- Diseases, Disorders & Conditions
Viral Hepatitis: Clinical Importance And Health Implications Of Its Different Types
Jaundice In A Hepatitis Patient
Hepatitis A Virus (HAV)
Several viruses can cause the syndrome of acute viral hepatitis. This is characterized by diffuse inflammation of the liver as the predominant feature. Three viruses are mainly responsible for the vast majority of cases- Hepatitis A virus (HAV), hepatitis B virus (HBV) and non-A non-B viruses (NANB).
Hepatitis A virus (HAV): It is small RNA virus (27 nm). It is present in the feces of cases from 2 weeks before the onset of the symptoms. Infection is by the fecal-oral route. In tropical countries and in communities where food hygiene is low, this infection is prevalent and the vast majority of sufferers are children. Contamination of drinking water supply with sewage is responsible for several outbreaks from time to time. Most of the adults acquire immunity due to subclinical infection or overt disease. They show the presence of specific antibody which is protective. With improvement in hygiene, the disease becomes less common in children and older age groups are affected more. Other methods of transmission include oral-anal sexual contact in homosexual men and rarely the parenteral route. The incubation period varies from 15 to 50 days. This virus has been grown in tissue culture. This infection does not usually become chronic.
Symptoms Of Hepatitis B Viral Infection
Hepatitis B virus (HBV)
It is a DNA virus, 42 nm in size. It is present in the serum of patients many weeks before the acute illness and it disappears after 3 months. The virus can be demonstrated in the serum of infected persons during the acute phase, under the electron microscope as spherical particles known as Dane particles. The Dane particles have an outer shell and inner core. The outer protein shell is formed by the surface antigen (HBsAg). The inner core consists of a core antigen (HBcAg), a double-stranded DNA, an enzyme-DNA polymerase and an antigen (HbeAg). In many regions, eg, tropical Africa and south east Asia, the carrier rate among the population ranges from 8 to 20% and hence the whole population is at risk of infection. Aroung 30 to 50% of all cases of clinical viral hepatitis are due to HBV.
In many instances, infection occurs perinatally or during early childhood. Transmission from mother to the new born can occur if the mother is a chronic carrier or if the mother suffers from acute hepatitis in the last trimester of pregnancy. Transplacental transmission may be uncommon. Infection occurs more often during birth by ingestion of amniotic fluid or maternal blood. Close contact between mother and baby in the postnatal period favours transmission. About 90% of babies infected their mothers become chronic carriers because their immune system, is incapable of clearing the virus. In communities where the carrier rate is low (1 in 1000 or less), HBV infection is seen in special population groups such as new borns of carrier mothers, homosexuals and personnel working in dialysis units and laboratories. The HBV spreads by parenteral introduction of the infective agent along with blood or blood products or through needle pricks. The virus can also be spread by hetero- or homosexual intercourse. In homoseuxlas, the transmission rate is high. Risk factors include multiple casual sexual partners, anal intercourse and a high carrier rate among these subjects. The incubation period is 12 weeks (28 to 180 days). Oral-oral spread in saliva. Accidental ingestion of infected blood can transmit the disease.
© 2014 Funom Theophilus Makama