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Life cycle of Toxoplasma gondii. 1 - Insporulated oocysts are shed in the cat’s feces. 2 – Intermediate host in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts. 3 – Oocysts transform into tachyzoites shortly after ingestion. These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites. 4 - Cats eat infected animals (such as rodents or birsds) and shed unsporulated oocysts. 5 – Intermediate hosts (such as pigs and cows) ingeset oocysts from contaminated water, soil, or plant material. 6 – Humans can become infected when they eat undercooked meat of infected animals harboring tissue cysts. 7 – Humans can also become infected when they consume food or water contaminate with cat feces or by handling fecal-contaminated soil or cat’s litter box. 8 – Humans can also become infected via the placenta from fetus to mother. 10 – Tissue cysts can form in skeletal muscle, myocardium, brain, and eyes. 11 – Diagnosis of congenital infection can be achieved by detecting T. gondii DNA in amniotic fluid using molecular methods such as PCR.
The infectious cycle of Toxoplasma gondii . (credit: “diagram”: modification of work by Centers for Disease Control and Prevention; credit “cat”: modification of work by “KaCey97078”/Flickr)
A) A micrograph of curved cells with a nucleus. B) micrograph of a sphere with many smaller spheres inside.
(a) Giemsa-stained Toxoplasma gondii tachyzoites from a smear of peritoneal fluid obtained from a mouse inoculated with T. gondii . Tachyzoites are typically crescent shaped with a prominent, centrally placed nucleus. (b) Microscopic cyst containing T. gondii from mouse brain tissue. Thousands of resting parasites (stained red) are contained in a thin parasite cyst wall. (credit a: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by USDA)
  • How does T. gondii infect humans?

Babesiosis

Babesiosis is a rare zoonotic infectious disease caused by Babesia spp . These parasitic protozoans infect various wild and domestic animals and can be transmitted to humans by black-legged Ixodes ticks. In humans, Babesia infect red blood cells and replicate inside the cell until it ruptures. The Babesia released from the ruptured red blood cell continue the growth cycle by invading other red blood cells. Patients may be asymptomatic, but those who do have symptoms often initially experience malaise, fatigue, chills, fever, headache, myalgia, and arthralgia. In rare cases, particularly in asplenic (absence of the spleen) patients, the elderly, and patients with AIDS , babesiosis may resemble falciparum malaria, with high fever, hemolytic anemia, hemoglobinuria (hemoglobin or blood in urine), jaundice, and renal failure, and the infection can be fatal. Previously acquired asymptomatic Babesia infection may become symptomatic if a splenectomy is performed.

Diagnosis is based mainly on the microscopic observation of parasites in blood smears ( [link] ). Serologic and antibody detection by IFA can also be performed and PCR-based tests are available. Many people do not require clinical intervention for Babesia infections, however, serious infections can be cleared with a combination of atovaquone and azithromycin or a combination of clindamycin and quinine .

Micrograph of red blood cells with dark circles inside.
In this blood smear from a patient with babesiosis, Babesia parasites can be observed in the red blood cells. (credit: modification of work by Centers for Disease Control and Prevention)

Chagas disease

Also called American trypanosomiasis , Chagas disease is a zoonosis classified as a neglected tropical disease (NTD). It is caused by the flagellated protozoan Trypanosoma cruzi and is most commonly transmitted to animals and people through the feces of triatomine bugs. The triatomine bug is nicknamed the kissing bug because it frequently bites humans on the face or around the eyes; the insect often defecates near the bite and the infected fecal matter may be rubbed into the bite wound by the bitten individual ( [link] ). The bite itself is painless and, initially, many people show no signs of the disease. Alternative modes of transmission include contaminated blood transfusions, organ transplants from infected donors, and congenital transmission from mother to fetus.

Questions & Answers

what is cell
Avi Reply
is unit of life
Kamaluddeen
Ok
mohamed
who is an industrial microbiologist
Cynthia Reply
I want to know the biochemical composition of bacteria
Josh Reply
It contains peptidoglcon, DNA nd RNA
Asiya
bacteriophage disadvantage
Momina Reply
disease due to __________ abnormalities are termed primary immunodeficiencies
Tayee Reply
Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system.
Prince
Examples of primary immunodeficiencies include: chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency etc
Prince
thank you
Nana
explain microbial mutation
Emerald
what is mutation
Cynthia Reply
alteration in genetic makeup
UDEME
Hi, I'm new here. I'm Bello Abdul Hakeem from Nigeria.
BELLO Reply
welcome on board
Kamaluddeen
Thanks brother I'm an undergraduate. I hope to study for MBBS.
BELLO
pls guys help me out
Linda
what is limitation of plate
Linda
limitation of plate load test . there are some that should be considered while performing load test which are given below, this test is usually performed on relatively similar plate ,usually 1 or 2 square foot area the reason is that the plate of greater are the economically not feasible
yemi
iam new here my name shafiu umar from Nigeria
Shafiu
thanks shafiu
gambo
how to differentiate Gram positive from Gram negative bacteria?
Faheem
by the cell membrane
Tim
with gram staining which has 4 steps
Freedom
Mechanism of bacterial pathogenicity
rashida Reply
Toxicity
Ibrahim
write a short note on Algea
najaatu Reply
green minutes plants organisms that are produced in turf.
Prince
Algae is a kind of a photosynthetic organism, which is usually grown in the moist areas. These are usually the simple plants that grow near to the water bodies. It contains a kind of chlorophyll pigments that act as a primary coloring agent.
Avi
they are eukaryotic and most lived in fresh water. they are photosynthetic that's, they contain chlorophyll and store starch in discrete chloroplast.
Prince
are bacteria important to man
just Reply
yes, depending on the type of bacteria .eg the normal florals, the latic acid batteries etc are important to man
Lois
I mean latic acid bacterial
Lois
I don't understand this topic
Jane Reply
what topic is that
Rose
sahi kon hai bhosri ke
saurabh Reply
define metabolism of carbohydrates with example
Thavasi Reply
what is sterilization a
Sani
the process of keep equipment free from bacteria
shar
is it only bacteria?
Lois
no undesirable fungi and contamination also.
Khushbu
what is streak plate method
Offikwu
what is the biofilm
Dimingu
metabolism is the sum of all the biochemical reaction required for energy generation and use of that energy to synthesize cell materials from small molecules in environment.
Alex
boclenia
Pooja
what are granulocytes
Shawnitta Reply
e.coli
Sukhdeep
granulocytes are type of WBCs which contains granules in the cytoplasm
Owili
what is mutation
Cynthia
it is the interchange of genes from their normal sequence
Esther
is an heritable change of the base-pair sequence of genetic material
Elizabeth
suitable example for prokaryotes
Suvetha Reply
one of the possible early sources of energy was
Suvetha
uv radiation and lighting
Anisha
e coli is the example of prokaryotes
Sukhdeep
archaea too
Noel

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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