The most lethal conditions are lower respiratory infections, AIDS and diarrhoeal diseases. Also deadly are perinatal conditions that affect children in the period from just before to soon after birth. These conditions, which include low birth weight, birth asphyxia and birth trauma, kill 2.5 million babies a year.

Millions of people in developing countries die every year of conditions that are easily treatable elsewhere. They die not only because of lack of medicines but also because many are so undernourished that relatively mild complaints become killers.

The most vulnerable are children under five years old. More than 9 million die each year of diseases and perinatal conditions, nearly half because of malnutrition.

But disease not only kills. It can also debilitate people for life and make it harder for them to work. This perpetuates a vicious cycle that pushes them and their families further down the poverty ladder, making them even more susceptible to illness.

One caveat to bear in mind when researching health issues is that data is patchy for Africa, Middle East and Asia. The World Health Organisation relies on member states for health statistics, but not all countries conduct surveys and millions of births and deaths go unreported. That makes it difficult to build up an accurate picture of how diseases affect countries.

BIGGEST KILLER DISEASES AND CONDITIONS

Disease/condition and Global annual death rates

Lower respiratory infections : 3.9 million AIDS (WHO 2002, UNAIDS 2005) : 2.8 million Perinatal conditions : 2.5 million Diarroeal disease : 1.8 million Tuberculosis (WHO 2002, 2005): 1.6 million Malaria : 1.3 million Traffic accidents (included for comparison) : 1.2 million Measles : 600,000 Maternal conditions : 500,000 War (included for comparison) : 200,000

(Source: OMS)