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.

Yellow Fever


Related Terms

  • Jungle Fever
  • Jungle Yellow Fever
  • Urban Yellow Fever

Differential Diagnosis

Specialists

  • Infectious Disease Internist
  • Internal Medicine Physician

Comorbid Conditions

  • Compromised immune system
  • Malnutrition

Factors Influencing Duration

Length of disability may be influenced by the severity of the disease, any complications that develop, and the general health of the individual.

Medical Codes

ICD-9-CM:
060.0 - Yellow Fever; Sylvatic; Jungle; Sylvan
060.1 - Yellow Fever, Urban
060.9 - Yellow Fever, Unspecified

Overview

Yellow fever is a hemorrhagic viral disease transmitted by mosquitoes (Aedes aegypti or Haemagogus spp.) and characterized by fever, headache, muscle pain, vomiting, and exhaustion.

The yellow fever virus is an important arbovirus (arthropod-borne virus) and the prototype member of the Flaviviridae family ("flavi" is the Latin word for yellow, in reference to yellow fever). Once the virus enters the body, it travels to the lymph nodes, where it multiplies. It then enters the blood and spreads to the liver, spleen, kidney, or bone marrow. Infection with yellow fever usually prevents reinfection (life-long immunity).

Yellow fever involves two different disease cycles. Jungle yellow fever is transmitted to humans via mosquitoes who have bitten infected monkeys. Urban yellow fever occurs when an infected human moves or travels to a city and a domestic species of mosquito transfers the disease from individual to individual.

Yellow fever is a preventable with vaccination. Even though it is rare for travelers to endemic areas to contract the disease, many countries in Africa and South America still require proof of vaccination prior to entering the country. Travelers should contact the Centers for Disease Control and Prevention (CDC) for more information.

Incidence and Prevalence: Yellow fever was the cause of epidemics in the US in the nineteenth century. Mosquito control has now eliminated the virus in the US and decreased the risk in countries where the disease was once prevalent. Between 1970 and 2011 a total of only 9 cases were reported in unvaccinated travelers from the US and Europe. Eight (89%) of these 9 were fatal. The CDC estimates the risk of an unvaccinated traveler contracting the disease as 50 in 100,000 for a 2-week stay in endemic areas of Africa, and 5 in 100,000 for the sane stay in endemic areas of South America ("Yellow Fever" [CDC]). Yellow fever is considered a potential public health problem in the southeastern US because of the presence of suitable mosquito vectors. Yellow fever is endemic in sub-Saharan Africa and tropical South America. Cases are underreported because the infected individuals often live in areas without access to diagnostic laboratories and reporting facilities. The World Health Organization (WHO) estimates that worldwide about 200,000 cases occur annually (90% in Africa); death occurs in 30,000 of these cases ("Yellow Fever" [WHO]).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Failure to vaccinate is the greatest risk factor. The death rate is greater for unvaccinated individuals ("Yellow Fever" [CDC]).

Yellow fever is still common in the jungles of Africa and South America. Individuals most likely to become infected with jungle yellow fever are those who work in the forest such as nut pickers, woodcutters, and road builders. Those most likely to contract urban yellow fever live in crowded conditions where there is poor mosquito control.

Source: Medical Disability Advisor



Diagnosis

History: The time between being bitten by an infected mosquito and when symptoms first appear (incubation period) is usually 3 to 6 days, but can be longer. The infection may be asymptomatic (5-50% of cases). Individuals most likely will report a recent visit to an area where yellow fever is endemic. During the acute phase symptoms include a vague feeling of bodily discomfort (malaise), sudden onset of fever, chills, severe headache, dizziness, low back pain, generalized muscle aches and pain (myalgias), loss of appetite (anorexia), nausea, vomiting, constipation, irritability, and extreme lack of energy and exhaustion (prostration).

Although symptoms may disappear about the third day, in some individuals a toxic phase follows (malignant yellow fever); by the fifth day abdominal pain may develop, and bleeding (hemorrhage) from the nose, mouth, eyes, skin, bladder, and gastrointestinal tract may occur. Urine may contain blood (hematuria), and vomit may be blood-tinged (black vomit). Production of urine may be abnormally small (oliguria). Delirium and seizures followed by coma are common.

Physical exam: The individual may have a fever and initially a fast heart rate (tachycardia). The pulse then slows and becomes weak after a few days. The membrane covering the eye (conjunctiva) may be red and have a discharge (conjunctivitis). The infected individual may also develop a flushed face. The tongue may be red and coated.
If the individual's temperature has fallen only to rise again (toxic phase), the physical exam may reveal yellowing of the skin and whites of the eyes (jaundice) and dark-colored urine. Heartbeat may be irregular (arrhythmia). The individual may become dehydrated, blood pressure may fall (hypotension), and kidney (renal) and liver failure may develop. Delirium, stupor, seizures, coma, and death may follow.

Tests: Yellow fever may initially be confused with other, more common infections. Accurate diagnosis requires viral cultures, as well as enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) for identification of viral antigen and virus-specific IgM and IgG antibodies. Blood and biochemical tests include a complete blood count (CBC), bilirubin, serum chemistry detailing liver enzyme levels (alanine aminotransferase [ALT], aspartate aminotransferase [AST]), electrolyte levels, and coagulation studies (prothrombin time [PT], partial thromboplastin time [PTT], and clotting time).

