COCCIDIAN PARASITES

- DR.AKIF A.B

COCCIDIAN PARASITES

1)Toxoplasma gondii

2)Cyclospora

3)Isospora

4)Cryptosporidium

5)sarcocystis

TOXOPLASMA GONDII- DR.AKIF A.B

TOXOPLASMA GONDII-MODE OF TRANSMISSION : 1) ingestion of sporulated oocyst from contaminated soil,water or food

2) ingestion of tissue cysts containing Bradyzoites from undercooked meat

3) by blood transfusion or vertical transmission tachyzoites are infective form

CONGENITAL TOXOPLASMOSIS-Maximum chances of transmission = 3rd Trimester

-Severity is more if transmission occurs in= 1st trimester

-C/F : 3C + 2M

Chorioretinitis :MC manifestation

Cerebral calcification

Convulsions

Microcephaly

Mental Retardation

CONGENITAL TOXOPLASMOSIS

-Intracerebral calcification in basal ganglia region

DIAGNOSIS OF CONGENITAL TOXOPLASMOSIS

1) IgM detection in fetal blood

2) Toxoplasma Ag in amniotic fluid.

TOXOPLASMOSIS IN ADULTS

-In adults : Mostly asymptomatic

- MC symptom = Cervical Lymphadenopathy

TOXOPLASMOSIS IN HIV patient

-MC manifestation = Encephalitis

-MC site = Brainstem

-Occrs when CD4 cont is = <100/micro litre

TOXOPLASMA GONDIISporulated Oocyst

Transforms into Tachyzoites in blood

Transfors into Bradyzoites inTissues

MICROSCOPY FOR TOXOPLASMA

-Blood smear : shows comma shaped Tachyzoites (Indicates active lesion)

-Biopsy from tisse : Shows tisse cysts wit bradyzoites(Indicates past or chronic infection)

TOXOPLASMA GONDII

SABIN FELDMAN TEST- Gold stadard test

-Highly sensitive and specific test

-But can not distinguish between recent or past infection

-Antibody detection test

TREATMENT1) Immunocompetent hosts = No treatmet

2) Toxoplasmosis In Pregnancy = Spiramycin

3) In HIV = Cotrimoxazole

Q. A 36-year-old man with AIDS develops right-sided weakness involving the lower, but not the upper, limb. MRI scans reveal a ring-enhancing lesion within the white matter of the left frontal lobe. A biopsy shows coagulative necrosis of brain parenchyma with macrophage-rich chronic inflammatory infiltration admixed with microscopic cysts that contain characteristic bradyzoites. Which is the most common source of this type of infection? (AIPG 2011)

A Anopheles mosquitoes

B Bird droppings C Cats

D Cooling systems

Ans. C Cats a. This is the history of toxoplasmosis.

b. The commonest source is oocysts shed in the definitive host i.e cat. The intermediate host is mouse, human.

c. Most of the infections in immunocompetent people are asymptomatic.

d. In immunocompromised people it causes encephalitis (HIV/AIDS).

e. The infection can also be transmitted from the pregnant mother to the fetus through placenta. The highest chance of transmission in during the third trimester, however, the infection in the fetus is most severe if the infection is transmitted in the first trimester of pregnancy.

f. The serological test used for diagnosis is Sabin & Feldman dye test and ELISA.

2. All of the following statements about toxoplamosis are true except:

A Oocyst in freshly passed cat faeces is non-infectious

B May spread by organ transplantation

C Maternal infection acquired during third trimester has high risk of transmission

D Arthalgia, sore throat and abdominal pain are the most common manifestations

Ans. D Arthalgia, sore throat and abdominal pain are the most common manifestations

Definite host in toxoplasmosis is cat.The intermediate host is man or any other mammal like sheep or pig.Stages-a. Trophozoite (tachyzoites): crescent shaped: Indicates ACute

Infection

b. Tissue cyst: formed during chronic infection. Skeletal, heart muscle, brain. 200m. Bradyzoites

d. Infective form for man-tissue cyst in poorly cooked meat of infected animal and food or water contaminated by feces with sporulated oocyst. The oocyst in cat feces becomes infectious in 1-2 days after passage in cat feces.e. Common symptoms in immunocompetent people are cervical lymphadenopathy, fever and malaise.f. Tissue cyst with bradyzoites in organ can transmit disease via organ transplantation.

3. Acute toxoplasmosis is commonly associated with all of the following except (AIIMS May 2011)

A Cervical lymphadenopathy

B Axillary lymphadenopathy

C Muscle pain

D Myocarditis

Ans. D Myocarditis

Myocarditis is a rare complication of acute toxoplasmosis

3. A 24 year old primi in her 8th month of pregnancy develops a positive igm titer to T. Gondii for the first time. She should be advised by her physician that

A That this child and all future fetuses would be infected

B That the new born with positive anti-toxoplasma igg response should be treated with anti-parasitics

C That future infections can be avoided by proper vaccination and deworming of cats

D That chorioretinitis can be prevented by drug treatment of an infant with positive igm response.

Ans. D That chorioretinitis can be prevented by drug treatment of an infant with positive igm response.

a. Presence of igm in the primi in 8th month of pregnancy indicates recent primary infection.

c. Infection acquired in the first trimester by women who were not treated with anti–T. Gondii drugs results in congenital infection in 10% to 25% of cases.

d. For second- and third-trimester infections, the incidences of fetal infection ranged between 30% and 54% and 60% and 65%, respectively.

e. Majority of children born of women who acquire their infection during the third trimester as in this case are born with the subclinical form of the infection.

If IgM to toxoplasma is positive in the neonate, then appropriate treatment will prevent the complication

5. A person who had recently consumed half a box of raspberries came down with severe watery diarrhoea. What is the most likely diagnosis?

A Cyclospora B Cryptosporidium

C Isospora

D Vibrio

Intake of contaminated raspberries or basil followed by diarrhea suggests cyclospora infection.

A Cyclospora

6. A person having diarrhea of six month duration. AFB of size 12 micron are found in stool. Most likely cause is:

A Cryptosporidium

B Isospora

C Cyclospora

D Giardia

Ans. C Cyclospora

a. Cyclospora oocysts are of 12 micron size. They contain 2 sporocysts with 2 sporozoites each.

b. Isospora oocysts are of 20-33 micron size. They contain 2 sporocysts with 4 sporozoites each.

c. Cryptosporidium oocysts are 4-5 micron in size and contain 4 naked sporozoites.

d. Giardia cyst are not acid fast.

Acid fast staining of stools is used for all except

A Cyclospora caytenensis

B Isospora belli

C Blastocystis hominis

D Cryptosporidium

Ans. C Blastocystis hominis

Blastocystis hominis is non acid fast.

An AIDS patient presents to his primary care physician with a two week history of watery, nonbloody diarrhea. The most likely diagnosis is which of the following? (AIIMS May 2012)

A Acid-fast bacilli

B Enterocytozoon

C Cryptosporidium

D Cyclospora

Ans. C Cryptosporidium

The most common cause of diarrhea in HIV/AIDS is Cryptosporidium.