaetal colitis are milder, with mild hyperemia and excess mucus observed on the mucosa of large intestine. Microscopically, there may be abundant spiral-shaped organisms colonizing epithelium, accompanied by mild nonsuppurative inflammation.


A field diagnosis of SD often can be made on the basis of clinical signs and typical gross lesions. A simple aid in diagnosis is the demonstration of many spirochetes in stained smears made from colonic scrapings. Brachyspira hyodysenteriae is weakly Gram-negative so organisms are best demonstrated with crystal violet or Victoria blue 4-R stains. Other spirochetes are easily mistaken for B. hyodysenteriae, so it is advisable to get laboratory confirmation of the diagnosis, especially if the outbreak is an initial one or there is doubt about the diagnosis. B. hyodysenteriae often can be cultured and identified from rectal swabs or colonic scrapings from acutely affected, unmedicated pigs. Biochemical differentiation of pathogenic and nonpathogenic strains can be challenging. Polymerase chain reaction (PCR) techniques are available for detection of the organism and provide differentiation to the species level; their use is encouraged.

Several diarrheal diseases of swine must be differentiated from SD. These include proliferative enteritis, whipworm infestation, gastric ulcers, spirochaetal colitis (B. pilosicoli), and salmonellosis. Severe whipworm infections mimic mucohemorrhagic SD and worms are not grossly visible until three to four weeks after infestation. Salmonellosis lesions usually are not confined to the large intestine, as are swine dysentery lesions. Lesions of salmonellosis tend to extend deeper into the mucosa as ulcers and may be patchy in distribution with less mucus. Necropsy of several pigs and microscopic study of the colon often are helpful in separating the two diseases. Dual infections can occur. Spirochaetal colitis is best diagnosed by necropsy of acutely affected pigs, histopathology, isolation of the weakly beta-hemolytic causative organism, and definitive identification biochemically or by PCR.


Preventing the introduction of B. hyodysenteriae to negative herds is a high priority. Additions to the herd should be only from herds known to be free of swine dysentery. They should be added only after a quarantine period of 30-60 days. Some veterinarians recommend treating high-risk animals with tiamulin or carbadox during quarantine to reduce the possibility of carriers being introduced.

Three methods are used to eliminate swine dysentery and have been quite successful in the US. Early weaned piglets (< three weeks) taken to a clean site and raised there usually remain free of B. hyodysenteriae. Meanwhile, the infected herd can be marketed, and the facilities cleaned and disinfected. This method allows one to retain valuable genetic stock. Segregated rearing with all in/all out production techniques has been quite successful in eliminating SD.

A second method relies on medication. Reduction of a herd to a minimal number of animals, followed by intensive treatment of those retained, is often used. Debilitated animals must be disposed of since they may not consume enough medicated feed or water. Prolonged, intensive treatment is expensive so numbers of swine to be treated should be minimized. Three widely used therapeutic agents include carbadox, lincomycin and tiamulin. Directions for their use should be followed carefully and every animal must be treated.

The third method of complete depopulation may be useful on premises with endemic swine dysentery where biosecurity and sanitation are difficult to implement. Depopulation should be done during warm, dry weather. During depopulation all facilities and equipment should be thoroughly cleaned and disinfected. The premises should be left vacant for at least two weeks, depending on the weather and level of achievable sanitation. Brachyspira hyodysenteriae usually will not survive for more than two weeks in soil or grass pens kept dry and relatively free of feces during dry, warm weather. Repopulation should be made with swine free of SD.

Any effort to eradicate SD requires an initial accurate diagnosis of SD, a commitment from the owners, and initial agreement on a protocol for accomplishing eradication and ongoing veterinary supervision. The eradication effort should be made during the warmest time of the year. A professionally-managed rodent control program is essential. Eradication must be coordinated with pig flow so that thorough cleaning and disinfection can be accomplished when the premises are vacant or the population minimal. If infected animals must be retained during the effort, a barrier system must be set up to separate clean from potentially contaminated areas.

