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Alternative Names: Trichiniasis or trichinellosis.
Trichinosis is a foodborne disease caused by a microscopic parasite. It is an excruciatingly painful disease that is among the most dreaded of human afflictions.
Causes & Development
Anyone who eats undercooked meat of infected animals can develop trichinosis. Pork products are implicated more often than other meats.
Trichinae are tiny roundworms found in the muscle of infected animals, usually pigs, that cause trichinosis, a disease characterized by intestinal disorders, fever, muscular swelling, pain and insomnia.
The threadlike worms spend most of their lives curled up inside a protective capsule or cyst in muscle tissue. When the meat is eaten, the digestive juices in the stomach free these encysted worms or larvae from their capsules. They then pass into the small intestine where they develop into mature males and females in about 2 days. After mating, the females give birth to large numbers of young (called larvae), starting about the sixth day after infection. One female will give birth to between 1,000 and 1,500 larvae. These microscopic young worms penetrate the lining of the intestines, pass into the lymphatic system or the blood, and are carried to the heart. From there they are carried throughout the body by the circulating blood. They have an attraction for muscular tissue, so they invade the striated (voluntary) muscles of the body. They grow there for about 3 weeks, then coil up tightly, and in about 30 days develop a protective capsule - thus completing the cycle.
The worms can remain in this encysted form for many years - ready to infect any mammal that might eat the muscle tissue. Trichinae are about 1/250 of an inch long when they are born. When they reach the muscle tissue, they grow to a length of 1/25 inch, coiling up in a cyst about 1/50 inch long. When they develop into adult males and females in the intestine, they are about 1/8 and 1/6 inch long, respectively.
Animals such as pigs, dogs, cats, rats and many wild animals including fox, wolf and polar bear may harbor the parasite. When parasites are passed in the feces, they infect new animals. When humans eat infected pork that has been improperly cooked, they become infected. Improperly cooked wild animal meat may also be responsible for infecting humans. Person-to-person spread does not occur.
Signs & Symptoms
The symptoms usually start with fever, muscle pain/soreness (especially muscle pain when breathing, chewing, or using large muscles), pain and swelling around the eyes. Thirst, profuse sweating, chills, weakness and tiredness may develop. Chest pain may be experienced since the parasite may become imbedded in the diaphragm (the thin muscle separating the lungs from abdominal organs). Additional symptoms include abdominal discomfort, cramping and diarrhea. The incubation period varies depending upon the number of parasites in the meat and the amount eaten. It can range from five to 45 days but is usually 10 to 14 days.
Diagnosis & Tests
Common tests:Treatment & Prevention
There is no specific treatment for trichinosis once the larvae have invaded the muscles.
The best means of prevention is to make sure that pork (and other) products are properly cooked. If you eat pork, be careful since even a small uncooked portion can lead to infection. Always cook pork until it's well done, the desirable temperature being at least 150°F. Storing infected meat in a freezer with a temperature no higher than -13°F for 10 days will also destroy the parasite.
Prognosis; Complications
Most people with trichinosis have no symptoms and their infection resolves on its own. More severe infections may be more difficult to treat, especially if the lungs, the heart, and/or the brain is involved.
Trichinosis can result in death when infection is heavy - although fewer than 2% of all reported cases are fatal. Partial immunity may develop from infection, but failure to treat can be fatal.
Possible complications include arrhythmias from heart inflammation (myocarditis); heart failure; encephalitis; pneumonia.
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Conditions that suggest Trichinosis:
Risk factors for Trichinosis:
Trichinosis suggests the following may be present:
Recommendations and treatments for Trichinosis:
KEY | | Strong or generally accepted link |  | | Proven definite or direct link |  | | Likely to help |  | | Highly recommended |
GLOSSARY
Abdomen (Abdominal)
That part of the body between the chest and the hips that contains the stomach, intestines, liver, bladder, pancreas and other organs.
Arrhythmia (Arrhythmias)
A condition caused by variation in the regular rhythm of the heartbeat. Arrhythmias may cause serious conditions such as shock and congestive heart failure, or even death.
Biopsy
Removal of a sample of tissue from a living being for diagnosis. A pathologist later uses a microscope to look for certain features, such as cancer cells, in the sample. A fine-needle aspiration biopsy involves inserting a thin needle to remove a small amount of tissue, sometimes using CT or ultrasound to guide the needle. A core biopsy involves obtaining a sample of tissue with a thick needle or by inserting a thin, lighted tube (laparoscope) into a small incision in the abdomen. Another biopsy method is to remove tissue during an operation.
Complete Blood Count (CBC)
A set of measurements that are generally determined by specially designed machines that analyze the different components of blood in less than a minute. The values generally included are:- White blood cell count (WBC). The number of white blood cells in a volume of blood. Normal range varies slightly between laboratories but is generally between 4,300 and 10,800 cells per cubic millimeter. This can also be referred to as the leukocyte count and can be expressed in international units as 4.3 - 10.8 x 10^9 cells per liter.
- Automated white cell differential. A machine-generated percentage of the different types of white blood cells, usually split into granulocytes, lymphocytes, monocytes, eosinophils, and basophils.
- Red cell count (RBC). The number of red blood cells in a volume of blood. Normal range varies slightly between laboratories but is generally between 4.2 - 5.9 million cells per cubic millimeter. This can also be referred to as the erythrocyte count and can be expressed in international units as 4.2 - 5.9 x 10^12 cells per liter.
