Tropical disease
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2008-07-03T06:31:57Z
Nunquam Dormio
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/* Relation of climate to tropical diseases */ References
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'''Tropical diseases''' are [[infectious disease]]s that are prevalent in or unique to [[tropics|tropical]] and [[subtropics|subtropical]] regions. These diseases are less prevalent in [[temperate climate]]s, due in part to the occurrence of a cold [[season]], which controls the insect population by forcing hibernation during the cold season.<ref>"[[Guns, Germs, and Steel]]" by Jared Diamond </ref> 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 any of the diseases listed here.<ref>See the Wikipedia articles for the respective diseases</ref>
Some of the strategies for controlling tropical diseases include:
* Draining wetlands to reduce insect populations
* The application of [[insecticide]]s (or to a lesser extent, perhaps [[insect repellent]]s) to strategic surfaces such as: clothing, skin, buildings, insect habitats, and bed nets.
* The use of a [[mosquito net]] over a bed (also known as a "bed net"), to reduce nighttime transmission, since tropical mosquitoes often feed only at night.
* Use of water [[well]]s, and/or [[water filtration]], [[water filter]]s, or [[water treatment]] with water tablets to produce drinking water free of parasites.
* Development and use of vaccines to promote disease immunity
* Funding and subsidizing the use of medicinal treatments to treat disease after infection
* Assisting with economic development in endemic regions. For example by providing [[microloan]]s to enable investments in more efficient and productive agriculture. This in turn can help [[subsistence farming]] to become more profitable, and these profits can be used by local populations for disease prevention and treatment, with the added benefit of reducing the poverty rate.<ref>[[Jeffrey Sachs]]</ref>
Human exploration of [[tropical rainforest]]s and increased international air travel and other tourism to tropical regions has led to an increased incidence of such diseases.{{Fact|date=March 2008}}
==Diseases==
In 1975 the [[United Nations Children's Fund]], the [[United Nations Development Programme]], the [[World Bank]] and the [[World Health Organization]] established the Special Programme for Research and Training in Tropical Diseases (TDR) to focus on [[Neglected Diseases|neglected infectious diseases]] which disproportionately affect poor and marginalized populations in developing regions of [[Africa]], [[Asia]], [[Central America]] and [[South America]]. The current TDR disease portfolio includes the following ten entries:<ref>{{cite web |url= http://www.who.int/tdr/diseases/default.htm |title= Disease portfolio |accessdate=2008-01-21 |work= Special Programme for Research and Training in Tropical Diseases}}</ref>
* [[Malaria]]
: Caused by a [[Protozoan]] [[parasite]]s transmitted by ''[[Anopheles]]'' '''[[mosquito]]es'''. It infects 300-500 million people each year, killing more than 1 million.<ref>[http://www.cdc.gov/malaria/faq.htm Frequently Asked Questions | CDC Malaria]</ref>
* [[African trypanosomiasis]]
: or '''sleeping sickness''', is a [[parasitic]] [[disease]], caused by [[protozoa]] and transmitted by the '''[[tsetse fly]]'''
* [[Dengue fever]]
: a [[virus]] transmitted by '''mosquitoes'''
* [[Leishmaniasis]]
: caused by [[protozoan]] [[parasite]]s, and transmitted by the bite of certain species of '''[[sand fly]]'''.