Producers trying to control, but not eliminate infection with endemic swine dysentery can use preventive and therapeutic levels of antibiotics administered in feed and/or water. Those herds often can be treated intermittently to advantage. Although several products are FDA-approved for swine dysentery, carbadox, lincomycin, and tiamulin seem to be most effective. Antibiotic resistance is an increasing problem with this organism, making control programs (as opposed to elimination) a poor long term strategy. Vaccination has not proved to be reliably effective in control or elimination programs.

Control of B. pilosicoli should follow the same principals of sanitation and husbandry. The disease usually responds favorably to the antimicrobials listed for swine dysentery.

See the table: Diseases Associated with Hemorrhage in Intestine


What is swine dysentery caused by? ›

Swine Dysentery (SD) is a severe mucohaemorhagic enteric disease of pigs caused by Brachyspira hyodysenteriae, which has a large impact on pig production and causes important losses due to mortality and sub-optimal performance.

Is swine dysentery contagious? ›

Swine dysentery is a contagious diarrhoea which affects mainly the large intestine. Animals suffering from the disease have a severe diarrhoea, often bloodstained and mucoid.

What is swine dysentery also known as? ›

Swine Dysentery has long been recognised as a major disease of pigs throughout the world and can be seen in all types of pig keeping operations. The causative bacterium was identified back in the 1960's now referred to as Brachyspira hyodysenteriae, but previously known as Treponema and Serpulina hyodysenteriae.

Is there a vaccine for swine dysentery? ›

In March 2012, when the company was set up, the Brachyspira hyodysenteriae, strains were transferred to Aquilón for use in the development of a vaccine to improve the control of this important disease. A vaccine prototype, that has been patented and demonstrated efficacy in controlled infection tests, is now available.

What is the cure of swine dysentery? ›

Although several products are FDA-approved for swine dysentery, carbadox, lincomycin, and tiamulin seem to be most effective. Antibiotic resistance is an increasing problem with this organism, making control programs (as opposed to elimination) a poor long term strategy.

How is swine dysentery treated? ›

Antimicrobials are an effective treatment for swine dysentery if started early, and water medication may be preferred. Increasing resistance to antimicrobials has been reported in several countries; thus, minimum inhibitory concentration testing is recommended before starting antimicrobial treatment.

Is swine dysentery fatal? ›

Swine dysentery has an incubation period of 5-21 days preceding symptoms and can be fatal, with morbidity and mortality up to 50% among untreated pigs.

Can dysentery be passed from person to person? ›

Bacillary and amoebic dysentery are both highly infectious and can be passed on if the poo (faeces) of an infected person gets into another person's mouth. This can happen if someone with the infection does not wash their hands after going to the toilet and then touches food, surfaces or another person.

What are the signs and symptoms of swine dysentery? ›

This disease affects all ages. The key clinical signs are watery, bloody diarrhoea; wasting body condition; and dehydration. Mortality can occur if dehydration persists.

What is dysentery called today? ›

The disease is called shigellosis. About 500,000 people in the U.S. get it every year. Amoebic dysentery comes from a parasite called Entamoeba histolytica. You're more likely to get this kind of dysentery if you travel to a tropical location that doesn't have good sanitation.

Is dysentery the same as salmonella? ›

Bacillary dysentery: A bacterial infection causes bacillary dysentery. Some of the most common bacteria that cause bacillary dysentery include Shigella, Salmonella, Campylobacter and Escherichia coli (E. coli). Bacillary dysentery is the most common type of dysentery.

Was dysentery a pandemic? ›

In late 1968 an epidemic of bacterial dysen- tery began in southwestern Guatemala; during 1969 it spread rapidly to surrounding countries; and by 1970 cases had been reported through- out Central America and Mexico. Investigations of the pandemic revealed that it had several unique features (1, 2).

How do you treat and prevent swine dysentery? ›

When the first signs of the disease are present, water must be medicated with lincomycin, tiamulin or tylosin for at least 7 days. The most affected pigs must be injected with lincomycin, tiamulin or tylosin. Medicating the diet only helps prevent the development of clinical disease.

