toxoplasma gondii and cyclospora

1. Toxoplasma gondii
Presented By : Niteesh Kumar
Para :- 18
Roll No : - 46

2. Toxoplasma Gondii
 Obligate intracellular protozoal parasite.
 Very common infection affect about 1/3rd of world but mostly
remains asymptomatic but significant in immunocompromised
patients and congenital infection of fetus.
 Discovered by Charles Nicolle & Louis Manceaux.
 Toxoplasma – Toxon – Curved shape of Trophozoite ( Tachyzoite ).
 Infect all nucleated cells.
 M/C parasitic zoonotic infection ( Prevalence : 5-75%)

3. Taxonomical Tree
Domain : Eukaryota
Kingdom : Protista
Phylum : Protozoa
Subphylum : Apicomplexa
Order : Eucoccidiorida
Family : Sarcocystidae
Genus : Toxoplasma
Species : Toxoplasma gondii

4. Morphology
Asexual Form Sexual Form
Tachyzoite – Acute infection
Tissue cyst – Chronic infection
Oocyst
Seen in human & other
mammals
Seen in cat & other feline
Intermediate host Definitive Host

5. (A) (B) (C) (D) (E)
(A) Tachyzoites; (B) Pseudocyst; (C) Tissue cyst;
(D) Sporulated oocyst; (E) Sporulated oocyst in cat’s feces (saline mount)

6. Tachyzoite
 Actively multiplying parasitic form
 Seen in acute infection
 Crescent shaped , 6μm ₓ 2μm
 Anterior end : Pointed and have rhoptries & micronemes which help
in adhesion & invasion.
 Posterior end : Blunt
 Dense granules & nucleus @ central & posterior end.
 Show endodyogeny (Internal budding ).

7. Pseudocyst – Distension of host cell due to proliferation of tachyzoite .
Later on it get raptured to produce more tachyzoite to
infect adjoining cells.
Numerous tachyzoites of
Toxoplasma gondii are visible
within a pseudocyst in a
myocyte

8. Tissue Cyst
 Resting stage of parasite.
 Seen in chronic infection
 Vary in size ( 2-5 μm ₓ 100μm ).
 M/C site of tissue cyst –
Muscle – Oval shaped
Brain – Spherical shape

9.  Tachyzoite Bradyzoite
Crescent shaped
Slowly multiplying
More slender
Covered by round/oval cyst wall
7μm ₓ 1.5μm
Resistant to gastric juice
Strongly PAS +ve amylopectin granule
IFN-ᵞ
NO
HSP

10. Oocyst
 Sexual form.
 In cats and other felines.
 Covered by refractile & resistant double layered
colourless cyst wall.
 Unsporulated oocyst - Excreted out in cat’s feces,
Non infective.
Sporulated oocyst – Infective form
2-3
Days

11. A) Tachyzoites (arrowhead) in smear. Giemsa stain. Note nucleus dividing into two nuclei (arrow).
B) A small tissue cyst in smear stained with Giemsa and a silver stain. Note the silver-positive tissue cyst wall
(arrow head) enclosing bradyzoites that have a terminal nucleus (arrow).
C) Tissue cyst in section, PAS. Note PAS-positive bradyzoites (arrow) enclosed in a thin PAS-negative cyst wall
(arrowhead).
D) Unsporulated oocysts in cat faeces. Unstained.

