From Wikipedia, the free encyclopedia
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. 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.
Human exploration of tropical rainforests, deforestation,
and increased international air travel and other tourism to tropical regions has led to an
increased incidence of such diseases.
Special Programme for Research and Training in Tropical 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 infectious
diseases which disproportionately affect poor and marginalized
populations in developing regions of Africa, Asia,
America and South America. The current TDR disease
portfolio includes the following entries:
- (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 [[Vector (epi
- 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
- caused by protozoan parasites of the genus
Leishmania, and transmitted by the bite of certain species of
- (or Hansen's disease) is a chronic
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.
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
- 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
- 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
infects 300-500 million people each year, killing more than 1
- (pronounced /ɒŋkoʊsɜrˈsaɪ.əsɪs/) or river
blindness is the world's second leading infectious cause of blindness. It is caused by Onchocerca
volvulus, a parasitic worm. 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.[11
] About 18 million people are currently infected
with this parasite. Approximately 300,000 have been irreversibly
blinded by it.[12
- (pronounced /ˌʃɪstoʊsɵˈmaɪ.əsɪs/) 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.
- Sexually transmitted infections
- TB/HIV coinfection
- (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
population has been infected by the TB bacterium.
- † Although leprosy and tuberculosis are not
exclusively tropical diseases, their high incidence in the tropics
justifies their inclusion.
Other neglected tropical
Additional neglected tropical diseases include:
Some tropical diseases are very rare, but may occur in sudden epidemics, 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 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), 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, 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
warming caused by the greenhouse effect, and the resulting
increase in global temperatures, 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. 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.
treatment of tropical diseases
Some of the strategies for controlling tropical diseases
- Draining wetlands to reduce populations of insects and other vectors.
- The application of insecticides and/or insect
repellents) 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 certain species
of tropical mosquitoes
feed mainly at night.
- Use of water wells, and/or water filtration,
water filters, or
treatment with water tablets to produce drinking water free of
- Development and use of vaccines to promote disease immunity.
- Pharmacologic pre-exposure prophylaxis (to prevent disease
before exposure to the environment and/or vector).
- Pharmacologic post-exposure prophylaxis (to prevent disease
after exposure to the environment and/or vector).
- Pharmacologic treatment (to treat disease after infection or
- Assisting with economic development in endemic regions. For
example by providing microloans 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.
"Guns, Germs, and Steel" by Jared
See the Wikipedia articles for the respective diseases
Deforestation Boosts Malaria
Rates, Study Finds
UK 'faces tropical disease
threat', BBC News
Special Programme for Research and Training in Tropical
Diseases. http://www.who.int/tdr/diseases/default.htm. Retrieved
- ^ Kenneth J. Ryan and C.
George Ray, Sherris Medical Microbiology Fourth Edition McGraw Hill
Leviticus 13:59, Artscroll Tanakh and Metsudah Chumash
translations, 1996 and 1994, respectively.
Supali, T; Ismid, IS; Wibowo, H;
Djuardi, Y; Majawati, E; Ginanjar, P; Fischer, P (Aug 2006).
"Estimation of the prevalence of lymphatic filariasis by a pool
screen PCR assay using blood spots collected on filter paper".
Tran R Soc Trop Med Hyg 100 (8): 753–9.
doi:10.1016/j.trstmh.2005.10.005. ISSN 0035-9203. PMID 16442578.
Frequently Asked Questions | CDC Malaria
The World Bank | Global Partnership to Eliminate Riverblindness.
Accessed November 04, 2007.
"Causes of river
blindness". http://www.sightsavers.org/What%20We%20Do/Eye%20Conditions/River%20Blindness/World1629.html. Retrieved
"What is river
blindness?". http://www.sightsavers.org/What%20We%20Do/Eye%20Conditions/River%20Blindness/World1622.html. Retrieved
- ^ World Health Organization
(WHO). Tuberculosis Fact sheet N°104
- Global and regional incidence. March 2006, Retrieved on 6
Hotez, P. J.; Molyneux, DH; Fenwick,
A; Kumaresan, J; Sachs, SE; Sachs, JD; Savioli, L (September 2007).
"Control of Neglected Tropical
Diseases". The New England Journal of Medicine
357 (10): 1018–1027. doi:10.1056/NEJMra064142. 17804846. ISSN 0028-4793. PMID 17804846. http://content.nejm.org/cgi/content/full/357/10/1018. Retrieved
Climate change brings malaria
back to Italy The Guardian 6 January 2007
BBC Climate link to African
malaria 20 March 2006
Pounds, J. Alan et al. "Widespread Amphibian Extinctions from
Epidemic Deisease Driven by Global Warming." Nature 439.12 (2006)
- WHO Neglected Tropical
- Drugs for Neglected Diseases Initiative
- WHO Tropical Disease Research homepage
- Tropical diseases from
Maya Paradise, The Río Dulce, Guatemala Information Web Site
- American Society for Tropical Medicine and
- Treating Tropical Diseases
U.S. Food and
- Travelers' Health - National Center for
Infectious Diseases - Centers for
Disease Control and Prevention
- Professor Andrew Speilman,
Harvard School of Tropical Medicine Freeview Malaria video by
the Vega Science Trust.
- Rob Hutchingson, Entomolgoist,
London School of Tropical Medicine, Mosquitoes Freeview
'Snapshot' video by the Vega Science Trust.
- Links to pictures of tropical
diseases (Hardin MD/Univ of Iowa)
- Tropical Diseases Web
- Tropicology Library. In Portuguese.
- Institute for Tropical Medicine - Antwerp -
- Lecture Notes ITM -
Antwerp - Belgium
- Faculty of Tropical Medicine, Mahidol University
- Bangkok - Thailand
- '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
- NIH/National Institute of Allergy
and Infectious Diseases (2007, December 28). "Neglected Tropical Diseases
Burden Those Overseas, But Travelers Also At Risk".
ScienceDaily. http://www.sciencedaily.com/releases/2007/12/071226003700.htm. Retrieved