Can humans get porcine virus? ›

Both swine hepatitis E virus (swine HEV) and swine influenza virus (SIV) are zoonotic, not only infect pigs but humans as well.

What kills dysentery? ›

Amebic dysentery is treated with metronidazole (Flagyl) or tinidazole (Tindamax). These drugs kill the parasites. In some cases, a follow-up drug is given to make sure all the parasites are gone. In severe cases, your doctor may recommend an intravenous (IV) drip to replace fluids and prevent dehydration.

Do pigs recover from swine flu? ›

Swine influenza – animal facts

Influenza in swine is an acute viral infection of the respiratory tract in pigs caused by type A influenza viruses. The mortality rate is low in pigs and recovery usually occurs within 7–10 days.

What is the most dreaded disease in swine? ›

African swine fever (ASF) is considered one of the most dreaded diseases of swine. Although currently confined to Africa, Eastern Europe and the Italian island of Sardinia, the disease continues to spread, seriously threatening previously unaffected countries.

What is the mortality rate of dysentery? ›

Efforts to prevent dysentery include hand washing and food safety measures while traveling in countries of high risk.
TreatmentDrinking sufficient fluids, antibiotics (severe cases)
FrequencyOccurs often in many parts of the world
Deaths1.1 million a year
11 more rows

What is the clear jelly in poop? ›

A small amount of mucus in stool is usually nothing to worry about. Stool normally contains a small amount of mucus — a jellylike substance that your intestines make to keep the lining of your colon moist and lubricated.

What is the fastest way to cure dysentery? ›

Home Remedies for Treating Dysentery:
  1. Add rock salt to buttermilk and consume.
  2. Drink at least two glasses of fresh orange juice a day.
  3. Make a milkshake with pomegranate skin and consume.
  4. Drink lemon juice.
  5. Eat a lot of bananas. ...
  6. Mix milk, honey and lemon together and consume.
  7. Drink black tea.
Mar 1, 2022

Can dysentery be cured? ›

As dysentery usually gets better on its own after 3–7 days, people do not usually need treatment. If the person has diarrhea, they should drink plenty of fluids to avoid dehydration. If the diarrhea is bloody, they should avoid taking anti-diarrheal medication.

How do you know if a pig has swine flu? ›

What are signs of swine flu in pigs? Signs of swine flu in pigs can include fever, depression, coughing (barking), discharge from the nose or eyes, sneezing, breathing difficulties, eye redness or inflammation, and going off feed. Some pigs infected with influenza, however, may show no signs of illness at all.

Is dysentery worse than diarrhea? ›

These two health conditions have similar symptoms. Dysentery is the more severe of the two conditions, but diarrhea can become a health problem, too. They are both intestinal disorders but are brought on for different reasons.

Is dysentery the same as E coli? ›

Depending on the virulence factors they possess, virulent Escherichia coli strains cause either noninflammatory diarrhea (watery diarrhea) or inflammatory diarrhea (dysentery with stools usually containing blood, mucus, and leukocytes).

What is the difference between diarrhea and dysentery? ›

Diarrhoea is a common health condition in which a person suffers from watery and loose stool. Dysentery, on the other hand, is an infection or inflammation of the intestine that can lead to the presence of blood in the watery stool. It is also referred to as bloody diarrhoea.

What is the best antibiotic for dysentery? ›

The following antibiotics are used to treat Shigella dysentery:
  • Beta-lactams: Ampicillin, amoxicillin, third-generation cephalosporins (cefixime, ceftriaxone), and pivmecillinam (not available in the United States)
  • Quinolones: Nalidixic acid, ciprofloxacin, norfloxacin, and ofloxacin.
  • Macrolides: Azithromycin.

How is dysentery diagnosed? ›

Diagnosis and Tests

A healthcare provider can diagnose bacillary dysentery with a stool culture. This type of bacteria culture test takes a sample of your poop and tests it for the presence of certain bacteria.

