Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Trichinosis


Related Terms

  • Trichinelliasis
  • Trichinellosis
  • Trichiniasis

Differential Diagnosis

Specialists

  • Cardiovascular Internist
  • Family Physician
  • Infectious Disease Internist
  • Internal Medicine Physician
  • Nephrologist
  • Neurologist
  • Ophthalmologist
  • Pulmonologist

Comorbid Conditions

  • Compromised immune system

Factors Influencing Duration

The length of disability will be influenced by the severity of disease and the development of complications, particularly complications of the heart, lungs, or CNS. If the individual is immunocompromised, more severe disease and a longer disability period may be expected. Disability will be longer for those who perform heavy work.

Medical Codes

ICD-9-CM:
124 - Trichinosis; Trichinella spiralis Infection; Trichinellosis; Trichiniasis

Overview

Trichinosis is a disease found in many mammals, including humans, resulting from infection by a parasite of the genus Trichinella. Right species of Trichinella can cause trichinosis; the most common is T. spiralis. Individuals become infected with Trichinella after eating raw or undercooked infected meat. Trichinosis is usually attributed to eating undercooked pork; however, wild game, such as bear and boar, as well as walrus and seal meat, has also been linked to human infection.

When infected meat containing living immature parasites (larvae encased in cysts) is eaten, the larvae are deposited into the small intestine mucosa where they develop into mature worms (enteral phase). About 5 to 7 days after the initial infection, mature female worms begin releasing new larvae that penetrate the intestinal wall, pass into the bloodstream, and travel through the circulatory and lymphatic system until they settle in muscle tissue or other tissues where they are encapsulated (encysted). This is the invasive parenteral stage. The larvae can remain fully encysted and viable for several years. Mature females continue to release larvae for about 4 weeks until they are expelled in feces.

The most common sites of infection are the skeletal muscles, particularly the lower leg (gastrocnemius or calf muscle), upper arm (biceps), tongue, and diaphragm, as well as muscles of the lower back, jaw and neck, and the muscles around the eyes. The heart (cardiac muscle) can also be affected, as can the lungs and other organ systems.

Pork is the meat most commonly associated with trichinosis. Hogs usually become infected when fed uncooked meat scraps. Regulations requiring commercial farmers to sterilize all garbage fed to hogs have substantially reduced the incidence in the US over the past several years.

Incidence and Prevalence: Documented cases in the US are largely sporadic or small clusters associated with eating home-processed meats from noncommercial farm-raised pigs or wild game. From 2008-2010, an average of 20 cases yearly were reported to the Centers for Disease Control and Prevention (CDC) ("Parasites - Trichinellosis") This compares with 500 cases in 1948. Immigration from developing countries poses a risk of an increase in incidence in the US and other developed countries (Arnold). Most cases are mild and probably remain undiagnosed; death is rare in the absence of neurologic and cardiac involvement. Trichinosis is more common in rural areas than in cities, with the incidence higher in Alaska and the northeastern US. Trichinosis occurs throughout the world except in Australia and in some Pacific Islands. The rate of trichinosis in Europe is low because of mandatory pork inspection. European infection usually comes from eating horse or wild boar. The rate is much higher in Latin America and Asia, where there is no regulation of pig feed and little meat inspection.

Source: Medical Disability Advisor



Causation and Known Risk Factors

Individuals who eat raw or rare pork products, wild game (but not usually deer meat), walrus, or seal meat are at higher risk of infection. Tasting uncooked, homemade sausages for seasoning is another risk factor. Individuals who raise their own pigs for consumption and who include raw meat scraps in their feed are at increased risk for infection.

Men and women are equally at risk of contracting trichinosis. Infection is independent of age and race, although some culturally dictated cooking practices may increase the risk of infection among some groups, especially immigrants from Southeast Asia.

