Parasitology Flashcards
Compare 2 forms of protozoa
Trophozoite: motile
Cyst: non-motile, infectious
Diagnosis for intestinal protozoa
stool microscopy for cysts / trophozoites
Diagnosis of Entamoeba histolytica
Stool microscopy:
- trophozoite with ingestion of red cells (active)
- cysts / trophozoite without internalized red cells (carrier)
Blood: Serology
Liver abscess aspirate: PCR
Imaging
Treatment for Entamoeba histolytica
Paromomycin + Metronidazole / Tinidazole
Microscopy showing trophozoite with internalised red cells. Which pathogen?
Entamoeba histolytica
Intestinal protozoa with flagella, in falling leaf movement under microscope
Giardia lamblia
Which pathogen gives diarrhoea with greasy stool with horrific odour?
Giardia lamblia
Treatment for Giardia lamblia
Metronidazole / Tinidazole
Pathogen that gives chronic diarrhoea in uncontrolled AIDS patients
Cryptosporidium spp.
Diagnosis for Cryptosporidium spp.
Stool microscopy (with acid-fast stain)
Treatment for Cryptosporidium
Nitazoxanide
Pear-shaped trophozoite, no cyst stage
Trichomonas vaginalis
Protozoa with flagella, with jerking or twitching movement
Trichomonas vaginalis
Treatment for Trichomonas vaginalis
Metronidazole / Tinidazole
Plasmodium spp. with
(a) irregular fever
(b) tertian fever (how many hour interval?)
(c) quartan fever (how many hour interval?)
(d) non-human infection
(e) severe manifestations
(f) continual reproduction in liver
(a) P. falciparum
(b) P. vivax, P. ovale (48h)
(c) P. malariae (72h)
(d) P. knowlesi
(e) P. falciparum
(f) P. vivax, P. ovale
Life cycle of Plasmodium spp.
Sporozoites –> Schizont –> Merozoites –> Trophozoites
Ring form within red cells under microscope
Plasmodium spp.
Non-human host of Toxoplasma gondii
Cat
Triad for congenital infection of Toxoplasma gondii
chorioretinitis + hydrocephalus + intracranial calcification
Which pathogen is transmitted by kissing bug?
Trypanosoma cruzi
Pathogen for Chagas disease
Trypanosoma cruzi
Pathogen for African sleeping disease
Trypanosoma brucei
Pathogen for Kala-azar
Leishmania spp.
List of protozoa (4+1+3)
Intestinal
- Entamoeba histolytica
- Giardia lamblia
- Cryptosporidium
- Microsporidia
Vaginal
- Trichomonas vaginalis
Blood & tissue
- Plasmodium
- Toxoplasma gondii
- Trypanosoma cruzi
Classification of Helminths
(A) Flukes (Trematodes)
(B) Tapeworms (Cestodes)
(C) Roundworms (Nematodes)
A&B are flatforms (Platyhelminths)
Body parts of tapeworms (2)
scolex
proglottids
Schistosoma spp. (3)
(Which is MC in HK?)
S. mansoni 曼森
S. japonicum (MC)
S. haematobium
Pathogenesis of Schitosoma
habitat: fresh water
penetrate through skin –> invade venous system –> larvae & eggs stimulate immune system
eggs deposited in liver / bladder –> granulomatous reaction
Pathogen for swimmer’s itch, Katayama fever
Schistosoma
Diagnosis of Schistosoma infection (2)
Eggs in stool / urine
Rectal / renal biopsy
Treatment for Schistosoma
Praziquantel
MC parasite in HK
Clonorchis sinensis
Transmission of Clonorchis sinensis
raw, undercooked freshwater fish
Treatment for Clonorchis sinensis
Praziquantel, Albendazole
Diagnosis of Clonorchis sinensis
Eggs in stool, duodenal aspirate
Imaging showing flukes in bile ducts / gallbladder
Which pathogen is transmitted by ingestion of infected crustaceans?
Paragonimus westimani
Which parasite mimics TB?
Paragonimus westimani
(bloody sputum)
Diagnosis of Paragonimus westimani
eggs in stool / sputum
Treatment for Paragonimus westimani
Praziquantel
Which parasite is transmitted by ingestion of raw or undercooked pork? (How about beef?)
