HEPATITIS D VIRUS - detection from blood

HEPATITIS D VIRUS (HDV) 

KEY FACTS AND OVERVIEW:

Hepatitis D virus (HDV) requires hepatitis B virus (HBV) for its replication; it affects around 5% of chronic HBV infected people. 

Indigenous populations, recipients of haemodialysis and people who inject drugs are more likely to have HBV and HDV co-infection. Since 1980s,  successful global HBV vaccination coincided with decreased HDV infection worldwide. 

The combination of HDV and HBV infection is considered the most severe  form of chronic viral hepatitis due to more rapid progression towards liver-related death and hepatocellular carcinoma and liver-related death. Hepatitis D infection can be prevented by hepatitis B immunization, but treatment success rates are low.  

Hepatitis D: liver inflammation caused by HDV. Vaccination against hepatitis B: the only prevention method.  

GEOGRAPHICAL DISTRIBUTION:

Geographical hotspots of high HDV infection prevalence: Mongolia, the Republic of Moldova, countries in western and central Africa. 

TRANSMISSION:

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 rare. Vaccination against HBV prevents HDV coinfection and hence expansion of childhood HBV immunization programs 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. 

SYMPTOMS:

In acute hepatitis, simultaneous infection with HBV and HDV can lead to signs and symptoms indistinguishable from those of other types of acute viral hepatitis infections: fever, fatigue, loss of appetite, nausea, vomiting, dark urine, pale-colored stools and jaundice (yellow eyes).

In a superinfection, HDV can infect a person already chronically infected with HBV. HDV superinfection accelerates progression to cirrhosis almost a decade earlier than HBV mono-infected persons. Patients with HDV induced cirrhosis are at an increased risk of hepatocellular carcinoma.

DIAGNOSIS:

HDV infection is diagnosed by high levels of anti-HDV immunoglobulin G (IgG) and immunoglobulin M (IgM), and confirmed by detection of HDV RNA in serum. However, HDV diagnostics are not widely available. 

TREATMENT:

Pegylated interferon alpha is the generally recommended treatment for HDV infection. 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. This treatment is associated with significant side effects and should not be given to patients with decompensated cirrhosis, active psychiatric conditions and autoimmune diseases.

PREVENTION:

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.

HEPATITIS E VIRUS - detection from blood

HEPATITIS E VIRUS (HEV)

KEY FACTS:

HEV infection causes inflammation of the liver. 

Transmission: fecal-oral route, especially contaminated water. HEV: found worldwide; most common East and South Asia. 

OVERVIEW:

HEV has 4 different types: genotypes 1, 2, 3 and 4. Genotypes 1 and 2: only in humans; genotypes 3 and 4: in pigs, wild boars and deer without causing any disease, and occasionally infect humans. 

The virus: shed in the stools of infected persons; 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 leads to fulminant hepatitis (acute liver failure); it can be fatal. 

TRANSMISSION:

HEV infection is found worldwide, but common in low- and middle- income countries with limited access to essential water, sanitation, hygiene and health services. Here, it occurs both as outbreaks and as sporadic cases. The outbreaks follow periods of faecal contamination of drinking water supplies. Sporadic cases are also believed to be related to contamination of water, albeit at a smaller scale. The cases in these areas are caused mostly by infection with genotype 1 virus, and much less frequently by genotype 2 virus. In areas with better sanitation and water supply, HEV infection is infrequent, with only occasional sporadic cases. Most of these cases are caused by genotype 3 virus and are triggered by infection with virus originating in animals, usually through ingestion of undercooked animal meat.

SYMPTOMS:

Incubation period: 2-10 weeks (5-6 weeks average). The infected persons excrete the virus beginning from a few days before to 3-4 weeks after onset. Typical sings and symptoms: 

- initially: mild fever, reduced appetite (anorexia), nausea and vomiting (a few days);

- abdominal pain, itching, skin rash, or joint pain;

- jaundice, dark urine and pale stools;

- enlarged, tender liver (hepatomegaly)

These symptoms typically last 1-6 weeks. 

Rarely, acute hepatitis E can be severe and results in fulminant hepatitis (acute liver failure) - risk of death. Cases of chronic HEV infection: in immunosuppressed people, particularly organ transplant recipients on immunosuppressive drugs, with genotype 3 or 4 HEV infection (uncommon). 

DIAGNOSIS:

Hepatitis E cases: not clinically distinguishable from other acute viral hepatitis. However, diagnosis can often be strongly suspected when for example 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. 

Definitive diagnosis of HEV infection is usually based on the detection of specific anti-HEV immunoglobulin M (IgM) antibodies in a person's blood. Rapid tests are available for field use. Additional tests: reverse transcriptase polymerase chain reaction (RT-PCR) to detect the HEV RNA in blood and stool.

TREATMENT:

As the disease is usually self-limiting, hospitalization is generally not required. Acetaminophen, paracetamol and medication against vomiting should be used sparingly. Hospitalization: required for fulminant hepatitis and symptomatic pregnant women. For immunosuppressed people with chronic hepatitis E: ribavirin treatment. In some specific situations, interferon has also been used successfully. 

PREVENTION:

At the population level, HEV transmission and infection  can be reduced by: 

- maintaining quality standards for public water supplies;

- establishing proper disposal systems for human faeces.

On an individual level, infection risk can be reduced by: 

- maintaining hygienic practices;

- avoiding consumption of water and ice of unknown purity.