Mike Oyahkire 19/03/2011 00:00:00
HEPATITIS C virus (HCV):
According to the World Health Organization, there are at present 170 million people infected with the hepatitis C virus(HCV), equivalent to 3 percent of the total world population. Inc prd 40 to 50 days.
In some countries there are three to four times more patients living with HCV than with HIV/AIDS.
Commonly associated with homosexuals seropositive for HIV, tribes who practice body and ear piercing, for cultural or religious reasons, dangerous living-those having many sexual partners in a short time, and intranasal/intravenous drug users.
Liver damage and progression to liver failure is far worse and faster with HBV/HCV co infection.
Laboratory tests may not show HBsAg , but high mutation rate leaves surplus protein particles that can be assembled by other viruses for further invasion .
Alcohol even in small doses increase HCV replication and quickens onset of liver failure, particularly for patients in the age group 40 to 50 yrs.
Use of steroids has similar effects though through different mechanisms.
Heterosexual transmission is lower for HCV than for HBV
Progression to cancer is worse when cirrhosis develops.
Mother-to-child transfusion occurs in 5 percent of cases and this increases when there is coinfection with HIV I& II. At the moment, prevention of mother to child transmission for HCV is fruitless.
Hepatitis E virus( HEV)Incubation period is 14 to 65 days.
Genotype 2 is prevalent in Nigeria and it is strongly ssociated with immune depression.
Source - usually cytologist monkeys, pigs, deer, and humans.
Mother-to-child transmission is common but not through breast milk.
Obstetric complications are common and include DIC APH, IUD, with severe life-threatening bleeding, preterm birth and stillbirth. Fulminate hepatitis with jaundice constitute bad prognosis in pregnant women.
No treatment options are currently available other than close monitoring. Data for vaccine is inconclusive. Complication may also include kidney disease, lymphoma,- cancer of the blood other and, poly viral infection as earlier stated.
Hepatitis D
This variant is common amongst heroine addicts and homosexuals. With an incubation period of 14 to 85 days, Hepatitis delta (depend virus) is considered the most severe form of viral hepatitis in humans. The hepatitis delta virus (HDV) is a defective RNA virus which requires the hepatitis B virus (HBV) surface antigen (HBsAg) for complete replication and transmission. Hence, it is common in HBsAg-positive individuals either as acute co infection or as super infection in patients with chronic hepatitis B in 90 percent of cases.
Several studies have shown that chronic HDV infection leads to more severe liver disease than chronic HBV mono-infection. Course of fibrosis is accelerated as well as marked disease progression, an increased risk of hepatocellular carcinoma and early decompensation.
Animal experiments have shown that simultaneous HBV and HDV infection is more severe than infection with HBV alone in chimpanzees.
Acute HBV and HDV co-infection tends to be more severe than acute HBV infection alone, and super infection with HBV often occurs.
Hepatitis A virus ( HAV)
WHO estimates about 10 to 30 persons/10,000/year get their infection from unsafe drinking water.
Incubation period is 15 to 49 days, and major route of transmission is from faeces to mouth but also via anal sex and fisting sexual intercourse
Child-to-child transmission very important. Children may be asymptomatic, so, excrete the virus in daycare centers, nursery and primary schools.
Co-infection with HBV can change the immunological profile of the patient and in the setting of poor sanitation, inadequate water supply, children are at risk at home and in the nursery schools.
In one study, it was found that two years old children placed their hands in their mouth every two (2) minutes . Infected parents can therefore transmit the disease to the communities through their children.
A severe fulminant course of HAV with hepatic failure is found more often in patients with underlying liver disease. Patients with chronic hepatitis C have a greatly increased risk of hepatic failure, while HBV co-infection is less dangerous.
Pathogenesis and virulence
Commonalties exist; most of them prefer the liver of humans to organs of other animals.
Nearly all elements regulating virus transcription have building sites for liver specific transcription factors.
The three laboratory specific surface proteins of HBV are believed to function as activators of transcription, but the presence of HBsAg may indicate less tendency to chronic liver disease meaning that in cases of co-morbidity with HIV, we need to check what antiretroviral agents the patient is getting.
HCV is cytolytic and can accelerate the progression of HBV down hill.
90 percent of cases of HIV co-infection with HIV leads to chronic hepatitis with very poor prognosis.
Cancer of the liver in HCV infection is probably due to prolonged immune reaction and the resultant chronic inflammation.
Several different virus induced immune escape mechanisms
Co infection with HSI & II promotes rapid CD4 depletion giving rise to opportunistic and other infections.
Reverse transcription - errors leading to mutations repair system overload.
Transcription as cellular genes
Together with proliferation – act as transforming genes and hence to cancer.
Faulty proof reading of the RNA dependent RNA polymerase leads to the production of large quantities HBV and HCV mutations every day.
A cellular protein, cyclophilin B expressed in many human tissues is involved in HCV replication.
- Ethnically - Duffy gene variants in Nigerian Africans.
- Obesity – the Leptin/C D 4 relationship or ratio – High cholesterol HDL, LDL & VDL may promote HCV replication
A fat matured lady is less likely to contract HIV compared with a slim young lady swhereas the opposite is the case if it is HCV.
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