Internal parasites

1. Ascarids (Roundworms)

This is a very common parasite in swine worldwide. It can severely damage the health and productivity of a pig. Furthermore, it is a parasite that (through poor sanitation) is often passed from swine to humans. Severe infestations of roundworms can cause death in young pigs. Lesser infections can stunt growth.

Life Cycle

The adult worm is usually yellowish or pinkish in color, 8 to 12 inches long, and almost the size of a lead pencil.

1. The female worms lay eggs in the small intestines which are passed in the feces. These eggs are very resistant to chemical agents.

2. A small larva develops in the egg and remains there until the egg is swallowed by the pig (or human) along with contaminated feed or water. Then it emerges from its shell, bores through the wall of the intestine, and enters the bloodstream. It passes through the liver (producing white spots on the liver) and is carried to the lungs.

3. In the lungs, the larvae break out of the capillaries, enter the windpipe, and migrate to the throat. While in the throat, they are swallowed and lodge in the intestines where they develop into sexually mature worms, thus completing their life cycle.

Prevention

1. The best way to prevent roundworms is by disrupting their life cycle through removing pigs from potential contact with the roundworm. This la impossible in free-range environments. If the pigs are penned or on pasture then rotation of the pens or pastures to prevent large buildups in the roundworm population can be practiced. The first step to control of roundworms is confining the pigs and then managing their pens or pastures. If the pigs are already penned then practice these 3 steps (if they are appropriate to your village and resources).

a. Disinfect the farrowing quartets.
b. Wash sow before moving into farrowing quarters.
c. Keep the sow and litter on "clean" pasture until they are at least four 'months old.

Symptoms

1. The adult worms do not produce obvious symptoms that are detectable.
2. The larvae can cause serious lesions of the liver and lungs. General unthriftiness and foes of weight are often seen. Coughing and a "thumpy" breathing may occur also.

Treatment

1. Dichlorvos (Atgard) Use 0.0384% in the feed. For swine of less than 70 pounds limit the treatment to two days. For boars and open or bred gilts divide the dose in half and feed for 2 days.

2. Piperazine (Piperazine monohycrochloride -17 grams per 100 ml.) Use 1 fluid ounce to 1 gallon of drinking water per 100 pounds of body weight. Caution: There are other forms of Piperazine of varying strengths and dosages vary.

3. Thiabendazole is mixed at varying strengths by different manufacturers. Check the label for dosage.

2. Coccidiosis

This disease is produced by protozoan organisms called coccidia that live in the cells of the intestinal lining. The coccidia that affect swine are specific to swine and do not infect other animals. Coccidia are endemic worldwide. They rarely cause death, but do lower weight gains.

Life Cycle

Infected swine can pass thousands of coccidia (oocysts) daily in their feces. With favorable temperature and moisture, these oocysts sporulate to maturity in 3-5 days producing 8 infective sporozites. The oocyst is then swallowed by the pig in contaminated feed or water. In the pig's intestines, the outer membrane of the oocyst, acted on by the digestive juices, ruptures and liberates the 8 sporozites within. Each sporozite then penetrates and destroys an epithelial cell. While destroying the cell the coccidia undergoes sexual multiplication and fertilization with the formation of new oocysts. The new oocysts are then passed in the feces to later reinfect other pigs.

Prevention

1. Coccidia thrive in wet and filthy conditions and are resistant to freezing and ordinary disinfectants.
2. These are impossible to control in a free-ranging environment. Only when you can control the quality of the feed and water can you eliminate coccidia. Oocysts are destroyed by sunlight and drying.

Symptoms

1. Minor infections are difficult to detect with a lab examination of the feces. Reduced weight gain may be your only symptom.

2. Severe infections may produce diarrhea (may or may not be bloody) due to damage to the intestinal wall. Pigs 1 to 3 months old are most strongly affected.

Treatment

If the pigs are not exposed to continual reinfection then the infection will last only a week or so before subsiding. Enteric sulfonamides such as sulfamethazine or sulfaquinoxaline are commonly used.

a. Sulfamethazine: Orally or IV, 100 mg./lb. of body weight the first day and then 50 mg./lb. daily for 3 to 4 days.

b. Sulfaquinoxaline: 6 mg./lb. of body weight orally, daily for 3-5 days.

