Malaria causes: Difference between revisions

Jump to navigation Jump to search
No edit summary
No edit summary
Line 1: Line 1:
'''Malaria''' is a [[Vector (biology)|vector]]-borne [[infectious disease]] caused by [[protozoan]] [[parasite]]s. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, it causes disease in approximately 650 million people and kills between one and three million, most of them young children in Sub-Saharan Africa. Malaria is commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development.
__NOTOC__
{{Malaria}}
{{CMG}}
 
==Overview==
Malaria is a [[Vector (biology)|vector]]-borne [[infectious disease]] caused by [[protozoan]] [[parasite]]s. Malaria is commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development.
[[Image:Malaria.jpg|thumb|left|250px|A ''Plasmodium'' sporozoite traverses the cytoplasm of a mosquito midgut epithelial cell in this false-color [[electron micrograph]].]]
[[Image:Malaria.jpg|thumb|left|250px|A ''Plasmodium'' sporozoite traverses the cytoplasm of a mosquito midgut epithelial cell in this false-color [[electron micrograph]].]]
==Causes==
==Causes==
=== Malaria parasites ===
=== Malaria Parasites ===
Malaria is caused by [[protozoa]]n [[parasite]]s of the genus ''[[Plasmodium]]'' (phylum [[Apicomplexa]]). In humans malaria is caused by ''[[Plasmodium falciparum|P. falciparum]]'', ''[[Plasmodium malariae|P. malariae]]'', ''[[Plasmodium ovale|P. ovale]]'', and ''[[Plasmodium vivax|P. vivax]]''. '' P. vivax'' is the most common cause of infection, responsible for about 80 % of all malaria cases. However, ''P. falciparum'' is the most important cause of disease, and responsible for about 15% of infections and 90% of deaths.<ref>{{cite journal | author = Mendis K, Sina B, Marchesini P, Carter R | title = The neglected burden of Plasmodium vivax malaria. | url=http://www.ajtmh.org/cgi/reprint/64/1_suppl/97.pdf | journal = Am J Trop Med Hyg | volume = 64 | issue = 1-2 Suppl | pages = 97-106 | year = 2001 | pmid = 11425182}}</ref> Parasitic ''Plasmodium'' species also infect birds, reptiles, monkeys, chimpanzees and rodents.<ref>{{cite journal | author = Escalante A, Ayala F | title = Phylogeny of the malarial genus Plasmodium, derived from rRNA gene sequences. | url=http://www.pnas.org/cgi/reprint/91/24/11373 | journal = Proc Natl Acad Sci U S A | volume = 91 | issue = 24 | pages = 11373-7 | year = 1994 | pmid = 7972067}}</ref> There have been documented human infections with several [[Wiktionary:simian|simian]] species of malaria, namely ''[[Plasmodium knowlesi|P. knowlesi]]'', ''P. inui'', ''P. cynomolgi''<ref>{{cite book | last=Garnham | first=PCC | date=1966 | title=Malaria parasites and other haemosporidia | publisher=Blackwell Scientific Publications|Location=Oxford }}</ref>, ''P. simiovale'', ''P. brazilianum'', ''P. schwetzi'' and ''P. simium''; however these are mostly of limited public health importance. Although avian malaria can kill chickens and turkeys, this disease does not cause serious economic losses to poultry farmers.<ref>Investing in Animal Health Research to Alleviate Poverty. International Livestock Research Institute. Permin A. and Madsen M. (2001) [http://www.ilri.cgiar.org/InfoServ/Webpub/fulldocs/investinginanimal/Book1/media/PDF_Appendix/Appendix8.pdfLiterature Appendix 2: review on disease occurrence and impact (smallholder poultry)]. Accessed 29 Oct 2006</ref> However, since being accidentally introduced by humans it has decimated the endemic birds of Hawaii, which evolved in its absence and lack any resistance to it.<ref>{{cite journal |author=Atkinson CT, Woods KL, Dusek RJ, Sileo LS, Iko WM |title=Wildlife disease and conservation in Hawaii: pathogenicity of avian malaria (''Plasmodium relictum'') in experimentally infected iiwi (''Vestiaria coccinea'') |journal=Parasitology |volume=111 Suppl |issue= |pages=S59-69 |year=1995 |pmid=8632925 |doi=}}</ref>
