Viral Hepatitis
HEPATITIS A
Hepatitis A(formerly known as “infectious” hepatitis or epidemic jaundice) is an acute infectious disease caused by hepatitis A virus(HAV). The disease is benign with complete recovery in several weeks. The case fatality rate of icteric cases is less than 0.1%, usually from acute liver failure and mainly affects older adults. Although the disease has, in general, a low mortality, patient may be incapacitated for many weeks. Hepatitis A virus is classified as hepatovirus is a small, undeveloped symmetrical RNA virus.Problem statement:
According to WHO about 10-50 persons per 100,000 are affected annually. Evidence from several developed countries indicate that the incidence of hepatitis A is declining. Hepatitis A virus is very common in all the countries of SEAR(South-East Asia region). Poor standard of hygiene and sanitation facilities the spread of HAV in high endemic areas. Study of the aetiology of sporadic hepatitis cases conducted in these countries demonstrated that HAV infection is responsible for approximately 10 to 25% of the total cases of hepatitis in children, while in adults HAV infection is responsible for only 1 to 5%. Outbreak of HAV infection that have been well documented, mostly in urban settings, are associated with unsafe drinking water and food.Countries in transition from developing to developed economies gradually move from high endemicity to intermediate endemicity, and HAV likely to become more serious problem in these areas.Agent factors:
a) Agent:
The causative agent is an enterovirus( type 72) of the Picornaviridae family. It multiplies only in hepatocytes. Faecal shedding of the virus is at its highest during the later part of the incubation period and early acute phase of illness. Only one serotype is known.b) Resistance:
The virus is fairly resistant to heat and chemicals. It has been shown to survive more than 10 weeks in well water. It withstands heating to 60 degree calculus’s for one hour, and is not affected by chlorine in doses usually employed for chlorination. Formalin is states to be an effective disinfectant.In short the virus survives for long period under variable conditions and resists many procedures that eliminate or inactivate most bacterial agents.c) Reservoir of infection:
The human cases are the only reservoir of infection. The cases range from the asymptomatic infections to severe ones. Asymptomatic infections are especially common in children. These cases play an important role in maintaining the chain of transmission in the community.There is no evidence of chronic carrier state.d) Period of infectivity:
The risk of transmitting HAV us greatest from 2 weeks before to 1 week after the onset of jaundice.f) Infective material:
Mainly man’s faeces, blood, serum and other fluids are infective during the brief stage of viraemia.d) Virus excretion:
HAV is excreted in the faeces for about 2 weeks before the onset of jaundice and for up to one week thereafter. The virus may also be excreted in urine.HOST Factors:
a) Age:
Infection with HAV is more frequent among children than in adults. People from all ages may be infected if susceptible. In young children infections tend to be mild or sub-clinical; the clinical severity increases with age.b) Gender:
Both genders are equally susceptible.c) Immunity:
Immunity after attack probably lasts for life; second attack have been reported in about 5% of patients. Most people in endemic areas acquire immunity through sub- clinical infection. The IgM antibody appears early in the illness and persists for over 90 days. IgG appears more slowly, and persists for many years.ENVIRONMENTAL factors:
1. Low socioeconomic status2.Poor sanitary conditions
3. Overcrowding
Mode of Transmission:
a) Faecal-oral route:
This is the major route of transmission. It may occur by direct( person to person) contact or indirectly by way of contaminated water, food or milk etc.b) Parenteral route:
Hepatitis A is rarely, if ever, transmitted by the parenteral route i.e., by body and blood products. This may occur during the stage of viraemia. This mode of transmission is of minor importance.c) Sexual transmission:
Hepatitis A may occur mainly among homosexual men because of oral-anal contact.Incubation period:
This disease exhibits three phases:1. Incubation period(averaging 28 days, range=15-50 days)
2.Acute hepatitis(generally lasting 2 months)
3. Convalescence
Clinical presentation:
Signs and symptoms:
•pre-icteric(three period prior to the appearance of jaundice) non specific influenza- like symptoms consisting of anorexia, nausea, fatigue, and malaise• Abrupt onset on anorexia, nausea, vomiting, malaise, fever, headache, and right upper quadrant abdominal pain with acute illness
•Icterichepatits: dark urine, acholic(light-colored) stools, and worsening of systemic symptoms
•Pruritus is often a major complaint of icteric patients.
Physical exam:
• Icteric sclera skin, and secretions
• Mild weight loss of 2-5 kg
• Hepatomegaly
Lab investigations:
+ve serum immunoglobulin M anti-hepatitis A virus.• Mild elevations of serum bilirubin, gamma globulin and hepatic transaminase(alanine transaminase and aspartate transaminase) values to about twice normal in acute anicteric( not accompanied with jaundice) disease.
• Elevations of alkaline phosphate, gamma glutamyl transferase and total total bilirubin in patients with cholestatic illness.
Diagnosis of Acute HAV infection clinically:
• Acute onset of fatigue• Abdominal pain
• Loss of appetite
• Intermittent nausea and vomiting
• Jaundice or elevated serum amino transferase levels.
• Serologic testing for immunoglobulin(Ig) G anti- HAV
Treatment:
•No specific treatment options exists for HAV.• Management of HAV infection is primarily supportive.
Prevention:
• Control of reservoir• Control of transmission by avoiding exposure.
• The most important measures to avoid exposure includes good hand washing techniques and good personal hygiene practices.
•Current vaccination strategy in the US vaccinating all children at 1 year of age
Hepatitis A Vaccination:
Several inactivated vaccines have been developed against HAV but only 4 are currently available internationally. All four vaccines are similar in terms of efficacy and side effect profile.The vaccines are given parentally, as a 2- dose regimen, 6-18 months apart.No vaccine is licensed for children aged less than 1 year. A combination vaccine containing inactivated hepatitis A and recombinant hepatitis B vaccines has been licensed since 1996 for use in children aged 1 year or older in several countries. The combination vaccine is given as a 3 doses series, using a 0,1,6 months schedule.Recommendations:
• All children at 1 year of age.• In areas without existing hepatitis A vaccination programs, catch- up vaccination of children aged 2-18 years can be considered.
• Persons traveling to or working in countries that have high or intermediate endemic rates of HAV infection.
• Homosexual males.
• illegal- drug users.
• People who have occupational risk for infection(e.g.,persons who work with HAV- infected primates or HAV in a research laboratory setting).
• Persons who have clotting factor disorders.
Persons who have chronic liver disease(e.g., persons with chronic liver disease caused by hepatitis B or C and persons awaiting liver transplants).
• Two inactivated vaccines are currently licensed in the US, Havrix (0.5ml for 1-18 years old and 1ml for 19 years old and onward)and Vaqta(0.5ml till 18 years old and 1 ml for greater than 18 years old)
• Numbers of doses is 2.
• In Pakistan AVIXIM, Epaxal BERNa
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