Always read the label for recommended dosages as well.

3. Kidney Worm

The kidney worm is found worldwide and is second only to roundworms in the damage inflicted on swine. They are especially a problem in warm and moist climates. It is a thick-bodied black and white worm that may reach 2 inches in length when fully grown. It has an adverse affect on swine growth, but is not transferrable to humans. It can infect cattle that are grazing with swine.

Life Cycle

Adult kidney worms may be found around the kidneys and in cysts in the ureter (tubes leading from the kidneys to the bladder). The mature female worms lay many eggs that are discharged with the urine. It has been estimated that as many as one million eggs may be passed in the urine of a moderately infected hog in one day. When eggs fall on moist, shaded soil, a tiny larva hatches from each egg in 1 to 2 days (depending on temperature). In another 3 to 5 days, the larva develops into the infective stage. Hogs then obtain kidney worms by swallowing the infective larvae as they root and forage. Kidney worm larvae can also enter the bodies of pigs through the skin if there is an open wound, but this is not a common source of the infection. Once inside the hog, they enter the bloodstream and migrate to the liver where they remain for 2-3 months causing extensive damage. They then enter the abdominal cavity and pass through the lungs eventually reaching the kidneys. 12 to 14 months after the larvae enter the pig, the adult female kidney worms begin to produce eggs, thus completing the life cycle.

Prevention

1. Rotation of pastures, sanitation, and good management practices are one type of prevention that is not always possible in low level management (free-ranging) situations.

2. In areas where the kidney worms are a major problem (such as the south of the U.S.) farmers practice the "gilt-only method". With this method, gilts are bred only once; then, after farrowing and weaning off their first litter, they are sent to slaughter before mature kidney worms develop. This system is based on the fact that it may take the kidney worm as long as a year to reach the egg-laying stage.

Symptoms

There are no symptoms of this worm that are indicative solely of a kidney worm infection. Pus may appear in the urine and growth rates will decline. Positive diagnosis can only be made through lab tests of samples of the urine.

Treatment

Feeding a concentration of 0.185 of thiabendazole in the ration for 14 days can prevent migration of kidney worm larvae. There is no treatment yet that will eliminate the adult worm.

4. Lungworms

This is a fairly common parasite of swine that is endemic worldwide. They are not transferrable to humans. There are 3 species that are common in hogs yet all 3 are threadlike in diameter, 1 to 1 1/2 inches in length, and white or brownish in color. They are found in the bronchi, or air passages, of the lungs. They are more common in warm and moist climates. Besides reducing the rate of growth, there is evidence that they are involved in the spreading of swine flu and cholera.

Life Cycle

Female lungworms produce large numbers of thick-shelled eggs, each containing a larva. The eggs are coughed up, swallowed, and eliminated in the feces. Earthworms, the intermediate host, feed on the feces, then swallow the eggs, which hatch in the earthworms' intestines. The larva then develops within the earthworm for 3-4 weeks, after which it is capable of producing an infection. Infection of the pig results from the swallowing of the earthworm while rooting and foraging for food in manure piles, trash, and in moist feces-contaminated soil. After being eaten by the pig, the lungworm larvae leave the earthworm and migrate through the lymphatic and blood circulatory systems to the lungs. They remain in the lungs and begin to produce 1-1/2 months later, thus completing the life cycle.

Prevention

The only means of prevention is preventing hogs from foraging or rooting for food in soil that contains earthworms.

Symptoms

Positive diagnosis can only be made by examination of the feces in a lab or through post-mortem examination. Infected hogs will have with threadlike worms in the air tubes of the lungs (revealed easily in a cross-section of lung). Stunted growth and spasmodic coughing are signs of heavy infection.

Treatment

1. Levamisole (drench, bolus, pellet, or water) 2-5 mg./lb. of body weight.
2. Cambendazole (paste, bolus, crumbles, or pellets) 9 mg./lb. of body weight.

5. Nodular Worms

These are called nodular worms because of the nodules or lumps they cause in the large intestine. Four species occur in swine, but all of them are slender, whitish to grayish in color, and one third to one half inch in length. As with other worms, they thrive in warm and moist climates and are endemic in many tropical countries. They are not transferrable to humans.