* [[Schistosomiasis]]
: also known as '''snail fever''', is a [[parasitic disease]] caused by several species of '''[[flatworm]]''' in areas with freshwater '''[[snail]]s''', 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 [[snail]]s and the parasite. More than 200 million people worldwide are infected by schistosomiasis.<ref>[http://www.who.int/mediacentre/factsheets/fs115/en/index.html WHO | Schistosomiasis]</ref>
* [[Tuberculosis]]<sup>†</sup>
: (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 [[particulate|aerosol]] expectorant from a cough, sneeze, speak, kiss, or spit. Over one-third of the [[World population|world's population]] has been infected by the TB bacterium.<ref name="WHO2004data">[[World Health Organization]] (WHO). [http://www.who.int/mediacentre/factsheets/fs104/en/index.html Tuberculosis Fact sheet N°104 - Global and regional incidence.] March 2006, Retrieved on 6 October 2006.</ref>
* [[Chagas disease]]
: (also called ''American trypanosomiasis'') is a [[parasitic disease]] which occurs in [[the Americas]], particularly in [[South America]]. Its [[pathogen]]ic [[Vector (biology)|agent]] is a [[flagellate]] [[protozoa]]n named ''[[Trypanosoma cruzi]]'', which is transmitted mostly by [[hematophagy|blood-sucking]] '''[[assassin bug]]s''', however other methods of transmission are possible, such as ingestion of food contaminated with [[parasite]]s, [[blood transfusion]] and [[fetus|fetal]] transmission. Between 16 and 18 million people are currently infected.<ref>[http://www.cdc.gov/MMWR/preview/mmwrhtml/mm5110a3.htm Chagas Disease After Organ Transplantation --- United States, 2001]</ref>
* [[Leprosy]]<sup>†</sup>
: (or '''Hansen's disease''') is a [[chronic]] [[infectious disease]] caused by a [[Bacteria|bacterium]]. Leprosy is primarily a [[granuloma]]tous disease of the [[peripheral nerves]] and [[mucosa]] of the [[upper respiratory tract]]; skin lesions are the primary external symptom.<ref name= Sherris>Kenneth J. Ryan and C. George Ray, Sherris Medical Microbiology Fourth Edition McGraw Hill 2004. </ref> 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''.<ref>Leviticus 13:59, Artscroll Tanakh and Metsudah Chumash translations, 1996 and 1994, respectively.</ref>
:Worldwide, two to three million people are estimated to be permanently disabled because of Hansen's disease.<ref name=WHO_1995 /> [[India]] has the greatest number of cases, with [[Brazil]] second and [[Myanmar]] third.<ref name=WHO_1995>{{cite journal |author=WHO|title=Leprosy disabilities: magnitude of the problem |journal=Weekly Epidemiological Record |volume=70 |issue=38 |pages=269–75 |year=1995 |pmid=7577430}}</ref>
:The exact mechanism of transmission of leprosy is not known: prolonged close contact and transmission by nasal droplet have both been proposed.<ref>{{cite journal |author=Reich CV |title=Leprosy: cause, transmission, and a new theory of pathogenesis |journal=Rev. Infect. Dis. |volume=9 |issue=3 |pages=590–4 |year=1987 |pmid=3299638 |doi=}}</ref> It is treated with multidrug therapy (MDT).
:[[Incidence (epidemiology)|incidence]] is spread throughout the world, and fluctuates between 640,000 - 767,000 new cases detected per year. It is [[endemic (epidemiology)|endemic]] to 91 countries.
:According to the WHO, new cases detected worldwide decreased by approximately 20% per year from 2001 to 2004. The global registered prevalence of HD was 286,063 cases; 407,791 new cases were detected during 2004.
* [[Filariasis|Lymphatic filariasis]]
: is a [[parasite|parasitic]] disease caused by thread-like parasitic filarial worms called [[nematode worm]]s, all transmitted by '''[[mosquito]]es'''. [[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. <ref>{{cite journal | author=Aupali T, Ismid IS, Wibowo H, ''et al.'' | title=Estimation of the prevalence of lymphatic filariasis by a pool screen PCR assay using blood spots collected on filter paper | journal=Tran R Soc Trop Med Hyg | year=2006 | volume=100 | issue=8 | pages=753–9 | doi=10.1016/j.trstmh.2005.10.005 }}</ref>
:The most noticeable symptom is [[elephantiasis]]: a thickening of the skin and underlying tissues.
