Molecular evolutionary analysis based on coalescent theory can provide important insights into epidemiologic processes worldwide.
Dr Yasuhito Tanaka and colleagues analyzed Hepatitis C epidemiologic-historical background linked with hepatocellular carcinoma in different countries.
The research team analyzed the Hepatitis C virus gene sequences of 131 genotype 1b strains from Japan.
The team also assessed 38 Hepatitis C virus-1a strains from the United States, and 33 Hepatitis C virus-1b strains from Spain.
A further 27 Hepatitis C virus-3a strains from the former Soviet Union, and 47 Hepatitis C virus-4a strains from Egypt were assessed.
| Tansition from constant size to rapid exponential growth occurred in Europe in the 1940s|
In addition, the team evaluated 25 Hepatitis C virus-5a strains from South Africa, and 24 Hepatitis C virus-6a strains from Hong Kong.
The researchers coalescent analysis indicated that a transition from constant size to rapid exponential growth occurred in Japan in the 1920s.
However, this was not noted until the 1940s for the same genotype in Spain and other European countries.
The team estimated that spread time of Hepatitis C virus-1a in the United States occurred in the 1960s.
Spread time of the Hepatitis C virus-3a in the former Soviet Union, and Hepatitis C virus-5a in South Africa, was in the 1960s, and mid 1950s, respectively.
The researchers noted that Hepatitis C virus-6a spread time in Hong Kong was in the late 1970s.
The team determined 3 different linear progression curves.
The relationship between Hepatitis C virus seroprevalence and hepatocellular carcinoma mortality in different geographic regions was analyzed.
A steep ascent indicated the greatest progression to hepatocellular carcinoma in Japan.
The team showed that a near horizontal line indicated the least progression in the United States and the former Soviet Union.
An intermediate slope was observed in Europe.
Dr Tanaka's team concluded, “These findings strongly suggest that the initial spread time of Hepatitis C virus is associated with the progression dynamics of hepatocellular carcinoma in each area, irrespective of genotype.”