What foods help dysentery? ›

While affected with dysentery, it is better to stick to a bland diet (bananas, rice, soda crackers, applesauce, toast) and avoid milk products. Dysentery can be prevented to some extent by practising careful personal hygiene.

How did dysentery start? ›

A stool sample from a patient infected with Shigella dysenteriaeWIKIMEDIA, CDCShigella dysenteriae, the bacterium that causes dysentery, originated in Europe and was spread to the rest of the world decades ago by emigrants and colonizers, according to a new genomic analysis of hundreds of strains of the pathogen.

How did they treat dysentery in the 1800s? ›

A bowel infection, dysentery was marked by bloody diarrhea, fever, nausea, and cramps. Because physicians did not know what caused the disease, they treated the symptoms, often using purgatives like turpentine or castor oil, which in fact, only made the problem worse. The disease was not always fatal.

Why did people get dysentery? ›

Dysentery is transmitted through the ingestion of food or water that has been contaminated by the feces of a human carrier of the infective organism. The transmission is often by infected individuals who handle food with unwashed hands.

How long is dysentery contagious? ›

Dysentery is very contagious. Stay home from work or school until you've been diarrhea-free for at least 48 hours to avoid passing the infection to others.

Is dysentery spread through air? ›

The bacteria are transmitted by the fecal-oral route via contaminated water, food, or person-to-person contact.

Is swine fever contagious to humans? ›

African Swine Fever (ASF) is a highly contagious viral disease of pigs. In its acute form the disease generally results in high mortality. ASF is a different disease to swine flu. The virus does not affect people and there is no impact on human health.

Which pig disease can be transmitted to humans? ›

Leptospirosis in people: Leptospirosis is a disease caused by bacteria called Leptospira that infect both people and a wide range of animals. It occurs worldwide but is more common in temperate and tropical areas of the world.

What color is dysentery stool? ›

This blood can sometimes appear in the stool, making it red. Dysentery: Diarrhea with blood is known as dysentery. The most common causes of dysentery are Shigella bacteria or Entamoeba histolytica, a type of parasite. These can cause severe infections that inflame the intestines enough to result in bleeding.

Is dysentery caused by poor hygiene? ›

Dysentery is usually spread as a result of poor hygiene. For example, if someone who has dysentery doesn't wash their hands after using the toilet, anything they touch is at risk. The infection is also spread through contact with food or water that has been contaminated with fecal matter.

Which organ is affected by dysentery? ›

Dysentery is inflammation and infection of the intestines, which results in diarrhea containing blood or mucus. Other possible symptoms include stomach cramps, nausea, vomiting, and fever. Dysentery can occur as a result of a bacterial or parasitic infection.

Where is dysentery most common in the world? ›

It commonly occurs in less developed areas of Central and South America, Africa, and Asia. Dysentery has been described at least since the time of Hippocrates.

Can you eat pigs with swine fever? ›

African swine fever does NOT affect humans. Meat or other products from pigs do NOT pose any food safety risk for humans.

Can swine fever be cured? ›

No treatment or effective vaccine exists for African swine fever. It has proven difficult to control transmission of the disease. Often, movement restriction and herd depopulation are necessary control measures because of how quickly and easily the virus spreads.

Can a pig survive swine fever? ›

DEFINITION. A highly contagious viral disease of domestic pigs, ASF manifests itself as a haemorrhagic fever and results in up to 100 percent mortality.

Do pigs carry STD? ›

Chlamydia abortus, Chlamydia pecorum, Chlamydia psittaci and Chlamydia suis can infect pigs.

Can humans get STDS from pigs? ›

Generally speaking, the STIs (sexually transmitted infections) we associate with person-to-person sexual contact, including HIV, cannot be transmitted through sexual contact between humans and animals because these infections are species-specific.

Can you get sick from a pet pig? ›

"Animals can transmit disease to people, but pigs are no more dangerous than any other kind of livestock." Pigs can carry ringworm or bacteria that cause intestinal illnesses in humans. Families with young children should practice good hand washing, according to Blackmore.


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