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The causes of hepatitis are varied and include viruses, bacteria, and protozoa, as well as drugs and toxins (eg, isoniazid, carbon tetrachloride, and ethanol). The clinical symptoms and course of acute viral hepatitis can be similar, regardless of etiology, and determination of a specific cause depends primarily on the use of laboratory tests (Box 1). Hepatitis may be caused by at least six different viruses whose major characteristics are summarized in Table 1. Non-A-non-B (NANB) hepatitis is a term previously used to identify cases of hepatitis not caused by hepatitis A or B.

Hepatitis D (Delta Hepatitis)

Delta hepatitis is spread just as hepatitis B and is most prevalent in groups at high risk of hepatitis B infection. Injection drug users are those at greatest risk in the western world, and ~ 50% of such individuals may have IgG antibody to the delta virus antigen. Delta virus infection is rare in the U. S., northern Europe, and Japan but largely prevalent in southern Europe, Africa, and South America.

Hepatitis B

Hepatitis B infection is found worldwide, with prevalence rates varying markedly among countries. Chronic carriers constitute the main reservoir of infection: in some countries, particularly in the Far East, ~ 5-15% of all persons carry the virus, though most are asymptomatic. Of patients with HIV infection, 10% are chronic carriers of hepatitis B.

Hepatitis A

Hepatitis A virus is the cause of what was formerly termed infectious hepatitis or short-incubation hepatitis. It was first detected in the early 1970s in stools of patients incubating the disease. Humans appear to be the major natural hosts of hepatitis A virus.

Other Gastrointestinal Viruses

Even in developed countries, antibodies to caliciviruses are nearly universal by age 5. Infections tend to occur in family or community outbreaks. In underdeveloped countries, infection by these viruses occurs presumably as a result of poor sanitation. In developed countries, outbreaks that occur year-round have been described in schools, resorts, hospitals, nursing homes, restaurants, and cruise ships.


Rotavirus is the most common etiology of acute diarrheal illness in children < 2 years old. It is responsible for > 1 million cases of reported diarrheal illness each year in children ages 1-4 years in the United States. Rotavirus is responsible for an average of 150 deaths per year in this same group. All of these deaths are secondary to severe dehydration.


The herpesvirus group of the family Herpesviridae comprises large, enveloped, double-stranded DNA viruses found in both animals and humans. They are ubiquitous and produce infections ranging from painful skin ulcers to chickenpox to encephalitis. The major members of the group to infect humans are the two herpes simplex viruses (HSV-1 and -2), cytomegalovirus (CMV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), herpesvirus 6, and the recently discovered human herpesvirus types 7 and 8. Occasionally, the simian herpesvirus, herpes B virus, has caused human disease.

Varicella-Zoster Virus

VZV infection, the cause of both varicella (chickenpox) and herpes zoster, is ubiquitous (Box 4). Nearly all persons contract chickenpox before adulthood, and 90% of cases occur before the age of 10. The virus is highly contagious, with attack rates among susceptible contacts of 75%. Varicella occurs most frequently during the winter and spring months.

Buy Cheap Famciclovir (Famvir) No Prescription 250mg

After oral administration, famciclovir is well absorbed (systemic availability 77%), with little intersubject variability, and is rapidly converted to penciclovir. This compares favorably with aciclovir, the absorption of which is slow and incomplete, with a highly variable systemic availability of only 10-20%.