- Hemoglobin (Hb). The amount of hemoglobin in a volume of blood. Normal range for hemoglobin is different between the sexes and is approximately 13 - 18 gm/dl for men and 12 - 16 for women (international units 8.1 - 11.2 millimoles/liter for men, 7.4 - 9.9 for women).
- Hematocrit (Hct). The ratio of the volume of red cells to the volume of whole blood. Normal range for hematocrit is different between the sexes and is approximately 45 - 52% for men and 37 - 48% for women.
- Mean cell volume (MCV). The average volume of a red cell. This is a calculated value derived from the hematocrit and red cell count. Normal range is 86 - 98 femtoliters.
- Mean cell hemoglobin (MCH). The average amount of hemoglobin in the average red cell. This is a calculated value derived from the measurement of hemoglobin and the red cell count. Normal range is 27 - 32 picograms.
- Mean cell hemoglobin concentration (MCHC). The average concentration of hemoglobin in a given volume of red cells. This is a calculated volume derived from the hemoglobin measurement and the hematocrit. Normal range is 32 - 36%.
- Red cell distribution width (RDW). A measurement of the variability of red cell size. Higher numbers indicate greater variation in size. Normal range is 11 - 15.
- Platelet count. The number of platelets in a volume blood. Platelets play a vital role in blood clotting. Normal range varies slightly between laboratories but is in the range of 150,000 - 400,000 per cubic millimeter (150 - 400 x 10^9 per liter).
Cramp (Cramping, Cramps)
A sudden, involuntary, painful muscular contraction.
Cysts (Cyst)
A closed pocket or pouch of tissue; a cyst may form within any tissue in the body and can be filled with air, fluid, pus, or other material. Cysts within the lung generally are air-filled, while cysts involving the lymph system or kidneys are fluid filled. Cysts under the skin are benign, extremely common, movable lumps. These may develop as a result of infection, clogging of sebaceous glands, developmental abnormalities or around foreign bodies.
Diaphragm
The thin muscle under the lungs and heart that separates the chest from the stomach/abdomen.
Diarrhea
Excessive discharge of contents of bowel.
Enzymes (Enzyme)
Specific protein catalysts produced by the cells that are crucial in chemical reactions and in building up or synthesizing most compounds in the body. Each enzyme performs a specific function without itself being consumed. For example, the digestive enzyme amylase acts on carbohydrates in foods to break them down.
Eosinophil (Eosinophilia, Eosinophils)
The eosinophils, ordinarily about 2% of the granulocyte count (60 to 75% of the white blood cells), increase in number in the presence of allergic disorders and parasitic infestations.
Immune System (Immune Response, Immunity)
A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation. The process may involve acquired immunity (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing).
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Lymphatic System
A network of vessels which collect fluid from the tissues of the body and return it to the blood. Lymphatic fluid (also called lymph) is rich in white blood cells that fight infection and an important part of the body's immune system.
Myocarditis
Inflammation of heart muscle. It can be mild, with virtually no noticeable symptoms, or more serious, leading to weakening of the heart muscle. It can then cause heart failure (with symptoms of shortness of breath, fatigue, fluid accumulation in the lungs, etc.) as well as heart rhythm irregularities from inflammation and/or scarring of the electrical system of the heart.
Parasite (Parasites, Parasitic, Parasitical)
An organism living in or on another organism.
Pneumonia (Pneumonitis)
Inflammation, usually infectious, of the lungs. Unless the result of only moderate chemical or smoke irritation, it is a potentially life-threatening condition. There are so many defenses against an infection this deep in the body that the very presence of pneumonia signals a pathogen of great virulence or impaired or exhausted immunity, or all three. Pneumonitis: Inflammation of the lungs, from whatever cause. It may be concurrent with pneumonia or pleurisy.
Small Intestine (Small Bowel)
The small intestine lies between the stomach and the large intestine. It is about 6 meters (20 feet) long and its primary function is to digest (break down) food and absorb nutrients (vitamins, minerals, proteins, carbohydrates, and fats). The small intestine makes up more than 70% of the length and 90% of the surface area of the gastrointestinal (GI) tract.
Stomach
A hollow, muscular, J-shaped pouch located in the upper part of the abdomen to the left of the midline. The upper end (fundus) is large and dome-shaped; the area just below the fundus is called the body of the stomach. The fundus and the body are often referred to as the cardiac portion of the stomach. The lower (pyloric) portion curves downward and to the right and includes the antrum and the pylorus. The function of the stomach is to begin digestion by physically breaking down food received from the esophagus. The tissues of the stomach wall are composed of three types of muscle fibers: circular, longitudinal and oblique. These fibers create structural elasticity and contractibility, both of which are needed for digestion. The stomach mucosa contains cells which secrete hydrochloric acid and this in turn activates the other gastric enzymes pepsin and rennin. To protect itself from being destroyed by its own enzymes, the stomach’s mucous lining must constantly regenerate itself.
Trichinosis (Trichinella spiralis, Trichinellosis)
A disease caused by ingestion of raw or insufficiently cooked meat (usually pork) containing Trichinella larvae. The disease has variable clinical manifestations including diarrhea, eosinophilia, fever, myalgia and periorbital edema. The incubation period varies between 5 and 45 days. GI symptoms may appear within a few days, whereas the systemic symptoms usually appear about 8 to 15 days after ingestion of infected meat.
Last updated: Oct 08, 2008
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