[Hepatitis C in tropical areas]

The tropical features of hepatitis C have not yet been fully elucidated due to the scarcity of data. However it has been estimated that two-thirds of the infected population lives in tropics. The most heavily affected regions are Africa, China, and southeast Asia with prevalence rates of 5.3, 3.0, and 2.4 p. 100 respectively. In several countries mostly in Africa, prevalence rates range from 5 to 10 p. 100 or higher. Age is a major risk factor for infection. The classic transmission modes, i.e., blood transfusion and intravenous drug use, do not account for these high prevalence rates. Another mechanism could be parenteral injection under unsafe conditions. The most widespread genotypes in tropical areas are genotypes 1, 2, and 3. Other genotypes can be encountered locally including genotype 4 in black Africa and Egypt, genotype 6 in southeast Asia, and genotypes 1 and 3 in India. The association of hepatitis C with chronic liver disease has been the focus of several studies, mainly in Africa. The seroprevalence of virus C ranges from 2 to 55 p. 100 in cases of chronic hepatitis or cirrhosis and from 0 to 47 p. 100 in cases of hepatocellular cancer. Hepatitis C could be the underlying cause of 33 to 50 p. 100 of chronic liver diseases not linked to virus B. It is observed more often in patients with chronic hepatitis or cirrhosis than cancer in which virus B is dominant. Infection by both virus is rare without liver disease but is more frequent in patients with cancer than chronic non-tumoral liver disease.