Source: Medical Disability Advisor



Diagnosis

History: Individuals often report eating raw or undercooked pork, wild game, walrus, or seal meat within the past week. Mild infections may not cause symptoms (asymptomatic). The most common initial complaints during the enteral phase are diarrhea, along with abdominal cramping, and nausea. During the invasive parenteral stage, symptoms may include high persistent fever, headache, muscle soreness or pain (myalgia), facial edema or swelling around the eyes (periorbital edema), weakness, constipation, sensitivity to light (photophobia), a dry cough, and fatigue. Symptoms gradually subside in about 3 months, when the larvae become fully encysted in muscle; mild myalgia or tiredness (lethargy) may last up to 6 months.

Central nervous system (CNS) involvement occurs in 10%-24% of individuals (Smith). CNS involvement may be manifested by headache, deafness, ocular disturbances, weakness, and slight or incomplete paralysis of a single extremity or part of an extremity (monoparesis).

Physical exam: Clinical signs vary depending on the number of ingested larvae and the phase of the parasitic invasion. Infected muscles may be tender and prone to spasm. Fever may be noted, but tends to come and go. Temperature can reach 104° F (40° C). The individual may experience photophobia. Conjunctivitis may be noted, and bleeding of certain parts of the eye (subconjunctival hemorrhage, retinal hemorrhage) may occur. Maculopapular rash, rapid heartbeat (tachycardia), inflammation of the lung(s) (pneumonitis), or bleeding under the fingernails or toenails (splinter hemorrhages) may be present.

If the parasite has spread to other organs, there may be signs of inflammation of the membrane of the brain or spinal cord (meningitis), inflammation of the lungs (pneumonia, pneumonitis), or kidney inflammation (nephritis).

Tests: In the second week, there are occasional immature worms in the blood or stomach washings. Between the second and fourth weeks, a complete blood count (CBC) usually shows an increase in the type of white blood cells called eosinophils (eosinophilia). Blood tests will also reveal increased levels of the enzymes creatine phosphate kinase (CPK) and lactate dehydrogenase (LDH) and certain proteins (gamma globulin). Urinalysis may reveal the presence of myoglobin, a breakdown product of muscle (myoglobinuria).

In the third to fourth weeks, biopsy from swollen or tender skeletal muscle may reveal the encysted larvae. After several weeks, a test that measures the sedimentation rate of red blood cells (erythrocyte sedimentation rate [ESR]), will reveal an increase in this rate. The parasite is seldom identified from stool samples.

A type of blood test called the bentonite flocculation test is highly sensitive and nearly 100% specific. It becomes positive for Trichinella in about the third week and reaches its maximum at 2 months. Antibodies can be detected from blood samples, but not until 3 to 5 weeks after infection. Immunofluorescence tests become positive in the second week, but are less sensitive than the bentonite flocculation test.

Computed tomography (CT) may help the physician see muscle cysts. Magnetic resonance imaging (MRI) may be indicated to assess neurological involvement, and chest x-rays may be necessary to evaluate the possibility of lung involvement. Imaging tests are most useful when there appears to be CNS involvement.

Source: Medical Disability Advisor



Treatment

Most mild cases resolve spontaneously, and are treated with bed rest and nonprescription medication to reduce fever and pain (nonsteroidal anti-inflammatory drugs [NSAIDs]), as needed.

Severe cases may require hospitalization and supportive care. Treatment with anti-parasite (anthelmintic) medication such albendazole or mebendazole may be required to eliminate intestinal larvae and worms. Drugs are not effective against larvae already encysted within the muscle, but will likely prevent spreading. Additionally, corticosteroids may be used to reduce inflammation, particularly in severe or complicated cases.

In cases of severe heart involvement, implantation of a device to regulate heartbeat (pacemaker) has been required.

Source: Medical Disability Advisor



Prognosis

The prognosis for trichinosis in otherwise healthy individuals is very good. The infection often subsides on its own. Encysted larvae may remain viable for several years. Five to ten percent of cases are severe, with death resulting in less than 1%. In those severe cases where death occurs, it is normally a result of cardiac failure or pneumonia (usually occurring during the fourth to eighth week of infection), or of CNS involvement (with a mortality rate of 50%) (Smith).

There is no clear evidence that ongoing (chronic) trichinosis exists.

