What is viral hepatitis
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What is Viral Hepatitis
Hepatitis is an inflammation of the liver, most commonly caused by a viral infection. There are five main hepatitis viruses, referred to as types A, B, C, D and E. These five types are of greatest concern because of the burden of illness and death they cause and the potential for outbreaks and epidemic spread.
What makes hepatitis a global health problem
Every 30 seconds, someone dies from a viral hepatitis related illness. However, with the existing prevention, testing and treatment services that are available every hepatitis related death is preventable.
Hepatitis can affect anyone, but it has a disproportionate affect on the people and communities most underserved by health systems.
Cure: Most people make a full recovery
Hepatitis A is an inflammation of the liver caused by the hepatitis A virus (HAV). The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person. The disease is closely associated with unsafe water or food, inadequate sanitation, poor personal hygiene and oral-anal sex.
Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease but it can cause debilitating symptoms and rarely fulminant hepatitis (acute liver failure), which is often fatal. WHO estimates that in 2016, 7134 persons died from hepatitis A worldwide (accounting for 0.5% of the mortality due to viral hepatitis).
Hepatitis A is common in low- and middle-income countries with poor sanitary conditions and hygienic practices. Infection rates are low in high-income countries with good sanitary and hygienic conditions. Disease may occur among adolescents and adults in high-risk groups, such as persons who inject drugs (PWID), men who have sex with men (MSM), people travelling to areas of high endemicity and in isolated populations, such as closed religious groups. In the United States of America, large outbreaks have been reported among persons experiencing homelessness.
Symptoms of hepatitis A range from mild to severe and can include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the eyes and skin). Not everyone who is infected will have all the symptoms.
Hepatitis A sometimes relapses, meaning the person who just recovered falls sick again with another acute episode. This is normally followed by recovery.
There is no specific treatment for hepatitis A. Recovery from symptoms following infection may be slow and can take several weeks or months.
Improved sanitation, food safety and immunization are the most effective ways to combat hepatitis A.
The spread of hepatitis A can be reduced by:
- adequate supplies of safe drinking water;
- proper disposal of sewage within communities; and
- personal hygiene practices such as regular handwashing before meals and after going to the bathroom.
Cure: In development
Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV). It is a major global health problem. It can cause chronic infection and puts people at high risk of death from cirrhosis and liver cancer.
A safe and effective vaccine that offers 98% to 100% protection against hepatitis B is available. Preventing hepatitis B infection averts the development of complications including chronic disease and liver cancer.
The burden of hepatitis B infection is highest in the WHO Western Pacific Region and the WHO African Region, where 116 million and 81 million people, respectively, are chronically infected. Sixty million people are infected in the WHO Eastern Mediterranean Region, 18 million in the WHO South-East Asia Region, 14 million in the WHO European Region and 5 million in the WHO Region of the Americas.
Hepatitis B is most commonly spread from mother to child at birth (perinatal transmission) or through horizontal transmission (exposure to infected blood). The development of chronic infection is common in infants infected from their mothers or before the age of 5 years.
Hepatitis B is also spread by needlestick injury, tattooing, piercing and exposure to infected blood and body fluids, such as saliva and menstrual, vaginal and seminal fluids. Transmission of the virus may also occur through the reuse of contaminated needles and syringes or sharp objects either in health care settings, in the community or among persons who inject drugs. Sexual transmission is more prevalent in unvaccinated persons with multiple sexual partners.
Most people do not experience any symptoms when newly infected. However, some people have acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting and abdominal pain. People with acute hepatitis can develop acute liver failure, which can lead to death. Among the long-term complications of HBV infections, a subset of persons develops advanced liver diseases such as cirrhosis and hepatocellular carcinoma, which cause high morbidity and mortality.
As of 2019, 30.4 million people (10.5% of all people estimated to be living with hepatitis B) were aware of their infection, while 6.6 million (22%) of the people diagnosed were on treatment. According to latest WHO estimates, the proportion of children under five years of age chronically infected with HBV dropped to just under 1% in 2019 down from around 5% in the pre-vaccine era ranging from the 1980s to the early 2000s.
Chronic hepatitis B infection can be treated with medicines, including oral antiviral agents. Treatment can slow the progression of cirrhosis, reduce incidence of liver cancer and improve long term survival. In 2021 WHO estimated that 12% to 25% of people with chronic hepatitis B infection will require treatment, depending on setting and eligibility criteria.