* [[Onchocerciasis]]
: (pronounced {{IPA|[ɒn.kəʊ.sɜːˈkaɪə.sɪs]}}) or '''river blindness''' is the world's second leading [[infectious]] cause of [[blindness]]. It is caused by ''Onchocerca volvulus'', a [[parasitic worm]].<ref>http://www.worldbank.org/afr/gper/disease.htm The World Bank | Global Partnership to Eliminate Riverblindness. Accessed [[November 04]], [[2007]].</ref> 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.<ref name="titleCauses of river blindness">{{cite web |url=http://www.sightsavers.org/What%20We%20Do/Eye%20Conditions/River%20Blindness/World1629.html |title=Causes of river blindness |accessdate=2008-01-28 |format= |work=}}</ref>
:About 18 million people are currently infected with this parasite. Approximately 300,000 have been irreversibly blinded by it.<ref name="titleWhat is river blindness?">{{cite web |url=http://www.sightsavers.org/What%20We%20Do/Eye%20Conditions/River%20Blindness/World1622.html |title=What is river blindness? |accessdate=2008-01-28 |format= |work=}}</ref>
* [[Trachoma]]
: is an infectious [[List of eye diseases and disorders|eye disease]], and the leading cause of the world's infectious blindness.<ref>[http://gnntdc.sabin.org/what/aboutntds.html About Neglected Tropical Diseases (NTDs)]</ref> Globally, 84 million people suffer from active infection and nearly 8 million people are visually impaired as a result of this disease.<ref>[http://www.who.int/blindness/causes/trachoma/en/ WHO | Trachoma]</ref>
<!-- As of Mar 2, 2008, all information for the above summaries was taken from the main articles. -->
:<sup>†</sup> <small>Although leprosy and tuberculosis are not exclusively tropical diseases, their high incidence in the tropics justifies their inclusion.</small>
Additional neglected tropical diseases include:<ref>{{cite journal |year= 2007 |month= September |title= Control of Neglected Tropical Diseases |journal= The New England Journal of Medicine |volume= 357 |issue= 10 |pages= 1018–1027 |id= 17804846 |url= http://content.nejm.org/cgi/content/full/357/10/1018 |accessdate= 2008-01-21 |doi= 10.1056/NEJMra064142 |author= Hotez, P. J. |pmid= 17804846}}</ref>
*[[Ascariasis]]
*[[Trichuriasis]]
*[[Hookworm]]
*[[Human African trypanosomiasis]]
*[[Dracunculiasis]]
*[[Buruli ulcer]]
*[[Treponematoses]]
*[[Leptospirosis]]
*[[Strongyloidiasis]]
*[[Foodborne trematodiases]]
*[[Neurocysticercosis]]
*[[Scabies]]
Some tropical diseases are very rare, but may occur in sudden [[epidemic]]s, such as the [[Ebola]] hemorrhagic fever, [[Lassa fever]] and the [[Marburg virus]]. There are hundreds of different tropical diseases which are less known or rarer, but that, nonetheless, have importance for [[public health]].
==Relation of climate to tropical diseases==
The called "exotic" diseases in the tropics has long been noted both by travelers, explorers, etc., as well as by physicians. One obvious reason is that the hot climate present during all the year and the larger volume of [[rain]]s directly affect the formation of breeding grounds, the larger number and variety of [[natural reservoir]]s and animal diseases that can be transmitted to humans ([[zoonosis]]), the largest number of possible [[insect]] [[vector (biology)|vectors]] of diseases. It is possible also that higher temperatures may favor the replication of pathogenic agents both inside and outside biological organisms. Socio-economic factors may be also in operation, since most of the poorest nations of the world are in the tropics. Tropical countries like [[Brazil]], which have improved their socio-economic situation and invested in [[hygiene]], [[public health]] and the combat of transmissible diseases have achieved dramatic results in relation to the elimination or decrease of many [[endemic (epidemiology)|endemic]] tropical diseases in their territory.{{Fact|date=December 2007}}