Source: Medical Disability Advisor



Complications

Trichinosis may be complicated by inflammation of the lining of the spinal cord and brain (meningitis), inflammation of the brain (encephalitis) with brain damage, inflammation of the heart (myocarditis) with associated congestive heart failure (CHF), inflammation of the kidney (nephritis, glomerulonephritis), inflammation of the sinuses (sinusitis), or inflammation of the lungs (pneumonitis).

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

In most cases, work restrictions and accommodations will not be required, as most individuals have few symptoms.
When symptoms are noted, accommodations and restrictions will depend on the individual's symptoms. Muscle pain and weakness, as well as heart involvement, may require reassignment to lighter duties. Photophobia may prevent work outdoors or under bright lights or may require prescription and/or protective sunglasses. Individuals who have been prescribed medication may require frequent breaks over a several-week period in order to take medications at the prescribed times.

Risk: Recurrence is dependent on educating the individual about the method of disease transmission and the importance of cooking meat, particularly pork, thoroughly.

Capacity: Capacity may be affected in symptomatic individuals with CNS or cardiopulmonary involvement; those with severe myalgia may be temporarily unable to perform heavy or very heavy work. Once treated, there would usually be no expected long term impact on capacity.

Tolerance: Tolerance is not anticipated to be a factor for individuals with mild trichinosis. In the enteral stage of infection, individuals with diarrhea and abdominal cramping will require ready access to bathroom facilities to remain productive during recovery.

Accommodations: Employers willing to accommodate activities as needed can have employees return to work earlier.

Source: Medical Disability Advisor



Maximum Medical Improvement

10 days.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Did individual experience symptoms of infection in the skeletal muscles, such as tenderness or muscle spasms?
  • Were other, more serious symptoms noted, such as rash, tachycardia, retinal or subconjunctival hemorrhage, or other areas of inflammation or hemorrhage?
  • Has individual recently eaten raw or undercooked meat?
  • Did blood tests reveal eosinophilia or CPK and LDH elevation?
  • Were additional diagnostic tests done, such as CT or MRI, to detect extent of muscle or organ system involvement?
  • Was a bentonite flocculation test done to confirm the diagnosis?
  • If the diagnosis was uncertain, were other conditions with similar symptoms considered in the differential diagnosis, such as rheumatic fever, arthritis, angioedema, botulism, collagen vascular disease, dermatomyositis, encephalitis, eosinophilia-myalgia syndrome, gastroenteritis, idiopathic hypereosinophilic syndrome, idiopathic polymyositis, influenza, meningitis, pneumonitis, polyarteritis nodosa, polymyositis, and typhoid fever?

Regarding treatment:

  • Were conservative interventions (bed rest, NSAIDs) effective in resolving the symptoms?
  • If not, were hospitalization and more aggressive therapy needed?
  • Did treatment address other organ system involvement (such as placement of pacemaker, respiratory care, etc.)?

Regarding prognosis:

  • Is individual's employer able to make appropriate work accommodations so the individual can return to work safely?
  • Does individual have any underlying conditions (such as immune system compromise) that could impact recovery and prognosis?
  • Has individual experienced any complications associated with the disease (i.e., meningitis, encephalitis, brain damage, myocarditis with associated CHF, nephritis, glomerulonephritis, sinusitis, or pneumonitis) that could impact recovery and prognosis? If so, are the complications being addressed appropriately in the treatment plan?

Source: Medical Disability Advisor



References

Cited

"Parasites - Trichinellosis (also known as Trichinosis)." CDC. 8 Aug. 2012. Centers for Disease Control and Prevention. 21 Jul. 2015 <http://www.cdc.gov/parasites/trichinellosis/epi.html>.

Arnold, L. Kristian. "Trichinellosis/Trichinosis." eMedicine. 12 May. 2014. Medscape. 21 Jul. 2015 <http://emedicine.medscape.com/article/787591-overview#showall>.

Smith, Darvin Scott. "Trichinosis Clinical Presentation." eMedicine. 16 Apr. 2013. Medscape. 21 Jul. 2015 <http://emedicine.medscape.com/article/230490-clinical#showall>.

Source: Medical Disability Advisor






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