<< Chapter < Page Chapter >> Page >

In addition, some trophozoites alternatively develop into male and female gametocytes. The gametocytes are taken up when the mosquito takes a blood meal from an infected individual. Sexual sporogony occurs in the gut of the mosquito. The gametocytes fuse to form zygotes in the insect gut. The zygotes become motile and elongate into an ookinete. This form penetrates the midgut wall and develops into an oocyst. Finally, the oocyst releases new sporozoites that migrate to the mosquito salivary glands to complete the life cycle.

Diagnosis of malaria is by microscopic observation of developmental forms of Plasmodium in blood smears and rapid EIA assays that detect Plasmodium antigens or enzymes ( [link] ). Drugs such as chloroquine , atovaquone , artemether , and lumefantrine may be prescribed for both acute and prophylactic therapy, although some Plasmodium spp. have shown resistance to antimalarial drugs. Use of insecticides and insecticide-treated bed nets can limit the spread of malaria. Despite efforts to develop a vaccine for malaria, none is currently available.

Life cycle of Plasmodium. [Human Liver Stages] 1 – Mosquito take a blood meal and injects Plasmodium into a human. 2 – Plasmodium infects liver cell. 3 – Plasmodium multiplies in liver cell. [Human Blood Stages] 4 – Plasmodium enters blood. An immature ring stage looks like a signet ring in a red blood cell. This becomes a mature ring stage and undergoes mitosis to produce schizonts which are released by rupturing the red blood cells. 5 – Gametes (1n) produced by meiosis. [Mosquito Stages] 6  - Moquito takes a blood meal and ingests gametes. 7 – Microgametes fertilizes macrogamete. 8 – Zygote (2n) forms. 9 – Zygote undergoes mitosis. 10 – Parasite differentiates and enters the saliva of the mosquito.
The life cycle of Plasmodium . (credit: modification of work by Centers for Disease Control and Prevention)
A micrograph showing red blood cells. A dark ring in the center of one cell is labeled ring form. A larger dark region in another cell is labeled schizont.
A blood smear (human blood stage) shows an early trophozoite in a delicate ring form (upper left) and an early stage schizont form (center) of Plasmodium falciparum from a patient with malaria. (credit: modification of work by Centers for Disease Control and Prevention)
  • Why is malaria one of the most important infectious diseases?


The disease toxoplasmosis is caused by the protozoan Toxoplasma gondii . T. gondii is found in a wide variety of birds and mammals, A.M. Tenter et al.. “ Toxoplasma gondii : From Animals to Humans.” International Journal for Parasitology 30 no. 12-13 (2000):1217–1258. and human infections are common. The Centers for Disease Control and Prevention (CDC) estimates that 22.5% of the population 12 years and older has been infected with T. gondii ; but immunocompetent individuals are typically asymptomatic, however. Centers for Disease Control and Prevention. “Parasites - Toxoplasmosis (Toxoplasma Infection). Epidemiology&Risk Factors.” 2015 http://www.cdc.gov/parasites/toxoplasmosis/epi.html. Accessed July 28, 2016. Domestic cats are the only known definitive hosts for the sexual stages of T. gondii and, thus, are the main reservoirs of infection. Infected cats shed T. gondii oocysts in their feces, and these oocysts typically spread to humans through contact with fecal matter on cats’ bodies, in litter boxes, or in garden beds where outdoor cats defecate.

T. gondii has a complex life cycle that involves multiple hosts. The T. gondii life cycle begins when unsporulated oocysts are shed in the cat’s feces. These oocysts take 1–5 days to sporulate in the environment and become infective. Intermediate hosts in nature include birds and rodents, which become infected after ingesting soil, water, or plant material contaminated with the infective oocysts. Once ingested , the oocysts transform into tachyzoites that localize in the bird or rodent neural and muscle tissue, where they develop into tissue cysts. Cats may become infected after consuming birds and rodents harboring tissue cysts. Cats and other animals may also become infected directly by ingestion of sporulated oocysts in the environment. Interestingly, Toxoplasma infection appears to be able to modify the host’s behavior. Mice infected by Toxoplasma lose their fear of cat pheromones. As a result, they become easier prey for cats, facilitating the transmission of the parasite to the cat definitive host J. Flegr. “Effects of Toxoplasma on Human Behavior.” Schizophrenia Bulletin 33, no. 3 (2007):757–760. ( [link] ).

Questions & Answers

what is fermentation example ?
Sonal Reply
is proceess in which an agent couses of an oganic substances breakdown into simpler substance,especially in aneorobic breakdown of suger into alcohol.
is it better to study microbiology and then medicine it makes no difference to go directly to medicine?
Jessee Reply
Dray's mathdme cell wall konse color k hote he
Jinal Reply
what is dray's mathdme cell wall
I confused. please help me
just confused
l don't understand it please explain it for me.
Karen Reply
epitopes are present on the surface of
Rohit Reply
at the tip of variable region on the antibody...where antigen and antibody binding sites combine...
The term that is used refer to moving microbes under a microscope are referred to as?
Lee Reply
Members of the genus Neisseria cause which of the folowing human diseases?
Farah Reply
genital infections
4. Which of the following specimens should not be refrigerated? a. Urine b. Urogenital swab
Zahraa Reply
Details about McConkey agar
what is bacteria
anamika Reply
a member of large number of unicellular microorganism which have cell wall but lack of cell organelles an oranised nucleus including somewhat can cause disease
Bacteria are usually composed of one cell onl to that are neither plants nor animals, microscopic, that may cause diseases or may be beneficial(in gut)... it depends upon their weapons. Nearly all animal life is dependent on Bacteria for their survival
what factor make bacteria colony large and how could we sterlise it in large scale
nutrient concentration temp gaseous conc ph ion or salt concentration mositure condition factors contribute to make large colony. by autoclaving we will sterilize bactetia
Colony is actually visible growth of Bacteria that is as a result of suitable environment for growth i.e optimal conditions for growth, temperature, moisture etc. there're many methods to get rid of bacteria. If We stop giving them optimal conditions for living Bacteria will die soon .
what's the difference between an antigen and a pathogen?
Pathogens are organisms that cause disease in other organisms whereas Antigen is a part of a pathogen that triggers the immune response..
so it is the antigen that dendritic cells present to the T cells and not the pathogen itself?
no no antigen are the west product or part of the pathogen. in such case bacteria it self fight with over immune response & in another case bacteria release antigens
& other antigen like pollan grain, dust particles etc.....
pathogen are microbes that can infect the body and causw illness....antigens are the part of pathogens that alert the body to an infection
antigen is a part of blood and pathogen is foreign particle which causes diseases
antigen could be non microorganism.... where as pathogen is mixroorganism
a pathogen is a disease causing organism while an antigen is a protein in the white blood cells which combats pathogens.
what type of widal test
sobhit Reply
this test determine for typhoid in this test if H,O antigen are present that indicate the positive test bac. are salmonella typhy
what h.o denotes
o: body of bacteria, h: flagellate
Explain Mould
Chinenye Reply
Explain mycoses and it's classification
why do we have hiccups?
Manisha Reply
shakey diaphragm
The antibody binding site is formed primarily by:
Asalla Reply
How many types of MICROORGANISMS do we have?
Hope Reply
Hello friends
microorganisms are divided into seven type Bacteria archaea protozoa algae fungi virus and multicellular animal parasites

Get the best Microbiology course in your pocket!

Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microbiology' conversation and receive update notifications?