Infectious Diseases

Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another. Zoonotic diseases are infectious diseases of animals that can cause disease when  transmitted to humans. (WHO-definition)

Among the indefinite number of microorganisms on earth, only relatively few cause diseases in otherwise healthy humans and animals. Nonetheless, infectious and parasitic diseases rank second among the "top killers" of the world, according to a WHO report¹ on the global burden of disease. In low-income countries, especially in Africa, these diseases are even the dominant causes of death. In the developed world, the incidence of bacterial, viral and parasitic infections was dramatically reduced throughout the 20th century, mainly as a result of improved hygiene and sanitation and the development of vaccines and antibiotics.

Some 90% of all infectious disease-related deaths are caused by only six deadly infections: HIV/Aids, malaria, diarrhoea, measles, pneumonia and tuberculosis². Children and young adults suffer the most: diarrhoeal diseases such as cholera, dysentery or typhoid fever, for example, kill about 2 million children under age 5 – year after year². The situation is even worse in the case of pneumonia. This deadliest form of acute respiratory infection (ARI) kills more children than any other infectious disease². Malaria is another primary cause of child mortality, causing more than 10 percent of all childhood death in developing countries³.

Above all, millions of people are disabled every year by infectious diseases. Measles, for example, can result in blindness, deafness or brain damage. Lymphatic filariasis, a parasitic worm disease also known as Elephantiasis, affects about 120 million people worldwide, and 40 million people are disabled and disfigured by it⁴.

But the burden infectious diseases impose on humans goes far beyond the high death toll or the individual’s fate. They keep children away from school and adults away from work. Costs for treatment are often unaffordable for patients and drive already poor families into ruin. The countrywide economic loss due to disease is immense, cementing poverty and underdevelopment in many regions of the world.

In Africa, for example, malaria is estimated to reduce gross domestic product growth by 1.3% per year⁵. The HIV/Aids epidemic also dramatically impacts the social and economic situation on the continent. Due to the high rates of HIV infection in southern Africa, the life expectancy of the population decreased from 62 years in 1990–1995 to 48 years in 2000–2005⁶. This is not only a human tragedy, it also results in a massive loss of the most economically productive individuals, affecting the countries’ growth rates, health care, education and political stability⁶.

The growing concern about the detrimental impact of infectious diseases found its way into the United Nations Millennium Declaration, adopted by world leaders in September 2000. Millennium Development Goal⁷ number 6, for example, is to "combat HIV/Aids, malaria and other diseases"; more specifically, by 2015 the spread of HIV/Aids and the incidence of malaria and other target diseases should be halted or even reversed. By 2010, universal access to treatment for HIV/Aids should exist. Other millennium goals are indirectly related to infectious diseases, such as the goals to eradicate extreme poverty and hunger, to reduce child mortality or improve maternal health.

On following pages you’ll find short descriptions of the most relevant infectious diseases  - relevant in that they affect a high number of people, cause considerable deaths around the world and have a prominent impact on the economies of affected countries. All these diseases are unified by the fact that they can be combated effectively; some could even be eradicated with an appropriate and purposeful strategy, a strong will and, of course, enough money.

Literature
1. WHO, The global burden of disease: 2004 update www.who.int/healthinfo/global_burden_disease/2004_report_update/en/index.html
2. WHO report on infectious diseases: www.who.int/infectious-disease-report/index-rpt99.html
3. Malaria facts, Centers for Disease Control and Prevention (CDC): www.cdc.gov/malaria/
4. WHO fact sheet Nr. 102, Lymphatic filariasis: www.who.int/mediacentre/factsheets/fs102/en/
5. Malaria Foundation International. The Abuja Declaration on Roll back Malaria in Africa by the African heads of State and Government. April 25, 2000
6. Baylor College of Medicine: www.bcm.edu/molvir/eidbt/eidbt-mvm-id.htm
7. UN Millennium Declaration, Development goals: www.un.org/millenniumgoals/bkgd.shtml