 | Infectious disease: Encyclopedia II - Infectious disease - Mortality from infectious diseases
Infectious disease - Mortality from infectious diseases
The World Health Organization collects information on global deaths by International Classification of Disease (ICD) code categories. The following table lists the top infectious disease killers which caused more than 100,000 deaths in 2002 (estimated). 1993 data is also included for comparison.
Lower respiratory infections
HIV/AIDS
Diarrheal diseases
Tuberculosis (TB)
Malaria
Measles
Pertussis
Tetanus
Meningitis
Syphilis
Hepatitis B
Tropical diseases (6)
(Note: The other categories of death are maternal and perinatal conditions (5.2%), nutritional deficiencies (0.9%), noncommunicable conditions (58.8%), and injuries (9.1%).)
The top three single agent disease killers are HIV/AIDS, TB, and malaria. Lower respiratory infections (which include various pneumonias) and diarrheal diseases are caused by many different viruses, bacteria or parasites.
Childhood diseases include pertussis, poliomyelitis, diphtheria, measles, and tetanus. Children also make up a large percentage of lower respiratory and diarrheal deaths.
Tropical diseases include trypanosomiasis, Chagas disease. schistosomiasis, leishmaniasis, lymphatic filariasis, and onchocerciasis.
From 1993 to 2002, the death ranking for AIDS went up from 7th to 2nd and Hepatitis B went down from 6th to 11th. While the number of deaths has decreased in almost every disease, it has increased four-fold in AIDS.
Infectious disease - Historic pandemics
A pandemic (or global epidemic) is a disease that affects people over an extensive geographical area.
- The Influenza Pandemic of 1918 or Spanish Flu killed 25 to 40 million in 1 year (about 2% of world population of 1.7 billion).
- Influenza now kills about 250,000 to 500,000 worldwide each year.
- The Black Death of 1347 to 1352 killed 25 million in Europe over 5 years (estimate of 25 to 50% of Europe, Asia, and Africa - world population was 500 million).
Infectious disease - New diseases and pandemics
In many cases, a microorganism and its host live in perfect harmony. Such is the case for many tropical viruses and the insects, monkeys, or other animals in which they have lived and reproduced for thousands or millions of years. Because the microbes and their hosts have evolved together, the hosts have gradually become resistant to the microorganisms. But when a microbe jumps from a long-time animal host to a human being, it may cease being a harmless parasite and—simply because it is new to the human species—become a pathogen. (See infection).
With most new infectious diseases, some human action is involved, changing the environment so that an existing microbe can take up residence in a new ecological niche. Once that happens, a pathogen that had been confined to a remote habitat appears in a new or wider region, or a microbe that had infected only animals suddenly begins causing human disease.
Several human activities have led to the emergence and spread of new diseases:
Encroachment on wildlife habitats. The construction of new villages and housing developments in rural areas brings people into contact with animals--and the microbes they harbor.
Changes in agriculture. The introduction of new crops attracts new crop pests and the microbes they carry to farming communities, exposing people to unfamiliar diseases.
Destroying rain forests. As tropical countries make use of their rain forests, building roads through forests and clearing areas for settlement or commercial ventures, people encounter insects and other animals harboring unknown microorganisms.
Uncontrolled urbanization. The rapid growth of cities in many developing countries concentrates large numbers of people in crowded areas with poor sanitation, which foster the transmission of contagious diseases.
Modern transport. Ships and other cargo carriers often harbor unintended "passengers," such as insects and rats, that can spread diseases to faraway destinations.
High-speed globe-trotting. With international jet-airplane travel, people infected with a new disease can carry the disease to the far side of the world before their first symptoms appear.
Eventually, a pathogen may adapt itself to its human hosts and cause a milder illness. It is in the microbe's best interest to do so, because if a disease is rapidly fatal, the host is likely to die before the microbe can get passed along to another host. But it takes time for a microbe and a new host species to get accustomed to each other, so an emerging pathogen may hit its earliest victims especially hard. It is usually in the first wave of a new disease that death rates are highest.
Other related archives1632, 1723, AIDS, Albert Sabin, Anopheles, Anton van Leeuwenhoek, Big killer, Black Death, Chagas disease, Copenhagen Consensus, Diarrheal diseases, Doctors, Epidemiology, HIV, Hepatitis B, Important publications in infectious diseae, Infection, Infectious diseases, Influenza, International Classification of Disease (ICD) code categories, Jonas Salk, Koch's postulates, List of infectious diseases, Louis Pasteur, Lower respiratory infections, Malaria, Measles, Meningitis, Microbiology, Mycobacteria, PCR, Pertussis, Plasmodium falciparum, Robert Koch, Spanish Flu, Staphylococcus, Streptococcus, Syphilis, TB, Tetanus, Treponema pallidum, Tropical diseases, Tuberculosis, VDRL, Wassermann test, World Health Organization, X-rays, antibiotic, antibiotic resistance, antibiotics, antibodies, bacteria, bacterium, biological, blood, broad-spectrum antibiotics, burns, chemical, chemotherapy, common cold, culture, cultured, diagnosis, diphtheria, disease, endemic, epidemic, fungi, growth medium, host, human, immunocompromised, immunologists, infection, infections, infectious agent, internal medicine, internist, intoxication, leishmaniasis, lymphatic filariasis, malaria, measles, medical treatment, medicine, microbe, microbiological culture, microbiologist, mosquito, niche., onchocerciasis, outbreak, pandemic, parasite, parasites, pathogen, pertussis, physical, pneumonia, pneumonias, polio, poliomyelitis, primary care, protozoa, , pulmonologist, schistosomiasis, secretions, serological, serology, spirochete, syphilis, tetanus, therapy, tropical diseases, trypanosomiasis, tuberculosis, vector, viral, virus, viruses
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