Malaria is caused by [[protozoa]]n [[parasite]]s of the genus ''[[Plasmodium]]'' (phylum [[Apicomplexa]]). In humans malaria is caused by ''[[Plasmodium falciparum|P. falciparum]]'', ''[[Plasmodium malariae|P. malariae]]'', ''[[Plasmodium ovale|P. ovale]]'', and ''[[Plasmodium vivax|P. vivax]]''. '' P. vivax'' is the most common cause of infection, responsible for about 80 % of all malaria cases. However, ''P. falciparum'' is the most important cause of disease, and responsible for about 15% of infections and 90% of deaths.<ref>{{cite journal | author = Mendis K, Sina B, Marchesini P, Carter R | title = The neglected burden of Plasmodium vivax malaria. | url=http://www.ajtmh.org/cgi/reprint/64/1_suppl/97.pdf | journal = Am J Trop Med Hyg | volume = 64 | issue = 1-2 Suppl | pages = 97-106 | year = 2001 | pmid = 11425182}}</ref> Parasitic ''Plasmodium'' species also infect birds, reptiles, monkeys, chimpanzees and rodents.<ref>{{cite journal | author = Escalante A, Ayala F | title = Phylogeny of the malarial genus Plasmodium, derived from rRNA gene sequences. | url=http://www.pnas.org/cgi/reprint/91/24/11373 | journal = Proc Natl Acad Sci U S A | volume = 91 | issue = 24 | pages = 11373-7 | year = 1994 | pmid = 7972067}}</ref> There have been documented human infections with several [[Wiktionary:simian|simian]] species of malaria, namely ''[[Plasmodium knowlesi|P. knowlesi]]'', ''P. inui'', ''P. cynomolgi''<ref>{{cite book | last=Garnham | first=PCC | date=1966 | title=Malaria parasites and other haemosporidia | publisher=Blackwell Scientific Publications|Location=Oxford }}</ref>, ''P. simiovale'', ''P. brazilianum'', ''P. schwetzi'' and ''P. simium''; however these are mostly of limited public health importance. Although avian malaria can kill chickens and turkeys, this disease does not cause serious economic losses to poultry farmers.<ref>Investing in Animal Health Research to Alleviate Poverty. International Livestock Research Institute. Permin A. and Madsen M. (2001) [http://www.ilri.cgiar.org/InfoServ/Webpub/fulldocs/investinginanimal/Book1/media/PDF_Appendix/Appendix8.pdfLiterature Appendix 2: review on disease occurrence and impact (smallholder poultry)]. Accessed 29 Oct 2006</ref> However, since being accidentally introduced by humans it has decimated the endemic birds of Hawaii, which evolved in its absence and lack any resistance to it.<ref>{{cite journal |author=Atkinson CT, Woods KL, Dusek RJ, Sileo LS, Iko WM |title=Wildlife disease and conservation in Hawaii: pathogenicity of avian malaria (''Plasmodium relictum'') in experimentally infected iiwi (''Vestiaria coccinea'') |journal=Parasitology |volume=111 Suppl |issue= |pages=S59-69 |year=1995 |pmid=8632925 |doi=}}</ref>
{{#widget:SchemaSnippet}}
== Mosquito vectors and the ''Plasmodium'' life cycle ==
The parasite's primary (definitive) hosts and transmission [[vector (biology)|vector]]s are female [[mosquito]]es of the ''[[Anopheles]]'' genus. Young mosquitoes first ingest the malaria parasite by feeding on an infected human carrier and the infected ''[[Anopheles]]'' mosquitoes carry ''Plasmodium'' [[sporozoite]]s in their [[salivary gland]]s. A mosquito becomes infected when it takes a blood meal from an infected human. Once ingested, the parasite [[gametocytes]] taken up in the blood will further differentiate into male or female [[gametes]] and then fuse in the mosquito gut. This produces an [[ookinete]] that penetrates the gut lining and produces an [[oocyst]] in the gut wall. When the oocyst ruptures, it releases [[sporozoites]] that migrate through the mosquito's body to the salivary glands, where they are then ready to infect a new human host.  This type of transmission is occasionally referred to as anterior station transfer.<ref>{{cite journal | author = Talman A, Domarle O, McKenzie F, Ariey F, Robert V | title = Gametocytogenesis: the puberty of Plasmodium falciparum. | journal = Malar J | volume = 3 | issue = | pages = 24 | year = | id = PMID 15253774}}</ref> The sporozoites are injected into the skin, alongside saliva, when the mosquito takes a subsequent blood meal.


