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Tropical diseases are diseases that are prevalent in or unique to tropical and subtropical regions. The diseases are less prevalent in temperate climates, due in part to the occurrence of a cold season, which controls the insect population by forcing hibernation.〔"Guns, Germs, and Steel" by Jared Diamond〕 Insects such as mosquitoes and flies are by far the most common disease carrier, or vector. These insects may carry a parasite, bacterium or virus that is infectious to humans and animals. Most often disease is transmitted by an insect "bite", which causes transmission of the infectious agent through subcutaneous blood exchange. Vaccines are not available for most of the diseases listed here, and many do not have cures. Human exploration of tropical rainforests, deforestation, rising immigration and increased international air travel and other tourism to tropical regions has led to an increased incidence of such diseases.〔(Deforestation Boosts Malaria Rates, Study Finds )〕〔(UK 'faces tropical disease threat' ), BBC News〕 ==Special Programme for Research and Training in Tropical Diseases (TDR)== In 1975 the Special Programme for Research and Training in Tropical Diseases (TDR) was established to focus on neglected infectious diseases which disproportionately affect poor and marginalized populations in developing regions of Africa, Asia, Central America and South America. It was established at the World Health Organization, which is the executing agency, and is co-sponsored by the (United Nations Children's Fund ), United Nations Development Programme, the World Bank and the World Health Organization. TDR's vision is to foster an effective global research effort on infectious diseases of poverty in which disease endemic countries play a pivotal role. It has a dual mission of developing new tools and strategies against these diseases, and to develop the research and leadership capacity in the countries where the diseases occur. The TDR secretariat is based in Geneva, Switzerland, but the work is conducted throughout the world through many partners and funded grants. Some examples of work include helping to develop new treatments for diseases, such as ivermectin for onchocerciasis (river blindness); showing how packaging can improve use of artemesinin-combination treatment (ACT) for malaria; demonstrating the effectiveness of bednets to prevent mosquito bites and malaria; and documenting how community-based and community-led programmes increases distribution of multiple treatments. (TDR history ) The current TDR disease portfolio includes the following entries:〔(【引用サイトリンク】title= Disease portfolio )〕 * Chagas disease *: (also called ''American trypanosomiasis'') is a parasitic disease which occurs in the Americas, particularly in South America. Its pathogenic agent is a flagellate protozoan named ''Trypanosoma cruzi'', which is transmitted mostly by blood-sucking assassin bugs, however other methods of transmission are possible, such as ingestion of food contaminated with parasites, blood transfusion and fetal transmission. Between 16 and 18 million people are currently infected.〔(Chagas Disease After Organ Transplantation --- United States, 2001 )〕 * Dengue * Helminths * African trypanosomiasis *: or sleeping sickness, is a parasitic disease, caused by protozoa called trypansomes. The two responsible for African trypanosomiasis are Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense.These parasites are transmitted by the tsetse fly * Leishmaniasis *: caused by protozoan parasites of the genus Leishmania, and transmitted by the bite of certain species of sand fly. * Leprosy† *: (or Hansen's disease) is a chronic infectious disease caused by Mycobacterium leprae. Leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions are the primary external symptom.〔Kenneth J. Ryan and C. George Ray, Sherris Medical Microbiology Fourth Edition McGraw Hill 2004.〕 Left untreated, leprosy can be progressive, causing permanent damage to the skin, nerves, limbs, and eyes. Contrary to popular conception, leprosy does not cause body parts to simply fall off, and it differs from tzaraath, the malady described in the Hebrew scriptures and previously translated into English as ''leprosy''.〔Leviticus 13:59, Artscroll Tanakh and Metsudah Chumash translations, 1996 and 1994, respectively.〕 * Lymphatic filariasis *: is a parasitic disease caused by thread-like parasitic filarial worms called nematode worms, all transmitted by mosquitoes. Loa loa is another filarial parasite transmitted by the deer fly. 120 million people are infected worldwide. It is carried by over half the population in the most severe endemic areas. The most noticeable symptom is elephantiasis: a thickening of the skin and underlying tissues. Elephantiasis is caused by chronic infection by filarial worms in the lymph nodes. This clogs the lymph nodes and slows the draining of lymph fluid from a portion of the body. * Malaria *: Caused by a Protozoan parasites transmitted by female ''Anopheles'' mosquitoes, as they are the blood-feeders. The disease is caused by species of the genus Plasmodium. Malaria infected an estimated 190-311 million people in 2008 and 708,000-1,003,000 died mostly in Sub-Sahara Africa.〔http://www.cdc.gov/malaria/〕 * Onchocerciasis *: or river blindness is the world's second leading infectious cause of blindness. It is caused by ''Onchocerca volvulus'', a parasitic worm.〔http://www.worldbank.org/afr/gper/disease.htm The World Bank | Global Partnership to Eliminate Riverblindness. Retrieved 2007-11-04.〕 It is transmitted through the bite of a black fly. The worms spread throughout the body, and when they die, they cause intense itching and a strong immune system response that can destroy nearby tissue, such as the eye. About 18 million people are currently infected with this parasite. Approximately 300,000 have been irreversibly blinded by it. * Schistosomiasis *: also known as ''schisto'' or snail fever, is a parasitic disease caused by several species of flatworm in areas with freshwater snails, which may carry the parasite. The most common form of transmission is by wading or swimming in lakes, ponds and other bodies of water containing the snails and the parasite. More than 200 million people worldwide are infected by schistosomiasis.〔(WHO | Schistosomiasis )〕 * Sexually transmitted infections * TB-HIV coinfection * Tuberculosis† *: (abbreviated as TB), is a bacterial infection of the lungs or other tissues, which is highly prevalent in the world, with mortality over 50% if untreated. It is a communicable disease, transmitted by aerosol expectorant from a cough, sneeze, speak, kiss, or spit. Over one-third of the world's population has been infected by the TB bacterium.〔World Health Organization (WHO). (Tuberculosis Fact sheet N°104 - Global and regional incidence. ) March 2006. Retrieved 2006-10-06.〕 :† 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tropical disease」の詳細全文を読む スポンサード リンク
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