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==Causes==
==Causes==
'' 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>. The remainder of human malaria infections are caused by ''P. ovale'', ''P. malariae'', and ''P. knowlesi.''
'' 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> The remainder of human malaria infections are caused by ''P. ovale'', ''P. malariae'', and ''P. knowlesi.''




The following table distinguishes between the different strains of ''Plasmodium'' species, all of which are causative agents of malaria infection.
The following table distinguishes between the different strains of ''Plasmodium'' species, all of which are causative agents of malaria infection.
{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
|+'''''Comparison of ''Plasmodium'' Species Implicated in Human Malaria''''' ({{cite web |url=http://www.cdc.gov/dpdx/malaria/dx.html |title= Malaria |date= Nov. 29 2013 |website= Center for Disease Control and Prevention|publisher= Center for Disease Control and Prevention (CDC)|accessdate=Jul 24 2014}})
! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Strain}}
! style="background: #4479BA; width: 550px;" | {{fontcolor|#FFF|Appearance of Erythrocyte (RBC)}}
! style="background: #4479BA; width: 550px;" | {{fontcolor|#FFF|Appearance of Parasite}}
! style="background: #4479BA; width: 550px;" | {{fontcolor|#FFF|Clinical Significance}}
|-
| style="padding: 5px 5px; background: #DCDCDC;" |'''''P. falciparum'''''
| style="padding: 5px 5px; background: #F5F5F5;" |
*Normal appearance with Maurer's clefts: Ring, trophozoite, and schizont forms.
*Distorted appearance: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" |
*Chromatin dots and "appliqué" (accolé): Ring form
*Clump of mass and dark pigment: Trophozoite and schizont forms
*Crescent or sausage shape: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" | Tertian/subtertian fever (every 48 hours), causes severe malaria in up to 24% of cases, and is often drug resistant.
|-
| style="padding: 5px 5px; background: #DCDCDC;" |'''''P. vivax'''''
| style="padding: 5px 5px; background: #F5F5F5;" |
*Normal with fine Schüffner dots: Ring form
*Enlarged with fine Schüffner dots: Trophozoite, schizont, and gametocyte forms
| style="padding: 5px 5px; background: #F5F5F5;" |
*Large cytoplasm with pseudopods: Ring form
*Large ameboid cytoplasm with yellow-brown pigment: Trophozite form
*Large mass that fills all RBC with yellow-brown coalescent pigment: Schizont form
*Large mass that fills all RBC with scattered brown pigment: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" |
Tertian fever (every 48 hours), causes severe malaria in up to 22% of cases, and is often drug resistant. Relapse is common due to dormant liver phase.
|-
| style="padding: 5px 5px; background: #DCDCDC;" |'''''P. ovale'''''
| style="padding: 5px 5px; background: #F5F5F5;" |Normal with fine Schüffner dots
| style="padding: 5px 5px; background: #F5F5F5;" |
*Sturdy cytoplasm and large chromatin: Ring form
*Compact cytoplasm with dark-brown pigment: Trophozoite form
*Large nuclei clustered around mass of dark-brown pigment: Schizont form
*Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" |Tertian fever (every 48 hours), rarely causes severe malaria or drug resistance. Relapse is common due to dormant liver phase.
|-
| style="padding: 5px 5px; background: #DCDCDC;" |'''''P. malariae'''''
| style="padding: 5px 5px; background: #F5F5F5;" |Normal with Ziemann's stippling
| style="padding: 5px 5px; background: #F5F5F5;" |
*Sturdy cytoplasm and large chromatin: Ring form
*Compact cytoplasm with occasional band forms and coarse dark-brown pigment: Trophozoite form
*Large nuclei clustered around mass of coarse, dark-brown pigment and occasional rosettes: Schizont form
*Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" | Quartan fever (every 72 hrs), rarely causes severe malaria or drug resistance. Although dormant liver phase is uncommon, infection persistence is commonly seen.
|-
| style="padding: 5px 5px; background: #DCDCDC;" |'''''P. knowlesi'''''
| style="padding: 5px 5px; background: #F5F5F5;" | Normal with Sinton and Mulligan stippling
| style="padding: 5px 5px; background: #F5F5F5;" |
*Delicate cytoplasm with appliqué (accolé) forms: Ring form
*Compact cytoplasm and large chromatin with band forms and dark-brown pigment: Trophozoite form
*Segmented with large nuclei around mass of coarse brown pigment and occasional rosettes: Schizont form
*Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
| style="padding: 5px 5px; background: #F5F5F5;" | Daily fevers, may cause severe malaria in up to 10% of cases. Drug resistance is rare.
|-
|}


