Following are key facts about the world's 10 biggest killer infectious diseases, ranked by mortality rates:

LOWER RESPIRATORY INFECTIONS

* Pneumonia and other diseases of lungs, windpipe or bronchial tubes including Legionnaire's disease kill more than four million people a year, mostly children under five.

* They are often associated with AIDS.

HIV/AIDS

* Some 39.4 million live with human immunodeficiency virus (HIV), the underlying cause of acquired immunodeficiency syndrome (AIDS), which attacks the immune system.

* More than 3 million deaths were attributed to AIDS in 2004.

* 65 percent of HIV cases are in sub-Saharan Africa.

MALARIA

* The mosquito-borne disease kills between 1 and 5 million each year, with 90 percent of deaths in Africa.

* Malaria kills an African child every 30 seconds.

* The disease is responsible for 20 percent of Africa's under-five mortality and 10 percent of continent's overall disease burden.

* Less than five percent of people at greatest risk have insecticide-treated mosquito nets to sleep under.

DIARRHOEA

* Is caused by dysentery, cholera and many lesser-known infections from bacterial, viral or parasitic organisms.

* Kills around 2.2 million people each year, mostly through dehydration.

* In South and Southeast Asia, is responsible for up to 8.5 percent of all deaths and in Africa 7.7 percent of deaths.

TUBERCULOSIS

* The respiratory disease infects a third of the world's population, most of whom carry it without showing symptoms, and kills 2 million a year.

* Is a frequent killer of people with AIDS. African states suffering the HIV/AIDS pandemic have experienced an annual 10 percent rise in TB cases.

MEASLES

* The virus infects more than 30 million people each year, mostly children, and kills about 530,000.

* Africa and South and Southeast Asia account for 82 percent of the global measles death toll.

* It costs $1 to immunise a child.

WHOOPING COUGH

* This acute bacterial disease of the respiratory tract affects 20-40 million people annually, killing 200,000 to 300,000.

* Ninety percent of cases are in developing countries, mostly in sub-Saharan Africa.

TETANUS

* Also known as lockjaw, the potentially fatal disease of the central nervous system affects 500,000 people a year, killing 214,000.

* Most deaths are in sub-Saharan Africa, and South and Southeast Asia, accounting for 84,000 and 82,000 deaths respectively.

* Can be prevented with a vaccine.

MENINGITIS

* Is a frequently fatal infection of tissues covering brain and spinal cord, killing 174,000 people a year.

* The "Meningitis Belt", with world's highest incidence rates, stretches from Senegal in western Africa to Ethiopia in the east.

* 10-20 percent of survivors suffer brain damage, hearing loss or learning disabilities.

SYPHILIS

* Mainly spread by sexual contact, it kills 157,000 people a year and infects 12.2 million worldwide.

* Southeast Asia, sub-Saharan Africa and Latin America -- in that order -- have the highest rates.

* Many common antibiotics do not work against syphilis, although it can be treated with penicillin.