Source: Medical Disability Advisor



Treatment

Since there is no specific treatment for yellow fever, the goal is to relieve symptoms and prevent or manage complications (supportive care). Medication such as paracetamol (acetaminophen) may be prescribed to reduce fever and pain; salicylates should be avoided because of their association with platelet dysfunction and increased risk of bleeding. Antacids and histamine blockers are often prescribed to protect the stomach from bleeding. Intravenous fluids may be given to treat dehydration, maintain blood volume, increase blood pressure, and correct low blood sugar (hypoglycemia). Oxygen may also be provided. Individuals usually require 1 to 2 weeks of bed rest. Transfusions of whole blood or plasma may be needed to control severe bleeding disorders. Dialysis may be needed if renal failure develops.

Immunizations for yellow fever are often required for entry into countries where the disease is endemic. About 10-30% of those immunized report mild adverse reactions to the vaccine ("Yellow Fever" [CDC]). Rare severe reactions are infrequently reported. Travelers to areas where yellow fever exists should be vaccinated and protect themselves from mosquito bites by wearing full protective clothing, using insect repellant, and living in screened areas.

Source: Medical Disability Advisor



Prognosis

Mortality is contingent on the susceptibility of the individual and the virulence of the infecting virus strain, and varies from 50% without medical treatment to about 5% with first-world medical care. Individuals recover or die from yellow fever in 7 to 12 days. Death usually occurs between the sixth and tenth day. Those who recover have life-long immunity. Weakness may prolong convalescence for 2 to 3 weeks. Initial prognosis is always guarded since a sudden change for the worse is common.

Source: Medical Disability Advisor



Complications

Complications may include liver and kidney failure, irregular heartbeat (arrhythmia), inflammation of the heart muscle (myocarditis), heart failure, secondary bacterial infection, inflammation of the brain (encephalitis), nerve damage, and necrosis of the liver, kidney, or stomach.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Weakness may prolong convalescence. Individuals who perform physical work may need a lighter workload for several weeks.

Risk: Yellow fever is usually not directly transmitted between individuals; therefore, there is no risk to coworkers. Individuals traveling to countries where yellow fever is endemic should be vaccinated against the disease to prevent infection, and should use mosquito repellents and fully protective clothing by day and sleep beneath mosquito nets at night.

Capacity: Capacity may be temporarily reduced in individuals showing symptoms of the infection and in those who develop malignant yellow fever; such individuals may need a leave of absence for the first 7 to 12 days, and then may require more sedentary work until recovery is complete. Once recovered, there would be no impact on capacity.

Tolerance: Once the individual has recovered from an uncomplicated yellow fever infection, there is no expected impact on tolerance.

Source: Medical Disability Advisor



Maximum Medical Improvement

30 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:

  • Does individual have jungle or urban yellow fever?
  • Has individual traveled to an area where yellow fever is endemic?
  • Did individual have a sudden onset of fever, chills, and severe headache?
  • Does individual also have low back pain and generalized muscle aches and pain?
  • Does individual have loss of appetite, nausea, vomiting, and prostration?
  • Has individual developed a red tongue, flushed face, and reddening of the eyes?
  • Did the symptoms disappear about the third day and then reappear?
  • Has individual's temperature fallen and then risen again?
  • Has individual developed stomach pain and hemorrhages from the nose, mouth, skin, bladder, and gastrointestinal tract? Are urine and vomit blood-tinged?
  • Did individual develop delirium and seizures, followed by coma?
  • On exam, was a fever and tachycardia present?
  • Did the pulse then slow and becomes weak after a few days?
  • Are the conjunctiva red and producing discharge? Is the tongue coated?
  • Were jaundice and dark-colored urine then present?
  • Is individual dehydrated? Hypotensive? Did renal failure develop?
  • Did delirium, stupor, seizures, and coma follow?
  • Has individual had a CBC, bilirubin, liver enzymes, electrolyte levels, coagulation studies, viral cultures, ELISA testing, and PCR?
  • Have conditions with similar symptoms been ruled out?

Regarding treatment:

  • Has treatment relieved symptoms and prevented or managed complications?
  • Was medication given to reduce fever and pain and reduce the risk of gastric bleeding?
  • Was individual given intravenous fluids?
  • Were transfusions needed?
  • Was dialysis necessary?

Regarding prognosis:

  • Is individual's employer able to accommodate any necessary restrictions?
  • Does individual have any conditions that may affect ability to recover?
  • Does individual have any complications such as liver and kidney failure, arrhythmias, myocarditis, heart failure, encephalitis, nerve damage, or necrosis of the liver, kidney, or stomach?

Source: Medical Disability Advisor



References

Cited

"Yellow Fever." Centers for Disease Control and Prevention. 10 Mar. 2013. U.S. Department of Health and Human Services. 3 Aug. 2015 <http://wwwnc.cdc.gov/travel/diseases/yellow-fever>.

"Yellow fever." WHO. Mar. 2014. World Health Organization. 3 Aug. 2015 <http://www.who.int/mediacentre/factsheets/fs100/en/>.

Source: Medical Disability Advisor






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