Parasitology Flashcards
Amoebiasis in Intestine features
Flash shaped ulcers which contains Erythrophagocytosis by trophozoites
Anchovy sauce appearance is seen in
Liver amoebiasis
How many stool samples for amoebiasis
3 consecutive
Medium for stool culture
- Polyxenic medium- has added bacterial supplements
- Axenic medium- pure medium
Examples of Axenic medium
Diamond medium
Examples of Polyxenic medium
Nelson culture
Balamuth culture
Boeck and DrBohlav medium
Craige’s medium
Differentiate between E. histolytica vs Entamoeba coli trophozoite
E. histolytica has engulfed RBC, central karyosome. E. coli has no RBC, eccentric karyosome
Differentiate between E. histolytica vs Entamoeba coli cysts
E. histolytica-
1-4 nuclei (cartwheel app)
Thick chromatoid body made of ribonucleoprotein
E. coli-
1-8 nuclei
thin chromatoid body
Diagnosis of amoebiasis in liver
Trophozoites in pus
Amoebiasis:
1. Infective form
2. Transmission
3. Infective dose
- Mature/ Quadrinucleate cyst
- Feco oral
- Very less
Organisms with small infectivity dose
EHEC
Shigella
Cryptosporidium
E. histolytica
Giardia
Examples of free living amoeba
Naegleria fowleri
Acanthamoeba
Naegleria fowleri
1. Causes
2. Infective form
3. Spread of disease in the body
4. Diagnosis:
5. Tx
- Primary amoebic meningoencephalitis
- Trophozoites
- Neural
- CSF- trophozoites, Incr PMNL, Culture in NNA medium with lawn culture of E. coli
PCR- Gold standard - Ampho B
Acanthamoeba
1. ___ course
2. Spread in the body
3. Causes
4. Diagnosis
5. Infective form
6. Mostly seen in
7. Tx
- C/c
- Blood
- Granulomatous amoebic encephalitis
- Brain biopsy- shows trophzoites and cysts
- Trophzoites and cysts
- Immunodeficient people
- Pentamidine + Sulfonamide + Azole + Flucytosine
Similarities and differences between Balamuthia and acanthamoeba
Causes GAME. Shows cysts and trophozoites
Diff: FIsh shaped trophozoites, In all people (not just immunodef)
Balantidium coli
- Cysts and trophozoites have 2 nucleus each- one big kidney shaped, one small
- In large intestine
- Ciliated cyst
- Largest member of amoeba family
Examples of flagellates
Giardia lamblia
Trichomonas vaginalis
Giardia lamblia
1. Site
2. Route
3. Motility
4. Infective form
5. Tests
6. Treatment
- Duodenum
- Feco oral rute
- Falling leaf
- Cyst
- Stool- trophozoites- 2 nuclei and 4 pairs of flagella. Pear/ Tennis racket shaped trophozoite. Cyst- 4 nuclei
String test/ E test
HPE- luminal organism- sickle shape - Tx: Metronidazole, Tinidazole
MC parasite infection in the world
Giardia lamblia
MC parasite found in stools
Giardia
MCC of STD, NGU
Trichomonas
Trichomonas vaginalis
1. Reservoir
2. Infective form
3. Male symptoms
4. Female symptoms
5. Motility
6. Structure of flagella
7. Culture
8. Tx
- Females
- Trophozoite
- D/c (green)
- Strawberry cervix
- Twitching/ Jerky
- 4 pairs of ant flagella, one posterior, undulating member
- Lash media, Diamond medium
- Metronidazole. Treat both partners
Examples of Hemoflagellates
Trypanosoma:
- T. cruzi- Chagas d/s/ American sleeping sickness
Vector: Reduvid bug/ Triatomine bug (nocturnal)
- T. brucei- African sleeping sickness. Vector: Tsetse fly
Leishmania: Vector- Sandfly
Life cycle of Trypanosoma cruzi
Trypomastigote enters human–> Amastigote –> Trypomastigote–> leaves human–> Enters insect–> Epimastigote–> leaves insect–> Trypomastigote–> cycle continues