[[Climate change]], and [[global warming]] caused by the [[greenhouse effect]], and the resulting increase in global [[temperature]]s, are causing tropical diseases and vectors to spread to higher altitudes in mountainous regions, and to higher latitudes that were previously spared, such as the Southern [[United States]], the Mediterranean area, etc.<ref>[http://www.guardian.co.uk/environment/2007/jan/06/italy.climatechange Climate change brings malaria back to Italy] ''The Guardian'' [[6 January]] 2007</ref><ref>BBC [http://news.bbc.co.uk/2/hi/science/nature/4827362.stm Climate link to African malaria] [[20 March]] 2006</ref>
== References ==
{{reflist}}
== Further reading ==
===Books===
*[http://www.elsevier-international.com/catalogue/title.cfm?ISBN=0702026409 Manson's Tropical Diseases]
*[http://www.ppidonline.com/ Mandell's Principles and Practice of Infectious Diseases] or [http://www.intl.elsevierhealth.com/catalogue/title.cfm?ISBN=0443066736 this site]
===Journals===
* [http://www.astmh.org/journal.html American Journal of Tropical Medicine and Hygiene]
* [[Japanese Journal of Tropical Medicine and Hygiene]]
* [http://www.blackwell-science.com/~cgilib/jnlpage.asp?Journal=tmih&File=tmih Tropical Medicine and International Health]
* [http://www.tm.mahidol.ac.th/seameo/publication.htm The Southeast Asian Journal of Tropical Medicine and Public Health]
* [http://www.scielo.br/scielo.php?script=sci_serial&lng=en&pid=0036-4665 Revista do Instituto de Medicina Tropical de São Paulo]
* [http://www.scielo.br/scielo.php?script=sci_serial&lng=en&pid=0037-8682 Revista da Sociedade Brasileira de Medicina Tropical]
* [http://www.scielo.br/scielo.php?script=sci_serial&lng=en&pid=1678-9199 Journal of Venomous Animals and Toxins including Tropical Diseases]
===Websites===
* [[GIDEON-Global Infectious Disease Epidemiology Network]]
== See also ==
* [[Hospital for Tropical Diseases]]
* [[Tropical medicine]]
* [[List of epidemics]]
==External links==
* [http://www.who.int/neglected_diseases/en/ WHO Neglected Tropical Diseases]
* [http://www.dndi.org/ Drugs for Neglected Diseases Initiative]
* [http://www.who.int/tdr/ WHO Tropical Disease Research] homepage
* [http://www.mayaparadise.com/diseasee.htm Tropical diseases] from Maya Paradise, The Río Dulce, Guatemala Information Web Site
* [http://www.astmh.org/ American Society for Tropical Medicine and Hygiene]
* [http://www.fda.gov/fdac/features/1997/197_trop.html Treating Tropical Diseases] U.S. [[Food and Drug Administration]]
* [http://www.cdc.gov/travel/ Travelers' Health] - National Center for Infectious Diseases - [[Centers for Disease Control and Prevention]]
* [http://www.vega.org.uk/video/programme/87 Professor Andrew Speilman, Harvard School of Tropical Medicine] Freeview Malaria video by the Vega Science Trust.
* [http://www.vega.org.uk/video/programme/52 Rob Hutchingson, Entomolgoist, London School of Tropical Medicine, Mosquitoes] Freeview 'Snapshot' video by the Vega Science Trust.
* [http://www.lib.uiowa.edu/hardin/md/tropical.html Links to pictures of tropical diseases (Hardin MD/Univ of Iowa)]
* [http://h.webring.com/hub?ring=malaria Tropical Diseases Web Ring]
* [http://www.tropicologia.org.br/ Tropicology Library]. In Portuguese.
* [http://www.itg.be Institute for Tropical Medicine] - Antwerp - Belgium
* [http://www.tm.mahidol.ac.th Faculty of Tropical Medicine, Mahidol University] - Bangkok - Thailand
* [http://www.gresham.ac.uk/event.asp?PageId=45&EventId=696 'Conquest and Disease or Colonisation and Health'], lecture by Professor Frank Cox on the history of tropical disease, given at [[Gresham College]], 17th September 2007 (available for download as video and audio files, as well as a text file).
* {{cite web
| url = http://www.sciencedaily.com/releases/2007/12/071226003700.htm
| title = Neglected Tropical Diseases Burden Those Overseas, But Travelers Also At Risk
| accessdate = 2007-12-28
| author = NIH/National Institute of Allergy and Infectious Diseases (2007, December 28)
| publisher = ScienceDaily
}}
[[Category:Infectious diseases]]
[[Category:Tropical diseases| ]]
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