What is the most common disease in the world? from Onur Türk's blog

​The most common disease in the world is pneumonia/bronchitis. It is followed by diarrhoea, HIV/AIDS and depression (World Health Organization, 1999). According to calculations, 10 percent of women and 3-5 percent of men around the world suffer from clinical (that is, serious) depression every year.

The rate of depression in Turkey is 24 percent for women and 3 percent for men. The situation is also serious in other countries: the number of people suffering from depression in Britain is around 3.2 million (7 per cent) and is constantly rising. The number of prescriptions written for depression in Britain increased by more than ten million between 1990 and 2000.

According to estimates, the depression cost the British economy £8bn; This includes time missed from work, medical expenses, suicides and reduced productivity (equating to £160 per year per woman, man and child). 25 million Americans (9 percent of the population) are clinically depressed at some point in their lives.

In Australia, children as young as five are treated for depression. The most common disease in Bangladesh is by far diarrhea, followed by intestinal worm infections. But depression is also a common illness (especially among women), with a rate of 3 percent.

In Africa, depression ranks eleventh among the most common diseases; The first two are HIV and malaria. Suspicion of mental illness in many developing country cultures means that diagnosis is difficult and symptoms are more likely to be physically manifested than in the West...