‘TAT TET cycle’
Forms of Trypanosoma seen in T. brucei infection
Epimastigote in Insects
Trypomastigote in humans
Forms of Leishmania seen in infection
In humans and insect- both amastigote and promastigote seen
Kinetoplast includes
Blepharoplast and parabasal body
Post nuclear kinetoplast is seen in
Trypomastigote
Romana’s sign-
periorbital edema seen in A/c chagas d/s
C/c chagas disease features
MMM
Myocarditis
Megacolon
Megaesophagus
Chagas disease-
1. Sample
2. Culture
3. Treatment
- Blood/ buffy coat
- NNN
- Benznidazole
Types of African sleeping sickness
T. brucei gambiense-
- primary reservoir: Humans
- West African sleeping sickness
- Winterbottom sign- Lymphadenopathy +++
- Tx: Pentamidine
T. brucei rhodesiense-
- primary reservoir: animals
- East African sleeping sickness
- Tx: Suramine
- More aggresive
Parasites that cause myocarditis
TTTTE
Trypanosoma cruzi
Trypanosoma brucei rhodescience
Toxoplasma gondii
Trichinella spiralis
Echinococcus
Leishmania
1. Infective form
2. Diagnostic form
- Promastigote
- Amastigote/ LD bodies
LD bodies
Macrophages inside which amastigote forms are seen of Leishmania
Diagnosis of Leishmania
- Spleen sample to see LD bodies (most sensitive but difficult as it can cause bleeding)
BM (most pref) and blood taken
BAL (HIV- as liver/ spleen may not function) - Hypergammaglobulinemia- Napier’s aldehyde test, Chopra Antimony test (only theory)
- NNN media- promastigotes seen
- Rapid card test- RK39 antigen
- PCR- definitive
Treatment for Leishmania
Liposomal amphotericin B
What organisms can be grown on NNN media?
Trypanosoma cruzi
Leishmania
What is Post Kala Azar Dermal Leishmaniasis (PKDL)?
A condition that appears 1-2 years after treatment of visceral leishmaniasis (Kala Azar) with Liposomal Amphotericin B.
What are the characteristic skin lesions in PKDL?
Hypopigmented nodules on the skin.
What is the treatment for Post Kala Azar Dermal Leishmaniasis (PKDL)?
Oral Miltefosine.
What is another name for Leishmania tropica infection?
Oriental Sore / Delhi Boil / Aleppo Button.
What type of leishmaniasis is caused by Leishmania brasiliensis?
Mucocutaneous Leishmaniasis / Espundia.
Leishmaniasis Recidivans
AKA Relapsing Leishmaniasis
D/t inadeqate treatment
Nodular lesions or rash around central healing
Examples of coccidian parasites
Cryptosporidium
Isospora
Cyclospora
Sarcocystis
Toxoplasma gondii
What is the primary mode of transmission for Toxoplasma gondii?
Ingestion of oocysts from cat feces (contaminated food, water, soil)
Consumption of undercooked meat containing tissue cysts
Transplacental transmission (congenital toxoplasmosis)
Organ transplantation or blood transfusion (rare)
What is the classic triad of congenital toxoplasmosis?
Chorioretinitis (inflammation of retina and choroid)
Hydrocephalus (due to CSF obstruction)
Intracranial calcifications (diffuse)
(+ possible deafness and seizures)
What is the definitive host of Toxoplasma gondii? Intermediate hosts?
Cats (definitive host) – sexual reproduction of T. gondii occurs in the intestines of cats, leading to oocyst shedding.
Humans
What is the characteristic brain lesion seen in cerebral toxoplasmosis in AIDS patients?
Multiple ring-enhancing lesions on MRI/CT, primarily in the basal ganglia.
