Let us look at an example to explain the causal sequence – or chain  of events leading to death.

A 50-year-old woman was admitted to the hospital vomiting blood and was diagnosed as having bleeding oesophageal varices. Investigation revealed portal hypertension. The woman had a history of Hepatitis B infection. Three days later, she died.

• In this case Hepatis B was the underlying cause of death.
• The liver cirrhosis developed as a consequence of the Hepatitis B
• And the portal hypertension developed due to the liver cirrhosis
• The immediate cause of death was the bleeding oesophageal varices, which was a consequence of the portal hypertension.

Hepatitis B was the underlying cause of death. Knowing this, the public health response is to implement immunisation programmes against Hepatitis B virus to prevent such deaths in future.