12. Life Cycle
Host
Definitive Host Intermediate Host
In cat & feline In human & other mammals
Sexual cycle Asexual cycle
(Enteric cycle) ( Exoenteric cycle )

13. Mode of Transmission Infective Form
Contaminated soil , food , water Sporulated cyst
Undercooked meat Bradyzoite
Blood transfusion , Needle stick
injuries, Laboratory accidents,
Organ transplantation ,
Transplacental transmission
Tachyzoite

14. Asexual ( Exoenteric ) Cycle
In human intestine –
Sporulated cyst Sporozoite
Tachyzoite
Tissue cyst Bradyzoite
Invade intestinal epithelial

15. Tachyzoite – Migrate to mesenteric lymph node
Also migrate to distant extraintestinal organs
( Brain , Eye , Liver , Muscle etc )
Bradyzoite
Tissue Cyst

16. Sexual ( Enteric ) Cycle
 Within cat and felines – Meat of rodents & other animals.
 Bradyzoite Invade intestinal epithelium of cat Few
cycle of Schizogony
Tissue cyst Sexual Cycle (Male & Female)
( Meat )
Zygote
Sporulated oocyst Unsporulated oocyst Oocyst

19. Risk Factors for Toxoplasmosis
 Geographical Area : Cold climate, hot climate, high altitude a/w low
prevalence.
 Age : Old & fetus
 Exposure to cats and their feces.
 Food Habit : Undercooked meat of cat and felines (France)
 Immune status : Patient with HIV, Malignancies ,
Immunocompromised person
 Patients undergone blood transfusion , organ transplantation etc.

21. Clinical Features
Immunocompetent Patients :
Usually asymptomatic & self limiting.
1) Cervical lymphadenopathy
2) Headache
3) Fever
4) Malaise
5) Fatigue

22. Immunocompromised Patients
 Causes focal necrosis of tissue.
 HIV : M/C opportunistic infection – Toxoplasmosis (15-40%)
May be due to latent infection or new infection.
Toxoplasma encephalitis (TE) – M/C symptom
 Pulmonary infection
 Chorioretinitis

23. Toxoplasma Encephalitis
 Most common areas involved in TE are the brainstem, basal
ganglia, pituitary gland and corticomedullary junction
 CD4+ T-Cell count : ≤100/μl
 Necrotising encephalitis.
 Altered mental status, seizures, sensory abnormalities,
cerebellar signs and focal neurologic findings including motor
deficits, cranial nerve palsies and visual-field loss

24. Congenital Toxoplasmosis
 As the gestation proceeds ,chances of transmission increases and severity
of disease decreases.
Infection
Before Pregnancy 1st Trimester 3rd Trimester
Usually fetus remains Transplacental Probability of transplacental
Uninfected unless she is infection – 15 % infection- 65%
Immunocompromised. Most severe form Usually asymptomatic at birth

25.  Ocular symptoms – Profound visual impairment
Blurred vision
Scotoma, Glaucoma
Photophobia , Strabismus
 Others : Still birth, Intracerebral calcification , Microcephaly ,
Hydrocephaly , Psychomotor disturbance.
 TORCH Infection :- Toxoplasma,
Others ( Treponema pallidum, Varicella)
Rubella
Cytomegalovirus
Herpes simplex virus

26. Laboratory Diagnosis
Direct Microscopic Examination :
 Specimen : BM aspirate , CSF, Amniotic fluid, Peripheral blood
Bronchoalveolar lavage of HIV
 Stains : Giesma stain , PAS, Silver Stain , Immunoperoxide stain
 Direct Fluorescent Antibody Test (DFA)
 Detect tachyzoites in blood and tissue cyst in tissue biopsy .

27. Giesma stained Tachyzoite T. GONDII OOCYSTS IN A FAECAL FLOTATION

28. Antibody Detection :
1) Sabin-Feldman Dye Test : Gold standard for antibody detection.
Complement mediated neutralisation test which require live tachyzoite.
Can’t differentiate btw recent & remote infection.
2) IgG Detection : ELISA & Indirect Fluorescent Ab Test (IFA)
3) IgG Avidity Test : Low avidity – Recent infection
Strong avidity – Past infection

29. Indirect Fluorescent Antibody Test

30. 4) IgM Detection :- Acute infection
Double sandwich IgM-ELISA
 Toxoplasma Antigen Detection Test :- ELISA
 Molecular Diagnosis :- Real Time PCR
 Animal Inoculation :- Intraperitoneal inoculation in mice.
 CT Scan/MRI :- Multiple ring enhancing lesion in basal ganglion.
 CSF Analysis :- Increased Intracranial Pressure
Lymphocytosis
Increased protein concentration

31. Diagnosis of Congenital Toxoplasmosis
1) Toxoplasma antigen in amniotic fluid .
2) PCR
3) Double sandwich IgA-ELISA
4) IgG detection after 6 month of birth.

