Hepatitis A is a vaccine preventable disease
About Hepatitis A
Hepatitis A is caused by Hepatitis A virus is relatively benign infection in children but as age increases the severity and mortality increases. 85% of children less than 2 year old who got infected with Hepatitis A usually have no symptoms or have mild symptoms and no jaundice. 50% of children 2-5 years age who got infected with Hepatitis A have mild symptoms and may not have jaundice. Mild symptoms mean fever, malaise, diarrhea, cough like any other viral infection. On contrary 70-95% adults who got infected are symptomatic of Hepatitis and mortality is 1 percent.
Table of Contents
Hepatitis A Global Burden:
· More than 12.6 crore people are generally affected by Hepatitis A each year according to WHO estimates.
· There are more than 35 thousand deaths because of Hepatitis A worldwide.
· The people are getting affected increasing numbers and also the number of deaths are increasing worldwide each year.
· Contrary to other diseases the number of affected and deaths are increasing with increased socioeconomic status and good hygienic standards.
· There is epidemiologic shift in occurrence of disease leading to increasing number of incidences and deaths by the disease.
· In general overall 0.5 percent deaths caused by viral hepatitis are caused by Hepatitis A.
· Sever infection and deaths are lesser in children but more in adults.
· As age increases severity of illness and possibility of deaths also increases.
· In affluent population small amount of people get infected in childhood and so they don’t have antibodies to fight till adulthood. If they get infected in adult age, the disease is more likely to be sever and possibility of death is more.
· In developed parts of world though the antibodies are present in less number of adults but so the disease cases are low too as the disease is also prevented by good hygiene.
· Affluent population with no antibodies but staying in country with more number of cases have highest risk of getting disease in adulthood.
Hepatitis A burden in India:
· India used to be highly endemic region in the past, with time the endemicity pattern is changing.
· In past nearly 90 percent population had presence of antibodies to Hepatitis A till age 9.
· Now the seroprevalence studies in different parts of India show that nearly 30-60 percent population is not immune and susceptible.
· People with good socio-economic status are more susceptible and also there are regionwise differences in susceptibility.
· Population of Kerala is more susceptible than other socioeconomically poor population.
· Population in cities is more susceptible than rural population.
· Epidemiology of Hepatitis A is changing in India too.
· The children from affluent class are less immune to Hepatitis A.
· The children and adolescents who have educated parents have less prevalence of Hepatitis A antibodies in their serum.
· The children who have toilets in their houses have less prevalence of antibodies than those children who were going in open fields for defecation.
· Indeed with increasing levels of socio-economic status the risk of getting infected in older age is increasing with increased possibility of getting more complications.
About Hepatitis A virus:
· Hepatitis A virus was isolated for the first time by Purcell in 1973.
· Hepatitis A virus is enterovirus of Picornaviridae family.
· It is single stranded, positive sense linear RNA enterovirus.
· This virus needs human liver cells for its replication and assembly.
· Humans are yet only known reservoir for the virus.
· HAV is icosahedral-nonenveloped virus.
· It can resist acid environment of ph 3 and temperature as high as 56 degree centigrade and as low as -20 degree centigrade.
· It remains viable for many years. Boiling, chlorination and iodination are effect means to destroy it.
Pathophysiology of Hepatitis A:
· The virus is spread almost exclusively by faeco oral route.
· It can also spread by person to person contact.
· Spread of Hepatitis A through blood product is known.
· Incubation period is 2-6 weeks.
· Incubation period is usually dose related that is higher the number of virus got during infective phase less is the incubation period.
· Severity of disease increases with the increasing age. Greater the age at the time of infection in susceptible person more sever are the symptoms.
· The infected person can most effectively spread the virus during anicteric phase which can last up to 21 days.
· When reaches the liver it is attached to the liver cells by specific receptors and then taken inside the cells.
· Inside the cells it goes to nucleus and then replicates and also produces the required proteins for its assembly using the host cells machinery ribosomes inside the cell cytoplasm.
· Very few morphological changes are produced in the liver cells during this phase.
· The assemble virions are excreted in the billiary tree into the feces of infected person.
· The salivary secretions of infected person may contain the virions.
· Though Hepatitis A virus doesn’t produce much morphologic changes in liver cells the immune response is induced against it.
· The lymphocytes infiltrates are found in billiary and peri portal region causing the inflammation.
· The lever cell injury is caused by the inflammatory cytokine response by the infiltrating immune cells.
· This might be the reason that adults are affected more than children and more severely.
How does Hepatitis A virus spreads?
· Hepatitis A is highly contagious disease.
· It almost always spreads by person to person by fecal-oral route.
· Perinatal transmission can occur rarely.
· It can spread by blood and blood products too though rare.
· Increased risk of infection is for household contacts, child care centers, contact with infected persons.
· Increased risk of infection is there when someone comes in contaminated food and water and after travel to endemic areas.
· Contaminated shellfish, berries and raw vegetables have caused common sourse outbrakes in past and keep occurring even today in developing parts of the world.
· Mean incubation period is around 3 weeks and the fecal excretion starts in late incubation period.
· The fecal excretion after starting in late incubation period it peaks just before onset of symptoms and lasting up to 2 weeks of start of jaundice.
· In infants though disease is less sever but fecal excretion of virus lasts for prolonged period.
What are clinical manifestations of Hepatitis A?
· Hepatitis A is often the cause of acute hepatitis only.