Taenia solium
(Taenia saginata)
Pathogen for cysticercosis
Taenia solium
Pathogenesis of cysticercosis
ingest eggs –> develop into larvae –> penetrate through intestine –> form cysticercus in organs
(in brain ==> neurocysticercosis)
Diagnosis of taeniasis and cysticercosis
[taeniasis] eggs & proglottids in stool
[cysticercosis]
- brain scan
- radiological survey of skeletal muscles
- serology
Treatment for taeniasis and cysticercosis
[taeniasis] Praziquantel
[cysticercosis] Albendazole, Praziquantel
Compare 2 Echinococcus spp.
Echinococcus granulosus: solitary cyst
Echinococcus multilocularis: multiple cysts
Pathogen for Hydatid disease
Echinococcus
Treatment for hydatid disease
PAIR: percutaneous aspiration, injection of chemicals, re-aspiration
Which parasites will migrate to alveoli and cause respiratory symptoms (e.g. cough)? (1+3)
Paragonimus westimani
Ascaris lumbricoides, Hookworms, Strongyloides stercoralis
Treatment for Ascaris lumbricoides (3)
Mebendazole, Albendazole, Pyrantel
Hookworms (2)
Ancylostoma duodenale
Necator americanus
Which parasite gives IDA (sucking blood) and intense itching and rash between the toes?
Hookworms
Pathogen for hyperinfection syndrome (what is it?)
Strongyloides stercoralis
(repeated autoinfection under immunosuppression)
Treatment for Strongyloides stercoralis
Ivermectin
Pathogen for perianal itching (Diagnosis (3))
Enterobius vermicularis
Dx:
1. Scrotch tape test [morning]
2. Observe for adult worms by naked eyes in perianal area [night]
3. eggs in nails
Treatment for Enterobius vermicularis
Mebendazole, Albendazole, Pyrantel
Which intestinal parasite tends to migrate to cecum & ascending colon and cause abdominal pain?
(Diagnosis and Treatment)
Trichuris trichiura
Dx: eggs in stool
Tx: Mebendazole, Albendazole
Which intestinal parasite migrates to skeletal muscles and causes muscular aches?
(Diagnosis (2) and Treatment)
Trichinella spiralis
Dx: encysted larvae in muscle biopsy, ↑ CPK
Tx: Mebendazole, Albendazole
Which intestinal parasite is transmitted by ingestion of undercooked marine fish?
Anisakis
Pathogens for elephantiasis (2) (what is it?)
Filariae
Chlamydia trachomatis serotype L1~L3
(lymphedema at lower legs & genitals, covered with thick, scaly skin)
Filariae (3)
Wuchereria bancrofti , Brugia malayi, Brugia timori
Diagnosis and treatment of filariae
Dx: microfilariae in blood smear
Tx: diethylcarbamazine
Pathogen for lizard skin and river blindness
Onchocerca volvulus
Diagnosis and treatment of Onchocerca volvulus
Dx: microfilariae in skin biopsies
Tx: Ivermectin
Pathogen for cutaneous larval migrans / creeping eruption (2)
Ancylostoma braziliensis, Ancylostoma caninum
Flukes (3)
Schistosoma
Clonorchis sinensis
Paragonimus westimani
Tapeworms (4)
Taenia solium
Taenia saginata
Echinococcus
Spirometra
Roundworms (7+4)
Intestinal
- Ascaris lumbricoides
- Hookworms
- Strongyloides stercoralis
- Enterobius vermicularis
- Trichuris trichiura
- Trichinella spiralis
- Anisakis
Blood & tissue
- Filariae
- Onchocerca volvulus
- Dirofilaria
- Ancylostoma
Ectoparasites (4)
Sarcoptes scabiei
Pediculus humanus
Phthirus pubis
Myiasis
Pathogen for burrows on skin (diagnosis)
Sarcoptes scabiei
Dx: skin scrape for mite, eggs
Management for scabies
Contact precautions
Scabicide: Permethrin, Benzylbenzoate, Lindane
Disinfection:
machine wash of clothing & bedding with hot water cycle 60°C
disinfest in a closed plastic bag for a week
Contact tracing: treat household contact
Treatment for body louse
Permethrin
Treatment for Phthirus pubis
Permethrin