Life Cycle

The 4 species of nodular worms affecting swine have similar life cycles. The adult worms are localized in the large intestine of the pig. The female worms deposit large numbers of partly developed eggs that become mixed with the intestinal contents and are eliminated with the feces. With favorable conditions of moisture and temperature, the larvae are infective to pigs. Pigs then become infected by swallowing the larvae while feeding on contaminated ground. In the digestive system of the pig, the larvae travel to the large intestine where they penetrate into the wall and grow for the next 2-3 weeks. They then move into the lumen, or cavity, of the large intestine where they continue to grow. Within 5-7 weeks after being eaten by the pig, the worms are fully grown and have mated and are producing eggs.

Prevention

Sanitation and pasture rotation are the only practical preventatives.

Symptoms

It is not possible to identify specific symptoms of this parasite that are different from other parasites. Lab tests are needed for positive diagnosis. General weakness, anemia, emaciation, and diarrhea are sometimes seen.

Treatment

Thiabendazole, levamisole, piperazines, and dichlorvos are used. For dosages specific to treatment of nodular worms read the label or manufacturer's recommendation.

6. Strongyloides (threadworm)

The pig is the only host of this parasite (S. ransom)). These worms are tiny; females are 3 to 4 mm. long. Like many other parasites it thrives in warm and moist climates.

Life Cycle

The life cycle is as follows: small, embryonated eggs are passed in the feces; at 70°F, they hatch in 12 to 18 hours; the larvae develop into the infective stage 22 to 24 hours after hatching; the infective larvae penetrate the skin and proceed to the lungs via the bloodstream, thence from the alveoli of the lungs to the bronchi, esophagus, stomach, and small intestine, where they become adults about 7 days after infection. Also, it has been shown that oral ingestion of the infective larvae can produce infection and that S. ransom) is capable of developing a free living generation of adult males and females, which, in turn, develop infective parasitic larvae. The larvae pass through the colostrum from sow to piglets.

Prevention

Sanitation and selecting dry, unshaded areas for grazing are the only practical ways to prevent this disease.

Symptoms

Reduced growth rate, diarrhea, vomiting, restlessness, irritability, and even death are symptoms of heavy infestations. Light and moderate infestations may not produce noticeable symptoms. Lab tests are required for positive diagnosis.

Treatment

1. Thiabendazole: Paste formulation, at 30 to 40 mg./lb. body weight.
2. Cambendazole: (paste, bolus, crumbles, or pellets) 9mg/lb. body weight.

7. Stomach worms

Three species of small stomach worms infect swine. Two of the species, A. strongylina and P. sexalatus, are commonly known as "thick stomach worms." These worms are reddish in color and nearly an inch long in the adult stage. The third species, H. rubidus, commonly known as the "red stomach worm" is a small, delicate, slender, reddish worm about one-fifth inch in length. These are not transferrable to man and it is unknown how endemic they are worldwide.

Life Cycle

It has been proven that the dung beetle serves as the intermediate host for the thick stomach worm. The female worm deposits eggs in the stomach of the pig, with each egg containing a tiny embryo. The eggs pass with the feces to the outside of the body of the pig, then hatch, and the tiny larvae enter the body cavity of various species of dung beetles, the intermediate host. After developing for about a month in the beetle, the larvae become infective to swine. Hogs feeding on contaminated ground then swallow the beetles.

In the stomach of the pig, the parasites leave the beetles and enter the mucus membrane of the stomach, where they grow to maturity. The life history of the red stomach worm differs from that of the thick stomach worm in that no intermediate host is necessary, the infections being directly acquired.

Prevention

Prevention is solely based on good management, sanitation, and pasture rotation to prevent contact between dung beetles and engine.

Symptoms

Inflammation and gastric ulcers. Loss of appetite and poor weight gain.

Treatment

Thiabendazole, levamisole, and dichlorvos are effective against H. rubidus. Carbon disulfide is recommended against P. sexalatus and A. strongylina. Check the label for recommended dosage.