WHO recommends that all infants receive the hepatitis B vaccine as soon as possible after birth, preferably within 24 hours, followed by 2 or 3 doses of hepatitis B vaccine at least 4 weeks apart to complete the vaccination series. Protection lasts at least 20 years and is probably lifelong. WHO does not recommend booster vaccinations for persons who have completed the 3-dose vaccination schedule.
In addition to infant vaccination, WHO recommends the use of antiviral prophylaxis for the prevention of hepatitis B transmission from mother-to-child. Implementation of blood safety strategies and safer sex practices, including minimizing the number of partners and using barrier protective measures (condoms), also protect against transmission.
Hepatitis C virus (HCV) causes both acute and chronic infection.
70% (55–85%) of persons will develop chronic HCV infection. Of those with chronic HCV infection, the risk of cirrhosis ranges from 15% to 30% within 20 years.
HCV occurs in all WHO regions. The highest burden of disease is in the Eastern Mediterranean Region and European Region, with 12 million people chronically infected in each region. In the South-East Asia Region and the Western Pacific Region, an estimated 10 million people in each region are chronically infected. Nine million people are chronically infected in the African Region and 5 million the Region of the Americas.
The hepatitis C virus is a bloodborne virus. It is most commonly transmitted through:
- the reuse or inadequate sterilization of medical equipment, especially syringes and needles in healthcare settings;
- the transfusion of unscreened blood and blood products; and
- injecting drug use through the sharing of injection equipment.
HCV can be passed from an infected mother to her baby and via sexual practices that lead to exposure to blood (for example, people with multiple sexual partners and among men who have sex with men); however, these modes of transmission are less common.
Hepatitis C is not spread through breast milk, food, water or casual contact such as hugging, kissing and sharing food or drinks with an infected person.
Those who are acutely symptomatic may exhibit fever, fatigue, decreased appetite, nausea, vomiting, abdominal pain, dark urine, pale faeces, joint pain and jaundice (yellowing of skin and the whites of the eyes).
Because new HCV infections are usually asymptomatic, few people are diagnosed when the infection is recent. In those people who go on to develop chronic HCV infection, the infection is often undiagnosed because it remains asymptomatic until decades after infection when symptoms develop secondary to serious liver damage.
Early diagnosis can prevent health problems that may result from infection and prevent transmission of the virus. WHO recommends testing people who may be at increased risk of infection.
About 2.3 million people (6.2%) of the estimated 3.7 million living with HIV globally have serological evidence of past or present HCV infection. Chronic liver disease represents a major cause of morbidity and mortality among persons living with HIV globally.
WHO recommends therapy with pan-genotypic direct-acting antivirals (DAAs) for persons over the age of 12 years. DAAs can cure most persons with HCV infection, and treatment duration is short (usually 12 to 24 weeks), depending on the absence or presence of cirrhosis.
Of the 58 million persons living with HCV infection globally in 2019, an estimated 21% (15.2 million) knew their diagnosis, and of those diagnosed with chronic HCV infection, around 62% (9.4 million) persons had been treated with DAAs by the end of 2019.
There is no effective vaccine against hepatitis C so prevention depends on reducing the risk of exposure to the virus in health care settings and in higher risk populations. This includes people who inject drugs and men who have sex with men, particularly those infected with HIV or those who are taking pre-exposure prophylaxis against HIV.
Primary prevention interventions recommended by WHO include:
- safe and appropriate use of health care injections;
- safe handling and disposal of sharps and waste;
- provision of comprehensive harm-reduction services to people who inject drugs;
- testing of donated blood for HBV and HCV (as well as HIV and syphilis);
- training of health personnel; and
- prevention of exposure to blood during sex.
Vaccine: No (although hepatitis D only affects people living with hepatitis B which there is a vaccine for)
Hepatitis D is an inflammation of the liver caused by the hepatitis D virus (HDV), which requires HBV for its replication. Hepatitis D infection cannot occur in the absence of hepatitis B virus. HDV-HBV co-infection is considered the most severe form of chronic viral hepatitis due to more rapid progression towards hepatocellular carcinoma and liver-related death.
Vaccination against hepatitis B is the only method to prevent HDV infection.
