Plasmodium/Human symbiosis

Life Cycle and Importance

What is Plasmodium?

Plasmodium is an apicomplexan (previously called sporozoans) that causes malaria in humans. An apicomplexan is a protist that disseminates small infectious cells called sporozoites., and has organelles that are specialized for penetrating host cells and tissues, which are called apical complexes.

The Plasmodium Life Cycle http://highered.mcgraw-hill.com/olc/dl/120090/bio44.swf http://www.youtube.com/watch?

v=s_nOgu8OnZA&NR=1&feature=fvwp

The Life Cycle of Plasmodium Continued

A female anopheles mosquito bites a person that has malaria, and picks up plasmodium gametocytes

Gametes form from the male and female gametocytes and fertilization occurs in the digestive tract of the mosquito.

An oocyst develops from zygote in wall of mosquito’s gut. Sporozoites develop in the oocyst and migrate to mosquito’s salivary gland.

Mosquito bites another person, releasing the plasmodium sporozoites into the bloostream, where they then travel to and enter the victim’s liver cells. This way, the small cells can avoid the lymphocytes (blood cells that identify invasions of foreign bodies) in the blood stream.

Several days pass, and the sporozoites undergo multiple divisions to become merozoites. The merozoites then use their apical complexes to penetrate the red blood cell and enter it.

The merozoites then grow and divide asexually, and repeatedly break out of the red blood cells in intervals of 48 or 72 hours, which triggers the response of the immune system, and subsequently the symptoms of the immune system response to malaria show; periodic chills and fever.

Other merozoites infect new red blood cells. Some merozoites divide sexually to form gametocytes, which can then be picked up

by the next anopheles mosquito to bite the infected person, and the cycle starts over again.

Trivia and Current Research

• A gene has recently been identified that may be the cause of plasmodium resisitance to chloroquine; an important antimalarial drug. This discovery may pave the way for methods of preventing drug resistance in plasmodium. •Bill Gates has recently told the BBC that a malaria vaccine is in “phase three” of its development, in other words, it has begun the trial phase. He added that “a fully effective vaccine will take five to ten years.”• BBC news: “Gates says malaria vaccine could ready in three years”

http://news.bbc.co.uk/2/hi/health/8479986.stm

Impact of Malaria

Source: http://www.cdc.gov/malaria/impact/index.htm

Leading Causes of Death in Children Under Five Years of Age, Estimates for 2000-2003(Source: World Health Organization, The World Health Report 2005)

Rank CauseNumbers

(thousands per year)

% of all deaths

1 Neonatal causes 3,910 37

2 Acute respiratory infections 2,027 19

3 Diarrheal diseases 1,762 17

4 Malaria 853 8

5 Measles 395 4

6 HIV/AIDS 321 3

7 Injuries 305 3

Other causes 1,022 10

Total 10,596 100.0

According to the World Health Report and the CDC, Malaria kills 853,000 children under 5 per year.

Review Questions and Additional Information What is an Apicomplexan? Where do the sporozoites go after being transferred into the blood

stream of the victim? What specialized organelle is responsible for penetrating host cells

and tissues? What do sporozoites become after multiple divsions in the liver? Where do these cells go, and how? What part of the mosquito do the sporozoites travel to? Where does the fertilization of gametocytes take place? Is plasmodium eukaryotic or prokaryotic?

Additional Information on Plasmodium and Apicomplexans

Page 527- Description of Apicomplexans

Page 528- Life Cycle of Plasmodium and Description

Answers To Review Questions An Apicomplexan is a protist that has specialized

organelles made for penetrating host cells and tissues

The liver Apical complex Merozoites Into the red blood cells, by penetrating the cell

with the apical complex The salivary glands The wall of the mosquito’s digestive tract Prokaryotic

Sources Cited

McGraw Hill: http://highered.mcgraw-hill.com/olc/dl/120090/bio44.swf

“The Impact of Malaria, a Leading Cause of Death Worldwide.”The Department of Health and Human Services Center for Disease Control

Biology. Campbell, Neil; Reece, Jane; Mitchell, Lawrence. 527-528

Animal Planet TV, “Monsters Inside Me: Living With the Enemy.” http://www.youtube.com/watch?v=s_nOgu8OnZA&NR= 1&feature=fvwp