33. Treatment
Immunocompetent
Patients
Congenital
Toxoplasmosis
Immunocompromised
Patients
Pyrimethamine +
Sulfadiazine/Clindamycin
Pyrimethamine(1mg/kg)
+
Sulfadiazine (100mg/kg)
+
Folinic acid
Primary Prophylaxis
Secondary Prophylaxis
For 1 month For 6 month

34. Prophylaxis For Immunocompromised Patient
Primary Prophylaxis Secondary Prophylaxis
CD4+ T-Cell count : 100/μl 200/μl +
H/O Toxoplasmosis
Clotrimazole (DOC) Dapsone-pyrimethamine +
Atovaquone ±
Pyrimethamine
Treat till CD4+ T-Cell count
reaches upto 200/μl at least for 3
months.
Treat till CD4+ T-Cell count
reaches upto 600/μl at least for 6
months.

35. Prevention
1) Consume thoroughly cooked meat.
2) Proper hygiene maintenance and hand cleaning of people
handling cats and other felines.
3) Regular prenatal and antenatal screening o detect Toxoplasma
infection in pregnant women.
4) Avoid materials contaminated with cat’s feces.
5) Screening of blood banks or organ donors for antibody to T.
gondii

36. CYCLOSPORA CAYETANENSIS
 Most recent described coccidian parasite.
 Described by Ashford in 1979.
 Named by Schneider in 1881.
 Host : Human – Only known host
 Transmission :- Food & water contaminated with sporulated
oocyst.
 Life Cycle :- Not fully understood but believed to be similar to C.
parvum

38.  Oocyst released in human feces Unsporulated oocyst
Sporulation take place in soil.
Sporulated oocyst
 8-10 μm in size.
 Contain 2 sporocyst and each sporocyst has two sporozoite.

39. (A). An unsporulated oocyst, with undifferentiated cytoplasm, is shown (far
left), next to a sporulating oocyst that contains two immature sporocysts. (B)
An oocyst that was mechanically ruptured has released one of its two
sporocysts. (C) One free sporocyst is shown as well as two free sporozoites,
the infective stage of the parasite. (D) Oocysts (E) Oocyst are auto-
fluorescent when viewed under ultraviolet microscopy

40. Clinical Features :
 Self limiting watery non-bloody diarrhoea.
 Biliary tract infection in HIV patients.
 Loss of appetite, weight loss, stomach cramps/pain,
bloating, increased gas, nausea, and fatigue.
 More common in Central America & South Asia.
 Less common in African countries.

41. Laboratory Diagnosis
 Stool examination :- Shows round oocysts
 Wet mount examination
 Acid fast stain :- Shows variably acid fast oocysts
 UV epifluorescence microscopy :- Shows autofluorescence oocysts
 Molecular diagnosis :- rt-PCR
 Serology (antibody detection)
 Histopathology of intestinal biopsies

42. (A) (B)
Cyclospora species
(A) saline mount preparation showing unsporulated oocyst;
(B) epifluorescence microscopy showing autoflourescent oocysts

43. (A) (B)
Cyclospora species modified acid fast stain shows variable acid fast oocyst
(A) Acid fast oocysts, (B) Non acid fast oocysts

44. Treatment
 Clotrimazole BDX7 Days
 Clotrimazole can be replaced by Ciprofloxacin/Nitazoxanide in
patients not tolerating Clotrimazole.

46. Thank You