· Hepatitis A is most commonly anicteric and many times indistinguishable from other viral gastro-enteritis illnesses often in infants and children.
· Hepatitis A is more likely to be symptomatic and severely symptomatic in adolescents and adults especially those with other underlying liver disease. Duration of illness is generally 7-14 days.
· The symptoms can be loss of appetite, nausea, vomiting, abdominal pain and jaundice.
· In severe cases symptoms and signs of acute or fulminant liver failure can be seen.
· Haemorrhage, altered sleep wake cycle, hypo proteinaemia, swelling of limbs or swelling of entire body, loss of consciousness, encephalopathy leading to death can occur. May need urgent liver transplant.
· Other organ system can be involved namely spleen leading to splenomegaly and lymphadenopathy.
· Bone marrow may get affected leading hypoplastic or aplastic anemia.
· Intestinal mucosa may show damage to villus structure and mucosal ulceration especially in fatal cases.
· Acute pancreatitis and myocarditis have been reported though rarely.
· Nephritis and arthritis, vasculitis and cryoglobulinemia occurs due to dysfunction of immune system.
Diagnostic tests for Hepatitis A:
· Anti HAV antibodies: These antibodies against HAV can be detected in serum. Anti HAV IgM are diagnostic of acute infection.
· Anti HAV IgM is detectable in serum by the time patient is symptomatic. It may remain detectable till 4 months.
· Anti HAV IgG is detectable after 2 weeks of infection and remains so for years. Development of IgG HAV is protective and confers lifelong immunity from the disease.
· Rise in liver enzymes ALT, AST, GGT, ALP, Sr Bilirubin is found in all Hepatitis A cases like all other hepatitis these findings do not help to differentiate the cause of hepatitis.
· Synthetic function of liver is assessed by PTINR. It may be abnormally high if liver failure.
· HBCBC, PBS helps to know the general conditions and also complications like aplastic bone marrow disease too.
What are complications of Hepatitis A?
· Acute liver failure needing liver transplant is main complication of Hepatitis A. Though maximum patients who get Hepatitis A recover without complication but as the disease is very common even less percent of people getting complications means a large number getting affected by the complications. Acute liver failure is particularly common in Hepatitis A patients who are adolescents or adults. Those having underlying liver disease along with Hepatitis A also have more risk of getting acute liver failure. Immunocompromised patients have similarly increased risk of getting acute liver failure. Those with high viral counts also have increased risk of getting acute liver failure. In endemic areas of the world 40 percent cases of acute liver failure in children are because of Hepatitis A.
· Prolonged cholestatic syndrome is a complication and may wax and wane over many months affecting person for prolonged period. Pruritus lasting for many months can be a frustrating issue in these cases. Fat malabsorption can occur needing supplemental fat soluble vitamins in these cases. So this prolonged cholestatic syndrome is managed with anti pruritic medications and fat soluble vitamin suppliments. This syndrome may be annoying but usually resolve in some months without any permanent sequelae.
About Hepatitis A vaccine:
· There are 2 types of Hepatitis A vaccine: active i.e live vaccine and inactive i.e killed vaccine.
· Killed vaccine as it name implies contains killed virus or virus particles. When these killed virus is injected to a susceptible person the immunity detects the antigens on the virus. The immunity develops against these antigen as they are recognized as foreign antigens. The antibodies are developed against these virus and when actual live virus enters the body the body fights with it as it has already received training to fight actual virus and also remembers how to fight this virus so even actual virus can not cause disease after vaccination.
· Live virus vaccine contains live Hepatitis A virus but with no capacity to cause disease. When this vaccine is injected it causes infection by vaccine virus. This vaccine virus multiplies inside the body of person who have got vaccine injection. Body recognizes it as foreign particles and develops immunity against it. In the process also the memory regarding how to fight the virus develops. When actual virus enters the body the person who received vaccine fights back the infection very vigorously so that disease cannot occur in vaccinated person.
· Killed vaccines are currently used more widely. Two doses confer lifelong immunity to Hepatitis A.
· It is given at age 12 months and second dose is to be given after 6 months.
· For older children and adolescents and adults who don’t have Anti HAV antibodies in there serum should receive 2 doses 6 months apart.
· Live vaccine is used in same schedule 2 doses but cannot be used in pregnancy and those with sever immunodeficiency.
· Fever and injection site pain are some common side effects of the vaccination. Few children may get nausea, vomiting and muscular pain.
· Sever reactions like anaphylaxis are very rare.
· This is passive form of immunity against HAV. Passive immunity means readymade immunity that body gets from outside. It lasts for a limited period of time precisely up to 3 months.
· HAV immunoglobulin can be used as pre exposure and post exposure prophylaxis.
· In pre exposure it is useful for those travelling to endemic area and travel is planned in less than 2 weeks before. Those who cannot take vaccine due to some allergy to vaccine component, those less than 1 year old, those who are severely immune deficient, pregnant can take immunoglobulin before travel.
· HAV immunoglobulin confers immediate immunity that lasts for 3 months.
· Post exposure the HAV immunoglobulin should be used as soon as possible as after 2 weeks of exposure it does not provide any benefit. Exposed individual who are non immune, less than 1 year old age, severely immune deficient, pregnant or having underlying lever disease need to get HAV immunoglobulins.
For the above all reasons the Hepatitis A vaccine is included in Vaccine schedule.
Dr Yatin Bhole,
We are near to Punawale, Kiwale and Akurdi too.