8. Thorn-headed worm (Macracanthorhynchus hirudinaceus)

So named because of the presence of rows of hooks-a spiny proboscis-through which it attaches itself to the wall of the small intestine of the pig. They are milk white to bluish in color and cylindrical to flat in shape, the largest being about the size of a lead pencil. They can severely weaken the intestine. They also thrive in warm and humid climates and are common in tropical countries. They are not found in man.

Life Cycle

Adult female thorn-headed worms produce numerous thickshelled brownish eggs, each containing a fully developed larva. Each female may produce as may as 600,000 eggs per day at the peak of her egg-producing capacity. The eggs, which pass out with the manure, are very resistant to destruction. White grubs, the larvae of June bugs (or May beetles), serve as the intermediate host. The grubs, feeding on infected manure or contaminated soil, swallow the parasite eggs. The eggs hatch in the bodies of the grubs and in 7-12 weeks develop to a stage that is infective to swine. Pigs rooting in manure or trash piles, rich soil, or low-lying pastures swallow the grubs. The young thorn-headed worms then escape from the bodies of the grubs or adult beetles through the process of digestion and develop to egg-laying maturity.

Prevention

Sanitation and pasture management designed to prevent the pigs from eating white grubs.

Symptoms

No special symptoms - general unthriftiness. A heavy infestation can kill young pigs. Poet mortem examination will reveal a weakened intestinal wall with swelling or nodules at the point of attachment.

Treatment

Lavamisole (drench, bolus, pellet, or water formulation) 2 to 5 mg./lb. body weight.

9. Trichinosis

This disease is a common public health problem in many different countries of the world. It is caused by T. spiralis and humans acquire the disease by eating infected pork that has not been fully cooked. It is probable that all mammals are susceptible to trichinosis. Although the parasite is often present in the muscle of swine, it does not produce recognizable symptoms. The disease is worldwide, but occurs moat frequently in countries where pigs are allowed to free-range and eat uncooked garbage. For more information on its effect on humane refer to Where There Is No Doctor.

Life Cycle

The adult parasite, which is a round worm from 1.5 to 4 mm. in length, lives in the small intestine of man, hogs, rats, and other mammals. The female worms penetrate into the lining of the intestines where they produce numerous larvae. The larvae pass from the wall of the intestine into the lymph abeam, then into the bloodstream, and finally into the muscle cells (particularly affected are the diaphragm, tongue, masseter, and the deltoid muscles). In the muscles, the larvae grow until they are about one-twenty fifth of an inch long, then roll in a characteristic spiral shape, and become surrounded by a capsule. In this environment and stage of development, these larvae may live for years or until the raw or improperly cooked muscle tissue is eaten by man or other species of meat eaters.

Prevention

1. Killing of rats in the area will help control it.
2. Disposing (burning or burying) of pigs that die.
3. Do not allow pigs to eat uncooked garbage.
4. Fully cook all pork meat before eating it (to at least 170°F).

Obviously, not all of the suggestions made here can be followed in a rural village with traditional (free-ranging) animal husbandry practices. That's why this is a difficult disease to control. Follow the suggestions when and where possible.

10. Whipworm (Trichuris suis)

Whipworms are usually found attached to the walls of the cecum and large intestine of swine. They are 1-2 inches in length. The worms have a very slender anterior portion and a much enlarged posterior. The anterior resembles the lash of a whip and the posterior the handle, hence the name whipworm. It is not known how prevalent this worm is worldwide but it doe a favor warm and moist climates. They are not transmissible to humans.

Life Cycle

No intermediate host is required for this parasite. The eggs are produced in large numbers within the hog and shed in the feces. An infective larva develops in the shell, and swine become infected by swallowing the eggs when feeding on soil that has been contaminated. The eggs hatch in the stomach and intestine, and the larvae enter the cecum where they grow to maturity in about 10 weeks or longer.

Prevention

Rotation of pastures, plenty of sunlight, and well-drained soils are the only known preventatives.

Symptoms

Depending on the severity of the infection, pigs may develop diarrhea or bloody diarrhea, growth may be stunted, and finally the animals may become weak and die. Inflammatory lesions will also be present in the cecum and adjacent large intestine.

Treatment

Dichlorvos and Levamisole. Check the label for dosage specific to whipworms.