Plasmodium malariae

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A Microbial Biorealm page on the genus Plasmodium malariae

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Plasmodium malariae


Classification

Higher order taxa

Domain: Eukarya
Phylum: Apicomplexa
Class: Aconoidasida
Order: Haemosporida
Family: Plasmodiidae
(NCBI)

Species

Plasmodium malariae

Description and significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

-Plasmodium malariae is a parasitic protozoa that causes malaria in humans. It is the cause of a fever that recurs in three-day intervals and is responsible for less death than malaria caused by other bacteria.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Not much is known about the genome of the species Plasmodium malariae specifically, because it is among the species for which the entire genome has not been sequenced yet. However, there are some important characteristics about its genome can be determined from the genome sequences of other species in the Plasmodium genus. It is estimated that the genome of an organism in the genus Plasmodium contains anywhere from 23 million to 27 million base pairs, in the form of 14 linear chromosomes. These 14 chromosomes code for about 5,500 genes, many of which function in invading the host immune system. (Winzeler) Some additional research shows that the mitochondrial genomes of Plasmodium are highly conserved throughout the genome as well. (Tanabe)

Cell structure and metabolism

Interesting features of cell structure; how it gains energy; what important molecules it produces.


Ecology

Habitat; symbiosis; contributions to the environment.

Malaria is a disease that is commonly found throughout most tropical and subtropical areas in the world. There are four malarial parasites from the Plasmodium genus that infect humans and cause symptoms indicative of the disease (Hayakawa T).

Plasmodium malariae is primarily found in one of the two host species it infects. It is transmitted by bites from the Anopheles mosquitos, and causes malaria symptoms when it infects humans. Not just limited to mosquitoes and humans, scientists at Osaka University in Japan have discovered strains of P. malariae in imported chimpanzees from Africa. Despite being infected, the chimps have not shown symptoms of disease (Hayakawa T).

Pathology

P. malariae is one of the four species of the genus Plasmodium that uses humans as a primary host. The other three species are P. falciparum, P. vivax,and P. vivale. The primary mode of transmission from host to host by these four species uses a female Anopheles mosquito as a vector. (DPDx) While the symptoms resulting from the different species are different, the life cycle only has minor differences. The life cycle is initiated when the mosquito vector injects sporozites into the human hosts during a blood-meal. The sporozites then migrate to the liver, where they reproduce asexually and produce merozites. These merozites then enter the bloodstream and infect erythrocytes, becoming trophozoites. The period of time that the trophozoites are enlarging is called the trophic period, and this ends when several divisions occur, but none of these cycles go through the cytokinesis stage, forming what is called a schizont. The erythrocyte then lyses, introducing new merozites into the blood cycle and starting the cycle over again, until an uninfected Anopheles mosquito takes a blood-meal from the infected host, and transmits the infection to another host. (Wiser)

Plasmodium life cycle

The main physical manifestations of malaria in a human host are febrile attacks that are known as malarial paroxysms. These symptoms appear during the blood stage of the life cycle; no symptoms will appear during other stages. The severity of the infection depends on the infecting species of Plasmodium and the health of the host prior to infection. (Wiser)

plasmodiumstats
Plasmodium life cycle































Current Research

Enter summaries of the most recent research here--at least three required

Researchers at the National Institute of Allergy and Infectious Diseases are using genetic studies of Plasmodium yoelii, isolated from wild African rodents to understand pathogenicity of malaria parasites. P. yoelii exhibits traits similar to human malaria viruses such as Plasmodium falciparum and Plasmodium malariae. The article is a methods video and article describing how to obtain a genetic cross of rodent malaria parasites. Published in January of 2011, http://www.jove.com/details.php?id=2365 .


Plasmodium malariae in Bangladesh

Plasmodium malariae malaria has been rarely reported from Bangladesh. Early stages of Plasmodium malariae can be difficult to distinguish from other species by microscopy alone. Severe malaria is an extremely rare manifestation of a monoinfection with Plasmodium malariae. A 32 year old Bangladeshi male laborer from Fatickchari, Bangladesh, was admitted to Chittagong Medical College Hospital in July 2008 because of a ten day history of evening fevers, chills, rigors, headache, anorexia, myalgia, dry cough, palpitations, drowsiness and several generalized convulsions. He also complained of abdominal pain and nausea without vomiting or diarrhea for the next five days. Initially he was treated with paracetamol, which controlled his fever, at his local health complex. However, he became disorientated and suffered from generalized convulsions, and was referred to Chittagong Medical College Hospital for further management.

A thin blood film test showed Plasmodium malariae with a parasitaemia of 3 per 1000 red cells (14 017/uL), with typical band form trophozoites, schizonts containing 4-6 merozoites, and occasional gametocytes. This patient showed rosette formation, the binding of two or more infected red cells to an uninfected red cell. Rosettes were observed in a frequency of 50 per 100 trophozoite infected red cells. Although rosetting is usually described only in Plasmodium falciparum after in-vitro maturation of the parasites, it is highly uncertain if rosettes in Plasmodium malariae significantly constrict microvascular flow, since parasitaemia is low. Usual treatment of uncomplicated Plasmodium malariae infection is with chloroquine or an artemisinin-based combination therapy. However, because of the disease severity, this patient was treated with intravenous quinine.(Rahman)

A polymerase chain reaction, based on the 18 s rRNA gene, performed on the same blood sample confirmed a diagnosis of Plasmodium malariae malaria. This is the first PCR confirmed case of Plasmodium malariae to be reported from Bangladesh.

In summary, a rare case of a PCR-confirmed monoinfection with Plasmodium malariae was present and rosetting occured in the peripheral blood film. The patient made a quick recovery with intravenous quinine.

Cool Factor

Describe something you find "cool" about this microbe.

References

-DPDx - Parasitology Diagnostic Web Site. "Parasites and Health - Malaria." Laboratory Identification of Parasites of Public Health Concern. Center for Disease Control (CDC), 20 July 2009. Web. 07 Oct. 2011. <http://dpd.cdc.gov/dpdx/html/Malaria.htm>.

-Hayakawa T, Arisue N, Udono T, Hirai H, Sattabongkot J, et al. (2009) Identification of Plasmodium malariae, a Human Malaria Parasite, in Imported Chimpanzees. PLoS ONE 4(10): e7412. doi:10.1371/journal.pone.0007412

-Pattaradilokrat, S., Li, J., Su, X. . Protocol for Production of a Genetic Cross of the Rodent Malaria Parasites. J. Vis. Exp. (47), e2365, DOI: 10.3791/2365 (2011) <http://www.jove.com/details.php?id=2365>.

-"Plasmodium Malariae." NCBI Taxonomy Browser. NCBI. Web. 05 Oct. 2011. <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi>.

-Winzeler, Elizabeth Ann. "Malaria research in the post-genomic era." Nature 455.7214 (2008): 751-756. Academic Search Premier. EBSCO. Print. 5 Oct. 2011.

-Wiser, Mark F. "Plasmodium Life Cycle." Tulane University. Web. 7 Oct. 2011. <http://www.tulane.edu/~wiser/malaria/mal_lc.PDF>.

-Rahman, W., K. Chotivanich, K. Silamut, N. Tanomsing, A. Hossain, M.a. Faiz, A.m. Dondorp, and R.j. Maude. "Plasmodium Malariae in Bangladesh." Transactions of the Royal Society of Tropical Medicine and Hygiene 104.1 (2010): 78-80. Print.

Edited by students of Iris Keren

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