<sup><center>Adapted from Center for Disease Control and Prevention (CDC) -  Malaria </center></sup>


==References==
==References==

Revision as of 22:40, 24 July 2014

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

Overview

Malaria is a vector-borne infectious disease caused by protozoan parasites. 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]

Causes

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.[2] The remainder of human malaria infections are caused by P. ovale, P. malariae, and P. knowlesi.


The following table distinguishes between the different strains of Plasmodium species, all of which are causative agents of malaria infection.

Comparison of Plasmodium Species Implicated in Human Malaria ("Malaria". Center for Disease Control and Prevention. Center for Disease Control and Prevention (CDC). Nov. 29 2013. Retrieved Jul 24 2014. Check date values in: |accessdate=, |date= (help))
Strain Appearance of Erythrocyte (RBC) Appearance of Parasite Clinical Significance
P. falciparum
  • Normal appearance with Maurer's clefts: Ring, trophozoite, and schizont forms.
  • Distorted appearance: Gametocyte form
  • Chromatin dots and "appliqué" (accolé): Ring form
  • Clump of mass and dark pigment: Trophozoite and schizont forms
  • Crescent or sausage shape: Gametocyte form
Tertian/subtertian fever (every 48 hours), causes severe malaria in up to 24% of cases, and is often drug resistant.
P. vivax
  • Normal with fine Schüffner dots: Ring form
  • Enlarged with fine Schüffner dots: Trophozoite, schizont, and gametocyte forms
  • Large cytoplasm with pseudopods: Ring form
  • Large ameboid cytoplasm with yellow-brown pigment: Trophozite form
  • Large mass that fills all RBC with yellow-brown coalescent pigment: Schizont form
  • Large mass that fills all RBC with scattered brown pigment: Gametocyte form

Tertian fever (every 48 hours), causes severe malaria in up to 22% of cases, and is often drug resistant. Relapse is common due to dormant liver phase.

P. ovale Normal with fine Schüffner dots
  • Sturdy cytoplasm and large chromatin: Ring form
  • Compact cytoplasm with dark-brown pigment: Trophozoite form
  • Large nuclei clustered around mass of dark-brown pigment: Schizont form
  • Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
Tertian fever (every 48 hours), rarely causes severe malaria or drug resistance. Relapse is common due to dormant liver phase.
P. malariae Normal with Ziemann's stippling
  • Sturdy cytoplasm and large chromatin: Ring form
  • Compact cytoplasm with occasional band forms and coarse dark-brown pigment: Trophozoite form
  • Large nuclei clustered around mass of coarse, dark-brown pigment and occasional rosettes: Schizont form
  • Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
Quartan fever (every 72 hrs), rarely causes severe malaria or drug resistance. Although dormant liver phase is uncommon, infection persistence is commonly seen.
P. knowlesi Normal with Sinton and Mulligan stippling
  • Delicate cytoplasm with appliqué (accolé) forms: Ring form
  • Compact cytoplasm and large chromatin with band forms and dark-brown pigment: Trophozoite form
  • Segmented with large nuclei around mass of coarse brown pigment and occasional rosettes: Schizont form
  • Round to oval form that fills all RBC with scattered brown pigment: Gametocyte form
Daily fevers, may cause severe malaria in up to 10% of cases. Drug resistance is rare.
Adapted from Center for Disease Control and Prevention (CDC) - Malaria

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. 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.

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