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Tropical diseases are diseases that are prevalent in or unique to
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
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. However, many were present in northern Europe and northern America in the 17th and 18th centuries before modern understanding of disease causation. The initial impetus for tropical medicine was to protect the health of colonial settlers, notably in India under the
British Raj The British Raj (; from Hindi ''rāj'': kingdom, realm, state, or empire) was the rule of the British Crown on the Indian subcontinent; * * it is also called Crown rule in India, * * * * or Direct rule in India, * Quote: "Mill, who was himsel ...
. 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 rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...
s, deforestation, rising immigration and increased international air travel and other tourism to tropical regions has led to an increased incidence of such diseases to non-tropical countries.


Health programmes

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 Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
,
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
,
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. C ...
and North 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: : :


Other neglected tropical diseases

Additional
neglected tropical diseases Neglected tropical diseases (NTDs) are a diverse group of tropical infections that are common in low-income populations in developing regions of Africa, Asia, and the Americas. They are caused by a variety of pathogens, such as viruses, bact ...
include: Some tropical diseases are very rare, but may occur in sudden
epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of patients among a given population within an area in a short period of time. Epidemics of infectious d ...
s, such as the Ebola hemorrhagic fever,
Lassa fever Lassa fever, also known as Lassa hemorrhagic fever (LHF), is a type of viral hemorrhagic fever caused by the Lassa virus. Many of those infected by the virus do not develop symptoms. When symptoms occur they typically include fever, weakness, h ...
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 so-called "exotic" diseases in the tropics have 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 rains directly affect the formation of breeding grounds, the larger number and variety of natural reservoirs and animal diseases that can be transmitted to humans (
zoonosis A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a hum ...
), the largest number of possible insect 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 Hygiene is a series of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refer ...
, public health and the combat of transmissible diseases have achieved dramatic results in relation to the elimination or decrease of many endemic tropical diseases in their territory. Climate change, global warming caused by the greenhouse effect, and the resulting increase in global temperatures, are possibly 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. For example, in the Monteverde cloud forest of Costa Rica, global warming enabled Chytridiomycosis, a tropical disease, to flourish and thus force into decline amphibian populations of the Monteverde Harlequin frog. Here, global warming raised the heights of orographic cloud formation, and thus produced cloud cover that would facilitate optimum growth conditions for the implicated pathogen, B. dendrobatidis.


Prevention and treatment


Vector-borne diseases

Vectors are living organisms that pass disease between humans or from animal to human. The vector carrying the highest number of diseases is the mosquito, which is responsible for the tropical diseases dengue and malaria. Many different approaches have been taken to treat and prevent these diseases. NIH-funded research has produced genetically modify mosquitoes that are unable to spread diseases such as malaria. An issue with this approach is global accessibility to genetic engineering technology; Approximately 50% of scientists in the field do not have access to information on genetically modified mosquito trials being conducted. Other prevention methods include: * Draining wetlands to reduce populations of insects and other vectors, or introducing natural predators of the vectors. * The application of
insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to ...
s and/or
insect repellent An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and cont ...
s) to strategic surfaces such as clothing, skin, buildings, insect habitats, and
bed net A mosquito net is a type of meshed curtain that is circumferentially draped over a bed or a sleeping area, to offer the sleeper barrier protection against bites and stings from mosquitos, flies, and other pest insects, and thus against the d ...
s. * The use of a mosquito net over a bed (also known as a "bed net") to reduce nighttime transmission, since certain species of tropical mosquitoes feed mainly at night.


Sexually transmitted diseases

Both pharmacologic pre-exposure prophylaxis (to prevent disease before exposure to the environment and/or vector) and pharmacologic post-exposure prophylaxis (to prevent disease after exposure to the environment and/or vector) are used to prevent and treat
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...


Community approaches

Assisting with economic development in endemic regions can contribute to prevention and treatment of tropical diseases. For example,
microloan :''This article is specific to small loans, often provided in a pooled manner. For direct payments to individuals for specific projects, see Micropatronage. For financial services to the poor, see Microfinance. For small payments, see Micropayme ...
s enable communities to invest in health programs that lead to more effective disease treatment and prevention technology. Educational campaigns can aid in the prevention of various diseases. Educating children about how diseases spread and how they can be prevented has proven to be effective in practicing preventative measures. Educational campaigns can yield significant benefits at low costs.


Other approaches

* Use of
water well A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. Th ...
s, and/or
water filtration A water filter removes impurities by lowering contamination of water using a fine physical barrier, a chemical process, or a biological process. Filters cleanse water to different extents, for purposes such as: providing agricultural irrigation ...
, water filters, or water treatment with water tablets to produce drinking water free of parasites. * Sanitation to prevent transmission through human waste. * Development and use of vaccines to promote disease immunity. * Pharmacologic treatment (to treat disease after infection or infestation).


See also

*
Hospital for Tropical Diseases The Hospital for Tropical Diseases (HTD) is a specialist tropical disease hospital located in London, United Kingdom. It is part of the University College London Hospitals NHS Foundation Trust and is closely associated with University College ...
* Tropical medicine * Infectious disease * Neglected diseases * List of epidemics * Waterborne diseases * Globalization and disease


References


Further reading


Books


TDR at a glance - fostering an effective global research effort on diseases of poverty

Le TDR en un coup d’oeilLe TDR en un coup d’oeil - favoriser un eff ort mondial de recherche eff icace sur les maladies liées à la pauvreté

TDR annual report - 2009

Monitoring and evaluation tool kit for indoor residual spraying

Indicators for monitoring and evaluation of the kala-azar elimination programme

Malaria Rapid Diagnostic Test Performance - results of WHO product testing of malaria RDTs: Round 2- 2009

Quality Practices in Basic Biomedical Research (QPBR) training manual: Trainer

Quality Practices in Basic Biomedical Research (QPBR) training manual: Trainee

Progress and prospects for the use of genetically modified mosquitoes to inhibit disease transmission

Use of Influenza Rapid Diagnostic Tests

Manson's Tropical Diseases

Mandell's Principles and Practice of Infectious Diseases
o
this site


Journals



* Japanese Journal of Tropical Medicine and Hygiene
Tropical Medicine and International Health


* ttp://www.scielo.br/scielo.php?script=sci_serial&lng=en&pid=0036-4665 Revista do Instituto de Medicina Tropical de São Paulo
Revista da Sociedade Brasileira de Medicina Tropical

Journal of Venomous Animals and Toxins including Tropical Diseases


Websites


Special Programme for Research and Training in Tropical Diseases -TDR
* GIDEON-Global Infectious Disease Epidemiology Network


External links


WHO Neglected Tropical Diseases

WHO Operational research in tropical and other communicable diseases
* European Bioinformatics Institute
open source drug discovery

Drugs for Neglected Diseases Initiative

Tropical diseases
from Maya Paradise, The Guatemala Information Web Site
American Society for Tropical Medicine and Hygiene


U.S. Food and Drug Administration
Travelers' Health
- National Center for Infectious Diseases -
Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georg ...

Tropicology Library
In Portuguese.
'Conquest and Disease or Colonisation and Health'
lecture by Professor Frank Cox on the history of tropical disease, given at Gresham College, 17 September 2007 (available for download as video and audio files, as well as a text file). * {{DEFAULTSORT:Tropical Disease Infectious diseases Global health