It is estimated that hepatitis D virus (HDV) affects nearly 5% of people globally who have a chronic infection with hepatitis B virus (HBV) and that HDV co-infection could explain about 1 in 5 cases of liver disease and liver cancer in people with HBV infection.
The routes of HDV transmission, like HBV, occur through broken skin (via injection, tattooing etc.) or through contact with infected blood or blood products. Transmission from mother to child is possible but rare. Vaccination against HBV prevents HDV coinfection and hence expansion of childhood HBV immunization programmes has resulted in a decline in hepatitis D incidence worldwide.
Chronic HBV carriers are at risk of infection with HDV. People who are not immune to HBV (either by natural disease or immunization with the hepatitis B vaccine) are at risk of infection with HBV, which puts them at risk of HDV infection.
Those who are more likely to have HBV and HDV co-infection include indigenous people, people who inject drugs and people with hepatitis C virus or HIV infection. The risk of co-infection also appears to be potentially higher in recipients of haemodialysis, men who have sex with men and commercial sex workers.
In acute hepatitis, simultaneous infection with HBV and HDV can lead to a mild-to-severe hepatitis with signs and symptoms of indistinguishable from those of other types of acute viral hepatitis infections. These include fever, fatigue, loss of appetite, nausea, vomiting, dark urine, pale-colored stools and jaundice (yellow eyes).
HDV diagnostics are not widely available and there is no standardization for HDV RNA assays, which are used for monitoring response to antiviral therapy.
Pegylated interferon alpha is the generally recommended treatment for hepatitis D virus infection. Treatment should last for at least 48 weeks irrespective of the patient’s response. The virus tends to give a low rate of response to the treatment; however, the treatment is associated with a lower likelihood of disease progression.
More efforts are needed to reduce the global burden of chronic hepatitis B and develop medicines that are safe and effective against hepatitis D and are affordable enough to be deployed on a large scale to those who are most in need.
While WHO does not have specific recommendations on hepatitis D, prevention of HBV transmission through hepatitis B immunization, including a timely birth dose, additional antiviral prophylaxis for eligible pregnant women, blood safety, safe injection practices in health care settings and harm reduction services with clean needles and syringes are effective in preventing HDV transmission. Hepatitis B immunization does not provide protection against HDV for those already infected with HBV.
Cure: Most people make a full recovery
Hepatitis E is inflammation of the liver caused by the hepatitis E virus (HEV).
The virus is shed in the stools of infected persons and enters the human body through the intestine. It is transmitted mainly through contaminated drinking water. The infection is usually self-limiting and resolves within 2–6 weeks. Occasionally a serious disease known as fulminant hepatitis (acute liver failure) develops, which can be fatal.
Hepatitis E infection is found worldwide and is common in low- and middle-income countries with limited access to essential water, sanitation, hygiene and health services. In these areas, the disease occurs both as outbreaks and as sporadic cases. The outbreaks usually follow periods of faecal contamination of drinking water supplies and may affect several hundred to several thousand persons. Some of these outbreaks have occurred in areas of conflict and humanitarian emergencies such as war zones and camps for refugees or internally displaced populations, where sanitation and safe water supply pose special challenges.
Typical signs and symptoms of hepatitis include:
- an initial phase of mild fever, reduced appetite (anorexia), nausea and vomiting lasting for a few days;
- abdominal pain, itching , skin rash, or joint pain;
- jaundice (yellow colour of the skin), dark urine and pale stools; and
- a slightly enlarged, tender liver (hepatomegaly).
Diagnosis can often be strongly suspected in appropriate epidemiologic settings, for example when several cases occur in localities in known disease-endemic areas, in settings with risk of water contamination when the disease is more severe in pregnant women or if hepatitis A has been excluded.
Hospitalization is generally not required. Most important is the avoidance of unnecessary medications.
Hospitalization is required for people with fulminant hepatitis and should also be considered for symptomatic pregnant women.
Prevention is the most effective approach against the infection. At the population level, transmission of HEV and hepatitis E infection can be reduced by:
- maintaining quality standards for public water supplies; and
- establishing proper disposal systems for human faeces.
On an individual level, infection risk can be reduced by:
- maintaining hygienic practices; and
- avoiding consumption of water and ice of unknown purity.