Introduction

The term ‘hepatitis" implies an inflammation and impaired function of the liver. There are many causes of hepatitis including several infectious agents, toxic substances including alcohol and medicines, and mechanical blockages of the drainage system of the liver. Most commonly, the layperson’s use of the word hepatitis implies one of the infectious diseases caused by several different viruses. Our discussion of this subject is confined to a few of the more common infectious causes.

Anatomy and Physiology of the Liver

The liver is a large organ located in the upper right quadrant of the abdomen. Tremendous amounts of blood pass through the liver to be filtered and detoxified. In broad terms, the liver is similar to a recycling centre for the body. The liver and kidney process most of the blood-borne toxins in the body and either eliminate the hazards or convert them into a less hazardous form. The liver eliminates hazards and passes them into the stool, while the kidney eliminates hazards into the urine. Most medications are "metabolized" or changed to a different form in the liver. These different forms may be either more active or less active than the original form.

The liver also processes nutrients and assists in the conversion of food to nutrients. In this role, the liver may convert sugars into more complex substances to be used slowly by the body using insulin. It also converts dietary cholesterol and fats into the healthy and unhealthy forms of cholesterol. The liver aids in fat digestion by producing bile which is stored in the adjacent gall bladder. The liver is an essential organ for daily functioning of the body.

Viral Infections of the Liver

Small virus particles may infect the liver and impair its ability to function. When this occurs, individuals may feel acutely fatigued, feverish, nauseated and lose their appetite. The urine may become very dark as the body tries to excrete a breakdown product of blood called bilirubin through the urine instead of the normal pathway through the liver and into the stool. The skin may turn yellow (jaundice) due to bilirubin deposition in the skin. In addition to the illness caused in the individual by hepatitis, a significant danger lies in its transmissibility to other people. Chronic forms of hepatitis may develop that lead to liver failure and liver cancer. There are many forms of infectious hepatitis. The most common are Hepatitis A, Hepatitis B and Hepatitis C.

Hepatitis A

Hepatitis A infects approximately 180,000 people in the US each year. Of the US population, 33% will be infected during their lifetime. The virus is found in contaminated food, water, milk and shellfish. It is primarily related to overcrowding, poor sanitation and poor personal hygiene. Contamination occurs when the virus excreted in the stool of an infected individual gets into drinking water or food. The most common scenarios occur with poor water processing facilities and poor hand washing in preparing food. A single individual can infect hundreds of people in a very short period of time. Major outbreaks have recently occurred in the US. Raw seafood, particularly oysters, which concentrate wastes dumped into the ocean, may also transmit the condition without being directly handled by an infected individual.

Hepatitis A may range in severity from almost no symptoms to being very ill. Symptoms include fatigue, fever, chills, headaches, nausea, vomiting, weight loss, jaundice, and darkened urine as discussed earlier. The condition is usually not fatal in otherwise healthy individuals. Symptoms occur from 15 to 45 days after the exposure to the virus. The symptoms usually last from one to two weeks with complete recovery within two months. There is no specific treatment other than supportive care and avoiding liver toxins such as alcohol. Even some over the counter medications such as Tylenol should generally be avoided. Once recovery is complete, the individual gains some immunity against future infection by that strain of virus.

Very rarely, death results from a fulminant infection. The diagnosis is made by testing the blood for antibodies to the hepatitis A virus and followed by monitoring blood enzymes from the liver. Elevated liver enzymes generally return to normal as the individual recovers, although this is not always the case.

Hepatitis B

Hepatitis B is a blood borne infection transmitted through contaminated body fluids. It affects 0.1% to 0.5% of low risk people in the US (128,000+ annually) and 200 million individual worldwide. Hepatitis B is the primary cause of liver cancer worldwide and is responsible for more cancer deaths than any other agent in the third world. In areas that have adopted Western lifestyles, it is less prevalent and cigarettes are a much more common cause of other fatal cancers. People at risk for Hepatitis B include intravenous drug users, those with high-risk sexual behavior, infants of mothers with hepatitis and health care workers exposed to infected blood and body fluids. Blood used for transfusion in the US is screened for infectious hepatitis.

Hepatitis B also has a wide range of symptoms, but is a potentially much more serious disease than hepatitis A. Up to 10% of infected people, over one million in the US, develop a chronic infection that is contagious (90% of infected infants). This condition also puts the individual at risk for hepatic carcinoma (liver cancer). A small percentage of people develop chronic, active hepatitis, a situation where recovery is incomplete. This may require long term treatment with medication that is poorly tolerated in some and may disqualify a pilot or controller from aviation duties. Finally, approximately 0.1-1.0% develop "fulminant hepatitis", a very aggressive and often fatal form of the disease. Nearly 6,000 deaths per year in the US are attributable to hepatitis B.

Hepatitis C

Hepatitis C is a relatively newly discovered form of liver disease that has recently received considerable public attention and media coverage. The virus was not discovered until 1988 and reliable testing did not exist until 1992. Unfortunately, the virus has infected many people prior to that time. Approximately four million Americans (2 percent of the population) are infected with hepatitis C and 10,000 will die of the disease each year. The current medical costs in the US associated with treating the disease are over $600 million annually.

