Taming A Vicious Silent Killer - Hepatitis B Virus (Hbv) Infection(2)(2)

(Continued from last week)

How is hepatitis B virus transmitted?
HBV is a virus with humans being the only known natural host. HBV can be transmitted through sexual or
household contact, or by unsafe injections, but chronic infections acquired during infancy or childhood account for a disproportionately large share of worldwide morbidity and mortality. The virus enters the liver via the bloodstream, and replication occurs only in liver tissue.

HBV is transmitted mainly through the skin or mucosal surfaces after exposure to infected blood or other body fluids. HBV transmission has been observed with numerous forms of human contact including perinatal, mother-to-child; household (nonsexual); sexual; needle-sharing; and occupational/health-care-related. The highest concentrations of infectious HBV are found in blood and serum.

However, other blood-derived body fluids, such as semen and saliva, are also infectious. The virus can remain stable and infectious on environmental surfaces for at least seven days, transmission may occur indirectly via contaminated surfaces and other objects.

The virus is efficiently transmitted by sexual contact. Men who have sex with men have long been known to have high rates of disease. Injection drug users are at high risk for HBV infection because of behaviors such as sharing of needles, syringes, and other drug paraphernalia. Outbreaks linked to other skin related risk of exposures besides injection drug use, such as tattooing and acupuncture, have been reported.

Provider-to-patient HBV transmission occur rarely. Most events have been associated with health care workers’ performing invasive procedures, and most occurred before the widespread use of hepatitis B vaccine and the implementation of universal precautions in standard infection control practice.

Transmission of HBV via transfusion of blood products has been largely eliminated in most parts of the world by screening blood donors and implementing techniques that ensure viral inactivation of products made from blood.

How do I recognise early infection with hepatitis B virus?
Persons with acute hepatitis B can show signs and symptoms that include nausea, abdominal pain, vomiting, fever, jaundice, dark urine, changes in stool color, and enlarged liver or spleen.

For the newly infected persons who develop acute hepatitis, the average incubation period (time from exposure to onset of jaundice) is 90 days (range: 60–150 days). The likelihood of developing symptoms of hepatitis as a result of a new HBV infection is age-dependent. Over 90 per cent of early neonatal (within one month of birth) HBV infections are without symptoms, while the typical features of infection are noted in 5 to 15 per cent of newly infected young children (one to five years of age) and in 33 to 50 per cent of older children, adolescents, and adults.

What are the ways of preventing hepatitis B infection?
Before the introduction of hepatitis B vaccines, numerous preventive measures had been employed to some degree, including screening of blood donors, preparation of blood-derived products in a way that inactivates HBV virus, implementation of infection control measures, and administration of hepatitis B ‘immune globulin’ injection following suspected exposure, especially for infants born to positive women. Although all of these activities can reduce the risk of HBV transmission, none have been as effective as active immunisation with hepatitis B vaccine, which remains the single most important hepatitis B prevention measure.

The hepatitis B vaccine is one of the safest and most widely used vaccines in the world. The protection offered lasts for at least 15 years. The most commonly reported adverse effects associated with hepatitis B vaccine are pain at the injection site and a little fever.

Hepatitis B vaccines are typically given in three-dose series. The three-dose vaccination coverage for children aged 19 to 35 months should be given at birth. Hepatitis B vaccine can be administered concurrently with other vaccines at any age.

Global Hepatitis B Vaccine Programme Implementation In 1992, the World Health Organisation recommended the integration of hepatitis B vaccine into the national immunisation programs of all highly endemic countries by 1995 and all other countries by 1997. As of 2004, more than 150 (78 percent) of 192 World Health Organisation member states had adopted universal childhood hepatitis B vaccination policies. Notably absent are several highly endemic countries, most of them located in sub-Saharan Africa.

Nigeria started observing the recommendation in 2000, although this is limited by high cost and limited availability of the vaccine. Despite several countries’ success in implementing broad vaccination policies, by the end of the 1990s most of the world’s population still lived in countries without universal infant vaccination, largely because of the expense of hepatitis B vaccine. The introduction of laws requiring immunisation prior to school entry should be considered a viable option for the Nigerian community to control the spread of the disease.

Taiwan is perhaps the best example of a highly endemic country with a substantial and measurable reduction in disease burden resulting from a long-standing policy of universal childhood hepatitis B vaccination. Infection rates among Taiwanese children decreased from 9.8 percent in 1984, the year when universal infant immunization began, to 0.7 per cent in 1999! Also in the Gambia, childhood infection has decreased from 10 percent to 0.6 percent since the introduction of routine infant and childhood vaccination in 1986.

Further progress towards the elimination of transmission of hepatitis B infection in Nigeria will require sustainable vaccination programs with improved vaccination coverage, practical methods of measuring the impact of vaccination programs, and targeted vaccination efforts for at high risk groups such as healthcare workers, public safety workers, homosexual men, correctional facilities, sexually transmitted disease clinics, substance abuse treatment centers, patients likely to receive multiple transfusions and kidney disease patients on dialysis treatment.

If I am infected, what are the available treatment options for me?
Members of the public should freely approach medical practitioners to request for blood tests to know their status. Generally, infected persons should avoid alcohol, imbibe safe sexual practices, immunisation of household contacts, and weight reduction should be advised. People who might spread hepatitis at work should either undergo treatment or change their profession.

Three drugs are currently approved for use in treating chronic infection. Your specialist doctor is the best person to approach.