Gold standard test for Toxoplasmosis
Sabin Feldman test- using Methylene Blue
Colorless- AB present
Color present- Ab absent
IgG- IgM+–Acute
IgG+, IgM + – Acute
IgG+ – c/c
Treatment for Toxoplasmosis
Pyrimethamine + Sulfadiazine
Folinic acid is given to prevent Bone marrow suppresion
What are the two forms of Toxoplasma gondii in human infection?
Tachyzoites – Rapidly dividing, invasive form seen in acute infection
Via Blood transfusion
Bradyzoites – Slow-growing form within tissue cysts, responsible for latent infection. Via Undercooked meat
Sporulated oocyst- via contaminated soil/ food/ water
What stain is used to visualize Toxoplasma gondii tachyzoites?
A: Giemsa or Wright stain
What is the major distinguishing factor between CNS lymphoma and toxoplasmic encephalitis on brain imaging?
Thallium SPECT scan –
Toxoplasmosis → hypometabolic (cold lesion)
CNS lymphoma → hypermetabolic (hot lesion)
Diarrhoea in immunocompromised host
Cryptosporidium- 4 sporozoites
Cyclospora- 4 sporozoites
Isospora- 8 sporozoites
What is the incubation period for different Plasmodium species?
P. falciparum: 9-14 days
P. vivax/P. ovale: 12-18 days
P. malariae: 18-40 days
P. knowlesi: ~10-12 days
What is the fever cycle in different malaria types?
P. vivax/P. ovale: Tertian fever (every 48 hours)
P. falciparum: Irregular fever patterns (malignant tertian)
P. malariae: Quartan fever (every 72 hours)
P. knowlesi: Daily fever (quotidian fever)
Which Plasmodium species can cause relapses and why?
P. vivax and P. ovale due to hypnozoites in the liver.
What is the gold standard for malaria diagnosis?
Peripheral blood smear (thick and thin smears) with Giemsa stain.
What are the characteristic blood smear findings in malaria?
P. falciparum: Multiple rings per RBC, banana-shaped gametocytes
P. vivax: Schüffner’s dots, large RBCs
P. ovale: Schüffner’s dots, oval-shaped RBCs
P. malariae: Band forms in RBCs
P. knowlesi: Ring stages resemble P. falciparum
What rapid test can be used for malaria diagnosis?
Malaria antigen rapid diagnostic tests (RDTs) – detects Plasmodium LDH or HRP-2 antigen.
What is the first-line treatment for uncomplicated malaria?
P. falciparum: Artemisinin-based combination therapy (ACT) (e.g., Artemether-Lumefantrine)
P. vivax/P. ovale: Chloroquine + Primaquine (to kill hypnozoites)
P. malariae/P. knowlesi: Chloroquine
What is the treatment for severe falciparum malaria?
IV Artesunate (preferred) or IV Quinine followed by ACT.
What must be tested before giving primaquine?
G6PD deficiency – primaquine can cause hemolysis in G6PD-deficient patients.
Which Plasmodium species is associated with nephrotic syndrome?
Plasmodium malariae
What genetic traits provide resistance to malaria?
Sickle cell trait (HbAS) – protects against P. falciparum
G6PD deficiency – limits parasite survival
Duffy antigen negativity – protects against P. vivax infection
What is the vaccine for malaria?
RTS,S/AS01 (Mosquirix) – targets P. falciparum by inducing immunity against the circumsporozoite protein (CSP).
What is blackwater fever?
A severe complication of P. falciparum malaria, characterized by massive hemolysis, hemoglobinuria, and renal failure.
What is the primary site of Plasmodium replication in humans?
Liver (exoerythrocytic phase) and RBCs (erythrocytic phase).
What is the life cycle of Plasmodium in humans?
Sporozoites enter liver via mosquito bite.
Schizogony in liver cells forms merozoites.
Merozoites infect RBCs, forming trophozoites.
Trophozoites mature into schizonts → release more merozoites.
Some trophozoites form gametocytes → taken up by mosquito.
