The virus Human Immunodeficiency Virus (HIV) will weaken the immune system.
When the virus replicates in the blood, a large number of virus particles are released, some of which will infect skin cells.
These infected skin cells can divide uncontrollably leading to a type of skin cancer called Kaposi's sarcoma.
Therefore, the communicable disease has directly influenced the normally non-communicable disease cancer.
Also, some non-communicable diseases can put stress on the body which can lead to the development of further non-communicable diseases.
Type II diabetes is caused by the resistance of cells to the over-production of the hormone insulin caused by poor diet.
As a result, sugar levels in the blood can become very high (hyperglycaemia).
This high level of sugar in the blood can cause damage to the walls of blood vessels.
Damage to blood vessels can lead to cardiovascular disease and result in very serious illnesses such as heart attacks or strokes.
Different types of disease may interact.
Defects in the immune system mean that an individual is more likely to suffer from infectious diseases. For instance, human immunodeficiency virus (HIV) infections, which lead to AIDS, affect the immune system and lead to an increase in infectious diseases.
Viruses living in cells can be the trigger for cancers. For instance, most cases of cancer of the cervix are linked with a virus present in the female reproductive system.
The reaction of the immune system to pathogens and other foreign bodies can trigger allergic reactions that lead to skin rashes and asthma. For instance, severe respiratory infections in babies can lead to asthma in later childhood.
Severe physical ill health can lead to depression and other types of mental illness.