Only female mosquitoes feed on blood, thus males do not transmit the disease. The females of the ''[[Anopheles]]'' genus of mosquito prefer to feed at night.  They usually start searching for a meal at dusk, and will continue throughout the night until taking a meal. Malaria parasites can also be transmitted by [[blood transfusion]]s, although this is rare.<ref>{{cite journal | author = Marcucci C, Madjdpour C, Spahn D | title = Allogeneic blood transfusions: benefit, risks and clinical indications in countries with a low or high human development index. | journal = Br Med Bull | volume = 70 | issue = | pages = 15-28 | year = | id = PMID 15339855}}</ref>
==References==
==References==
{{reflist|3}}
{{reflist|3}}

Revision as of 20:28, 18 December 2012

Malaria Microchapters

Home

Patient Information

Overview

Historical perspective

Classification

Pathophysiology

Causes

Differentiating Malaria from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Xray

Ultrasound

CT scan

MRI

Other Diagnostic Studies

Treatment

Medical Therapy

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case studies

Case #1

Malaria causes On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Malaria causes

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Malaria causes

CDC on Malaria causes

Malaria causes in the news

Blogs on Malaria causes

Directions to Hospitals Treating Malaria

Risk calculators and risk factors for Malaria causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Malaria is a vector-borne infectious disease caused by protozoan parasites. Malaria is commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development.

A Plasmodium sporozoite traverses the cytoplasm of a mosquito midgut epithelial cell in this false-color electron micrograph.

Causes

Malaria Parasites

Malaria is caused by protozoan parasites of the genus Plasmodium (phylum Apicomplexa). In humans malaria is caused by P. falciparum, P. malariae, P. ovale, and P. vivax. P. vivax is the most common cause of infection, responsible for about 80 % of all malaria cases. However, P. falciparum is the most important cause of disease, and responsible for about 15% of infections and 90% of deaths.[1] Parasitic Plasmodium species also infect birds, reptiles, monkeys, chimpanzees and rodents.[2] There have been documented human infections with several simian species of malaria, namely P. knowlesi, P. inui, P. cynomolgi[3], P. simiovale, P. brazilianum, P. schwetzi and P. simium; however these are mostly of limited public health importance. Although avian malaria can kill chickens and turkeys, this disease does not cause serious economic losses to poultry farmers.[4] However, since being accidentally introduced by humans it has decimated the endemic birds of Hawaii, which evolved in its absence and lack any resistance to it.[5]

References

  1. Mendis K, Sina B, Marchesini P, Carter R (2001). "The neglected burden of Plasmodium vivax malaria" (PDF). Am J Trop Med Hyg. 64 (1-2 Suppl): 97–106. PMID 11425182.
  2. Escalante A, Ayala F (1994). "Phylogeny of the malarial genus Plasmodium, derived from rRNA gene sequences". Proc Natl Acad Sci U S A. 91 (24): 11373–7. PMID 7972067.
  3. Garnham, PCC (1966). Malaria parasites and other haemosporidia. Blackwell Scientific Publications. Unknown parameter |Location= ignored (|location= suggested) (help)
  4. Investing in Animal Health Research to Alleviate Poverty. International Livestock Research Institute. Permin A. and Madsen M. (2001) Appendix 2: review on disease occurrence and impact (smallholder poultry). Accessed 29 Oct 2006
  5. Atkinson CT, Woods KL, Dusek RJ, Sileo LS, Iko WM (1995). "Wildlife disease and conservation in Hawaii: pathogenicity of avian malaria (Plasmodium relictum) in experimentally infected iiwi (Vestiaria coccinea)". Parasitology. 111 Suppl: S59–69. PMID 8632925.