They're the most common cause of stomach bugs (gastroenteritis) in the UK. Each year, it's estimated that between 600,000 and 1 million people in the UK catch norovirus. The illness is sometimes called the winter vomiting bug because it's more common in winter. However, you can catch the virus at any time of the year.hey're the most common cause of stomach bugs (gastroenteritis) in the UK. Each year, it's estimated that between 600,000 and 1 million people in the UK catch norovirus. The illness is sometimes called the winter vomiting bug because it's more common in winter. However, you can catch the virus at any time of the year.
On the contrary, individuals who are carriers for the sickle cell disease (with one sickle gene and one normal hemoglobin gene, also known as sickle cell trait) have some protective advantage against malaria.
HIV/AIDS. The human immunodeficiency virus (HIV) weakens the body's immune defenses by destroying CD4 (T-cell) lymphocytes, a type of white blood cell. T-cells normally help guard the body against attacks by bacteria, viruses and other germs. When HIV destroys CD4 cells, the body becomes vulnerable to many different types of infections.