Worldwide, 170 million people are infected. Hepatitis C is transmitted through contaminated blood and body fluids, similar to Hepatitis B. High-risk behaviours such as intravenous drug use and unprotected intercourse with infected individuals accounts for most of the transmission. Blood transfusions prior to improved testing of the blood supply prior to 1992 accounts for about 7% of the infections.

The clinical picture of hepatitis C, at least in the early stages, is quite different from Hepatitis A or B. Unlike the latter two, people infected with hepatitis C rarely have any symptoms for 10-30 years. They appear perfectly healthy, yet carry the disease and can infect others. Approximately 80% of people infected will develop chronic inflammation of the liver in 10-30 years and 20% will develop cirrhosis which destroys the liver, resulting in the need for a liver transplant to prevent death.

Other forms of hepatitis due to viruses include Hepatitis D, E and G. Transmission for most is similar to hepatitis B through infected blood. Hepatitis E is transmitted by contact with infected stool similar to Hepatitis A.

Prevention of Hepatitis A

Fortunately, prevention of these diseases is usually easy to accomplish. Exceptions can occur when hepatitis A contaminated food is unsuspectingly consumed in an area where transmission risk is usually very low (e.g. North America or Western Europe). When travelling to areas with poor hygiene, using the same steps one would use to avoid traveller's diarrhoea are fairly effective in preventing hepatitis A.

You should avoid uncooked foods and only eat fruits and vegetables that you personally peel. Avoid water or ice. Even "bottled" water may be contaminated if not obtained from a reliable clean source. In the past, people travelling to high risk areas were given "gamma Globulin" or immune serum globulin which gave a partial temporary immunity. These painful shots conveyed passive immunity, a transient protection gained from other infected persons’ serum.

Recently, vaccines for hepatitis A (Havrix and Vaqta) have been developed. They are much more effective in conveying a lifelong active (produced by your own body) immunity. The vaccine series is given as a two shot series with the second shot given 6 months after the first for adults. Significant immunity occurs within several weeks of the first immunization. These shots are usually very well tolerated and relieve the need for repeated painful gamma globulin injections. See the Practice Guidelines recommendations of the Advisory Committee on Immunization Practices for prevention of Hepatitis A.

For those individuals travelling to high risk areas, the vaccine is highly recommended. Information concerning high risk areas of the world may be obtained from the Centres for Disease Control and Prevention.

If an individual is infected with hepatitis A, household contacts should consider immunization and administration of immune globulin. Excellent personal hygiene and avoiding food preparation significantly decrease the risk of transmitting the disease.

Prevention of Hepatitis B

Immunizations for hepatitis B (Engerix-B and Recombivax-HB) are also available in a three shot series given as an initial dose followed by doses at one and six months. For those not engaging in high-risk behaviour, the risk of acquiring the disease is not significant. Those who may be exposed to blood or body fluids of infected persons, usually through sexual contact, should receive the immunization series. Chronically infected individuals may benefit from treatment with interferon. The treatment requires frequent injections and is often accompanied by a flu-like syndrome. This treatment must be reported to and generally is not cleared by the FAA for safety sensitive duty.

Prevention and Treatment of Hepatitis C

Currently, no vaccine exists for hepatitis C. Prevention, therefore, is limited to avoiding blood an body fluids of infected individuals. The blood supply is now tested for hepatitis C, but those individuals who received blood transfusions prior to 1992 may consider getting a simple blood test to screen for the disease. Those who are infected should avoid substances that may harm the liver, particularly alcohol, but also some medications. Some people advocate nutritional therapy to boost the immune system, though this has not been studied enough to be of proven to be of benefit.

Symptomatic people infected with hepatitis C may benefit from treatment with interferon-alpha and ribavirion, a recently approved FDA combination for the condition named Rebetol. The treatment is expensive and only improves symptoms in some individuals. It does not cure the disease and has significant side effects of fatigue, fever, muscle aches and flu-like symptoms.

The FAA briefly changed its policy and for several months allowed certification of pilots using alpha interferon for the treatment of hepatitis C. However, in late September 2001, the FAA reversed its earlier position because of concerns about depression secondary to use of alpha interferon. Currently, no forms of alpha interferon are approved for medical certification.

FAA Policies Regarding Hepatitis

The acute forms of hepatitis are disqualifying for aviation duties. If the condition resolves spontaneously, an individual may return to flying after clearance from the treating physician and when the pilot feels confident they can perform all of their required duties. This condition may be reported to the FAA at the time of the pilot's next FAA physical examination. Controllers must clear through the Regional Flight Surgeon before returning to safety sensitive duties.

Chronic hepatitis conditions requiring the use of medication must be cleared by the FAA prior to exercising the privileges of the aeromedical certificate. Certification is dependent upon minimal symptoms from the disease and tolerance of the medications. Periodic reports from the treating physician are required for continued certification. See an article in the Fall 2003 Federal Air Surgeon's Medical Bulletin, "Medical Certification in a Student Pilot With Hepatitis C Infection".

Summary

Hepatitis is a term covering a broad spectrum of diseases affecting the liver. Infectious forms of hepatitis are relatively common and can cause serious illness and death. Prevention is the key to avoiding the consequences of the disease. Medical certification of pilots/controllers with hepatitis depends on the seriousness of the disease and the method of treatment. Those pilots/controllers whose disease is well controlled, and who tolerate medication well, may be medically certified by the FAA after review and approval of appropriate medical documentation. Numerous credible resources for additional information on hepatitis exist.